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~ ~ W J DETERMINATION OF RATES OF REACTION
IN THE GAS-PHASE IN THE TROPOSPHERE


# THEORY AND PRACTICE

5. Rate of Indirect Photoreaction: Evaluation of the Atmospheric Oxidation Computer Program of Syracuse Research Corporation for Estimating the Second-Order Rate Constant for the Reaction of an Organic Chemical

with Hydroxyl Radicals

1 by

Asa Leifer

U.S. ENVIRONMENTAL PROTECTION AGENCY OFFICE OF POLLUTION PREVENTION AND TOXICS

WASHINGTON, DC 20460~ -

i CONTENTS

Abstract

. . . . . . . . . . . . . . . . . . . . . . . . . xii
I. Introduction

. . . . . . . . . . . . . . . . . . 1


### II. Mathematical Synopsis of the Structure/Reactivity

~ 

### Relationships of Atkinson and Meylan ...... 3

III. Syracuse Research Corporation Atmospheric

Oxidation Computer Program (Developed by Meylan)

. . . . . . . . . . . . . . . . . . . . 14
III . A. Introduction

. . . . . . . . . . . . . . . . . . 14


### III.B. Atmospheric Oxidation Computer Program (AOP)

.. 15
IV. Evaluation of the Atmospheric Oxidation

Computer Program for Estimating kOH and the Experimentally Measured kO H Data Listed in the Program

. . . . . . . . . . . . . 29
IV.A. Comments on the Group Rate Constants,

Substituent Factors, and Other Parameters Used by the Atmospheric Oxidation Program

... 29
IV.B. Some Comments on Hydroxyl Radical Addition to

Heteroaromatic and Fused Polyaromatic Ring Systems

. . . . . . . . . . . . . . . . . . . . 46 

### IV.C. H-Atom Abstraction from C-H and -OH Groups by

Hydroxyl Radicals

. . . . . . . . . . . . . . . 52 

### IV.C.1. Saturated Alkanes

. . . . . . . . . . . . . . . 52 IV.C.l.a. Evaluation of the Experimental kOg Data

.... 52 IV.C.i.b. Evaluation of the Estimated k O H Data ...... 57
IV. C. 2. Haloalkanes

. . . . . . . . . . . . . . . . . . 59 

### IV.C.2.a. Evaluation of the Experimental kpH Data

.... 59 IV.C.2.b. Evaluation of the Estimated k O H Data ...... 62 IV.C.3. Carbonyl Compounds

. . . . . . . . . . . . . . . 62 IV.C.3.a. Evaluation of the Experimental kpH Data

.... 62 IV.C.3.b. Evaluation of the Estimated kOH Data ...... 68 ii

### IV.C.4. Alcohols, Glycols, Ethers, and Hydroperoxides

. 71

IV.C.4.a. Evaluation of the Experimental kOH Data

.... 71 IV.C.4.b. Evaluation of the Estimated kOH Data ...... 71 IV.C.5. Alkyl Nitrates and Nitriles

. . . . . . . . . . 79 IV.C.5.a. Evaluation of the Experimental kOH Data

.... 79 IV.C.5.b. Evaluation of the Estimated kpH Data ...... 82 IV

. 

### C. 6

. 

### Nitroalkanes

. . . . . . . . . . . . . . . . . . 

### 82 IV.C.6.a. Evaluation of the Experimental kOH Data

.... 82 IV.C.6.b. Evaluation of the Estimated kOH Data ...... 85 IV. C. 7

. 

### Alkyl Nitrites

. . . . . . . . . . . . . . . . . 

### 87 IV.C.7.a. Evaluation of the Experimental kpH Data

.... 87 IV.C.7.b. Evaluation of the Estimated kOH Data ...... 88 IV.D. Addition of Hydroxyl Radicals to Alkenes,

Conjugated Dialkenes, Alkynes, and 1, 2-Dialkenes

. . . . . . . . . . . . . . . . . 

### 89 IV.D.1. Unsubstituted Alkenes

. . . . . . . . . . . . . 89 IV.D.i.a. Evaluation of the Experimental k OH Data

.... 89 IV.D.l.b. Evaluation of the Estimated kp H Data ...... 93 IV.D.2. Substituted Alkenes

. . . . . . . . . . . . . . 94 IV.D.2.a. Evaluation of the Experimental k OH Data

.... 94 IV.D.2.b. Evaluation of the Estimated k OH Data ...... 97 IV.D.3. Conjugated Dienes

. . . . . . . . . . . . . . . 97 IV.D.3.a Evaluation of the Experimental k OH Data

.... 97 IV.D.3.b. Evaluation of the Estimated k OH Data.

..... 99 IV.D.4. Alkynes and 1,2-Dienes (Allenes)

. . . . . . . . 99 IV.D.4.a. Evaluation of the Experimental k OH Data

.... 99 IV.D.4.b. Evaluation of the Estimated k O 

### H Data

..... 99 t



### iii,

IV.E. Reaction of Hydroxyl Radicals with Organic Compounds Containing Sulfur, Nitrogen, and Phosphorous Functional Groups . . . . . . . . . 101
IV.E.1. Reaction with Thiols, Sulfides, and Disulfides . 101 IV.E.i.a. Evaluation of the Experimental k OH Data

.... 101 IV.E.i.b. Evaluation of the Estimated kpH Data

...... 104 IV.E.2. Reaction with Sulfoxides and Sulfates

..... 105 IV.E.2.a. Evaluation of the Experimental k O H Data

.... 105 IV.E.2.b. Evaluation of the Estimated kOH Data

..... 105 IV.E.3. Reaction with Alkyl Amines, Alkyl Hydrazines,

and N-Substituted Amines .

. . . . . . . . . . . 108 IV.E.3.a. Evaluaticn of the Experimental kpH Data

.... 108 IV.E.3.b. Evaluation of the Estimated kOH Data

...... 108 IV.E.4. Reaction with Compounds Containing Phosphorous

Functional Groups

. . . . . . . . . . . . . . . 110 IV.E.4.a. Evaluation of the Experimental kOH Data

.... 110 IV.E.4.b. Evaluation of the Estimated kOH Data

...... 110
IV.F. Reaction of Hydroxyl Radicals with Aromatic

Compounds, Heterocyclic Aromatic Compounds, and Fused Ring Polyaromatic Compounds

..... 113 IV.F.1. Aromatic Compounds

. . . . . . . . . . . . . . . 113 IV.F.i.a. Evaluation of the Experimental kpH Data

.... 113 IV.F.i.b. Evaluation of the Estimated Data

........ 119 IV.F.2. Heterocyclic Aromatic Compounds

. . . . . . . . 120 IV.F.2.a. Evaluation of the Experimental kOH Data

.... 120 IV.F.2.b. Evaluation of the Estimated kOH Data

...... 122 IV.F.3. Fused Ring Polyaromatic Compounds

....... 123 IV.F.3.a. Evaluation of the Experimental kOH Data

.... 123 IV.F.3.b. Evaluation of the Estimated kOH Data

...... 123

ivIV.G. Evaluation of the Estimated Half-Life for the Reaction of Hydroxyl Radicals with Organic Chemicals in the Troposphere ...... 125
V. References . . . . . . . . . . . . . . . . . . . 127

vi

LIST OF TABLES

Table 1. Group Rate Constants for Hydrogen Abstraction



### and Radical Reaction .

. . . . . . . . . . . . 30 Table 2. Substituent F(X) Factors for Hydrogen

Abstraction

. . . . . . . . . . . . . . . . . 31 

### Table 3. Factors Used for Aliphatic Ring Strain

Ef f ects

. . . . . . . . . . . . . . . . . . . 33 

### Table 4. Group Rate Constants for OH Radical Addition

to Isolated Olefinic Units .

. . . . . . . . . 34 Table 5. Group Rate Constants for OH Radical Addition

to Conjugated Olefinic Units .

. . . . . . . . 35 Table 6. Group Rate Constants for OH Radical Addition

to Alkyne Units

. . . . . . . . . . . . . . . 37 

### Table 7. Group Rate Constants for OH Radical Addition

to 1,2-Dialkene (Allene) Units .

. . . . . . . 38 Table 8. Substituent Factors CC(X)] for OH Radical

Addition to Olefins and Acetylenes ...... 39 Table 9. Electrophilic Substituent Factors for OH

Radical Addition to Aromatic Rings ...... 40 Table 10. Experimental Values of Ai for Some

Monocyclic Heteroaromatic Compounds

. . . . . 47 Table 11. Experimental Values of Bi for Some

Polynuclear Aromatic Compounds

. . . . . . . 48 Table 12. Values of Bi for Polynuclear Aromatic

Hydrocarbon Structures Derived from Experimentally Measured Ionization Potentials

. . . . . . . . . . . . . . . . . . 49 

### Table 13. Values of Bi for Polynuclear Heteroaromatic

Structures Derived from Experimentally Measured Ionization Potentials

. . . . . . . . . . . . 50 Table 14.A. Comparison of the Estimated Values of

k 

### ~ H at 298 K for Saturated Acyclic A kanes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data Reported in AOP . . . . . . . . . . . . . . . 53



### vi

### Table 14.B. Comparison of the Estimated Values of kOH at 298 K for Saturated Cyclic Alkanes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data Reported in AOP . . . . . . . . . . . . . . . . 55 Table 15. Comparison of the Estimated Values of

kOH at 298 K for Haloalkanes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental k OH Data in AOP . . . . . . . . . . . . . . . . 60 Table 16. Comparison of the Estimated Values of

kOH at 298 K for Carbonyl Compounds from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOg Data in AOP . . . . . . . . . . . . . . . . . . . . . . 63 Table 17. Comparison of the Estimated Values of

k OH at 298 K for Alcohols, Glycols, Ethers, and Hydroperoxides from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental k OH Data Reported in the Literature Versus the Experimental k OH Data in AOP . . . . . . . . . 72 Table 18. Comparison of the Estimated Values of

kpH at 298 K for Alkyl Nitrates and Alkyl Nitriles from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP . . . . . . . . . . . . . . . . 80 Table 19. Comparison of the Estimated Values of

koH at 298 K for Nitroalkanes and Alkyl Nitrites from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experiment kOH Data in AOP . . . . . . . . . . . . . . . . . . 83 

# _

vii. q



### Table 20. Comparison of the Estimated Values of kOH at 298 K for Unsubstituted Alkenes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP. . . . . . . . . . . . . . . . . . . . . . 90 Table 21. Comparison of the Estimated Values of

k0H at 298 K for Substituted Alkenes from the Atmospheric Oxidation Computer Program (AOP) 

### and From a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP . . . . . . . . . . . . . . . . . . . . . . 

### 95 Table 22. Comparison of the Estimated Values of

kOH at 298 K for Conjugated Acyclic 

### and Cyclic Dialkenes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP . . . . . . . . . . . . . . . . . . 98 Table 23. Comparison of the Estimated Values of

kQH at 298 K for Alkynes and 1,2- Dialkenes (Allenes) from the Atmospheric Oxidation Computer Program (AOP) 

### and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP. . . . . . . . . . 100 Table 24. Comparison of the Estimated Values of

kOH at 298 K for Alkyl Thiols, Sulfides, and Disulfides from the Atmospheric Oxidation Computer Program (AOP) 

### and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP . . . . . . . . . 102



### viiif



### Table 25. Comparison of Estimated Values of kOH

at 298 K for Alkyl Sulfoxides and Sulfates from the Atmospheric oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental k OH Data Reported in the Literature Versus the Experimental kOg Data in AOP . . . . . . . . . . . . . . . . . . . . . . 106 Table 26. Comparison of the Estimated Values of

k0H at 298 K for Alkyl Amines, Hydrazines, and N-Substituted Amines from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kO H Data Reported in the Literature Versus the Experimental k OH Data in AOP. . . . . . . . . . . . . . . . . . . . . . 109 Table 27. Comparison of the Estimated Values of

kOH at 298 K for Aliphatic Compounds Containing Phosphorous Functional Groups from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP. . . . . . . . . . . . . . . . . . . . . . 111 Table 28. Comparison of the Estimated Values of

kOH at 298 K for Aromatic Compounds from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP. . . . . . . . . . . . . . . . . . . . . 114 Table 29. Comparison of the Estimated Values of

kOH at 298 K for Heterocyclic Aromatic Compounds from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental k O H Data in AOP . . . . . . . . . . . . . . . . . . . . . . 121

ixi



### Table 30. Comparison of the Estimated Values of k0H at 298 K for Fused Ring Polyaromatic Compounds (PAH) from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP . . . . . . . . . . . . . . . . . . 124

x

### LIST OF FIGURES

Figure 1. Atmospheric Oxidation Program Data

Entry Display

. . . . . . . . . . . . . . . . . 16 Figure 2. Atmospheric Oxidation Program Data Display

for the Compound ac-Methyl Styrene (2-Phenyl

### 1-Propene): Summary Hydroxyl Radical Data and Experimental Data. A. Screen Display when Key PgDn is pressed. .. 18 B. Screen Display when Key F-10 is pressed. .. 19 Figure 3. Atmospheric Oxidation Program Data Display

for the Compound ac-Methyl Styrene (2-Phenyl1-Propene): Summary Hydroxyl Radical and Ozone Data. A. Screen Display when Key PgDn is pressed. .. 22 B. Screen Display when Key F-10 is pressed. .. 23 Figure 4. Atmospheric Oxidation Program Data Display

for the Compound a-Methyl Styrene (2-Phenyl1-Propene): A. Screen Display of the Detailed Calculations for Hydrogen Abstraction. . . . .

. . . 24 B. Screen Display of the Detailed Calculations for OH Radical Addition to the Olef inic Bond

. . . . . . . . . . . . . 

### . . . . . . . 25 Figure 5. Atmospheric Oxidation Program Data Display

for the Compound a-Methyl Styrene (2-Phenyl1-Propene): A. Screen Display of the Detailed Calculations with 0 3 Reaction with the Olefinic Bond.

. . .. . . . . . . . . . 26 B. Screen Display of the Detailed Calculations of OH Radical Addition to the Aromatic Ring . . . . . . . . . . . . . . . . 27 Figure 6. Atmospheric Oxidation Program Data Display

for the Compound a-Methyl Styrene (2-Phenyl1-Propene): Screen Display for OH Addition to the Aromatic Ring and the Experimental Data. .... 28 :



### xia



### Abstract

Atkinson (of the University of California at Riverside), in support of the research programs of the Exposure Assessment Branch, Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency, developed structure/reactivity relationships (S/R) for estimating the second-order rate constant for the reaction of hydroxyl radicals with organic chemicals in the gas-phase in the troposphere (kOH). Meylan, of Syracuse Research Corporation, computerized these S/R relationships and, in addition, developed S/R relationships for a few other classes of organic chemicals. This computer program is called the Atmospheric Oxidation Program (AOP) 1 . Furthermore, at the request of Leifer, Meylan incorporated a data base of the experimental values of kOg for a large number of organic chemicals in AOP I

. 

### This computer program is operated by inserting in it the SMILES notation for a given molecular structure. This SMILES notation is a machine-readable code for the molecular structure of an organic chemical. AOP then estimates kOH, lists an experimental value (if available from the scientific literature),

t 

### This computer program also contains S/R relationships of Atkinson for estimating the second-order rate constant for the reaction of organic chemicals with ozone (k 0) in the gasphase in the troposphere. This report, howe4er, will only review the hydroxyl radical portion of this computer program.

2 

### AOP also lists the experimental values of k0 3 , if available; and also lists the experimental values of kN 0 for the reaction of an organic chemical with nitrate radicals NO3), 

### if available.

xii:



### gives a detailed description of the calculations, and estimates the half-life in the troposphere for this chemical. This computer program was thoroughly evaluated by comparing the estimated and experimental values of kO H from AOP with the hand calculated and experimental values of Leifer for 454 organic compounds covering a wide variety of classes of compounds. These k oH data are listed in Tables 14-30. When comparing the estimated values of k O H by AOP and those by Leifer in a hand calculation (HC), a few comments can be made about the number of significant figures used. In general, the summary table in AOP lists k(i) and kOH (the rate constant corresponding to each individual reaction pathway i and the total hydroxyl radical rate constant kOH, respectively) with up to a maximum of six significant figures. However, the group rate constants (e.g., kP, ks, kt, ko s , k 

# o o

, k (>N-), k(-SH), etc.) and the substituent factors F(i) and C(i) [e.g., F(-CH 2 -), F(-C1), F(>N-H), F(for strained rings containing n atoms), C(-F), C(=0), C(-CnN), etc.] are known, at best, to three significant figures and, in general, to two significant figures. Therefore, it is recommended that AOP show the detailed calculations to four significant figures and list k(la), k(ic), k(>N-), kadd,nar, kadd,ar, etc. and kOH in the summary table with three significant figures. In general, after evaluating all 454 chemicals covering a wide range of chemical classes, it was found that there was excellent agreement between the estimated values of kOH and HC.

xiii, 

### Furthermore, the S/R relationships of Meylan for fused ring

polyaromatic hydrocarbons are superior to those of Atkinson. In addition, Meylan's S/R relationships have been expanded to cover heterocyclic aromatic compounds such as the thiazoles, oxazoles, pyridines, furans, etc. whereas Atkinson does not have corresponding S/R relationships. However, it must be emphasized that considerably more experimental k O H data are needed for a number of substituted heterocyclic and fused ring polynuclear aromatic hydrocarbons to verify the S/R relationships of Meylan. There are, however, some differences between the estimated values of kOH from AOP and HC for a few classes of compounds which will be described in the following paragraphs. For the alkyl sulfides (both acyclic and cyclic), a comparison of the estimated values of kOH from AOP and HC indicates that kOH is larger from AOP. The reason for this discrepancy is that kOH was measured in the absence of oxygen and from Atkinson's S/R relationships, k(-S-) = 0 so that only H-atom abstraction is observed. However, AOP estimates kOH by assuming that k(-S-) = 2.0 and not 0. Hence, when estimating k OH for these compounds it is necessary to specify whether the estimation is made under the boundary condition of the presence or absence of oxygen. Therefore, it is recommended that AOP should be modified to take into account this boundary condition.For the aromatic compounds 3,5-dimethyl phenol, N,Ndimethylaniline, and 2,4-toluenediamine, AOP lists the maximum value for OH addition to an aromatic ring as 200 x 10 -12

xivi

s
s



### cm 3 molecule

- is -1 [i.e., k(7) = kadd,ar] Wherea.s HC lists a maximum value k OH of 200 x 10 -12 cm 3 molecule -I S" 1 . Since the maximum allowed collision rate is 200 x 10 -12 cm 3 molecule

- is -1 [Atkinson (1987)], this boundary condition must be invoked on the estimation of k O H and not on k(7)[=kadd,arl• Furthermore, by using this boundary condition, the estimated values of k OH for the above mentioned aromatic compounds are much closer to the experimental values [See Table 28 of this report and Leifer (1992a)]. It should be noted that this comment is only applicable to aromatic compounds and not to all compounds. For the compounds tetralin, indan, fluorene, and 2,3-dihydrobenzofuran, AOP makes a slight error in estimating the rate constant for the addition of OH radicals to the aromatic ring [i.e., k(7) = kadd,ar]• For these compounds, AOP uses the incorrect value of vm(-CH2-) = 0.06 ** instead of the correct value of 0.064 **. Furthermore, the compounds tetralin, indan, and fluorene contain five membered strained rings. In calculating k(ic) for these compounds, AOP makes an error by omitting the ring strain factor F(5) = 0.80. Thus, k(ic) and kOH

are erroneous. Atkinson did not develop S/R relationships for alkyl carboxylic acids, peroxides, sulfoxides, and sulfates because of the very limited availability of experimental kO H data. Meylan did develop S/R relationships for these classes of compounds; however, for a few reasons, these S/R relationships are not valid. For the alkyl carboxylic acids and hydroperoxides,

xvi

a 

### Meylan made an erroneous assumption about the mechanism of OH

reaction for these compounds. For example, for the S/R relationships of the alkyl carboxylic acids, Meylan assumed that OH radicals can react with these compounds by H-atom abstraction from the hydroxyl group in the carboxylic acid group {C(=0)OH, [k(2))} and from the C-H groups in the alkyl group [k(la)] and that the dominant reaction pathway was H-atom abstraction from the alkyl group. As a result, Meylan assumed that k(-OH) = 0.036, the same value as assigned to H-atom abstraction from the hydroxyl group in alcohols and glycols. However, based on the analysis of the experimental data of Wine et al. (1986) and Singleton et al. (1986), Atkinson (1989) and Leifer concluded that the major reaction pathway was H-atom abstraction from the hydroxyl group and k(-OH) > k(la). Therefore, it is recommended that the S/R relationships for the alkyl carboxylic acids and hydroperoxides be deleted from AOP. More experimental k OH data are needed for additional alkyl carboxylic acids and hydroperoxides to develop reliable S/R relationships. For the alkyl sulfoxides, Meylan developed S/R relationships by assuming that only C-H abstraction from the alkyl groups occurred. However, intuitively, it is expected that the sulfoxide group would undergo further oxidation to the sulfone. Therefore, considerably more experimental kOH data are needed for additional sulfoxides before reliable mechanisms and S/R relations are developed; and these S/R relationships should be deleted from AOP.

xvi:

~



### Based on the very limited data of the alkyl sulfates (onlydimethyl and diethyl sulfate), Meylan developed S/R relationships for this class of compounds. Comparison of the estimated kpg data with the experimental kOH indicated that dimethyl sulfate gave an error of >+250$ and diethyl sulfate gave an error of +540$. These results are very poor so that it is recommended that these S/R relationships be deleted from AOP until considerably more experimental kOH data is available for additional sulfates to develop reliable S/R relationships. Meylan, in AOP, used the S/R relationships of Atkinson for the nitroalkanes based on the available experimental k OH data for these compounds. However, it must be emphasized that some of the experimental data is suspect because nitroalkanes are very labile to direct photolysis and it is not clear whether photolysis occurred under the experimental conditions of the relative rate study of Nielson et al. (1988) or whether photolysis was taken into account. Therefore, it is recommendedthat AOP delete these S/R relationships. More reliable experimental kOH data are needed for these nitroalkanes under carefully controlled experimental conditions to eliminate, or account for, direct photolysis in order to develop more reliable S/R relationships. Comparison of the experimental values of kpH from AOP and Leifer for 454 chemicals indicates that, in general, the agreement is excellent. There are, however, a few differences. The primary difference is related to the number of significant 4

f



### xvii".. 

## ®
figures used in AOP. For example, for 2-methylpentane, AOP

lists an experimental value of 5.60 while Atkinson (1989) and Leifer (1992a) list a recommended value of 5.6; for 2,3- dimethyl-2-butene, AOP lists a value of 110.0 while therecommended value by Atkinson and Leifer is 110; for dimethylhydroxylamine, AOP lists a value of 90.0 while Atkinson and Leifer recommend a value of 90; for p-cresol, AOP lists a value of 47.0 while Atkinson and Leifer recommend a value of 47; for 4-chlorobiphenyl, AOP lists a value of 3.9 while Atkinson and Leifer list a value of 3.86. For other chemicals with differences, Leifer lists an average value from the literature while AOP selects one set. For example, for ns-1,4-hexadiene, Leifer lists an average value of 90.6 from two sets of experimental data while AOP selects only one value, namely 90.3; for 2,3-dimethyl-2-pentene, AOP selects one value which is 108.0 while Leifer cites an average value of 103 based on both sets of experimental data. Unless there is good reason for discarding specific sets of experimental kOH data, it is better to use an average value from both sets. For 12 chemicals, AOP does not list experimental values: for example, four ketenes; 0 3 -carene; g&Q 

### -butyl acetate; and 2- (chloromethyl)-3-chloro-i-propene. Differences were observed for a few compounds: e.g., for methane, AOP lists a value of 0.00841 while Atkinson 

### and Leifer list a recommended value of 0.00836; for 2-octanone, AOP lists a value of 10.0 while

xviii

# _ ~

Atkinson and Leifer list a value of 11.0; for 1,1,1-trifluoroethane, AOP lists a value of 0.017 while Atkinson and Leifer list a value of 0.0017.

xix•`-

~


### I. Introduction

Numerous chemicals, both natural and anthropogenic, are emitted to the troposphere from a variety of sources and may be removed by wet or dry deposition or by three important transformation processes. These three transformation processes

are:
(1) direct photoreaction which involves the absorption of

sunlight followed by transformation;
(2) indirect photoreaction which involves the reaction of a chemical with hydroxyl radicals (OH); and

(3) oxidation which involves the reaction of a chemical with ozone (03).
There is another indirect photoreaction process which involves the reaction of a chemical with nitrate radicals (NO 3 ) during the night. However, this transformation process only occurs for a few types of chemicals (e.g., olefins, phenols, and cresols); hence, it will not be considered when determining the rate of transformation in the troposphere. A quantitative measure of the three important transformation processes is given by the rate constants kdE, kOH, and k0 3 . The rate constant kdE represents the first-order rate constant for direct photoreaction, while k O g and k 0 3 

### represent second-order rate constants for indirect photoreaction and oxidation with OH and 0 3 , respectively.
-1-a

t



### The first report in a series titled "DETERMINATION OF RATES
OF REACTION IN THE GAS-PHASE IN THE TROPOSPHERE. THEORY AND PRACTICE" describes a hierarchal test scheme for determining the rate constants kdE , kOH, and k 03 and the half-lives [t(1/2)E] for each transformation process and the net half-life in the troposphere [Leifer (1989a)]. The second report describes a screening-level test guideline for determining the maximum rate of direct photoreaction [kdE]max and the minimum half-life [t(1/2)E]min by the use of Ultraviolet-Visible Absorption Spectroscopy [Leifer (1989b)]. The third and fourth reports in this series describe structure/reactivity (S/R) relationships for estimating k Og for the reaction of an organic chemical with hydroxyl radicals in the gas-phase in the troposphere. These methods were developed by Atkinson (1986, 1986a, 1987, 1987a, 1988) for the Exposure Assessment Branch of the Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency. Report No. 4 [Leifer (1992b)] represents a test guideline [§796.3900] for use in sections 4 and 5 of the Toxic Substances Control Act; report No. 3[Leifer (1992a)] represents the technical support document for this test guideline. Since these S/R relationships are excellent [Leifer (1992a)], they have been computerized by Syracuse Research Corporation [Meylan (1990a, 1990b)]. At the suggestion of Leifer, Syracuse incorporated a data base in this computer program which lists the experimental values of k O g as reported : a



### -2-s

r ` 

### in the literature [Meylan (1990b)]. This document, describes an

assessment of this computer program for estimating kOg and represents report No.5 in this series.
II. Mathematical Synopsis of the Structure/Reactivity Relationships of Atkinson and Meylan Atkinson (1986, 1986a, 1987, 1987b, 1988, 1988a) critically analyaed the hydroxyl radical rate data (kOH) for a large number of organic chemicals and developed a number of S/R relationships based solely on the molecular structure of these .chemicals. In developing these S/R relationships, he assumed that a number of OH radical reaction pathways exist and the various OH radical reaction pathways could be separated and treated individually. Therefore, he calculated rate constants for each of these reaction pathways. The reaction pathways and rate constants for each of these pathways were:

rs unsaturated -atom abstraction from acyclic k(1) = k aturated, cyclic saturated, and C-H groups by OH radicals
CH-atom abstraction from 0-H groups 

### ~ k(2) = k by OH radicals (2)

r 

### ~ >, C=C-O 

### H radical addition to >C=C<, k(3) = k C=C-C=C<, -C 

# N C-, and >C=C=C<, (3)

groups

k(4) = k r_S-,

H radical interaction with -SH, (4) and -S-S- groups
OH radical interaction with -NH2, k(5) = k 

# I >NH, and >N- groups (5)
-3-s

~



# ~ hosphorus H radical interaction with k(6) = k groups , (6)

k(7) = k[OH radical addition to aromatic rings] (7) 

# L

P OH radical addition to fused ring k(8) = k olyaromatic compounds (i.e., (8)

olyaromatic hydrocarbons)
Atkinson postulated that the overall OH radical rate constant kOH is equal to the sum of the rate constants for each of these reaction pathways. Therefore, the OH radical rate constant is given by the equation

8



# k a , _ ~ 

# ' k ( i )

( 9 )



### and the individual rate constants [k(1), k(2), •••••, k(8)] and kOH are all in the units cm 3 molecule

- is -1 . Structure/ reactivity relationships will be described for each of these reaction pathways.
Path av 1: H-atom abstraction from acyclic and cyclic

saturated and unsaturated C-H groups by OH radicals The overall rate constant for reaction pathway 1 is given by the equation

k(1) = k(la) + k(lc) + k(1, UNS CH) (10)
where k(la) represents the rate constant for H-atom abstraction from all acyclic saturated C-H groups by OH radicals at 298 K; :

~

-4-E_♦

a_ 

### k(lc) represents the rate constant for H-atom abstraction from

all cyclic saturated C-H groups by OH radicals at 298 K; and k(1, UNS CH) represents the rate constant for H-atom abstraction from all unsaturated C-H groups (e.g.,=C-H) by OH radicals at
298 K. The rate constant k(la) is given by the mathematical relationship
k(1a)= r

) kpFi (X) +,) ksF j(X ) F j(Y) iZ ~ (11)

± ~ r i k t F m (X)F m (Y)F m (Z)

k(ic)_ (,

~ ) ksF ~ (X)F ~ (Y) + m ~ ktF m (X)F m (Y)F m (Z)1 F(n) (12)



### k(1, UNS CH) = 0 (13)
where kP, ks, kt represent the group rate constants for primary (CH3-), secondary (>CH2), and tertiary (>CH-) groups, respectively, and the values for these parameters at 298 K are listed in Table 1 of an EPA report by Leifer (1992a), in Table 1 of a report by Meylan (1990b) 3 , and in Table 1, Section IV, of this report; r , 

## ~ , ~ , X , , represent the m c) 

### summation over all primary acyclic, secondary acyclic, tertiary acyclic, secondary and tertiary cyclic groups, respectively, in

3 Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1, 1990.

-5-

### the molecule; F(X), F(Y), F(Z) represent the substituent factors

for substituents X, Y, and Z and the values for various substituents at 298 K are listed in Table 2 of an EPA report by Leifer (1992a), in Table 6 of a report by Meylan (1990b) 3 , and in Table 2, Section IV, of this report; F(n) represents the ring strain factor for saturated and unsaturated rings and heterocyclic rings containing n(3,4,5) atoms at 298 K and the values are listed in Table 2 of an EPA report by Leifer (1992a), in Table 10 of a report by Meylan (1990b) 3

, 

### and in Table 3, Section IV, of this report. For rings with n(6,7,8, etc.), with essentially no ring strain, F(n) = 1.0 at 298 K.
Pathway 2: H-Atom abstraction from -O-H groups in alcohols and glycols by OH radicals The overall rate constant for reaction pathway 2 is given by the equation

k(2) = n(-O-H) k(-OH) (14)
where n(-O-H) represents the number of hydroxyl groups (-O-H) inthe molecule; k(-OH) represents the group rate constant for Hatom abstraction from the hydroxyl group in alcohols and glycols and is equal to 0.036 x 10 -12 cm 3 molecule

- ls -1 at 298 K[Table 1 of an EPA report by Leifer (1992a), in Table 1 of a report by Meylan (1990b) 3 , and in Table 1, Section IV, of this report). r

:



## mce

w

s

~ Pathwav 3 

### : OH radical addition to isolated alkene groups (>C=C<), nonaromatic conjugated groups (>C=C-C=C<), and other unsaturated groups (-CNC-, >C=C=C<, >C=C=O) 

### The overall rate constant for reaction pathway 3 is given by the equation

k(3) = kadd,nar

= rk o sCi (X) Ci (Y) + 

# E ka o Cj (X) Cj (Y) + T 

### (15) + ~ k ou Cm(X)Cm(Y)■ 

### where kos, k o o, kau represent the group rate constants for OH radical addition (add) to isolated (is) carbon-carbon double bonds, nonaromatic (nar) conjugated (co) carbon-carbon bond systems, and other unsaturated (ou) carbon-carbon systems, respectively, and the values of these group rate constants at 298 K are given in Tables 9, 11, and 12, respectively, of an EPA report by Leifer (1992a), in Tables 2, 5, (3 and 4), respectively, of a report by Meylan (1990b) 3 , and in Tables 4, 5, (6 and 7), respectively, Section IV, of this report; F, F,

, J 

### represent the summation over all isolated carbon-carbon■ 

### double bond systems, nonaromatic conjugated carbon-carbon double bond systems, and other unsaturated carbon-carbon groups, respectively, in the molecule; C(X) and C(Y) represent the substituent factors at 298 K for substituents X and Y and are listed in Table 10 of an EPA report by Leifer (1992a), in Table

-7-

### 7 of a report by Meylan (1990b) 3 , and in Table 8, Section IV, of

this report.
Pathway 4: OH radical interaction with -SH, -S-, and -S-Sgroups The overall rate constant for reaction pathway 4 is given by the equation
k(4) = n(-SH)k(-SH) + n(-S-)k(-S-) + n(-S-S-)k(-S-S-) (16)
where n(-SH), n(-S-), and n(-S-S-) represent the number of -SH, -S-, and -S-S- groups, respectively, in the molecule; k(-SH), k(-S-), k(-S-S-) represent the group rate constants for OH radical interaction with the -SH, -S-, and -S-S- groups, respectively, and the values of these group rate constants at 298 K are listed in Table 1 of an EPA report by Leifer (1992a), in Table 1 of a report by Meylan (1990b) 3 , and in Table 1, Section IV, of this report.


### Pathway 5 : OH radical interaction with -NH2, >NH, and >Ngroups The overall rate constant for reaction pathway 5 is given by the equation
k(5) = n(-NH2)k(-NH2) + n(>NH)k(>NH) + n(>N-)k(>N-) (17)
where n(-NH2), n(>NH), n(>N-) represent the number of -NH2, >NH, and >N- groups, respectively, in the molecule; k(-NH2), k(>NH), k(>N-) represent the group rate constants for -NH2, >NH, and >N-, respectively, and the values of these group rate constants 

# _

x

_

~

-8-c

~

~ at 298 K are listed in Table 1 of an EPA report by Leifer

(1992a), in Table 1 of a report by Meylan (1990b) 3 , and in Table 1, Section.IV, of this report.


### $athway 6: OH radical interaction with phosphorous groups The overall rate constant for reaction pathway 6 is given by the equation

k(6) = n[>P(S)-]k[>P(S)-] + n[>P(0)-]k[>P(0)-] (18)

+ n[>P(C1)<] k[>P(C1)<]
where n[>P(S)-], n[>P(0)], n[>P(C1)<] represent the number of >P(S)-, >P(0)-, and >P(C1)< groups, respectively, in the molecule; k[>P(S)-], k[>P(0)-], k[>P(C1)<] represent the group rate constants for OH radical interaction with the >P(S)-, >P(0)-, and >P(C1)< groups, respectively, and the values of these group rate constants at 298 K are listed in Table 1 of an EPA report by Leifer (1992a), in Table 1 of a report by Meylan (1990b) 3 , and in Table 1, Section IV, of this report.


### Pathway 7 : OH radical addition to aromatic rings 

### The overall rate constant k(7)[=kadd,ar] for reaction pathway 7 is given by the equation

k(7) = k(7A) + k(7B) (19)


### where k(7A) corresponds to the addition of OH radicals to an aromatic ring (ar) and k(7B) corresponds to OH reaction with an heteroaromatic (monocyclic) ring (ar').

~ 

## s3

~



### For reaction of OH radicals with an aromatic ring

k(7A) = k add,ar (20)

1 og10k'add,ar - 

## ~ ( 0.31 - 1.35 Min ( ,Eol 

## ~ (21)



### kadd,ar

- 10

- 12 

### kadd,ar (22)



### where 

## ~ represents the summation over all aromatic rings in the molecule; (EQl ) represents the summation of the electrophilic substituent constants of Brown and Okamoto (1958) with respect to a given ring position (i.e., ortho, meta, para); and Min(Q 

## ~ F ) ol ) represents the summation of the electrophilic substituent constants with respect to the ring hydrogen position that gives the most negative summation value (i.e., Min ). Electrophilic substituent constants (Qm and Qp) for a number of substituents are given in Table 22 of an EPA report by Leifer (1992a), in Table 8 of a report by Meylan (1990b) 3 , and in Table 9, Section IV, of this report. Atkinson did not develop S/R relationships for OH radical addition to a heteroaromatic ring (monocyclic) while Meylan (1990b) 4 did develop S/R relationships. For OH radical addition to the heteroaromatic ring (arl), AOP uses the equation

4 

### User's Guide for the Atmospheric Oxidation Program, Version 1.10, November 1, 1990. s

-10-

### k(7B) = kadd,ar' (23)

1 

### og10kadd,ar' _ 

# ~ tAi - 1.35 Min ( Eat ) 

# ~ (24) e
<

s



### where 

# ~ represents the

~ 

### Ai is a function of the basic, or parent, heteri

cm 3 molecule

- ls -1 [Table page 7 of a document by summation over all heteroaromatic rings, experimental value of kadd,ar' of the Daromatic ring in the units 10 -12 10, Section IV, of this report and on Meylan (1990b) 4 ]; and the other parameters have been described previously. The use of equations 23 and 24 will be discussed in more detail in Section IV.B.
Pathway 8: OH radical addition to fused ring polyaromatic

compounds
The overall rate constant k(8) for reaction pathway 8 is given by the equation

k(8) = k(8A) + k(8B) (25)


### where k(8A) corresponds to the addition of OH radicals to a polynuclear aromatic hydrocarbon ring (PAH) and k(8B) corresponds to the OH radical addition of OH radicals to a polynuclear heteroaromatic ring (PAH'). For OH addition to the polyaromatic hydrocarbon ring k(8A) = kadd,PAH (26)

1 

### og10k add,PAH = F,110.11 - 1.08 (IP)i - 1.35 Min( EQt ) 

# ~ (27)

-11-

# _ t

kadd,PAH = 10-12k'add,PAH (28)



### where represents the summation of all PAHs, (IP)i represents

~ - 

### the ionization potential of the parent PAH in electron volts (eV) obtained from Weast (1976-1977); ( ~ `Q 

# l ) is derived for the

4~ • 

### monocyclic substituted portion of the molecule to allow for the effects of substituent groups on the reactivity and represents the summation of the electrophilic substituent constants of Brown and Okamoto (1958) with respect to a given ring position (i.e., ortho, meta, para); and Min( ~Q~ ) represents the summation of

~ 

### the electrophilic substituent constants with respect to the ring hydrogen position that gives the most negative summation (i.e., Min ). Electrophilic substituent constants (Qm and QP) for a number of substituents are given in Table 22 of an EPA report by Leifer (1992a), in Table 8 of a report by Meylan (1990b) 3 , and in Table 9, Section IV, of this report. For OH radical addition to fused polynuclear aromatic hydrocarbon rings, Meylan (1990b) 3 , developed a different approach to estimate kadd,PAH• Meylan, in AOP, uses the equation

1 

### og10kadd,PAH a 

## ~ lBi - 1.35 del 

## ~ (29)

where 

## ~ represents the summation over all fused polynuclear

~ 

### aromatic hydrocarbon rings, Bi is a function of the experimental value of kadd,pAH of the basic, or parent, polynuclear hydrocarbon aromatic ring in the units 10 -12 cm 3 molecule

- is -1

-12-L

t

L 

### [Table il, Section IV, of this report and from Meylan (1990b) 4

for naphthalene, anthracene, and phenanthrene] or is given an assigned value based primarily on the experimental ionization potential of the basic, or parent, polynuclear aromatic hydrocarbon ring in the units 10 -12 cm 3 molecule

- ls -1 [Table 12, Section IV, of this report and from Meylan (1990b) 4 ] for 4, 5, and 6 fused benzene rings. The term det is related to the substituent factors cm and cP for various substituents and is determined in the following way. For monosubstituted PAH compounds, de# corresponds to the most negative value of Qm or aP for a given substituent on the ring. For polysubstituted PAH compounds, de 

## ~ corresponds to the sum of the average values of vm and cp for each substituent on both rings. For OH radical addition to polynuclear heteroaromatic rings (PAHI), Meylan (1990b) 4 uses a modified form of equation 29 which is

1 

### og10kadd,PAH' 

### - Ir IB! - 1.35 det 1 (30)

where Bi is now related to the experimental ionization potential of the basic, or parent, fused polynuclear heteroaromatic ring in the units 10 -12 cm 3 molecule

- ls -1 [obtained from Table 13, Section IV, of this report for a few fused polynuclear heteroaromatic rings and from Meylan (1990b) 4 ]. The term det is the same as the one described previously. It should be noted that at present, AOP cannot estimate kadd,PAH for fused ring structures contain-

-13-

### ing five-membered heterocyclic rings. The use of equations 29

and 30 will be discussed in more detail in Section IV.B.
III. Syracuse Research Corporation Atmospheric Oxidation Computer Program (Developed by Meylan) III.A. Introduction The Atmospheric Oxidation Computer Program [designated as AOP] was purchased from Syracuse Research Corporation by the Exposure Assessment Branch of the Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency, based on the recommendation of Leifer. The first version, labeled Version 1.00, was received July 10, 1990 [Meylan (1990a)]. The Atmospheric Oxidation Program estimates the second-order rate constant for the reaction of an organic chemical with hydroxyl radicals (k OH ) and ozone (k 03 ) in the gas-phase. These rate constants are then used to calculate the half-life [t(1/2)EJ for these two reaction pathways based on average hydroxyl radical and ozone concentrations in the troposphere. Based on a very preliminary evaluation of the hydroxyl radical portion of this program, a few errors were uncovered. After a discussion by phone with Meylan on August 2, 1990, changes were made in the hydroxyl radical portion of this program. The new AOP computer program, Version 1.30, was received on November 1, 1990 and contained a data base for experimental values for the reaction of organic chemicals with hydroxyl radicals (k O H), ozone (k 03 ), and nitrate radicals (k NO3 ). This report covers the evaluation of the hydroxyl -14-

# _

radical portion of AOP. Future EPA reports will be devoted to

the discussion of the S/R relationships of Atkinson and Carter (1984) for ozone and the evaluation of AOP for estimating k 03 and the corresponding half-life [t(1/2)El•
III.B. Atmospheric Oxidation Computer Program (AOP) The estimation methods used in AOP are based on the structure/reactivity relationships of Atkinson (1986, 1986a, 1987, 1987a, 1988, 1988a) for the gas-phase reaction of hydroxyl radicals with organic chemicals in the troposphere as described in detail in the report by Leifer (1992a) and the structure/ reactivity relationships of Atkinson and Carter (1984) for the gas-phase reaction of ozone with organic chemicals in the troposphere. As stated in Section III.A., only the AOP program for estimating k O

H and t(1/2)E will be discussed in this report. AOP has been designed for use in an IBM or series of personal computers running the MS-DOS operating systems. Approximately 350 K of free required to run AOP. A11 program outputs occur and are run from a floppy disk drive. The AOP program is started by pressing key an IBM-compatible
or PC-DOS
memory are in the text mode

F-8 of the Workstation Menu, typing in AOP, and then pressing the Enter key. Program execution begins by displaying the data input screen shown in Figure 1. The program version and date are displayed in the upper left corner of the screen. The present version is specified in three lines:Version:/SRC 1.30/Nov 1990. The large

-15-. s



### Fiqure 1. Atmospheric Oxidation Proqram Data Entry Display

V e r , s i. o n: I h1 h119 hl hl hl h1 hl M hl hl h119 h1 h119 M h1 1.111 M hl hl h1 !7 h1 hl h1 hl 1.119 J9 h1 h119 h1; SRC 1.3-0 , ATMOSF'HEE I C OX I DAT I ON F'ROr,EAM

. Nov 1990 . F;ate of Hvdroxvl F;adical °< Dzone . , Feaction fr , om Chemical Structur , e , H h1 hl h1 !9 h1 h1 h1/? h1 h1 hl hl h1 h119 h1 M h1 hl h1 J11? hl h1 J91

~ 1 h119 h1 hl h1/

~ 1 h11919h1

~ '
T hl hl h1 hl hl hl hl h1 h119 J419 hlhl hl h1 h119 hl hl hf h1 h1 J9 h1 hl hl hl hl h1 hl M h119 h1 J9 h1 h11919 hl hl M hl hl hl h1 h11919191919 hl hl/h1 M 1? h1 hl h1/9 f4/9 hl M hl hl hl M hl hl M h11? J9 1-119 : ; r_ir 7 0000r 7 0000000000000r_'r000000t700000r7r7r.7r7r70r.j0000r'iri0r7000r7ra00xj000r700r70r7r7000000riri :ir.ir_'

~ r?
~ : Enter , SMILES:O 000i ; r i 0 r i 0 0 r i o o i i oo o o o o r'.i 0 r:! s s 0r7r_'rr ir_'arl00r i0r 7 ri0r_'i0r70r_'r0000000r7000ri0000r70r7000000p00Q0r700r70000r_700000000rir.7r70000ri0r;7or.ic7 : . Enter , NAME : C) rir.;r:i> : 00ri0r70r70r7r7000000ri000r700Q0r7r7000r7p00000rir_70r_"10000r70ri00r7r7r70r_i00000000000U0000r7U0

~ :7r7r:r7.; H 19! 119 h1 h1 hl h1 h119 Mhl hl h1 h1 hl hl h119 J9 M h1 /9hl h1 1.1 h1 h1 h119 M h1191919 h1 J9 h1 h/ f9 hl h1 M hl f9 h1 h1 h1 h11h1 h11419 h119 h1191419 h1 h1 h1 hl !9 hl M J9 h1 !9 h1 h1 M M h1141919M M:`

INS: OFF' LnDnnnnnnnnn.nnnnnnnnnnnn_nnnnnnnnnnnnnnnnnnnnnnDnnn_nnnnnnnn_nDnnnnnnnn.D_nnnDDDn.n.Dn: , 3 Fi : CLEAR Input F6: Save l"nput to User Fi le PgDn: CAL_C!

~ LATE .3 3 F2: F'hEVIi7US Input F8: CAS File Input Alt-H: SMILEc:

~ . HELP 3 3 F4: User , FILE InpL.it F10: CALC °< SAVE Results Esc: EXIT ta DCiS .j 

### @nDnnnnDnnn _nnnnnnnDn _nnODnDnnl7nDDnnnnnDD _n _nnnnnnnnDnnnnnnnDDnn _nnnnnnnnnnD _n _nn _nnnDE»-

-16-~

,


### rectangular box in the upper center of the screen contains the

program name and purpose. A large box in the middle portion of the screen is used to enter the SMILES notation corresponding to the chemical to be used in the estimation. The SMILES notation is a computer readable molecular structure system. Currently, a maximum of 120 characters are allotted for the SMILES notation. Directly below the Enter SMILES box, is a box with Enter NAME. This box is used to enter the name of the chemical and a maximum of 60 characters are allotted for this purpose. The blank space in the lower portion of the screen is used to display error messages corresponding to the SMILES entry. Finally, the lower box contains the various edit keys. The reader is referred to the USERS GUIDE for AOP, Version 1.10, prepared by William Meylan of Syracuse Research Corporation, for a detailed discussion of the operation of AOP. The only data required for AOP to produce estimated and experimental values of kOH and t(1/2)E is the SMILES notation corresponding to the molecular structure of the chemical. The name of the chemical is optional and is not required to run AOP. As an illustration of the operation of AOP and the output data to the monitor screen, consider the chemical a-methyl styrene, (2-phenyl-l-propene) which has a SMILES notation C=C(C)cicccccl. This SMILES notation is entered at the point adjacent to the ENTER SMILES notation on the screen and pressing key PgDn. If the SMILES notation is correct, the data entry screen is removed and the kOg data are displayed on the screen, Figure 2.A. The

-17-~ ^^

Figure 2. Atmospheric Oxidation Program Data DispIay for the

Compound a l Styrene (2-PhenyI-I-Properte):

A. Screen Display when Key PgDn is pressed^

SMILES : C=C(C)c1ccccc1 CHEM : MOL FOR: C9 H10 MOL WT : 118.18 SUMMARY: HYDROXYL RADlCALS Hydrogen Abstraction = .1440 E-12 cm3/molecule-sec Reaction with N, S and -OH = .0000 E-12 cm3/m01ecu1e-sec Addition to Triple Bonds = .0000 E-12 cm3/molecule-sec ** Addition to Olefinic Bonds = 51.4000 E-12 cm3/molecule-sec ** Addition to Aromatic Rings = 1.9187 E-12 cm3/molecule-sec Addition to Fused Rings = .0000 E-12 cm3/molecule-sec OVERALL yOH Rate Constant = 53.4627 E-12 cm3/molecule-sec HALF-LIFE = .300 Days (at conc 5E5 yOH/cm3)

........................ ** Designates Estimation(s) Using ASSUMED Value(s) ZDDDDDDDDDDDDBBDDDDDDDD4 EXPERIMENTAL DATA CDDDDDDDDDDDDDDDDDDDDDDDDDD? -----3 3-- OV3 Name: 2-Phenyl-1-propene (4-methyl styrene) 3 HA3 CAS Number: 00098-83-9 3 3 Exper OH rate constant : 52.0 E-12 cm3/molecule-sec 3 3 Exper Ozone rate constant : --- cm3/molecule-sec 3 3 Exper NO3 rate constant : --- cm3/molecule-sec 3 3 3 3 3 @DDDDDDDDDDVDDDDDDD4 Press any key to continue... CDDDDDDDDDDDDDDDDDDDY , ^^

-18-~ ^`
" ~`

B. Screeo DispIay nhen Key F-I0 is pressed.

SMILES : C=C(C)c1ccccc1 IMHMHHHMMMMMMMMMMMMMHMx CHEM : : Summary Saved to: x MOL FOR: C9 H10 x file --> AOP1.DAT x MOL WT : 118.18 HHMHMMMHMHHHHMHHHHHHW< ------------------------- SUMMARY: HYDROXYL RADICALS ------------------------- Hydrogen Abstraction = .1440 E-12 cm3/molecule-sec Reaction with N, S and -OH = .0000 E-12 cm3/molecule-sec Addition to Triple Bonds = .0000 E-12 cm3/molecule-sec ** Addition to Olefinic Bonds = 51.4000 E-12 cm3/molecule-sec ** Addition to Aromatic Rings = 1.9187 E-12 cm3/molecule-sec Addition to Fused Rings = .0000 E-12 cm3/molecule-sec OVERALL yOH Rate Constant = 53.4627 E-12 cm3/molecule-sec HALF-LIFE = .300 Days (at conc 5E5 y0H/cm3>

............~........... ** Designates Estimation(s) Using ASSUMED Value(s) ZDDDDDDDDDDDDDDDDDDDDDD4 EXPERIMENTAL DATA CDDDDDDDDDDDDDDDDDDDDDDDDDD? -----3 3-- OV3 Name: 2-Phenyl-1-propene 14-methyl styrene) 3 HA3 CAS Number: 00098-83-9 3 3 Exper OH rate constant : 52.0 E-12 cm3/molecule-sec 3 3 Exper Ozone rate constant : --- cm3/molecule-sec 3 3 Exper NO3 rate constant : --- cm3/molecule-sec 3 3 3 3 3 @DDDDDDDDDDDDDDDDDD4 Press any key to continue... CDDDDDDDDDDDDDDDDDDDy

-19-. L

i
; 1 

### SMILES notation, molecular formula, and molecular viight of a-methyl styrene are displayed at the top left portion of the screen. Directly below these data and in the center of the screen, this figure displays the SUMMARY: HYDROXYL RADICALS data and the EXPERIMENTAL DATA. Directly under SUMMARY: HYDROXYL RADICALS, the estimated rate constants for each of the specific reaction pathways (ki) for a-methyl styrene are listed. Immediately below the summary data, the overall kOH rate constar* {which represents the sum of each of the individual rate constants [k(i)]} and the corresponding half-life are listed. The half-life (in days) corresponds to an average OH radical concentration of 5E5 radicals cm -3 and a 24-hour daylight day. The table in the lower box summarizes the available experimental kOH, k 03 , and k NO3 data for this compound. The experimental value of kOH is listed as 52.0 E-12 cm 3 molecule

- ls -1 as obtained from Atkinson (1989). No experimental rate data are available for the reaction of a-methyl styrene with ozone (k03) and with nitrate radicals (kp0 3 ). If, after the SMILES notation for a-methyl styrene is entered, key F-10 is pressed instead of PgDn, the results are then displayed on the screen as shown in Figure 2.B. In this case, the estimated and experimental data are the same as the data in Figure 2.A. except that the estimated data are now stored in a file as indicated in the top right corner box. Pressing key PgDn displays the same OH rate data but now the SUMrIARY: OZONE REACTION data replaces the available experimental -20-~

a „



### data, Figure 3A. The ozone data corresponds to the overall

estimated ozone rate constant (k0 3 ) and the associated half-life [t(1/2)E] in days corresponding to an average ozone concentration of 7E11 molecules cm -3 and a 24-hour day. If, after the SMILES notation for ac-methyl styrene is entered, key F-10 is pressed twice, then the results are depicted in Figure 3.B. In this case, the estimated data is the same as the data displayed in Figure 3.A. except that the data is now stored in a file as indicated in the box in the upper right corner. When pressing key F-9 five times, the screen displays sequentially for a-methyl styrene: (1) the detailed calculations for hydrogen abstraction [k(la)), Figure 4.A.; (2) OH addition to the olefinic group [k(3) = kadd,narl► 

### Figure 4.B.; (3) ozone reaction with the olefinic group, Figure 5.A.; (4) OH addition to the aromatic ring (ar) [k(7A) _ kadd,ar7, Figure 5.B; and (5) Figure 6, which corresponds to the same estimated data for OH addition to the aromatic ring (Figure 5.B.) and the experimental data in the lower box corresponds to the same experimental data displayed in Figure 2.A. If key F-9 is pressed again five times, the same sequence of data is displayed as described above. Pressing any key but F-9 returns the screen display to Figure 1 for entry of a SMILES notation for another compound. If key F-2 is pressed, Figure 1
-21-Figure 3. Atmospheric Oxidation Program Data DispIay for the Compound m-Methyl Styrene (2-PhenyI-I-Propeoe):

A. Screen Display when Key PgDn is pressed,

SMILES : C=C(C)c1ccccc1 CHEM : MOL FOR: C9 H10 MOL WT : 118.18

------------------------- SUMMARY: HYDROXYL RADICALS ------------------------- Hydrogen Abstraction = .1440 E-12 cm3/molecule-sec Reaction with N, S and -OH = .0000 E-12 cm3/molecule-sec Addition to Trip1e Bonds = .0000 E-12 cm3/molecule-sec ** Addition to Olefinic Bonds = 51.4000 E-12 cm3/molecule-sec ** Addition to Aromatic Rings = 1.9187 E-12 cm3/molecule-sec Addition to Fused Rings = .0000 E-12 cm3/molecule-sec OVERALL yOH Rate Constant = 53.4627 E-12 cm3/molecule-sec HALF-LIFE = .300 Days (at conc 5E5 y0H/cm3)

.... ,................... ** Designates Estimation(s) Using ASSUMED Value(s)
------------------------- SUMMARY: OZONE REACTION ---------------------------- OVERALL OZONE Rate Constant = 13.650000 E-17 cm3/molecule-sec HALF-LIFE = .084 Days (at conc 7E11 mol/cm3)

Press F9 to Show Calc Press ESC to STOP....anything else to continue~

, ^'

SMILES : C=C(C)c1ccccc1 IMHHMMMMHHHMMMMMHMHMMW

~ CHEM : : Summary Saved to:
~ MOL FOR: C9 H10 x fi}e --> A0P1.DAT

~ MOL WT : 118.18 HMHMHMMMMMMMMMMHMMMMMW

------------------------- SUMMARY: HYDROXYL RADICALS ------------------------- Hydrogen Abstraction = .1440 E-12 cm3/molecule-sec Reaction with N v S and -OH = .0000 E-12 cm3/molecule"sec Addition to Triple Bonds = .0000 E-12 cm3/molecule-sec ** Addition to Olefinic Bonds = 51.4000 E-12 cm3/molecule-sec ** Addition to Aromatic Rings = 1.9187 E-12 cm3/molecule-sec Addition to Fused Rings = .0000 E-12 cm3/molecule-sec OVERALL yOH Rate Constant = 53.4627 E-12 cm3/molecule-sec HALF-LIFE = .300 Days (at conc 5E5 yOH/cm3)

........................ ** Designates Estimation(s) Using ASSUMED Value(s)
------------------------- SUMMARY: OZONE REACTION ---------------------------- OVERALL OZONE Rate Constant = 13.650000 E-17 cm3/molecule-sec HALF-LIFE = .084 Days (at conc 7E11 mol/cm3)

Press F9 to Show Calc Press ESC to STOP....anything else to continue

-23-ra



### Figure 4. Atmospheric oxidation Program Data Display for the

Compound a-Methyl Styrene (2-Phenyl-l-Propene):

A. Screen Display of the Detailed Calculations for Hydrogen Abstraction.

Hyd•oqen Abetractj.on

[::'Prim = 0.144 F(:::-C=(

- ,::') = C.).144 ( = .144
H Abstraction I

- OTAL = .144 E•12 7 ' cm -1 /molecLt lo. ---sec -

F'r

- E- , ss arvy key tcj cont

- Inue

-24-~ °^

^^

B. Screen Display of the DetaiIed CalcuIations for

OH Addition to Olefinic Bonds

Kd = K(CH2=C<)C(-Pheny1 **) = 51.400(1.00) = 51.400 E-12 cm3/molecule-sec

..,...~.................... ASSUMED Value designated by: **

Press any key to continue

-25-Figure 5. Atmospheric Oxidation Program Data Display for the Compound a-Methyl Styrene (2-Phenyl-l-Propene):



### Ficrure 5
A. screen Display of the Detailed Calculations with 03 Reaction with the Olefinic Bond.

Ozorie R'eAct:L0n with Olefins

I -j en --j E— T 5 000

~ . 5 (-) 6 5 1 7 (:.. m

- / in o I E?C LA .1. E-?

--- SE-C

F'r- c- s s a n y k e y t- o i

- -- o n t j. rf

—26—~

~

" °^

B. Screen DispIay of the DetaiIed CaIcuIations of OH RadicaI Addition tm the Aromat:ic Ring.

OH Addition to Aromatic Rings

de+ = Most negative va1ue of ep+ or em+ (-C=C Log Kar = -11.69 - 1.35 de+ cm3/molecule-sec Ring #1 Kar = 1.9187 E-12 cm3/molecule-sec
TOTAL Kar = 1.9187 E-12 cm3/molecule-sec ......................Assumed values designated by **

Press any key to continue

-27-~ ^ ." Figure 6. Atmospheric Oxidation Program Data DispIay for the

Compound m-MethyI Styrene (2~ I~l-Propene): Screen Display for OH Addition to the Arcmatic Ikiog and the ExperimentaI Data.

OH Addition to Aromatic Rings

_______________________________ de+ = Most negative value of ep+ or em+ (-C=C .020 Log Kar = -11.69 - 1.35 de+ cm3/molecule-sec Ring #1 Kar = 1.9187 E-12 cm3/molecule-sec
TOTAL Kar = 1.9187 E-12 cm3/molecule-sec ......................Assumed values designated by **

ZDDDDDDDDDDDDDDDDDDDDDD4 EXPERIMENTAL DATA CDDDDDDDDDDDDDDDDDDDDDDDDDD? 3 3 3 Name: 2-Phenyl-1-propene (Wmethyl styrene) 3 3 CAS Number: 00098-83-9 3 3 Exper OH rate constant : 52.0 E-12 cm3/molecule-sec 3 3 Exper Ozone rate constant : --- cm3/molecule-sec 3 3 Exper NO3 rate constant : --- cm3/molecule-sec 3 3 3 3 3 @DDDDDDDDDDDDDDDDDD4 Press any key to continue... CDDDDDDDDDDDDDDDDDDDYe

-28-

### is reproduced with the original SMILES notation for a-methyl

styrene.
IV. Evaluation of the Atmospheric Oxidation Computer Program for Estimating kOH and the Experimentally Measured kOH Data Listed in the Program
IV.A. Comments on the Group Rate Constants, Substituent Factors, and Other Parameters Used by the Atmospheric Oxidation Program The group rate constants, substituent factors, and other parameters are listed in Tables 1 through 9 for a large number of classes of compounds as obtained from Meylan (1990b). A few comments will be made in this section on the numerical values of these parameters listed in these tables. More details will be given in Sections IV.C. through IV.F. on specific classes of compounds and specific compounds in each of these classes. First, consider Table 1 which summarizes the group rate constants for hydrogen abstraction and radical reaction. The value of the group rate constant k(>C<) is listed as zero with one significant figure. However, this value is known much more accurately; conservatively, it is known to three significant figures. Therefore, it is recommended that AOP use k(>C<) _ 0.000 which is consistent with the accuracy of the S/R relationships of Atkinson. Table 1 does not have an entry for H-atom abstraction from unsaturated carbon-carbon functional groups (i.e., =C-H). Even at temperatures up to 500 K, H-atom abstraction from these functional groups is zero [Atkinson (1987)]. Therefore, it is ic



### -29-~ r

> ~ 

### Table 1. Group Rate Constants for Hydrogen Abstraction and

Radical Reaction i

Group 

### Rate.Constant k X 10 12 cm 3 / molecule-sec
k(-CH3) 0.144 k(-CH2-) 0.838 k(>CH-) 1.83 k (>C<) 0 

### k(-OH) 0.036' k(-NH2) 20 k ( -NH- ) 60 

### k(>N-) 60 k ( -SH) 31 3 k(-S-) 2.0 k(-S-S-) 200 

### k(>N-NO) 0 k(>N-NO2) 0 k[P(=0)] 0 k[P(=S)] 55

1 

### Data from Table 1 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)].

Z 

### This group rate constant is only applicable to hydroxyl groups in alcohols and glycols.

3 

### Used only for aliphatic connections; connection to aromatics not included based upon experimental rate constant for thiophenol.

-30-~

Table 2. Substituent F(X) Factors for Hydrogen Abstractioni

(values marked with "**" are estimated/assumed values)

ubstituent Factor 1. -CH3 1.00 2. -CH2- 1.29 3. -CH2CL 0.57 4. -CH2Br 0.57 5. -CH2F 0.85 6. -CH2C(=O)- 4.4 7. -CH2ONO2 0.30 8. -CH2CN 0.5 9. -CH2I ** 0.57 10. >CH- 1.29 11. -CHCL2 0.57 12. -CHF2 .0.10 13. -CHBr2 ** 0.57 14. -CHI2 ** 0.57 15. >CHC ( -O ) - 4.4 16. >CHONO2 0.30 17. >C< 1.29 18. -CCL3 0.09 19. -CF3 0.075 20. -CBr3 ** 0.09 21. -CI3 ** 0.09 22. >CC(-O)- 4.4 23. >CONO2 0.30 24. -CF2CL 0.025 25. -F 0.099 26. -CL 0.38 27. -Br 0.30 28. -I ** 0.30 29. =O 8.8 30. -Aromatic 1.0 31. -OH 3.4 32. -O- 6.1 33. -ONO2 0.18 34. -CN 0.14 35. -OC(=O)R 1.5 36. -C=(0)CL 0.5 37. -C(=O)- 0.76 38. -CHO 0.76 39. -C(=O)OR 0.0 40. >C=C< 1.0 41. -C=C- 1.0 42. -SH 9.0 (given same value as -CH2Br)

(given same value as -CHCL2) (given same value as -CHCL2)

(given same values as -CCL3) (given same values as -CCL3)

(given same value as -Br)

-31-~

: -E Table 2. Continued

ueQt Fact2r 43. -S- 9.0 44. -SS- 9.0 45. -NH2 10 46. -NH- 10 47. -N< 10 48. -NNO 10 49. -NNO2 10 50. -NO2 0.18 51. -OP- 20 52. -SP- 20 53. -P- ** 1.0 54. =P ** 1.0 55. =N ** 1.0 56. =S ** 9.0 57. CH-Halogen ** 0.57 58. S(+4)=O ** 99.0 59. blank 1.0 60. Missing 0.0 61. -CH-2Halogens ** 0.57 62. -C-3Halogens ** 0.09 63. -CHF-Halogen ** 0.30 64. -O-O- ** 50 65. -O-N= ** 2.0

66. >CNO2 ** 0.30 67. >CHNO2 ** 0.30 68. CH2-NO2 0.30 69. CH2-0- 4.50 70. 2nd -O- 1.00 71. Sulfonic acid ** 0.20 72. 2nd alkyl ketone 1.00 73. -CH(Halogen)C=O ** 3.10 74. -CH(NO2)C=O ** 1.3 75. -CH(NO2)Halogen ** 0.21 76. >C(NO2)C-0- ** 1.3 77. >C(ONO2)C=0- ** 1.3 78. -CH(ONO2)C-O ** 1.3 79. >C-O- ** 4.5 (new Atkinson value)
(arbitrarily assigned a value of unity) (arbitrarily assigned a value of unity) (arbitrarily assigned a value of unity) (given same value as sulfur #s 42, 43, 44) (estimated by Asa Leifer) (based on dimethyl sulfoxide data)
(given same value as -CHCL2) (given same value as -CCL3) (assigned a value between -CHF2 and -CHCL2) (based on experimental OH rate constants for methyl and t-butyl hydroperoxides) (arbitrarily assigned based on other values for oxygen and nitrogen connections) (given same value as 68) (given same value as 68) (new nitroalkane data) (new Atkinson value) (new Atkinson value) (arbitrary estimate) (data for cyclobutanone) (combination of previous) (combination of previous) (combination of previous) (combination of previous) (combination of previous) (combination of previous) (given same value as CH2-O-)

~ Data from Table 6 in aroup Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)).

-32-Y

~

rTable 3. Factors Used for Aliphatic Ring Strain Effects'


### acto 3-Membered Ring 0.017 4-Membered Ring 0.22 5-Membered Ring 0.80 6-Membered Ring 1.00 7 to 10-Membered Ring 100 2

' Data from Table 10 in Group Rate Constants and Substituent 

### Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)].

2 

### Note: aliphatic rings containing more than 10 members do not 

### have any ring strain effect factor applied to them.

-33-.F

Table 4. Group Rate Constants for OH Radical Addition to

Isolated Olefinic Units'



### Structure k X 10 12 cm 3 /molecule-sec

CH2=CH- 26.3 CH2=CH< 51.4
-CH=CH- (cis-) 56.1
-CH=CH- (trans-) 63.7
-CH=C< 86.9
>C=C< 110.0
-CH=CH- (cyclic) 56.1 2

' Data from Table 2 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)].

2 The group rate constant for cyclic alkenes such as cyclopentene and cyclohexene is assumed to be the same as the cis-iosmer value although the trans-isomer value yields slightly better estimates.

-34-~ .

W ~ Table 5. Group Rate Constants for OH Radical Addition to

Conjuqated Olefinic Units i



### No. Alkyl Groups Structure k X 10 12 cm 3 /molecule-sec
1 CH2=CH-CH=CH- 105
1 CH2=CH- 

### ~ =CH2 105

2 ----------------------------------------------------------------- CH2=CH-CH=C< 135 2 CH2=CH- 

### ~ =CH- 135

2 CH2= 

### ~ -CH=CH- 135

2 -CH=CH-CH=CH- 135 2 CH2=?- 

### ~ =CH2 135

3 ----------------------------------------------------------------- CH2=CH-?=C< 180

3 CH2=f-CH=C< 180

3 -CH=CH-CH=C< 180 3 CH2=?-?=CH- 180

3 -CH=CH- 

### ~ =CH- 180

-35-Table 5. Continued



### No. Alkyl Groups Structure k X 10 12 cm 3 /molecule-sec

4 >C=CH-CH=C< 230
4 -CH=C-CH=C< 1 230



### 4 -CH=CH-C=C< 1 

### 230

4 CH2=C-C=C< 230



### 4 -CH=C-C-CH- i I 

### 230

5 ----------------------------------------------------------------- >C=C

- C=CH

1 1 285'

5 >C=CH-C=C< 285'

6 ----------------------------------------------------------------- >C=C-C=C< 350 2

~ 

### Data from Table 5 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)].

2 

### These values have been estimated .... estimates are based upon the increasing relationship for the 1 to 4 alkyl group structures.

-36-

### Table 6. Group Rate Constants for OH Radical Addition to Alkyne Units i

Structure k X 10 12 cm 3 /molecule-sec CH$C- 6.4
-CoC- 29.0

~ 

### Data from Table 3 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)]. y ~

-37-

### Table 7. Group Rate Constants for OH Radical Addition to 1,2-Dialkene (Allene) Units 1

Structure k X 10 12 cm 3 /molecule-sec
CH2=C=CH- 31.0
-CH=C=CH- 57.0 

### CH2=C=C< 57.0 2 

### -CH=C=C< 85.0 2
>C=C=C< 110.0 2

~ 

### Data from Table 4 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)].

2 

### These values have been estimated .... the estimates are based upon analogy to the single unit olefin rate constants (see Table 2).

-38-Table 8. Substituent Factors [C(X)] for OH Radical Addition to Olefins and Acetylenea l

(values marked with "**" are estimated/assumed values)
Substituent Factor

1. -F 0.4 2. -CL 0.20 3. -Br 0.26 4. -CH2CL 0.76 5. -CN 0.15 6. -CHO 0.26 7. -C(-O)CH3 0.91 8. -OCH3 1.3 9. -0 1.0 10. -I ** 0.26 (given same value as -Br) 11. -CH2Br ** 0.76 (given same value as -CH2CL) 12. -CH2F ** 0.76 (given same value as -CH2CL) 13. -CH2I ** 0.76 (given same value as -CH2CL) 14. -C-C ** 0.85 15. not used 16. -Phenyl ** 1.0 (Atkinson assumption, Int. J. Chem. Kinet. 17. -C(-O)X ** 0.91 (given same value as -C(-O)CH3 18. -OC ** 1.3 (given same value as -OCH3) 19. -C . C** 1.10 (based on experimental rate constant for diacetylene) 20. -S ** 1.0 ' (arbitrarily assigned a value of unity) 21. -O ** 1.0 (arbitrarily assigned a value of unity) 22. -P ** 1.0 (arbitrarily assigned a value of unity) 23. -NO2 ** 0.5 (arbitrary estimate) 24. -ONO2 ** 0.6 (arbitrary estimate) 25. =S ** 1.0 (arbitrarily assigned a value of unity) 26. -N ** 0.6 (arbitrary estimate) 27. =P ** 1.0 (arbitrarily assigned a value of unity) 28. =N ** 1.0 (arbitrarily assigned a value of unity) 29. cyclic C-0 ** 0.20 (based on data for naphthaquinone) 30. Missing 1.0 31. R 1.00 (for an alkyl or a cycloalkyl group) 19:822.)

~ Data from Table 7 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 [Meylan (1990b)).

-39-Table 9. Electrophilic Substituent Factors for OH Radical Addition to Aromatic Ringsi (values marked with "**" are estimated/assumed values)

The q, + , and + values which are t i considered "assumed" values are taken directly from th ~ n~

following reference: Brown, H.C. and Okamoto, Y(1958), "Electrophilic Substituent Constants", J. Am. Chem. Soc. 80: 4979-4987. Various "assumed" values are based on similar structures with known a + values.



### g a °p

1. Amino (-NH2) -0.16 -1.3 2. Dimethylamino (CH3-N-CH3) -0.16 ** -1.7 3. Anilino (C6H5-NH-) -0.16 ** -1.4 4. Acetylamino (CH3C(=O)-NH-) 0.21 ** -0.6 S. Benzoylamino (C6H5-C(=O)-NH-) 0.21 ** -0.6 6. Hydroxy (-OH) 0.121 ** -0.92 7. Methoxy (-OCH3) 0.047 -0.778 8. Phenoxy (C6H5-O-) 0.10 ** -0.50 9. Methylthio (CH3-S-) 0.158 -0.604 10. Methyl (CH3-) -0.066 -0.311 11. Ethyl (CH3-CH2-) -0.064 -0.295 12. Isopropyl (CH3-CH-CH3) -0.060 -0.280 13. tert-Butyl (-C(CH3)(CH3)(CH3)) -0.059 -0.256 14. Aromatic (phenyl) 0.109 -0.179 15. Chloromethyl (-CH2-CL) 0.14 -0.01 16. Fluoro (-F) 0.352 -0.073 17. Bromo (-Br) 0.405 0.150 18. Chloro (-CL) 0.399 0.114 19. Iodo (-I) 0.359 0.135 20. Trifluoro (-C-F3) 0.520 0.612 21. Cyano (-C$N) 0.562 0.659 22. Nitro (-NO2) 0.674 0.790 23. Carboxy (-C(-O)-OH) 0.322 0.421 24. Carbomethoxy (-C(-O)-O-CH3) 0.368 0.489 25. Carboethoxy (-C(-O)-O-CH2-CH3) 0.366 0.482 26. Carbethoxymethyl (-CH2-C(=O)-O-CH2-CH3) -0.01 -0.164 27. Bromomethyl (-CH2-Br) 0.14 ** -0.01 ** 28. Iodomethyl (-CH2-I) 0.14 ** -0.01 ** 29. Nitrate (-ONO2) 0.674.** 0.790 ** 30. Olefinic (-C=C) 0.02 ** 0.02 ** 31. Acetylenic (-CsC) 0.21 ** 0.23 ** 32. -O-R (assume methoxy) 0.047 ** -0.778 ** 33. Phosporus (-P) 0.0 ** 0.0 ** 34. Sulfur (-S) (assume methylthio) 0.158 ** -0.604 ** 35. Carbonyl (-C-O) 0.10 ** 0.35 ** 36. Aldehyde (-CHO) 0.36 ** 0.22 ** 37. -C-CL3 0.55 ** 0.65 ** 38. -C-Br3 0.55 ** 0.65 ** 39. -C-I3 0.55 ** 0.65 ** 40. -CH2-F 0.10 ** -0.05 ** 41. -CH2- (assume ethyl) 0.06 ** -0.295 ** 42. -CH- (assume isopropyl) 0.06 ** -0.280 ** 43. -CH-Halogen (assume chloromethyl) 0.14 ** -0.01 ** 44. >C< (assume t-butyl) -0.059 ** -0.256 **

-40-, <<

Table 9. Continued

~ 

## 4n ap

45. -NH- -0.16 ** -1.0 ** 46. -N= -0.03 ** 0.15 ** 47. -CH2-CN 0.17 ** 0.01 ** 48. -N=N 0.30 ** 0.64 ** 49. -O-C(=O)- 0.10 ** -0.10 ** 50. Undefined 0.0 ** 0.0 ** 51. -O-P 0.10 ** -0.20 ** 52. -S-CN 0.30 ** 0.25 ** 53. -S-CO 0.20 ** 0.15 ** 54. -O-Halogen 0.15 ** -0.10 **
For the 55-59, the X refers primarily to halogens, but the program also considers nitro and cyano groups. The estimated values are taken from Atkinson publications pertaining to estimated rate constants for PCBs.

55. -C6H4-X1 0.25 ** 0.02 ** 56. -C6H3-X2 0.39 ** 0.22 ** 57. -C6H2-X3 0.53 ** 0.42 ** 58. -C6H1-X4 0.67 ** 0.62 ** 59. -Phenyl-X5 0.81 ** 0.82 ** 60. -S03 0.50 ** 0.50 ** 61. -S-O -0.16 ** -1.30 **

1 Data from Table 8 in Group Rate Constants and Substituent Values Used by the Atmospheric Oxidation Program, Version 1.30, November 1990 (Meylan (1990b)).

-41-

### recommended that AOP adopt the group rate constant k(1, UNS CH) =

0.000, list it in Table 1, and show it in all detailed calculations for H-atom abstraction from various unsaturated functional groups (=C-H). For the compound O,O-dimethyl chlorophosphorothioate, Atkinson et al. 

### (1988) indicated that the group rate constant k(P-C1) = 0.00; and this should be added to Table 1 and to the computer program. Furthermore, the group rate constants k(>NNO), k(>N-NO 2 ), and k[P(=0)] should be listed as 0.00. Inspection of the data in Table 1 indicates that k(-S-) 

### = 2.0 5 . This value is applicable to OH radical reaction in the presence of air at 1 atmosphere pressure and thus in the presence of oxygen. In the absence of oxygen, k(-S-) = 0.00 [Atkinson et al. (1988)]. These facts are pertinent since AOP incorrectly estimates k0H for acyclic and cyclic sulfides and compares the estimated values 

### with the experimental values b . For example, for dimethyl sulfide, the recommended experimental value of k OH from Atkinson (1989) is 4.56, Table 24, which is valid in the absence of oxvqen. Therefore, in the data base for these compounds, the experimental value should be qualified to indicate that k OH was

It should be noted that for convenience, the factor 10 -12 cm 3 molecule

- ls -1 has been omitted. In all subsequent discussions on group rate constants, this factor will be omitted. In addition, in all subsequent discussions, all rate constants k(i) for all individual reaction pathways and k Og will be written without the factor 10 -12 cm 3 molecule

- is -1

. 6 

### From Meylan (1990b), page 10, "Estimation Accuracy of AOP vs. PCFAP." _y

-42-y :



### obtained from measurements in the absence of oxygen. If one

wants to compare the estimated value with the experimental value, then kpH should be estimated under the boundary condition in the absence of oxygen and kOH = 2.59 [since k(-S-) = 0.00]. Thus, a footnote should be added to the numerical value of the group rate constant k(-S-) in Table 1[i.e., for k(-S-)]. The numerical value should be (2.0) 3 and the footnote 3 at the bottom of this table should be --- 3 Applicble at 298 K and a total pressure of 1 atmosphere in air (and thus in the presence of oxygen). In the absence of air, and thus in the absence of oxygen, k(-S-) = 0.00. This is discussed in more detail in Section IV.E.i.b. From the experimental k O H data of diethylhydroxylamine, it was found that k(>NOH) = 0.00 [Leifer (1991a)] and this group rate constant should be entered into Table 1 and in the AOP Computer program. In Table 1, it is indicated that k(-SH) = 31 for RSH, where R is an alkyl group. This group rate constant is not valid when R is an aromatic group, based on the experimental rate constant for thiophenol [Meylan (1990b)]. For the present, this assignment can be tentatively used. However, the experimental k O H data from Barnes et al. (1986) may not be valid. Therefore, more experimental data is needed on thiophenol and other alkyl and aromatic thiols to confirm the assignment for k(-SH). In Table 1, the value of the group rate constant k(-OH) is only applicable to H-atom abstraction from the hydroxyl groups in alcohols and glycols and this fact must be noted in Table 1 for -43-> i

i 

### k(-OH) and in the computer program. This group rate constant is not applicable to H-atom abstraction from the hydroxyl groups in carboxylic acids and alkyl peroxides. See Section IV.C.3.b. for the discussion of the estimation of k O H for carboxylic acids and Section IV.C.4.b. for the discussion of the estimation of k OH for alkyl peroxides. In Table 2, item, No. 57, should be changed to F(R 2 CHC1) _ 0.57 [estimated by Leifer from the experimental data of 2,3- dichlorobutane from Mill et al. (1982); and an additional item F(R2CH- 1 Halogen **) = 0.57 (based on the assignment in No. 57) should be added before item 60. The substituent factor F(-0-0 **) = 50 should be deleted from Table 2 because of the erroneous assumption that k(-OH) _ 0.036 for methyl and t-butyl hydroperoxide. For the details, see Section IV.C.4.b. Similarly, the substituent factor dimethyl sulfoxide, No. 58, Table 2, should be deleted since it is expected that the sulfoxide would be readily oxidized to the sulfone. For the details, see 

### Section IV.E.2.b. Table 4 lists the group rate constant for the functional group >C=C< as 110.0; it should be 110 based on the experimental k OH data for 2,3-dimethyl-2-butene and the recommended value by Atkinson (1986,1989). Therefore, the last significant figureshould be deleted. Similarly, the group rate constant for -C=Cin Table 6 should be 29 and not 29.0 based on the recommendation of Atkinson (1987, page 814).

-44-

### In Table 8, some of the substituent factors C(X) are marked

with the symbol ** to indicate that they are based on estimated/ assumed values. However, if a substituent factor is based 

## on experimental k O g data, then the symbol ** should be omitted. For example, consider diacetylene, in Table 8, No. 19; this substituent factor is listed as {C[-COC-**]} = 1.10 (based on the experimental data for diacetylene). The entry in this table should be No. 19 C[-C=C-] = 1.10 (based on the experimental data of diacetylene). Similar comments are applicable to the substituent factors C(X) for numbers 29 and 16, Table 8. Therefore, for the substituent factor C[Cyclic C=0 **] (No. 29), the double asterisks should be removed since the value is based on the experimental kOH data of 1,4-naphthoquinone; similarly, for No. 16, C(phenyl **) = 1.0 should be C(phenyl) = 1.00, based on the experimental kCH data of styrene, c- and Q-methyl styrene, and fl-dimethyl styrene [Atkinson (1987, page 828)]. These comments also apply to the substituent factors F(X) marked with ** in Table 2. In Table 8, No. 14 is listed as C(CmC- 

### **) = 0.85 

### without any notation as to how this value was derived. Since this represents an estimated/assumed value, a qualifying statement should be added to designate how this assignment was made. Finally, in Table 9, the 

## vm value for substituent -CH 2 - (No. 41) is listed as 0.06 ** by analogy with the ethyl group. However, 

## Qm for the ethyl group is -0.064 and this value should be listed in No. 4, Table 9. .,

-45-

### IV.B. Some Comments on Hydroxyl Radical Addition to Heteroaromatic and Fused Polyaromatic Ring Systems Meylan (1990b) developed elegant S/R relationships for estimating the second-order rate constant for OH 

### radical addition to heteroaromatic (mono and fused polycyclic) rings and to fused polynuclear aromatic hydrocarbon (PAH) rings. For monocyclic heteroaromatic compounds (ar l ), AOP 

### uses equation 24; for fused ring polynuclear aromatic hydrocarbon compounds (PAH), AOP 

### uses equation 29; and for fused ring polynuclear heterocyclic compounds (PAH'), AOP 

### uses equation 30. The first term in each of these equations [i.e., Ai, 

### Bi, and Bi, respectively) was derived by Meylan from: (1) the experimental values of k OH for the basic, or parent, heterocyclic ring or the fused polynuclear aromatic hydrocarbon ring structure; or from (2) the experimental ionization potentials for the parent fused ring polynuclear aromatic hydrocarbons and fused ring polynuclear heteroaromatic compounds. Tables 10 and il list the values of Ai and Bi, respectively, for various heteroaromatic ring structures and polyaromatic hydrocarbons derived from the experimental k OH data for the parent aromatic compounds. Tables 12 and 13 list the values of Bi and Bi , respectively, derived from the experimental ionization potentials of the parent ring compounds.
AOP 

### has a SMILES interpreter which allows it to identify the parent aromatic ring structure and assign it the appropriate value of Ai, 

### Bi, or Bi . AOP 

### then adjusts this value for any substituent on the ring by utilizing the appropriate substituent

-46-.,

.,



### Table 10. Experimental Values of Ai for Some Monocyclic

Heteroaromatic Compounds*

Heterocyclic Aromatic Ring Structure

Pyrrole
Furan Thiofuran Imidazole Oxazole Thiazole Pyridine 1,3,5-Triazine Experimental Value of Ai (10 -12 cm 3 molecule

- ls -1 )

110.0 40.5 9.53 36.0 9.1 1.4 0.37 0.15

* Data from page 7 of the User's Guide for the Atmospheric Oxidation Program, Version 1.10, November 1, 1990 [Meylan (1990b)].

-47-R:

t i r



### Table 11. Experimental Values of Bi for Some Polynuclear

Aromatic Compounds*
Experimental Value of Bi Polynuclear Aromatic Ring Structure (10 -12 cm 3 molecule

- ls -1 )

Naphthalene 21.6 Anthracene 110.0 Phenanthrene 31.0

* Data from page 7 of the User's Guide for the Atmospheric Oxidation Program,*Version 1.10, November 1, 1990 [Meylan (1990b)].

-48-~ .

~
. Table 12. Values of Bi for Polynuclear Aromatic Hydrocarbon



### Structures Derived from Experimentally Measured 

### Ionization Potentials*

Polynuclear Aromatic Ring Structure

4 Fused Benzene Rings 5 Fused Benzene Rings 6 Fused Benzene Rings Assigned Value of Bi Based on the Experimentally Measured Ionization Potential (10 -12 cm 3 molecule -l s -1 )

80.0
150.0
200.0



### * Data from page 7 of the User's Guide for the Atmospheric Oxidation Program, Version 1.10, November 1, 1990 [Meylan (1990b)].

-49-Y f '( ~



### Table 13. Values of Bi for Polynuclear Heteroaromatic

Structures Derived from Experimentally Measured Ionization Potentials*

Assigned Value of BiBased on the Experimentally Measured Ionization Potential 

### Polynuclear Heteroaromatic Structure (10 -12 cm 3 molecule

- ls -1 )

Quinoline 6.5 Isoquinoline 6.5 

### Quinoxaline 2.0 Quinazoline 2.0 Acridine 27.5

* Data from page 7 of the User's Guide for the Atmospheric Oxidation Program, Version 1.10, November 1, 1990 [Meylan (1990b)]. ~

-50-~ -



### factors vm and vP for the substituents on the ring. For

example, for 1-chloronaphthalene, the•SMILES interpreter in AOP identifies the parent naphthalene ring and selects the value of Ai for this ring. AOP then adjusts this.value by considering the effect of the chlorine substituent on the reactivity of the ring. It should be noted that Meylan did not develop S/R relationships for fused ring aromatic compounds containing five membered heterocyclic rings. For example, AOP cannot estimate kpg for benzothiazole. In principle, however, the basic concepts of Meylan can be used. For example, if k O H is measured for benzothiazole, then Bi from equation 30 can be determined. Therefore, with this value of Bi, k OH can be estimated for substituted benzothiazoles utilizing the appropriate substituent factors v 

### ~ and vP for the substituents on the ring. More experimental kOg data is needed on a number of additional derivatives of these heteroaromatic (ar'), polynuclear aromatic hydrocarbons (PAH), and polynuclear heteroaromatic ring (PAH') structures to confirm the S/R relationships of Meylan (1990b) [i.e., confirm the validity of equations 24, 29, and 30]. It should be noted that in Tables 10, il, and 12, AOP lists a few of the values of Ai and Bi to four significant figures. At best, the experimental data used to derive these constants are only valid to three significant figures. Therefore, it is

-51-

### recommended that the values of Ai and Bi for pyrrole, anthracene,

and for 4, 5, and 6 fused benzene rings should be listed to three significant figures.
IV.C. H-Atom Abstraction from C-H and -OH Groups by Hydroxyl Radicals IV.C.1. Saturated Alkanes IV.C.i.a. Evaluation of the Experimental kOg Data Tables 14.A. and 14.B. summarize the pertinent experimental kOg data at 298 K for the reaction of OH radicals with acyclic and cyclic alkanes, respectively, as obtained from AOP and the literature. For this class of compounds, hydroxyl radical reaction only involves the abstraction of H-atoms from the various primary, secondary, or tertiary C-H groups. The first column in these two tables lists the name of each alkane; the second column lists the experimental value of kO H at 298 K in AOP [Meylan (1990b)] and is labeled Experimental/AOP; the third column lists kOH at 298 K as obtained by Leifer from Atkinson (1989) and/or from the literature and is labeled Experimental/(a); the fourth column lists the.estimated value of kOH at 298 K as obtained from AOP and is labeled Estimated/AOP; and finally the fifth column lists the estimated, hand calculated (HC), value of kOH at 298 K as obtained by Leifer using the S/R relationships of Atkinson and is labeled Estimated/HC. Atkinson (1989) critically analyzed the available experimental kOH data and recommended the best values along with the rationale behind each recommendation and the uncertainty for a



### -52-Table 14.A. Comparison of the Estimated Values of kOH at 298 K for Saturated Acyclic Alkanes from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data Reported in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Methane

-

44 - $a

- k 0.00841 0.00836* 0.00841b (c) Ethane ?q-g 4 k°o 0.268 0.268* 0.288 0.288 Propane 74. , q T-to 1.15 1.15 * 1.21 1.21 H-Butane 2.54 2. 54* 2.53 2.53 2-Methylpropane

~ S a g" ~ 2.34 2.34* 2.39 2.39 n-Pentane lb9-& 6- 3.94 3.94* 3.93 3.93 2-Methylbutane 3.90 3.9* 4.00 4.00 2, 2 -D imethy 1propane 0.849 0.849* 0.743 0.743 n-Hexane 3 5.61 5. 61* 5.32 5.32 2-Methylpentane 107 - 8 3- S 5.60 5.6* 5.39 5.39 3-Methylpentane 

## v 5.70 5.7* 5.77 5.77 2,2

- 

### Dimethylbutane 75

- 83

- 2 2.32 2.32* 1.82 1.83 2, 3 -Dimethy lbutane 7y-a C)- F 6.20 6.2* 5.46 5.46
n

- Heptane 

### IyV

- 

### 8a

- s' 7.15 7.15* 6.72 6.71 2,2-Dimethylpentane

~ 'JO' 3 S"a 3.37 3.37d 3.22 3.22 2,4-Dimethylpentane 5.16 5.16d' 6.86 6.85 2, 2, 3-Trimethylbutane , V6zf- 0

~ O-2. 4.23 4. 23* 3.29 3.30 n-Octane ///

-- 10.5 - ~ 8.68 8. 68* 8.11 8.11 2,2-Dimethylhexane 5gO- -:T3-S' 4.83 4.83d 4.61 4.61 2, 2, 4 

### -Tr imethy 1pentane 5 4 /0

- Ey -/ 3j 3.68* 4.68 4.68 2,3,4-Trimethylpentane ~ 6.97e 8.70 8.70 SGS-

~ 5

-- 3

M*CTable 14.A. Continued

10 12 k (cm 3 molecule

- ls -1 ) 

### Experimental Estimated Chemical AOP ( a) AOP HC 2,2,3,3-Tetramethylbutane 1.08 1.08* 1.11 1.11 g-Nonane 10.20 10.2* 9.51 9.50 2-Methyloctane 10.1 10.1d 9.58 9.58 4-Methyloctane 9.72 9.72d 9.95 9.95 2,3,5-Trimethylhexane/u&) -s3-0 7.88 7.88d 10.1 10.1 n-Decane la q- /fS = ,S 11.6 11.6* 10.9 10.9 D-Undecane //a a - o2/ - ~ C' I H.) y 13.2 13 . 2* 12.3 12.3 n-Dodecane l l a --

ya - 3 14.2 14 . 2* 13.7 13.7 n-Tridecane 6 , 9 y - SO

- ' 16.0 16* 15.1 15.0 n-Tetradecane 

### &aq

- ,;9

- `f 19.2 19.2* 16.5 16.5 n-Pentadecane 6 aq -- Co a 22.2 22.2f 17.9 17.9 n-Hexadecane 24.9 24.9f 19.3 19.3

a Experimental values from Atkinson (1989) and the literature. 

### b Estimated value is based on the measured value. c Cannot be estimated by the S/R methods of Atkinson. a Experimental value from Behnke et al. (1988). d 

### Experimental value from Atkinson et al. (1984). e Experimental value from Harris and Kerr (1988). f Experimental value from Noltinq et al. (1988).

-54-5

.~ ~

~

~ a a • Table 14.B. Comparison of the Estimated Values of kOH at 298 K for '= Saturated Cyclic Alkanes from the Atmospheric Oxidation

Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data Reported in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Cyclopropane 0.07 0.071b 0.0711 0.0711 &96- .1-Propylcyclopropane 2.84 2. 84c 2.85 2.85 Cyclobutane 1.20 1.2d 1.23 1.23 Cyclopentane 5.16 5.16* 5.58 5.58 Cyclohexane //c)- 8a-° 7.49 7.49* 8.37 8.37 Methy lcyc lohexane / o$'- a 10.4 10.4e 10.2 10.2 1,1,3-Trimethylcyclohexane 8.73 8.73f 9.18 9.18 3 0 7 - 3-& ( ." 3 Cycloheptane 12.5 12.59 9.76 9.77 

### Cyclooctane 99a-& 4-*r 13.7 13.7h 11.2 11.2 Bicyclo [2.2.1] heptaneM

- 23 -2 5.49 5.49 1 9.49 9.49 Bicyclo [ 2. 2. 2] octane 2f

~ o- 33-I 14.7 14.7i 16.2 16.2 Bicyclo [3.3.0] octane69y g ~~ y 11.0 11.0 1 10.4 10.4 

### cis -Bicyclo [4.3.0] nonane 17.2 17.2 1 14.1 14.1 

### trans -Bicyclo [4.3.0] nonane 17.6 17.6 1 14.1 14.1 

### cis -Bicyclo [4.4.0] decane 19.9 19.9 1 19.0 19.0

- /930/_ c

~ oN

~ e 

### trans -Bicyclot4.4.0]deoane 20.4 20.4 1 19.0 19.0

/F

~ 7:3- c~ -'~ C Tricyclo [5.2.1.0 2,6 ] decane 11.3 11.3 1 12.3 12.3 

### Tricyclo [3.3.1.1 3,7 ] decane 22.6 22.67 24.1 24.1

a Experimental values from Atkinson (1989) and the literature. b Average value from the experimental data of Zetzsch (1980) and Jolly et al. (1983). 

### c Experimental value from Atkinson and Aschmann (1988). d Experimental value from Gorse and Volman (1974). e Experimental value from Atkinson et al. (1984). f Experimental value from Behnke et al. (1988) as reported in Atkinson (1989). g Average value of the experimental data of Zetzsch (1980) and Jolly et al. (1985). 

### h Experimental value from Behnke et al. (1988) as reported in Atkinson , (1989). 

### 1 Experimental value from Atkinson, Aschmann, Carter (1983a). 7 Average value from the experimental data of Atkinson, Aschmann, and Carter (1983a) and Behnke et al. (1988). * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

M&C

### each recommendation. These recommended values have an asterisk

after each value. In general, the experimental values of k O H listed in AOP are the same as those obtained by Leifer; there are, however, a few differences. For methane, the recommended Atkinson value is 0.00836* while AOP lists 0.00841. For 2,3,4-trimethylpentane, the kOH value of 6.97 was obtained by extrapolation of the data and Kerr (1988) and appears to be the best value. The best value of k O H for cyclopropane should be 0.071 as obtained by averaging the data of Zetzsch (1980) and Jolly et al. (1985) rather than the value of 0.07 listed in AOP. For a few compounds, the incorrect number of significant figures was cited by AOP; the recommended values list two significant figures whereas AOP lists three significant figures. For example, for 2-methylbutane, the Atkinson recommended value is 3.9* while AOP lists 3.90. For cyclobutane, the value of kOH reported by Gorse and Volman (1974) and Atkinson (1989) is 1.2 and not 1.20 as listed in AOP. The experimental kOH data of Gorse and Volman is only good to two signif icant f igures . 

### It should be noted that the names of two tricyclic decanes {tricyclo [5.2.1.0] decane and tricyclo [3.3.1.1] decane} entered in AOP are incorrect. The correct names should be tricyclo [5.2.1.0 2 . 6 ] and tricyclo [3.3.1.1 3 j] decane since the superscript numbers on the last digit must be specified to identify the bridgehead carbons on the last ring. Finally, the a~

-56-

### name of inethylcyclohexane is the correct name and not

1-methylcyclohexane as listed in AOP.

IV.C.l.b. Evaluation of the Estimated kOH Data A preliminary evaluation of the AOP computer program [Meylan (1990a)] in July 1990 indicated that for some bicyclic and tricyclic alkanes, the method of estimating kOH in AOP was incorrect. The AOP computer program did not use the ring strain factors [F(3), F(4), F(5), or in Meylan's notation RS3, RS4, RS5] correctly in the calculations. The discrepancies were discussed with Meylan by phone and a set of the calculations were sent to him for evaluation. As a result, Meylan (1990b) revised the AOP computer program for these types of compounds to accurately reflect the Atkinson S/R relationships for strained ring compounds [Version 1.30, November 1, 1990]. In evaluating the estimated values of k OH by AOP and HC, a few comments can be made about the number of significant figures used. In general, the summary table in AOP lists the estimated kOH with a maximum of 

### six significant figures and the detailed calculations list k(la) or k(ic) with a maximum of five significant figures. However, the group rate constants kp, k s , and k e , [or kprim• ksec• and ktert in Meylan's notation] and the substituent factors F(CH3-), F(-CH2-), and F(>C<) are, at best, known to three significant figures. Therefore, it is recommended that AOP show the detailed calculations with four significant figures and list k(la) or k(ic), or k(la) + k(lc), and kOH in the ,



### -57-

### summary table rounded off to 3 

### significant figures. These

comments on the use of an excessive number of significant figures apply to all classes of chemicals and specific chemicals. Comparison of the estimated values of k OH from AOP with those from HC 

### (after rounding off all estimated values to three significant figures) in the last two columns in Tables 14.A. 

### and 14.B. indicates that, except for methane, the values are essentially the same. The trivial differences in the last digit are due to the method of rounding off the last digit in HC. 

### For methane, AOP lists a value of 0.00841 

### which is the experimental value [which really should be 0.00836* 

### as recommended by Atkinson] whereas HC does not list a value; kOH cannot be estimated by the S/R 

### relationships of Atkinson for this compound. The number of significant figures for RS3, RS4, 

### and RS5 

### for strained rings is incorrect. For example, for cyclobutane, RS4 = 0.22000 

### is used in the detailed calculation section. However, for RS4, 

### Atkinson listed it as 0.22. 

### The detailed calculations for H-atom abstraction are somewhat confusing when the ring strain factor is used. For example, for bicyclo [2.2.1] heptane, AOP gives

ksec 

### = 0.838 F(-CH2-)F(>CH-)(RS5)(RS5)

= 0.838(1.29)(1.29)(0.64) = 0.892



### It seems to me that a more consistent notation for RS5 

### would be (RS5) 2 =(0.80) 2 

### rather than (RS5)(RS5) = 0.64. 

### Therefore, ksec

-58-should read

ksec.= 0•838 F(-CH2-)F(>CH-)(RS5) 2 = 0.838 (1.29)(1.29)(0.80) 2 = 0.892

or

ksec a 0.838 F(-CH2-)F(>CH-)(RS5)(RS5)

= 0.838(1.29)(1.29)(0.80)(0.80) = 0.892

IV.C.2. Haloalkanes IV.C.2.a. Evaluation of the Experimental kOH Data Table 15 summarizes the pertinent experimental kpg data at 298 K for the reaction of OH radicals with haloalkanes as reported in AOP, in Atkinson (1989), and in the literature. In general, the literature values listed in the column Experimental/(a) are the same as those in the column Experimental/AOP; there are, however, some differences. For 1,1,1-trifluoroethane, AOP lists a value of 0.017, a ten-fold higher value than the correct value of 0.00171 from Martin and Paraskevopoulos (1983) and Atkinson (1989). [Please note that these values are listed in the units 10 -12 cm 3 molecule

- is -1 rather than 10 -14 cm 3 molecule

- ls -1 as listed in Table 15; see footnote 5, page 42.] For 1,1,2-trichloroethane, the extrapolated value from the data of Jeong and Kaufmann (1979) and Jeong et al. (1984) obtained by Leifer is 0.324 while AOP lists a value of 0.328. For three haloalkanes, AOP does not list an experimental value -59- x .

k. ;:Table 15. Comparison of the Estimated Values of kOH at 298 K for Haloalkanes ,

from the Atmospheric Oxidaticn Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kQH Data Reported in the Literature Versus the Experimental kOH Data in AOP

10 14 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Fluoromethane ,593 - s 3 " =) 1.68 1. 68 * 1.43 1.43 Chloromethane 7.41 °8' .7- 3 4.36 4. 36* 5.47 5.47 Bromomethane,7y-g3-y 4.02 4.02* 4.32 4.32 Difluoromethane 7,1 - /0

- 6 - 1.09 1. 09* 0.82 0.821 Fluorochloromethane 30- 4 4.41 4.41* 3.15 3.15 Dichloromethane 14.2 14.2* 12.1 12.1 Tr i f luoromethane 1,~ -y& 0.024 0. 024b 0.18 0.178 Difluorochloromethane 75'-N5

- w 0.468 0.468* 0.682 0.682 Fluorodichloromethane 75-Y3-4/ 3.03 3.03* 2.62 2.62 Trichloromethane 

### 67

- "-3 10.3 10.3* 10.0 10.0 Fluoroethane 35.3

- .3G- 23.2 23.2c 20.5 20.5 Chloroethane -7,5=o0- 3 39 39* 40.1 40.0 1,1-D i f luoroethane 3.4 3. 4* 3.23 3.23 1,2-Difluoroethane 70--(a 11.2 11.2d 14.1 14.1 1,1-Dichloroethane-7s 

## -3y-3 26 26. Oe 34.6 34.6 1,2-Dichloroethane 

### /0 7-U0 a 22 22.0e 36.3 36.3 1, 2-Dibromoethane /06 _ 93- 4l 25 25. Oe 28.7 28.7 1,1,1-Trifluoroethane4/ao- 4 16-, ~ 1.7 0.171d 1.08 1.08 1, 1, 1-Trichloroethane 

### 3/-SS=Ca 1.19 1.19* 1.30 1.30 1,1-Difluoro-l-chloroethane 0.358 0.358* 0.36 0.360 €~ 1,1,2-Trifluoroe

~s-~ h . ane 

### o'06'V 1.8 1.83 d 2.35 2.35 1, 1, 2 -Tr ichloroethane 

### q - oO

- S S 32.8 32.4f 33.2 33.3 1,1,1,2-Tetrafluoroe 6 thane_ a 0.854 0.854* 0.62 0.622



### ~ 1-Chloro-2,2,2-Trifluoro 1.62 1.62* 2.39 2.39 ethane 1,1,2,2-Tetrafluoroethane (j) 0.679 0.36 0.359

3s1-35 3

-60-D ♦ - Table 15. Continued

10 14 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Pentafluoroethane-35-y--'''-(

~ '

~~ NFS 0.25 0.249d 0.13 0.135 1-Chloro-1,2,2,2-Tetrafluoroethane 1.02 1.02* 0.52 0.516
c~ ~ 6.3'

~~ 7- e

~ c~i-~ F 1,1-Dichloro-

~ ,2,2-Trifluoroethan e 3.35 3.35* 1.98 1.98 30(o- 83"s;t Cc26fCQsF3 43.5k 1,2-Dibromo-3-chloropropane

~ -/a- ~ 44 50.3 50.3 2-Chlorobutane qg-86--y (j) 230 1 164 164 2, 3-Dichlorobutane ?.Sg) - (j ) 96 1 95.7 95.7



### a Experimental values from Atkinson (1989) and the literature. b since the experimental data was obtained at temperatures > 387 K, the value at 298 K should be used with caution [Atkinson (1989)]. c Experimental value from Nip et al. (1979). d Experimental value from Martin and Paraskevapoulos (1983). e Experimental value from Howard and Evenson (1976). f Extrapolated from the experimental data of Jeong and Karfmann (1979) and Jeong et al. (1984). g Extrapolated from the experimental data of Clyne and Holt (1979). h Experimental value from Tuazon et al. (1986). 1 

### Experimental value from Mill et al. (1982). j No experimental value given in the AOP data base. * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-61-

### (i.e., for 1,1,2,2- tetrafluoroethane, 2-chlorobutane, and 2,3-

dichlorobutane). For six compounds, the literature values have three significant figures while AOP lists two significant figures [e.g., for 1 1 1-dichloroethane, the literature value of Howard and Evenson (1976) is 0.260 while AOP lists 0.26].

IV.C.2.b. Evaluation of the Estimated k OH Data A comparison of the estimated values of kOH by AoP with HC in Table 15 indicates that they are essentially the same. The only differences being that in a few cases, AOP rounds off the estimated values to two significant figures. The estimated values of k O H are good to three significant figures. For example, 

### for trifluoromethane, the estimated value of k OH by HC is 0.178, while AOP rounds it off to 0.18.
IV.C.3. Carbonyl Compounds IV.C.3.a. Evaluation of the Experimental kOH Data Table 16 summarizes the pertinent experimental k OH data at 298 K for the reaction of OH radicals with 57 carbonyl compounds as reported in AOP, in Atkinson (1989), and in the literature. These carbonyl compounds can be divided into several classes of compounds: il aldehydes, 19 ketones, 3 c-dicarbonyls, 1 acyl halide, 18 esters, and 5 carboxylic acids. First, consider all the compounds except the carboxylic acids. In these classes of compounds, 12 of them listed by AOP had experimental k Og data with two significant figures. If the original literature sources and Atkinson (1989) are checked, a11 the k OH data are listed with three significant figures (e.g., formal, 3-hexanone, n-butyl r =

s



### -62-, s

~

Table 16. Comparison of the Estimated Values of k OH at 298 K for Carbonyl

Compounds from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kQH Data Reported in the Literature Versus the Experimental k OH Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP($Error)o HC A. ALDEHYDES

Formal 5

-

0

- 00 - O 9.7 9.77* 7.37 7.37 Ethana 1'7S

- C~ ~ - u' 15.8 15 . 8* 16.2 16.2 Propanal 1 , 23° 3 9 "& 19.6 19. 6* 22.0 22.0 Butanal /,)3- ;4z-_

.? 23.5 23.5* 25.5 25.5 2-Methyl Propanal 75 26.3 26.3* 23.4 23.4 Pentanal 110 -.3 28.5 28 . 5* 27.6 27.6 3-Methylbutanal 

### Sqp - 6( 0 - 3 27.4 27.4* 30.0 30.0 2, 2-Dimethylpropanal 6-1)- a'9 J,3 26.5 26. 5* 22.7 22.7 Trichloroacetaldehyde 

### 15 -- 8-7-!0 1.73 1.73a' 1.45 1.45 Hydroxyethanal / ~~- ~~,-~ 9.9 9.9b 23.0 23.0 (Glycolaldehyde) Pentane-1,5-Dial 

### 111-3o-g 23.8 23.8c 46.9 46.9

B. ACYCLIC KETONES
Propanone &7

- 6 4 1 -1 0.226 0.226* 0.219 0.219 2-Butanone 1.15 1. 15* 1.38 1.38 2-Pentanone 4.9 4.9* 4.80 4.81 3-Pentanone 2.0 2.0* 2.54 2.55 2-Hexanone 9.1 9.1* 6.95 6.96 3-Hexanone 5gg- -

;Jg-v 6.9 6.90d 5.97 5.97 4-Methy1-2-pentanone 14.1 14.1* 9.35 9.35 3, 3-Dimethyl-2-butanone

~ s c ~~

__ ~ , 1.21 1. 21e 2.01 2.01 2-Heptanone 110-43-0 8.67 8.67e 8.35 8.35

-63-Table 16. Continued

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/C mical AOP (a) AOP($Error)o HC
2,4-Dimethyl-3-pentanone 5.38 5.38d 5.32 5.31 2-Octanone 3 - /



### ~ , 10.0 11.0e 9.74 9.74 2-Nonanone 12.2 12.2e il. i 11.1 2,6-Dimethyl-4-heptanone` 27.5 27.5* 18.5 18.5 2-Decanone

~~

j_3 -- .S ~ ~~ 13 . 2 13 . 2 e 12.5 12.5 2,4-Pentanedione 1.15 1.15f 0.703 0.703 2,5-Hexanedione //D -/,3- 4 / 7.13 7.13f 5.82 5.82

C. CYCLIC KETONES
Cyclobutanone /1 q1 - 9S' 0.87 0.87f 1.17 1.17 Cyclopentanone/ 9U- c ?a
- 3 2.94 2.94f 8.92 8.92 Cyclohexanone /og_ 9

~ (- / 6.39 6.39f 12.6 12.6

D. ac-DICARBONYLS
Glyoxal 11.4 11.4* 24.5 24.5 Methylglyoxal 17.2 17.2* 12.3 12.3 Biacetyl q31- 0.3-$ 0.238 0.238* 0.219 0.219

E. ACYL CHLORIDES
Acetyl chloride 

### -7.S- 3(o-S 0.068 0.0689 0.0720 0.0720

F. ESTERS
Methyl formate /O:T-,3/-3 0.23 0.227h 0.216 0.216 r ;

-64-

### Table 16. Continued

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical C las /Chemical

' 

# ~ AOP (a) AOP(%Error)o HC Ethyl formate 109-9L
~ -41 1.0 1.02h 1.44 1.44 n-Propyl formate //0- L/ -7 ~ 2.4 2.38h 2.89 2.89


### n

- 

### Butyl formate J L 3.1 3. 12h 4.28 4.28 Methyl acetate 0.34 0.341 1 0.216 0.216 Ethyl acetate /q/

- 7$

- (0 1.6 1.6* 1.44 1.44 n-Propyl acetate /09-0 0-4 4 3.4 3.4* 2.89 2.89 i-Propyl acetate 3.4 3.4* 3.12 3.12 }1-Butyl acetate 4.2 4. 2* 4.28 4.28 $-Butyl acetate /o,5 --4 40 -4 i (n) 5.5* 4.99 4.99 Ethyl propionate 2.1 2.14 1 1.63 1.63 }1-Propyl propionate /U&

- 3 4
~ 1 S 4.0 4.02h 3.08 3.07 Methyl butyrate (p03'
~ O -7- 3.0 3. 04h 1.48 1.48 Ethyl butyy(rate 105 - S`f' `1 4.9 4. 94h 2.71 2.71 n-Propy 1 butyrate /ciS 'Ga 4-&' 7.4 7. 41h 4.16 4.16 n-Butyl butyrate 

### ln2- a)

-- ~ - 10.6 10.6h 5.55 5.55 Ethoxyethyl acetate///-/S

- g 13.0 13h 1 14.0 14.0 Methyl trifluoroacetate
4 131 -- ~~ 

### - v 0.05 0.052h 0.216 0.0518



### G. CARBOXYLIC ACIDS

Formic acid 1 $

- 4 , 0.45 0.45* 0.4367 (-3) (k) Acetic acid (o 4 1- /y

- 3'" 0.74 0.74 1 0.145 (-80) (k) Propionic acid :79-pg-1 1.22 1.22 1 0. 859 (-30) (k) L -Butyric acid 9Z- 2.4 2.4m 2.12(-12) (k) .i-Butyric acid 2 2.00 2.00 1 1.80 (-10) (k)


### a Experimental values from Atkinson (1989) and the literature. a
~ 

### Experimental value from Nelson et al. (1984) as reported by Atkinson (1989).

-65-

### Table 16. continued

b 

### Experimental value from Niki et al. (1987) c 

### Experimental data from Rogers (19891. This value of k O H represents the average value of 25.2 and 22.4x10 -1 cm 3 molecule

- ls -1 as measured with the reference compounds propene and 

### trans -2-butene, respectively. d Experimental value from Atkinson et al. (1982). e Experimental value from Wallington and Kurylo (1987). f Experimental value from Dagaut et al. (1988). g Experimental value from Atkinson (1987). h,Experimental value from Wallington et al. (1988). h Experimental data from Hartmann et al. (1986, 1987) as reported by Atkinson (1989). 1 

### Experimental value from Wallington et al. (1988). The data from Campbell and Par'Cinson (1978) was not used since the experimental method was probably not valid/Atkinson (1989)].

~ 

### Estimated by [Meylan (1990b)] assuming that k(HCOOH **) was 0.400. k Atkinson did not develop S/R relationships for carboxylic acids. 1 

### Experimental value from Dagaut et al. (1988b). The rate data of Zetzsch and Stuhl (1981) as reported in Atkinson (1989) is subject to significant uncertainties; hence it should not be used [Atkinson (1989)]. m Experimental value from Zetzsch and Stuhl (1981) as reported in Atkinson (1989). This value is subject to significant uncertainties and must be used with extreme caution [Atkinson (1989)]. n No experimental value is given in the AOP data base. A value of 5.5x10 -12 cm 3 molecule

- is -1 is given in the document "Estimated Accuracy of AOP versus PCFAP. o Based on the experimental values of k0U listed in column Experimental/(a). * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-66-

### formate, methyl butyrate). For ethoxyethyl acetate, AOP lists

the experimental value of kOH with three significant figures while Atkinson (1989) and Hartmann et al. (1986, 1987) list it with two significant figures. For 2-octanone, AOP lists a value of kOg of 10.0 while Wallington and Kurylo (1987) and Atkinson (1989) list a value of 11.0. For _q-butyl acetate, AOP does not list a value in the data base; from the document "Estimated accuracy of AOP versus PCFAP, AOP does list a value of 5.5 for this compound. The recommended value by Atkinson (1989) is 5.5*. Experimental k O H data listed in Table 16G. are available for a few alkyl carboxylic acids --- formic, acetic, propionic, and }1- and i-butyric acids as obtained from Atkinson (1989) and the literature. The k O H data from Zetzsch and Stuhl (1981) for acetic, propionic, and D,-butyric acids had very large uncertainties since the vapor pressures of these compounds were unknown. Hence, these data should not be used [Atkinson (1989)]. The experimental kOH data for acetic, propionic, and i-butyric acids were obtained from a single source [Dagaut et al. (1988)]; hence, these data should be used with caution until additional kOg data are obtained from other researchers to corroborate the assignments. It should be noted that for the aldehydes, the incorrect names are used in the AOP data base. Since, the aldehyde functional group can only be at the end of the alkyl chain, there is no need 

### to specify its position with a number. ®



### a-IFCs

~ r



### IV.C.3.b. Evaluation of the Estimated kOH Data A comparison of the estimated values of kOH reported by AOP with those from HC in Table 16 indicate that they are essentially the same except for methyl trifluoroacetate and the carboxylic acids. For most of these compounds, the differences are trivial and are due to the method of rounding off the third significant figure. For methyl trifluoroacetate, the estimated value of kOH in AOP is 0.216 in contrast to the estimated value of 0.0518 in HC from Leifer. The apparent error is due to the effect of the 

### very electrophilic group -CF 3 on the substituent factor F[-OC(0)R]. Leifer (1991a) derived a substitutent factor

F[-OC(0)CF 3 ] = 0.36 (31)


### which gives an estimated value of 0.0518. Therefore, it is recommended that the substituent factor listed in 31 be used in the AOP computer program and in Table 2. There are problems with the S/R relationships of Meylan (1990b) for the class of carboxylic acid compounds which will be described in the following paragraphs. For the alkyl carboxylic acids, Atkinson did not develop S/R relationships while Meylan (1990b), in AOP, did develop S/R relationships. For these compounds, two reaction pathways were postulated by Meylan: H-atom abstraction from an alkyl group and H-atom abstraction from the OH group. Therefore, for these two reaction pathways,

=.I- *]=R(=0)OH +•OH k(i) = k(la) 

## .R C(=0)OH + HOH (32)

k(2) = k(-OH) RC(=0)OH + •OH RC(=0)O• + HOH (33)
where R" is an alkyl free radical [i.e., •R I or for formic acid, it is •C(=0)OH]. The overall rate of reaction with hydroxyl radicals is then

kOH = k(1) + k(2) = k(la) + k(-OH) (34)
and Meylan assumed that reaction pathway 32 was the dominant pathway [i.e., k(la) > k(-OH)]. Therefore, Meylan used the group rate constant k(-OH) = 0.036, derived from the alcohols; and the rate constant k(la), for H-atom abstraction from the alkyl group, was calculated in the standard manner using the S/R relationship of Atkinson. These results were then used in equation 34 to calculate kOH. For formic acid, Meylan (1990b) assumed that

k(la) = k[HC(=0)OH ** ] = 0.400 (35)

so that
kOg (formic acid, estimated) = 0.436 (36)

and this result is listed in the fourth column of Table 16. The values of kOg (estimated) for the other carboxylic acids are calculated in the standard manner in AOP and these results are listed in Table 16. The percent error for these compounds, based

-69-

### on the experimental values of k O g listed in the column

Experimental/(a), are listed in parentheses in the column Estimated/AOP. Inspection of these results indicate that kOH (estimated) for acetic acid was very poor (an error of -80%). On the other hand, the average percent error for the other carboxylic acids was -14 which is excellent. Atkinson (1989) reviewed the available kOg data for the reaction of OH radicals (or OD radicals) with formic acid (or deuteroformic acids) over the temperature range 297-445 K. Based on the experimental data of Wine et al. (1986) and Singleton et al. (1986) for the reaction of OH radicals with HC(0)OH and DC(0)OH and OD radicals with HC(0)OD and DC(0)OD, Atkinson (1989) concluded that the major reaction pathway was H- or D-atom abstraction from the -OH(or-OD) groups. This contradicts the assumption of Meylan (1990b) in AOP; that is, k(-OH) = 0.036 and reaction 33 is the minor reaction pathway. Furthermore, as stated in Section IV.C.3.a., the experimental kOH data for these carboxylic acids are available from a single source and the kOH data for acetic, propionic, and butyric acids have large uncertainties so that these data must be used with caution. Considerably more experimental kOH data are needed for these carboxylic acids and for additional compounds in this class before reliable S/R relationships can be developed. It should be noted that for formic acid, the detailed calculation for H-atom abstraction from formic acid is listed in

-70-

### AOP as k[HCOOH **] = 0.400 (Measured). The molecular structure

for formic acid is [HC(=0)OH] and not HCOOH.
IV.C.4. Alcohols, Glycols, Ethers, and Hydroperoxides IV.C.4.a. Evaluation of the Experimental k O H Data Table 17 summarizes the pertinent experimental k O g data at 298 K for the reaction of OH radicals with 16 alcohols, 3 glycols, 26 acyclic ethers, 10 cyclic ethers, and 2 hydroperoxides as reported in AOP, in Atkinson (1989), and in the literature. Inspection of the experimental kO H data listed in columns 2 and 3 indicate that five compounds have differences. The differences in four of these compounds are related to the number of significant figures used. Inspection of the original literature references and the data in Atkinson (1989) clearly indicated that the preferred values are listed in the column Experimental/(a). The experimental values for 1-chloro-2,3- epoxypropane are different; the preferred value listed in the third column represents the average value from the experimental kpg data of Zetzsch (1985) and Edney et al. (1986) assuming that kOH = 0.55 of Edney.
IV.C.4.b. Evaluation of the Estimated kpg Data Comparison of the estimated values of kpg from AOP and HC for the alcohols, glycols, and ethers indicates that they are essentially the same. The trivial differences are due to the method of rounding off the third significant figure in HC. 

# _'.

-71-a t ~

c Table 17. Comparison of the Estimated Values of kOH at 298 K for Alcohols,

Glycols, Ethers, and Hydroperoxides from the Atmospheric Oxidation Computer Proqram (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental kOH Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) 

### Experimental Estimated Chemical Class/Chemi al AOP (a) AOP(%Error)m HC A. ALCOHOLS

Methanol 0.932 0.932* 0.526 0.526 Ethanol ~, c~ ~-/ ~~°~" 3.27 3. 27* 3.07 3.08 1-Propanol -7 1- a 3 5.34 5. 34* 4.98 4.99 2-PropanolX 5.21 5.21* 6.63 6.63 1-Butanol =7 I5&"` -

3 8.3 8. 31b 6.37 6.38 2-Methyl-2-Propanol&'3

- b.`)" C ' ) 1.12 1.12* 0.593 0.593 1-Pentanol 10.8 10.8c 7.77 7.77 2-Pentanol 6v-3V

- ~ 9'" + 11.8 11. 8d 10.9 10.9 3-Pentanol -U P° r 12.2 12.2d 12.9 12.9 3-Methyl-2-butanol 59$• :75

- 4 12.4 12.4d 11.0 11.0 1-Hexanol 12.4 12.4d 9.17 9.17 2-Hexanol 12.1 12.1d 12.3 12.3 1-Heptanol /// -:7(}- Co 13.6 13.6d 10.6 10.6 2-Chloroethanol /0

~ • o 1.4 1.4 2.07 2.07 1-Hydroxy-2-propanone

~ _3 r+ln u

~ , Cyclopentanol

~ jp-'//" ~ 3.02 10.7 3.02e

10. 7d 2.31

12.8 2.32

12.7

B. GLYCOLS
1, 2-Ethanediol ' 5'vo" 40 3-0 7.7 7.7 7.42 7.42 1,2-Propanediol 12.0 12 12.0 11.9

-72-Table 17. Continued

10 12 k (cm 3 molecule

- ls -1 )

Chemical Clas /Chemical Experimental Estimated AOP (a) AOP($Error)m HC C. ACYCLIC ETHERS
Dimethyl ether 2.98 2.98* 1.76 1.76 Diethyl ether

~ p-ac7 ~-~. 13.3 13.3* 11.5 11.5 Di-n-Propyl ether ///-y3-3 17.2 17 . 2* 21.1 21.1 Methyl- j t-butyl ether 

### 1(p3q-oLf-4 2.83 2.83* 2.82 2.82 Methy 1-n-buty 1 ether G,;) S 16.4 16.4d 13.6 13.6 Ethyl-n-butyl ether C ~ ~- ~~- ~ 18.1 18.1f 18.5 18.5 Ethyl- j t-butyl ether ~~ ~„y~ 3 6.9 6.88f 7.70 7.20 Methyl- j t-amyl ether 

### 99 4- O5 -- g 7.91 7.91d 6.13 6.13 Di-n-butyl ether 

### /j
~ 

### a. -go- 22.4 22.4f 25.5 25.5 D i-.i-buty l ether Gae^-

~ S T "

~ ' 26.0 26.Og 30.4 30.4 Di-n-pentyl ether & ) 1/ 2 )- &!:1 5-- ' :: ~ 34.7 34 .7d 28.2 28.2 1,1-Dimethoxy ethane

~ 3'-/- /S(o 8.89 8. 89e 13.1 13.1 Diethoxymethane 

### M&V-VI5 °3 16.8 16.8e 16.6 16.6 1, 2 -D imethoxypropane 7q-jg -$5-O 14.3 14.3e 22.9 22.9 2, 2-Dimethoxypropane 

### -71

- -76

- 9 3.92 3. 92e 3.05 3.05 2, 2-Diethoxypropane /.) 6 - aq- ) 11.7 11.7e 12.8 12.8 2-Methoxyethyl ether -,

~ ' -=1g 17.5 17.5e 28.1 28.1

1//-9w-Co t

~ kiyv

~ 3 1, 1, 3 -Tr imethoxypropane

~ -U 19.2 19.2e 28.5 28.5 2-Ethoxyethyl etherX 26.8 26.8e 37.9 37.8 Methoxy acetone, ~~ I - fi

- /`~ - -' ~ 6.77 6.77e 4.87 4.87 2-Methoxy ethanol 109-9'&- q 12.5 12.5e 11.2 11.2 2-Ethoxy ethanol // ~ -~O- ~ 15.4 15.4h 16.1 16.1 3-Ethoxy-l-propanol 1I1

- j~)

-- 3 22.0 22.0e 20.9 20.9 3-Methoxy-l-butanol ~~~~-1~ C3_ 3 23.6 23.6e 20.6 20.6 2-Butoxy ethanol ///- f6 18.6 18.6h 23.0 23.0 1 j

-73-S ~ 

### Table 17. Continued

10 12 k (cm 3 molecule

- is -1 ) Experimental Estimated Chemical Class/Chemica AOP (a) AOP($Error)m HC 2-Hydroxyethyl ether %// -1 4,- 6 

### (Dihydroxyethyl ether) 30.0 30 20.6 20.6

D. CYCLIC ETHERS
Ethylene oxide 0.076 0.076* 0.224 0.224 

### 1,2

- 

### Epoxypropane (propylene oxide) 

### S S

(o-y 0.052 0.52* 0.543 0.543 1-2 -Epoxy butane (1 ~ 2- - 7-

- - 3 Z ~ Butylene oxide) r y~~ ~ ~ 2.1 2.1 1.69 1.69 1-Chloro-2, 3-e o

p xypropane 0.44 0.50 i 0.662 0.662 

### Trimethylene oxide5,03 -.30" 0 10.3 10.3e 3.73 3.73 Tetrahydrofuran 

### 169-9 y- 9 16.1 16 .1* 18.3 18.3 1, 3-Dioxane 

### stj ,j ~ 

## aa - lo 9.15 9.15e 22.1 22.1 1,4-Dioxane 

### j

o ?,3- y/- ~ 10.9 10.9e 26.4 26.4 1,3,5-Trioxane 6.2 6.2i 15.3 15.3 Oxepane (Hexamethylene oxide) 15.4 15.4e 25.7 2.57



### 5%9, -- 90 .s" E. ALKYL HYDROPEROXIDES
Methyl hydroperoxide 3o31- Y3

- 0 5.54 5.54* 7.24(+31) (1) -t-Butyl hydroperoxide 

### 9 4 1- 2&

- 8 3.0 3.0k 1.98(-34) (1)

a Experimental values from Atkinson (1989) and the literature. b Experimental value from Wallington and Kurylo (1987a). The data from Campbell et al. (1976) was not used since the validity of the experimental method is questionable [Atkinson (1989)]. c Experimental value from Wallington and Kurylo (1987a). d Experimental value from Wallington et al. (1988b).

-74-1 •

1
y ~ 

### Table 17. continued
e Experimental value from Dagaut et al. (1988a). f Average value from the experimental data of Wallington et al. (1988b) and Bennet and Kerr (1989). g Experimental value from Bennett and Kerr (1989). h Experimental value from the experimental data of Hartmann et al. (1987) and , Dagaut et al. (1988a). 1 Average value from the experimental data of Zetzsch (1980) and Edney et al. (1986) assuming kOH = 0.55x10' 12 cm 3 molecule

- is -1 of Edney. 

### 7 Extropolated from the experimental data of Zabernick et al. (1988). k Experimental value from Anastasi et al. (1978). 1 

### Atkinson did not develop S/R relationships for alkyl hydroperoxides. m Based on the experimental values of kpU listed in column Experimental/(a). * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

/

-75-.~

~ 3 

### There are, however, problems with the S/R relationships for the alkyl hydroperoxides in AOP which will be described below. For the alkyl peroxides [RCOOH], Atkinson did not develop S/R relationships while Meylan (1990b), based on the experimental kOg data of inethyl and _t-butyl hydroperoxide, did develop S/R relationships. For alkyl peroxides, two reaction pathways were postulated by Meylan: H-atom abstraction from the alkyl group and H-atom abstraction from the hydroperoxy groups. Therefore,



### _ RCOOH + •OH (1) (la) .R I COOH + HOH (37)

k(2) = k(-OH) 

### RCOOH +

~ 

### OH ROO• + HOH (38)
where R is an alkyl group and •R' is an alkyl free radical group. The overall reaction with OH radicals is then

kOH = k(1) + k(2) = k(la) + k(-OH) (39)


### and reaction pathway 37 was considered by Meylan (1990b) to be the dominant reaction pathway. Therefore, Meylan assumed that k(-OH) = 0.036 and 

### F(-0-0- ** ) = 50 (40)


### and k(la) and kOH were calculated in the standard manner. For methyl and t-butylhydroperoxides, the estimated values from AOP were 7.24 and 1.98, respectively. The percent error for these two compounds, based on the experimental values listed in column Experimental/(a), were +31 and -34, respectively, and these 

### -76-s•

~ i 

### results were very good. However, these results, and the S/R

relationships of Meylan must be evaluated very carefully in the light of the experimental kOg data as described in the following paragraphs. Atkinson (1989) analyzed the experimental rate data of Vaghjiani and Ravishankara (1989) and Niki et al. (1983) for methyl hydroperoxide. The most comprehensive study is that of Vaghjiani and Ravishankara (1989) who studied the rates of reaction of 16 0H, 18 0H, and 16 0D radicals with CH300H and 16 0D radicals with CH300D. Based on an analysis of all the experimental data, the mechanism involves two reaction pathways; H-atom abstraction from the CH3 group and from the OH group. Therefore,



### CH300H + •OH k(2) = k(-OH) 

### CH300• + HOH (41)

k(1) = k(la) CH300H + •OH •CH2O0H + HOH (42)
with the •CH2O0H radical rapidly decomposing to give hydroxyl radicals and formaldehyde

•CH2=0 O-H Ra

P -+ CH 2 =0 + •OH (43)
The overall rate, from reactions 41 and 42, is

k OH = k(1) + k(2) = k(la) + k (-OH) (44)

-77-..

2 2 

### Relative rate studies gives k OH [= k(la) + k(-OH)] while flash photolysis or laser photolysis experiments, which measure the disappearance of OH radicals, gives only the rate constant k(-OH) assuming that OH radical regenerated contains the same oxygen isotope as the reactant OH radical. Therefore, the reaction of the 16 0H radical with CH30 16 0H (or 16 0D radical with CH30 16 0D) gives the rate constant k(-OH). Furthermore, reaction of OD radicals with CH300H yields the overall rate constant k OH [= k(la) + k(-OH)] for the OD radical reaction. Atkinson (1989) carrzed out a unit-weighted least-squares analysis of the experimental data of Vaghjiani and Ravishankara (1989) for the reaction of 18 0H and OD radical with CH300H over the temperature range 203-348K. Based on these data, Atkinson recommended the value of
k(-OH) = 3.73 (45)
at 298 K(in the units 10 -12 cm 3 molecule

- is -1 ); from the experimental data involving 18 0H and OD radicals over the temperature range 223-423 K, Atkinson recommended a value of

kOH = 5.54 (46)
at 298 K(in the units 10 -12 cm 3 molecule

- is -1 ). Hence,
k(la) = 1.81 (47)
and H-atom abstraction from the OH radical in methyl hydroperoxide is the major reaction pathway.

-78-..

.• ~ 

### For t-butyl hydroperoxide, Atkinson (1989) indicated that

because the C-H bonds in the CH 3 group are stronger than the O-H bond, the reaction is expected to proceed principally via H-atom abstraction from the weaker OH bond (reaction pathway 41) and this result is consistent with the magnitude of k O H determined experimentally by Anastasi et al. (1978). Therefore, all the data presented by Atkinson (1989) contradicts the S/R relationships of Meylan (1990b) for the alkyl hydroperoxides. Considerably more experimental rate data is needed for additional alkyl hydroperoxides to develop S/R relationships for this class of compounds.
IV.C.5. Alkyl Nitrates and Nitriles IV.C.5.a. Evaluation of the Experimental kOH Data Table 18 summarizes the pertinent experimental kOH data at 298 K for acyclic and cyclic alkyl nitrates and acyclic alkyl nitriles as reported in AOP, in Atkinson (1989), and in the literature. Inspection of the k O H data in columns 2 and 3 indicate that the experimental values for all acyclic and cyclic nitrates are identical. However, for the nitriles, there are differences. For acetonitrile, the correct value of kOH is 0.0214* as recommended by Atkinson (1989) and the correct value for propionitrile is 0.194 as given by Harris et al. (1981) and Atkinson (1989).

-79-; Table 18. Comparison of the

Nitrates and Alkyl Program (AOP) and kO H Data Reported in AOP Estimated Values of kpg at 298 K for Alkyl ,

Nitriles from the Atmospheric Oxidation Computer from a Hand Calculation (HC) and the Experimental in the Literature Versus the Experimental k OH Data

10 12 k (cm 3 molecule'ls' 1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC A. ACYCLIC NITRATES
Methyl nitrate - 

### ~`~ S' 

### ~ $' 

### ~ 0.034 0.034b 0.0259 0.0259 Ethyl nitrate( 

### ~

= sg- 

### ~ 0. 49c 0. 49c 0.194 0.194 1-Propyl nitrate /3 -A / 0.67 0.67d 0.632 0.632 2-Propyl nitrate 0.41 0.41e 0.416 0.416 1-Butyl nitrate n~~Y~N r~~~~~ - 1.78 1.78e 1.79 1.79 2-Butyl nitrate 

### ~~

yH

~ >tiu.3 0.92 0. 92e 0.905 0.905 2-Pentyl nitrate,, F 1.85 1.85f 2.06 2.06 3-Pentyl nitrate/ 1.12 1.12f 1.42 1.42 2-Methyl-3-butyl nitratex , 1.72 1.729 1.39 1.39 2,2-Dimethyl-l-propyl nitratey 0.85 0.859 0.752 0.752 2-Hexyl nitrate ~ n-N

~ -xyLti /T; ~:j~ 3.17 3.17f 3.45 3.45

20633

- i/

- s3 3-Hexyl nitrate 

### ~ 2.70 2.70f 2.58 2.58 2-Methyl-2-pentyl nitrate,; 1.72 1.729 1.68 1.68 3-Methyl-2-pentyl nitrate/` 3.02 3.029 2.63 2.63 3-Heptyl nitrate ;" 3.69 3.699 3.97 3.97

~ 3-Octyl nitrate - 39 - 3.88 3. 88 f 5.37 5.37 cBti ~~Nc~ 3
B. CYCLIC NITRATES
Cyclohexyl nitrate 210$ -(pU-q 3.30 3.309 5.38 5.38

C. ALKYL NITRILES

Acetonitrile

- 7~~ 05°8 0.021 0.0214* 0.0202 0.0202 Propionitrile 

### /p
~ 

### -- /a -Q 0.19 0.194h 0.189 0.189

-80-~ , , ~ •4' - ..

1i

4.i 

### Table 18. continued

a 

### Experimental values from Atkinson (1989) and the literature. b Atkinson 

## ~ 1987, 1989) reported a value of 0.034x10 -12 and 0.38x10 -1 cm 3 molecule

- ls -1 from Gaffney et al. (1986) and Kerr and Stocker (1986), respectively. Atkinson (1987) used the value of 0.034 x 10 -12 since it was more consistent with the entire set of kOH data used to develop the S/R relationships and the value from Kerr and Stocker was systematically too high. Atkinson (1989) also tentatively preferred the value of Gaffney et al. (1986) since the value of Kerr and Stocker was too high. c The experimental data of Kerr and Stocker (1986) was considered too high and was not considered to be valid [Atkinson (1987, 1989)]. d This value of kOH represents the average value from the experimental data of Kerr and Stocker (1986) and Atkinson and Aschmann (1989a). e Experimental value from Atkinson and Aschmann (1989a). f Experimental value from Atkinson et al. (1982a). g Experimental value from Atkinson et al. (1984b). h Experimental value from Harris et al. (1981). * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-8i-..

. ~ 

### IV.C.5.b. Evaluation of the Estimated k OH Data Inspection of the estimated values for the nitrates and nitriles in columns 4 and 5 indicate that both AOP and HC have exactly the same k OH data.

IV.C.6. Nitroalkanes IV.C.6.a. Evaluation of the Experimental k OH Data Table 19.A. summarizes the pertinent experimental kOH data at 298 K for nitroalkanes as reported in Atkinson (1989), in AOP, and in the literature. For nitromethane, AOP lists a range of experimental values for kOH. Atkinson (1989) evaluated the existing experimental kOH data for nitromethane and indicated that the data of Zabarnick et al. (1988) is preferred. Atkinson carried out a unit-weighted least squares analysis of the Zabarnick data using the equation

kOH = CT 2 exp(-D/T) (48)


### where C and D are constants and T is the absolute temperature in K and found that

kOH = 5.6 x 10 -19 T 2 exp(-360/T) cm 3 molecule

- is -1 (49)
over the temperature range 299-671 K. At 298 K, equation 49 gives

k O H = 0.0149 x 10 -12 cm 3 molecule

- is -1 (50)

-82-ar

~ t 

### Table 19. Comparison of the Estimated Values of kpg at 298 K for

Nitroalkanes and Alkyl Nitrites from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experiment k OH Data in AOP

10 12 k (cm 3 molecule

- is -1 ) Experimental Estimated Chemical Class/Chemica AOP (a) AOP($Error)j HC A. NITROALKANES

Nitromethane 75-5-a S (0.016-0.16) 0.0149b . 0.0259(+74) (c) Nitroethane 79-2 ~ f 3 0.15 0.15d 0.194(+29) (c) 1-Nitropropane /og-- 03- 2 0.24 0. 34d 0. 632 (+86) (c) 1-Nitrobutane 6.7

~ -- 1.45 1. 45e 1. 79 (+23 ) (c) 1-Nitropentane6a$- O5'7 3.30 3.30d 3.18(-4) (c)



### B. ALKYL NITRITES
Methyl nitrite (0.12-1.08)? (0.12-1.09)f 0.288 (---) (c) Ethyl nitrite /o9- ~S`~~ 1.75? 1.779 2. 32 (+31) (c) 

### 1-Propyl nitrite 5- Y3 -( 1- 9 2.38? 2.36h 6.12(+160) (c) 1-Butyl nitrite.,jy}--/&

- / (2.31-5.2)? 5.02h 8.29(+65) (c) 2-Butyl nitrite 9o?V- 5. 93? 5. 97 1 6. 17 (+3 ) (c) 

### 2-Methyl-l-propyl nitriteX 5.31? 5.35 1 10.8(+101) (c) 2-Methyl-2-propyl nitrite ~ 

### 1.40? 1.41 1 1.94(+38) (c)
a Experimental values from Atkinson (1989) and the literature. b Experimental value from Zabarnick et al. (1988) which represents the preferred value by Atkinson (1989). c Could not be calculated by Leifer since the S/R relationships and substituent factors were unknown.

-83-M14



### Table 19A. continued
d Experimental value from Nielsen et al. (1988). Atkinson (1989) tentativelv accepted this data since "The nitroalkanes are expected to photolyze [Taylor et al. (1990)) and it is not clear whether photolysis occurred under the experimental conditions of the relative rate study of Nielsen et al. (1988) or whether or not photolysis (if it occurred) was taken into account". More experimental kpH data are needed under controlled laboratory conditions to eliminate photolysis. e The average value from the data of Atkinson (1989) and Nielsen et al. (1988). See footnote (d) above relative to the experimental value from Nielsen et al. (1988). f Range in experimental kpH data as obtained from Atkinson (1989) and the literature in the units 10 -12 cm 3 molecule

- ls -1 : 0.12 relative to dimethyl ether and 0.21 relative to n-hexane [Tuazon et al. (1983)]; 1.00 [Baulch et al. (1985); 1.09 [Audley et al. (1982)j; and the data of Campbell and Goodman (1975) was omitted since there were fundamental problems associated with the relative method used [Atkinson (1989)]. g Experimental value from Audley et al. (1982) and Atkinson (1989). h Average value from the experimental data of Audley et al. (1982) and Baulch et al. (1985) is obtained from Atkinson (1989). i Experimental value from Audley et al. (1982).

~ 

### Percent error relative to the experimental values listed in column Experimental/(a).

-84-

### and this is the value listed in column three of Table 19.A. and

is the preferred (or recommended) value by Atkinson. For the remaininq nitroalkanes, only for 1-nitropropane is there a discrepancy in the kOH data in columns 2 and 3. The correct 

### experimental value for 1

- 

### nitropropane is tentatively 0. 34 

### as obtained from Nielsen et al. (1988) and Atkinson (1989). Some comments must be made about the validity of the experimental kpg data for nitroethane, 1-nitropropane, 1-nitrobutane and 1-nitropentane. For nitroethane, 1-nitropropane, and 1-nitropentane, the experimental data were obtained from Nielsen et al. (1988) and Atkinson (1989) while the experimental data for 1-nitrobutane was obtained from Atkinson and Aschmann (1989) and Nielsen et al. (1988). Atkinson (1989) 

### critically evaluated the experimental k OH data of Nielsen and stated that "The nitroalkanes are expected to photolyze [Taylor et al. (1980)J and it is not clear whether photolysis occurred under the experimental conditions of the relative rate study of Nielsen et al. (1988) or whether or not photolysis (if it occurred) was taken into account." As a result, Atkinson (1989) indicated that the data listed in the column Experimental/(a) for nitroethane, 1-nitropropane, and 1-nitropentane from Nielsen are only tentativelv preferred and, therefore, must be used with extreme caution.

IV.C.6.b. Evaluation of the Estimated k OH Data Leifer did not have available S/R relationships for the nitroalkanes from Atkinson; hence, no entries appear in Table ~ 

### s■

.;'

-85-:l

~

19.A., column Estimated/HC. Meylan (1990b) did have S/R relationships available for these compounds from Atkinson (unpublished results). For this class of compounds (RNO2), 

### Atkinson must have postulated that hydroxyl radicals can only react by abstracting a hydrogen from the C-H groups in R and the substituent factors were

F(-NO2) = 0.18 (51)

F(-CH2NO2) = 0.30 (52)
In addition, Meylan (1990b) gave the substituents >CHNO2 and > CNO2 the same F values as for the substituent -CH2NO2 listed in 

### equation 52. Thus, the assumed values for these two substitutes (designated **) are then

F(>CHNO2 ** ) = F(> CNO2 ** ) = 0.30 (53)
Using the above substituent factors, AOP estimated kOg for the 

### five nitroalkanes listed in Table 19.A. and these results are listed in the column Estimated/AOP. The percent error, relative to the experimental k OH data in column 3, are listed in parentheses adjacent to the estimated value from AOP. Inspection of these data clearly indicate that the results for nitromethane and 1-nitropropane are very poor. In addition, the average percent error ranged from +53 to -4. Therefore, in order to develop better substituent factors for the nitroalkanes, more experimental k OH data are needed for these five compounds and additional nitro compounds under carefully controlled laboratory i~

-86-

### conditions to eliminate direct photolysis. Until this work is

completed, the substituent factors and estimated values of kOH for the nitroalkanes must be used with extreme caution, or, better, delete them from AOP.
IV.C.7. Alkyl Nitrites IV.C.7.a. Evaluation of the Experimental kOH Data Table 19.B. summarizes the pertinent experimental kOH data at 298 K for the alkyl nitrites (RONO) as obtained from AOP, from Atkinson (1989), and from the literature. For these compounds, the experimental kOH.data from AOP have question marks immediately after the numbers to indicate that the data are questionable. For the experimental data for methyl nitrite, several values are available from the literature. Thus, the experimental kOH data in columns 2 and 3 list essentially the same range of values. For 1-butyl nitrite, AOP lists a range of values while the column Experimental/(a) lists the average value from the experimental data of Baulch et al. (1985) and Audley et al. (1982). For the other alkyl nitrates there are minor differences listed in columns 2 and 3. The values listed in the third column, as obtained from the literature and Atkinson (1989), appear to be the correct values. It should noted that for the compound CH3CH(CH3)CH2ON0, AOP lists the name 3-methyl-l-propyl nitrite which is incorrect. The correct name is 2-methyl-l-propyl nitrite. i

.

> ~

-87-a "L

a 

### IV.C.7.b. Evaluation of the Estimated k OH Data Leifer did not have available S/R relationships from Atkinson for the alkyl nitrites; hence, no entries appear in the column Estimated/HC. However, Meylan (1990b) did develop S/R relationships for this class of compounds (RONO) by assuming that the only reaction pathway is H-atom abstraction from the C-H groups in R. Based on the available experimental k O H data, Meylan assumed that for the nitrites

F(-O-N = ** ) = 2.00 (54)
Furthermore, for these compounds, where appropriate, Meylan used the substituent factor F(-CH2-O-) from Table 2. Using the above substituent factors, AOP calculated kOH; and these values are listed in Table 19.B. along with the percent error (in brackets adjacent to the estimated values). From an inspection of the percent error data, it is clear that theresults are generally very poor; 1-propyl nitrite and 2-methyl-lpropyl nitrite had percent errors greater than +100 while 1- butylnitrite had a percent error of +65. These results are not surprising since Atkinson (1989) Stated "Until the kinetics of OH radicals with alkyl nitrites are fully understood and product studies carried out, the reaction mechanisms remain uncertain. These may proceed via H-atom abstraction from the C-H bonds ---- and this is expected to be the major, if not the only, reaction pathway ---". Therefore, it is apparent that more reliable kOH data and product data are needed for the alkyl nitrites listed in

-88-~

a~ 

### Table 19.B. and for other alkyl nitrites in order to develop more

reliable S/R relationships.
IV.D. Addition of Hydroxyl Radicals to Alkenes, Conjugated Dialkenes, Alkynes, and 1,2-Dialkenes* IV.D.1. Unsubstituted Alkenes IV.D.i.a. Evaluation of the Experimental kOH Data Table 20 summarizes the pertinent experimental kOH data at 298 K for the reaction of OH radicals with unsubstituted alkenes as reported in AOP, in Atkinson (1989), and in the literature. A careful inspection of the experimental kO H data reported in the columns Experimental/AOP and Experimental/(a) indicates that, in general, they are the same; there are, however, some differences. For a few chemicals, AOP lists kOH to 4 significant figures while Experimental/(a) reports kOg to 3 significant figures. At best, the experimental kOH data is good to 3 significant figures. For example, for 2,3-dimethyl-2-butene, the experimental kOg data reported in the literature is only given to 3 significant and Atkinson (1989) recommended a value of 110* while AOP lists a value of 110.0. For the other chemicals with differences, Experimental/(a) lists an average value from the literature while AOP selects one set. Unless there is good reason to disregard specific sets of data, it is best to list an average value from all the data sets rather than the value from only one set. It should be noted that AOP does not list an experimental value for 4 3 - carene in column 2; however, a value is listed in the document "Estimation Accuracy of AOP versus PCFAP" (Meylan

-89-~

Table 20. Comparison of the Estimated Values of k O H at 298 K for Unsubstituted

Alkenes from the Atmospheric Oxidation Computer Program (AOP) a,rnd, from a Hand Calculation (HC) and the Experimental k QH Data Reperted in the Literature Versus the Experimental kOH Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemica AOP (a) AOP HC A. ACYCLIC ALKENES Ethene (Ethylene) 3 

## ~ - g , 5 " l 8.52 8.52* 8.5200q (r) Propene (Propylene) //j

- O 7°/ 26.3 26.3* 26.4 26.4 1-Butene /bCn- 9$-

~ '; 31.4 31.4* 27.3 27.3 

### cis

- 2

- Butene 56.4 56.4* 56.4 56.4 trans -2-Butene (a~-~~/ ~ cy/`g 64.0 64.0* 64.0 64.0 2-Methylpropene /iS-/i-

~~ : yi-IF 51.4 51. 4* 51.7 51.7 1-Pentene /oy- !o

- f'/ 31.4 31. 4* 28.6 28.6 cis -2-Pentene &;2 a0

- 3 65.4 65.7b 57.3 57.3 trans -2-Pentene (~ lo - 0 4 /'ff' 66.9 66.9c 64.9 64.9 2-Methyl-2-butene S13

- 

### 35 'y 86.9 86.9* 87.3 87.3 2-Methyl-1-butene j`( ~~ -~~ ~ 2 60.7 60. 6d 52.6 52.6 3-Methyl-l-butene ~3~~ " ~ 31.8 31.8* 28.5 28.5 1-Hexene 59, ~ • 1//- 4p 37.5 35.2e 30.0 30.0 2-Methyl-l-pentene Wo Z

~ - 29 -1 62.6 62.6f 53.9 53.9 2-Methyl-2-pentene &dY - 2

~ -- ~ 88.8 89.19 88.2 88.2 

### trans -4-Methyl-2-pentene6Y`/°

~ X- -0 60.8 60.5f 66.0 66.0 2, 3-Dimethyl-2-buteneS6,3-79- ) 110.0 110* ill ill 3,3-Dimethyl-l-butene-'b-8•3F --

~ 28.4 28.5h 26.9 26.9 1-Heptene ,5W- 

### ~ (,- 

### ~ - 40.5 38. 3 1 31.4 31.4 2,3-Dimethyl-2-pentene 5 ?y -3

~ S 108.0 103j 111 111 

### trans -4,4-Dimethyl-2-pentene 1e90-ou-i( 1,4-Pentadiene 

### 3 l/

- 93

- 5 54.5 53.3 54.5f

53.3c 64.4

53.4 64.4

53.4 

### trans -1,4-Hexadiene -0 90.3 90.6c 91.0 91.0 1, 5-Hexadiene

~~ 

## a - L f ~ -~- 62.1 62 . Oc 54.8 54.8

~~

~= Table 20. Continued

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/ emical AOP (a) AOP HC 2-Methyl-1,4-pentadiene-IA

- 3 0 "q 78.8 78.8c 78.7 78.7 2-Methyl-1,5-hexadiene ~~~~ 96.1 96. 1 c 80.0 80.0

- y ~~ -'~-~' ~, 2,5-D

~ ntethyl-1,5-hexadiene 120.0 120c 105 105

B. CYCLIC ALKENES
Cyclopentene /~a

- ~ bJ°Q 67.3 65.5k 58.9 58.9 Cyclohexene //p- 8 

## 3r-g 67.7 67.7* 61.1 61.1 1, 4-Cyclohexadiene 29797-09-9 99.4 99.5 1 114 114 Cycloheptene &p.28-qa-2, 74.4 74.4m 62.4 62.5 1-Methylcyclohexene 94.4 94.4n 92.0 92.0 Bicyclo [2.2.1]-2-hepteneyy 5 td- ~ 49.3 49.3m 62.7 62.7 c?14(3v Bicyclo[2.2.1]-2,5-heptadtene 120.0 120m 116 116 Bicyclo[2.2.2]-2-octene 40.8 40.8m 67.8 67.8 931- G4-4& a-Pinene S0R 5G- Es'' 53.7 53 . 7* 89.5 89.5 O-Pinene / a-7

- 9f

- 3 78.9 78 . 9* 54.2 54.1 d-Limonene

- ~~ - 5~'~ 171.0 160 n 145 145 0 3 -Carene ~~~/~,~ - ~~~9 (p) 87.8 0 87.6 87.6 y-Terpinene 177.0 177 0 178 178

a Experimental values from Atkinson (1989) and the literature. b Average value from the data of Ohta (1984) and Wu et al. (1976). c Experimental value from Ohta (1983) and Atkinson (1989). d Average value from the data of Ohta (1984) and Wu et al. (1976). The experimental value of kOH of Morris and Niki (1971) was considered to be too high and was discounted when making recommendations for other alkenes (e.g., for 1-pentene) by Atkinson (1989). e Average value from the experimental data of Wu et al. (1976) and Atkinson and Aschmann (1984). f Experimental value from Ohta (1984) and Atkinson (1989). g Average value of the relative rate data of Ohta (1984) using 2-methyl-2- butene and 

### cis -2-pentene as reference compounds.

-91-~

. ;, 

### h Experimental value from Wu et al. (1976) and Atkinson (1989). 1 

### Average value of the experimental data of Darnall et al. (1976) and , Atkinson and Aschmann (1984). 7 Average value of the relative rate data of Ohta (1984) using 2-methyl-2- butene and 2,3-dimethyl-2-butene as reference compounds. k Average value from the experimental data of Atkinson, Aschmann, and Carter .(1983) and the relative rate data of Rogers (1989) with cyclohexene as the reference compound. 1 

### Average value from the experimental data of Atkinson, Aschmann, and Carter (1983) and Ohta (1983). m Experimental value from Atkinson Aschmann, Carter (1983). n Experimental value from Darnall et al. (1976). o Experimental value from Atkinson, Aschmann, Pitts (1986). p No experimental value is q 

### iven in the AOP database. An experimental value of 87.8x10 -12 cm 3 molecule

- Is -1 is given in the document estimation accuracy of AOP versus PCFAP. q Estimated value is the experimental value. r Cannot be estimated by the S/R relationships of Atkinson. * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-92-i



### (1990b)]. The value of 87.8 should be listed in the AOP

database.

IV.D.l.b. Evaluation of the Estimated kO H Data Comparison of the estimated kpH data in columns 4 and 5 indicates that, in general, they are the same; there are, however, a few differences. For ethene, AOP lists a estimated value of 8.5200 in the summary table which corresponds to the experimental value while HC does not list a value; kp H cannot be estimated by the S/R relationships of Atkinson. Furthermore, AOP lists the estimated value to five significant figures whYch is incorrect since the recommended experimental value by Atkinson (1989) is 8.52* which only has three significant figures. For OH addition to olefinic bonds, the detailed calculations show an inconsistency. From the mathematical synopsis of the S/R relationships of Atkinson 

### (equation 15), substituent factors attached to the olefinic group can influence kadd,nar (or kd in Meylan's notation), Table 8; therefore, for consistency in calculating the rate constant for this reaction pathway, the term C(R) should be used, even 

### though C(R) = 1.00. For example, for 1-pentene, OH addition to the olefinic group should be

kadd,nar = ko s (CH2=CHR)[C(R)] = 26.3(1.00)

kadd,nar = 26.3 (55)

For 2-methyl-2-pentene,

kadd,nar = ko s (R1R2C=CHR3)[C(R1)C(R2)C(R3)] -93-kadd,nar - ko s (RiR2C=CHR3)(1.00)(1.00)(1.00)



### kadd,nar = 86•9 (56)
This comment is also applicable to the compounds listed in Table 22 for the conjugated dienes, and in Table 23 for the allenes and alkynes. For C-H abstraction from the olefinic group (e.g., =C-H), the detailed calculations should include this pathway, even though it is zero [i.e., k(1, UNS CH) = OJ. This comment, as well as the above comment, also applies to the other classes of compounds discussed in Section IV.D.

IV.D.2. Substituted Alkenes IV.D.2.a. Evaluation of the Experimental kOH Data Table 21 summarizes the pertinent experimental kOH data for the reaction of OH radicals with substituted alkenes as reported in Atkinson (1989), in AOP, and in the literature. A comparison of the experimental kOH data listed in columns 2 and 3 indicate that, in general, they are the same; there are, however, somedifferences. For six compounds [i.e., 2-(chloromethyl)-3-chloro1-propene, trans-2-butenal, and the four ketenes, no experimental k OH values are listed in AOP; however, values are reported in the document "Estimation Accuracy of AOP versus PCFAP "[Meylan (1990b)]. The appropriate values should be listed in AOP. For acrylonitrile, AOP lists an experimental value of 4.0 while the correct value should be 4.1, the average value of the ~

-94-;► ..

Table 21. Comparison of the Estimated Values of kp H at 298 K for Substituted

Alkenes from the Atmospheric Oxidation Computer Program (AOP) and From a Hand Calculation (HC) and the Experimental k QH Data Reported in the Literature Versus the Experimental k O H Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Cheic 1 AOP (a) AOP HC A. Haloalkenes.
Vinyl f luoride :75`-0 2- ' r 5.56 5. 56b 10.5 10.5 Vinyl chloride =~S

- 

### D/- 4 / 6.60 6.60b 5.26 5.26 Vinyl bromides9 ,

3-. G a - Z„ 6.81 6.81b 6.84 6.84 1, 1 -D if luoroethene - 7 2.1 2. ic 8.22 8.22 g"-1, 2-Dichloroethene /&30

- 7 3- 9 2.38 2. 38d 2.24 2.24 

### trans -1,2-Dichloroethene/6 , 30

- 3g

- O 1.80 1.80d 2.55 2.55 

### Trichloroethene 79 ... 0/ _(v (Trichloroethylene) 2.36 2.36* 0.695 0.695 Tetrachloroethene 

# x (Tetrachloroethylene) 0.167 0.167* 0.176 0.176 3-Chloro-l-propene /o- ~- vs°- 

### j (3-Chloropropylene) 17.0 17* 20.3 20.3 

### cis -1,3-Dichloro-l-propene 8.41 8.41d 8.85 8.85 10(j61-01 s 14.3 14.3d 10.0 trans



### - 1, 3 -Dichlor ~1~ ~~ op~e~ne~ 10.02-(Chloromethyl)-3-chloro1-propene (e) 33.5d 30.3

B. a,B-UNSATURATED CARBONYLS
Acrolein (2-Propenal)/04-0 Z-$ 19.9 19.9* 22.9 22.9 

### trans -Crotonaldehyde(trans2-Butenal) /a3-713- 

### 9 (e) 36* 32.8 32.8 Methacrolein(2-Methyl-2- propenal) 33.5 33.5* 29.6 29.6

-95-6 .Y

~ ~~u .~

E~ • f ~ A 

### Table 21. Continued

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC Methyl vinyl ketone ~~W ~~- ~ 

### 18.8 18.8* 24.0 24.0 Ketene 

### //& 3 ( e) 17 3 f 51.4 51.4 

### Methyl keteneX (e) 709 87.0 87.0 Ethyl ketene ~ 

### (e) 118f 87.9 87.9 Dimethyl ketene k (e) 107f 110 110 cis -3-Hexene-2, 5-dione 63.1 63.1h 46.7 46.7 a 

### trans -3-Hexene-2,5-dione 53.1 53.1h 53.0 53.0 

### _ 9
C. NITRILOALKENES
Acrylonitrile (Cyanoethene) 4.0 4.1 1 3.95 3.95

/0 ?-- 13 - / 

### D. ALKOXY ALKENES
Methyl vinyl ether 33.5 33.5b 35.1 35.1
a Experimental values from Atkinson (1989) and the literature. b Experimental value from Perry, Atkinson, Pitts (1977a). c Experimental data not reliable [Atkinson (1989)]. d Experimental value from Tuazon et al. (1988). This data is preferred since these experiments avoided or have taken into account the side reactions of chlorine atoms with the reference compounds [Atkinson (1989)). e No experimental value is given in the AOP data base. However, experimental values are given in the document Estimation Accuracy of AOP versus PCFAP [Meylan (1990b)]. f Experimental value from Hatakeyama et al. (1985). g Average value from the data of Hatakeyama et al. (1985). h Experimental value from Tuazon et al. (1985). 1 

### Average value from the experimental data of Harris et al. (1988) and Zetzsch (1983) as reported in Atkinson (1989). * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-96-

### experimental data of Harris et al. (1981) 

### and Zetzsch (1983) 

### as

reported in Atkinson (1989). 

### For 3-chloro-l-propene, the recommended value from Atkinson (1989) is 17*, which only has two significant figures, compared to a value of 17.0 listed in AOP.

IV.D.2.b. Evaluation of the Estimated k O H Data A comparison of the estimated values of k O H listed in AOP and HC for the compounds listed in Table 21 give the same results. The use of four significant figures in the detailed calculations and three significant figures in the summary table are applicable in the same manner as described in previous sections.
IV.D.3. Conjugated Dienes IV.D.3.a Evaluation of the Experimental kOH Data Table 22 compares the pertinent experimental k OH data at 298 K for the reaction of OH radicals with conjugated dienes as reported in Atkinson (1989), in AOP, and in the literature. A comparison of the experimental kOg data in columns 2 and 3 indicate that they are all 

### different. The difference involves the number of significant figures used. For 2-methyl-1,3- butadiene, Atkinson (1989) lists a recommended value of 101* and not 101.0 as listed in AOP. In all the other cases, AOP incorrectly lists kOH to four significant figures whereas the literature values listed in Atkinson (1989) and the literature contain only three significant figures.

-97-~ 

### Table 22. Comparison of the

Acyclic and Cyclic Program (AOP) and k 0 H Data Reported in AOP Estimated Values of k OH at 298 K for Conjugated ` Dialkenes from the Atmospheric Oxidation Computer from a Hand Calculation (HC) and the Experimental in the Literature Versus the Experimental k OH Data

10 12 k (cm 3 molecule

- is -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC A. ACYCLI DIALKENES
1, 3-Butadiene l06--9c)- o 66.6 66. 6* 66.60009 (h) 2is -1, 3-Pentadiene 101.0 101b 105 105 2-Methyl-1, 3-butadienelt'°7

- 9

-- T 101.0 101* 105 105 

### trans -1,4-Hexadienex 112.0 112 b 106 106 3-Methyl-1, 3-pentadiene W 4y-3y-() 136.0 136b 135 135 4-Methyl-1,3-pentadiene g26-

- %-: ~ 131.0 131 b 135 135 2,3-Dimethyl-1,3-butadiene 122.0 122b 135 135 si3- 8/- ~ 2,5-Dimethyl

~ 2,4-hexadie ~e 13 _~ 210.0 210 b 231 231 3

- 2~ ethylene

- 7~ methyl

- 1,6

- octadiene (Myrcene) /23

- 3S

- -3 215.0 215c 194 194 3,7-Dimethyl-1,3,6-octatriene 252.0 252c 223 223



### 1387-7- 9/

- .3 B. GYCLIC DIALKENES


### 1,3-Cyclohexadiene 

### 59a 164.0 164d 137 137 1, 3-Cycloheptadiene '/O 

### ~N ~~ -" 139.0 139e 139 139 a-Phellandrene q °

I - $ 3 - 2 - 313.0 313f 187 187 ac-Terpinene 

## g9 _g 6

- s - 363.0 363f 235 235


### a Experimental values from Atkinson (1989) and the literature. b Experimental value from Ohta (1983). c Experimental value from Atkinson, Aschmann, Pitts (1986). d Experimental value from Atkinson, Aschmann, Carter (1983). e Experimental value from Atkinson, Aschmann, Carter (1984a). f Experimental value from Atkinson et al. (1986). g Estimated value is the experimental value. h Cannot be estimated by the S/R relationship of Atkinson. * Recommended value by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-98-

### IV.D.3.b. Evaluation of the Estimated kOH Data.

A comparison of the estimated data in columns 4 and 5 of Table 22 indicates that they are identical except for the entree for 1,3-butadiene. For this compound, the value of 66.6000 corresponds to the experimental value [which should be 66.6* as recommended by Atkinson (1989)] and is not an estimated value. There is no entry under the column HC since there is no S/R relationship for this compound.
IV.D.4. Alkynes and 1,2-Dienes (Allenes) IV.D.4.a. Evaluation of the Experimental kOg Data Table 23 summarizes the pertinent experimental k O H at 298 K for the reaction of OH radicals with alkynes and 1,2-dienes (allenes) as reported in Atkinson (1989), in AOP, and in the literature. A comparison of the experimental kOH data reported in columns 2 and 3 are the same except for three differences; for propyne and 1-butyne, the correct values with two significant figures, as recommended in Atkinson (1989), should be used in AOP; the value for 1-hexyne reported by Boodegheans et al. (1987) and Atkinson (1989) is 12.6 and not 11.9 as reported by AOP; and finally for propadiene, Atkinson (1989) recommended a value of 9.84* and not 9.82 as reported by AOP.

IV.D.4.b. Evaluation of the Estimated kOH Data Except for ethyne, butadiyne, and propadiene, the estimated values of kOH at 298 K in columns 4 and 5 are identical. For these three compounds, no estimated values appear under the .r



### -99-i 11

2 2 Table 23. Comparison of the Estimated Values of k OH at 298 K for Alkynes and

1,2-Dialkenes (Allenes) from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental k O H Data Reported in the Literature Versus the Experimental k O H Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemic AOP (a) AOP HC A. ALKYNES
Ethyne (Acetylene) 7 4 /

- S" 6-4 - 0.815 0.815 0.8150b (c) Propyne 5.90 5. 9* 6.54 6.54 1-Butyne /0:7-00-Cfl 8.00 8.0* 7.42 7.42 2-Butyne 

### 6a 3 - 1-

~ 

### - 3 27.4 2 7. 4* 29.3 29.3 1-Pentyne 

### 6 a7

- /q

- 0 11.2 11.2d 8.75 8.25 1-Hexyne 693 - 02

- T 11.9 12. 6d 10.1 10.1 Butadiyne (Diacetylene) NI

~ O -1" -) -S 18.9 18.9* 14.08 (c)
B. 1,2 DIENES (ALLENES)
Propadiene 'I( 3-419--0 9.82 9.84* 9.820b (c) 1,2-Butadiene -1"qa- /%-Z 26.1 26.1e 31.1 31.1 1, 2-Pentadiene ", _ 1,5- -,7- 35.5 35. 5e 32.0 32.0 3-Methyl-1,2-butadiene 56.9 56.9e 57.3 57.3



## sa Experimental values from Atkinson et al. (1989) and the literature. b Estimated value is the experimental value. c Cannot be estimated by the S/R relationships of Atkinson. d Experimental value from Boodaghians et al. (1987). e Experimental value from Ohta (1983). * Recommended by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-100--,,

4 ~ 

### column Estimated/HC since Atkinson never developed S/R

relationships for these compounds. It should be noted that the values listed under the column Estimated/AOP for these three compounds are not estimated values but are experimental values and there are too many significant figures; they should only have 3 signif icant f igures .


### IV.E. Reaction of Hydroxyl Radicals with Organic Compounds Containing Sulfur, Nitrogen, and Phosphorous Functional Groups IV.E.1. Reaction with Thiols, Sulfides, and Disulfides IV.E.l.a. Evaluation of the Experimental k O H Data Table 24 summarizes the pertinent experimental kOH data for the reaction of OH radicals with alkyl thiols, sulfides, and disulfides as reported in Atkinson (1989), in AOP, and in the literature. A careful inspection of the experimental k O H data in columns 2 and 3 indicate that they are the same except for a few differences. For a few of the compounds, the experimental values in Experimental/(a) are listed with only two significant figures whereas the data listed in Experimental/AOP have three significant figures. A check on the original literature sources indicate that the kOH values with two significant figures are the correct ones. For example, for 1-butanethiol, the recommended value of kOg from Atkinson (1989) is 51* while AOP lists 51.0. For methyl ethyl sulfide, the experimental value from Hynes et al. (1986) and Atkinson (1989) is 8.50 and not 8.5 as listed in AOP. For dimethyl disulfide, AOP does not have an entry in column 2 whereas Atkinson (1989) recommends a value of 211*.
-101-

# _

~ T

a I 

### Table 24. Comparison of the Estimated Values of k OH at 298 K for Alkyl

Thiols, Sulfides, and Disulfides from the Atmospheric Oxidation Computer Proqram (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental koH Data in AOP 10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC A. THIOLS Methanethiol 32.9 32.9* 32.3 32.3 Ethanethiol 

### 75 -0 8

- 1 46.8 46.8* 38.7 38.7 1-Propanethiol jv

~ - d3

~ j 48.3 48.3* 42.0 42.0 

### 2-Propanethiol -7S - 3 3

- 2 42.0 42.0* 47.8 47.8 1-Butanethiol/aL?- 79- ~ 

### 51.0 51* 43.4 43.4 2-Methyl-l-propanethiol 45.0 45* 43.5 43.5 5 3- /3

- ~ y o 2-Butanethiol

~ -

j

~ 6-3_1 40.0 40* 53.7 53.7 2-Methyl-2-propanethiol 33.1 33.1* 31.6 31.6 2-Methy1-1-butaZtFiio1 1 54.0 54.3b 44.9 44.9 B.1. ACYCLIC SULFIDESe Dimethyl sulfide75-18

- 3 4.56 4.56* 4.59 2.59 Methyl ethyl sulfide 8.5 8.50c 11.0 9.02 Diethyl sulfide3(ooa- 2 4'e- 15.0 15* 17.5 15.5 Di-H-Propyl Sulfidei//-y3

- j 20.0 20.0d 24.0 22.0 B.2. CYCLIC SULFIDE e Tetrahydrothiophene 19.7 19.7* 19.8 17.8 C. DISULFIDES Dimethyl disulfide (f) 211* 203 203

~ 

### S - I $-3

a Experimental values from Atkinson (1989) and the literature. b Experimental value from Barnes et al. (1986). c Experimental value from Hynes et al. (1986). d Experimental value from Barnes et al. (1986). The experimental value of Nielsen et al. (1987) appear to be erroneous [Atkinson (1989)). e For these compounds, kpH was measured in the absence of oxyqen.

-102-

# _r

s. a 

### Table 24. continued
f No experimental value is given in the value of 211x10 -12 cm 3 molecule -l s -1 is Accuracy of AOP versus PCFAP" [Meyla *.Recommended value by Atkinson (1989) recommendation, and the uncertainty f AOP database. An experimental given in the document "Estimation n (1990b)]. with the rationale for the or the recommendation.

-103-y i
C



### Finally, for 2-methyl-l-butanethiol, the correct experimental value of kOH in column 3 is 54.3 obtained from Barnes et al. (1986) and Atkinson (1989), and not 54.0 as reported by AOP.

IV.E.i.b. Evaluation of the Estimated k O H Data A comparison of the estimated kOH data from AOP and HC indicates that they are the same except for the alkyl sulfides (acyclic and cyclic). For all these sulfides, kO H is larger from AOP than from HC. The reason for the differences will be described in the following paragraphs. In estimating kOH, there are two reaction pathways for the reaction of OH radicals with alkyl (acyclic and cyclic) sulfides: 

### (1) H-atom abstraction from the C-H groups in tl he alkyl groups; and (2) OH radical interaction with the sulfide group to form the adduct [>S••••OH] which then decomposes rapidly in the presence of oxygen to form the products. The total rate of reaction is then given by the eq , .sation

kOH = k(1) + k(4) = k(1) + k(-S-) (57)
In the absence of oxygen, k(-S-) is zero [Atkinson (1987) and Leifer (1992a)] so that equation 57 becomes
kOH = k(1) (58)
and only C-H abstraction from the alkyl groups takes place. In estimating k O H, AOP uses equation 57 while HC uses equation 58 and this is the reason why k OH (AOP) > k O H(HC). Since the experimental values listed in the column T



### -104-

### Experimental/(a) were obtained in rate measurements without

oxygen, kOH must be evaluated using equation 58. Therefore, AOP must qualify the experimental kpH value for the alkyl sulfides to indicate that the data were obtained in the absence of oxygen; and thus, only H-atom abstraction occurs. Then, in the detailed calculation section, AOP must indicate that k(-S-) = 0 in the absence of oxygen.

IV.E.2. Reaction with Sulfoxides and Sulfates IV.E.2.a. Evaluation of the Experimental k OH Data Table 25 summarizes the pertinent experimental kp g data at 298 K for alkyl sulfoxides and sulfates as reported in Atkinson (1989), in AOP, and in the literature. A comparison of the experimental data in columns 2 and 3 indicate that only for dimethyl sulfoxide is there a difference. The experimental value from Barnes et al. (1986) and Atkinson ( 

### 1989) is 62 and not 62.0 as listed in AOP.

IV.E.2.b. Evaluation of the Estimated kOH Data Atkinson did not develop S/R relationships for alkyl sulfoxides and sulfates; hence, there are no estimated values listed under the column Estimated/HC. Meylan (1990b) did develop S/R relationships for these classes of compounds as described in the following paragraphs. In developing S/R relationships for the alkyl sulfoxides, Meylan (1990b) assumed that only C-H abstraction occurred from the alkyl group. Therefore,

-105-a
a.~



### Table 25. Comparison of Estimated Values of k 0U at 298 K for Alkyl Sulfoxides

and Sulfates from the Atmospheric Oxidation Computer Program (AOP) and from a Hand Calculation (HC) and the Experimental k OH Data Reported in the Literature Versus the Experimental k O H Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP($Error)f HC

A. SULFOXIDES Dimethyl sulfoxide 62.0 62b 28.5(-54) (e)

B. SULFATES Dimethyl sulfate ~~~~ <0. 5 <0. 5c 1.76 (>+250) (e) Diethyl sulfate (
~~-~~- ` j 1.8 1.8d 11.5(+540) (e)



### a Experimental values from Atkinson (1989) and the literature. b Experimental value from Barnes et al. (1986). c Experimental value from Japar et al. (1990). d Experimental value from Japar et al. (1990a). e Atkinson did not develop S/R relationships for alkyl sulfoxides and sulfates. f Calculated using the experimental value listed in Experimental/(a).

-106-kOH ° k(1) (59)
F[S(+4) ** ] = 99.000 (Table 2) (60)


### Using equations 59, 60, and 11, AOP estimated that kOH was 28.5 and the percent error, relative to the experimental value listed in the column Experimental/(a), was -54 (listed in parentheses adjacent to the estimated value in column 4). However, intuitively, it is expected that the sulfoxide group would undergo further oxidation to the sulfone in the presence of
oxygen
O II Rapid R-S (=0) + • OH - 

### ~ ~ S • • • • OH 

### ~ 0 - 

### ~ Products ( 61) 2


### and this reaction pathway should be considered in the S/R relationships. Therefore, considerably more experimental kOH data are needed on OH radical reaction with a member of alkyl sulfoxides (both acyclic and cyclic) and aromatic sulfoxides to determine the reaction mechanism and to develop S/R relationships for this class of compounds. As a result, it is recommended that Meylan drop the S/R relationships for this class of compounds from AOP. For the alkyl sulfates, Meylan (1990b) assumed that

kOH = k(1) (62)
and the substituent factors F(-0-) and F(-CH2-0-) were valid. Using equations 62 and il along with the appropriate substituent ....- 

### ~

-107-ire . (1989) (1989) (1989) (1989) 10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated OP ( a ) AOP HC

9.0 59.Oc 60.8 60.8

4.0 244e 80.8 80.8

2.0 232e 122 122

5.8 46.8e 124 124

l.9 31.9e 68.6 68.6 .~

° Experimental data from Atkinson c Experimental data from Atkinson d Experimental data from Atkinson e Experimental data from Atkinson and Tuazon et al. (1986). and Atkinson et al. (1988) and Goodman et al. (1988). and Goodman et al. (1988a)

-112-a

N~ 

### trimethyl phosphate, the summary table should be Reaction with

N,P,S, and OH and the detailed calculation should be
R,eaction with Nitrocren, Phosphorous, Sulfur, and -OH

k[P(=0)] = 0.000 (63)


### and for (CH30)2P(=S)NH2, the summary table should be Reaction with N,P,S, and OH and the detailed calculation should be
Reaction with Nitrogen, Phosphorous, Sulfur, and -OH

k[P(=S)] = 55.0 (64)


### k(NH2) = 20.0 (65)
IV.F. Reaction of Hydroxyl Radicals with Aromatic Compounds, Heterocyclic Aromatic Compounds, and Fused Ring Polyaromatic Compounds IV.F.1. Aromatic Compounds IV.F.i.a. Evaluation of the Experimental kOH Data Table 28 summarizes the pertinent kOH data for the reaction of hydroxyl radicals with a number of chemicals in a variety of classes of aromatic compounds as reported in Atkinson (1989), in AOP, and in the literature. A careful inspection of the experimental kOH data in columns 2 and 3 indicate that they are the same except for some differences. In a few cases, AOP lists the experimental values with more significant figures than the values reported on the literature. For example, for styrene, AOP lists a value of 58.0 while the recommended value by Atkinson (1989) is 58*. For aniline, AOP lists a value of 111.0 while
-113-

# i
Table 28. Comparison of Estimated Values ofk OH at 298 K for Aromatic =,

Compounds from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kQH Data Reported in the Literature Versus the Experimental k O H Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) 

### Chemical Class/Chemical Experimental Estimated AOP (a) AOP HC A. UNSUBSTITUTED AROMATIC

COMPOUNDS

Benzene

- 7/

- q

3 '" 2 1.23 1.23* 2.04 2.04 Biphenyl 

### Cja Sa 7.2 7.2* 7.12 7.12

B. ALKYLBENZENES
Methylbenzene (Toluene) 5.96 5.96* 5.51 5.51 

### Ethylbenzene ~y~ 

### _y 7.1 7.1* 6.13 6.13 D

- Propylbenzene 6.0 6.0* 7.46 7.46 ,I-Propylbenzene Zfe

- 8 2

- 8' 6.5 6.5* 7.08 7.08 _t-Butylbenzene 

### vb 4.60 4.60b 5.08 5.08 Q- 

### Xylene 13.7 13.7* 6.88 6.88 M-Xylene /° g g 23.6 23 . 6* 14.4 14.4 g-Xylene 14.3 14. 3* 6.88 6.88 g-Ethyltoluene bl I - Iq - 3 12.3 12 . 3* 7.72 7.72 a-Ethy lto luene &a o-/`

~ - `/ 19.2 19 . 2* 14.6 14.6 g-Ethyltoluene

~ ,Pd-91 0 -9' 12.1 12.1* 7.72 7.72 1,2,3-Trimethylbenzene 32.7 32.7* 17.8 17.8

sp(o- 7L 3- $ 1,2,4-Trimethylbenzene 32.5 32.5* 17.8 17.8 °JS - (03

- (a 1,3,5-Trimethylbenzene 57.5 57.5* 37.5 37.5

/ 0 51 ` 60

- ~ " 3

-114-r

' Table 28. continued

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC C. ALKENYLBENZENES
Phenylethene (Styrene) 58.0 58* 28.2 28.2 

### 2-Phenyl-l-propene g3 ~ (a

~ -Methylstyrene)9 g 52c 53.5 53.5 1-Phenyl-l-propene (fl-Methylstyrene) 59c 65.8 65.71-Phenyl-2-methyl1

- propene (ft-Dimethylstyrene ~ 33.0 33d 89.1 89.1

D. HALOBENZENES

Fluorobenzene 

### y(oa-

~ 

### 06-4p 0.69 0.69* 2.56 2.56 Chlorobenzene 0.77 0.77* 1.43 1.42 Bromobenzene/v

~ - g(9-1 0.77 0.77* 1.28 1.28 Iodobenzene 

### 5' 0

))-5 - p-4/ 1.1 1.1* 1.34 1.34 Q-Dichlorobenzene 95' 5a -1 0.42 0.42e 0.414 0.414 ]g-Dichlorobenzene 

### 5 1 f1

- 7

- 3

- 1 0.72 0.72e 1.01 1.01 g-Dichlorobenzene 0.32 0.32e 0.414 0.414 1,2,4-Trichlorobenzene 0.532 0.532f 0.291 0.291 1ad

- a12

- I Hexafluorobenzene 0.172 0.172* 0.151 0.151

3y2. 3

### L-Propylpentafluorobenzene ~ 3.06 3.069 2.89 2.90 

### c;

~ 

### )

~ 

### } 3r-s

E. HALOALKYLBENZENES

Benzotrifluoride 

### jfs'oq`0 - 0.46 0.46h 0.406 0.406 4-Chloro enzotrifluoride 0.24 0.24h 0.285 0.285

ride c 

## ~ Benzyl c 

## ~~ 2.9 2. 9* 2.42 2.43 gg-s$- ~

-115-

# _

-~ c

~ Table 28. continued

10 12 k (cm 3 molecule

- ls -1 ) 

### Experimental Estimated Chemical Class/Chemical AOP (a) AOP HC ✓
F. MONOCHLOROBIPHENYLS
2-Chlorobipheny12a51' W

-- q 2.8 2.82 1 2.95 2.95 3-Chlorobiphenyl 

### Zd51

- ( 01-9 5.3 5.28 1 4.42 4.42 4-Chlorobipheny12a6{-1.2

- 9 3.9 3.86 1 2.95 2.95

G. HYDROXYBENZENES

Phenol 26.3 26.3* 35.7 35.6 2-Cresol 42.0 42* 43.9 43.9 a-Cresol Iv8

- 39-4 64.0 64* 93.9 93.9 p-CresollU ( -``H'S 47.0 47* 43.9 43.9 2,3-Dimethylpheno152to

- 75-0 80.2 80.27 115 115 2, 4-Dimethylphenolte , T-ts 4- `? 71.5 71. 5j 54.1 54.1 2,5-Dimethylphenole-75-S , 4A 80.0 80.07 115 115 2,6-Dimethylphenol546-24r 1 65.9 65.9j 54.1 54.1 3,4-Dimethylphenol°) , 5°(o , 5

- & 81.4 81.47 115 115 3, 5

- DimethylphenolfW -G;,g-7 113.0 113i 200.3 200 2, 3-Dichlorophenol 5'76-2)4-9 1.66 1. 66k 7.27 7.27 2, 4-DichlorophenolI Za-g_

- i- 'L 1.06 1. 06k 3.02 3.02

H. NITROBENZENES

Nitrobenzene 0.14 0.149 1 0.251 0.251 Q-Nitrophenol $V 0.90 0.90 4.42 4.42 Q-Nitrotoluene S

- 2

- 4Z' 2 - 0.70 0.70 0.805 0.805 M-Nitrotoluene C)4)_,a$- 0.95 0.95 0.605 0.605

-116-.10 Table 28. continued

10 12 k (cm 3 molecule

- is -1 ) Experimental Estimated Chemical Class/Chemica AOP (a) AOP HC I. AMINOBENZENES

Aniline (o;?-53-:5 111.0 ill* 136 136 N,N-Dimethylanilinel2l-dr

~ - 148.0 148m 263 200 p-Chloroaniline 83.0 83.0n 53.6 53.6 2,4-Toluenediamine 192.0 192 0 240 200

J. ADDITIONAL SUBSTITUTED

BENZENES
Methoxyben z ene 1 0

0 -(0 6

- 3 17.3 17 . 3* 23.8 23.8 Benzonitrile 100--y4-0 0.33 0.33 0.356 0.356 Benza ldehyde ) Gb -S a't 12.9 12 . 9* 17.1 17.1 Acetophenone c38-$G- Z 2.74 2.74p 1.61 1.61 Thiophenol /0$- 98-6- (Mercaptobenzene) 11.2 11.2q 13.3r 13.3r Benzyl alcohol 

### /a0

- 5

- 1

- 6 22.9 22.9 7.99 7.99 Tetralin (1,2,3,4- 11y_(a41- Z Tetrahydronaphthalene) 34.3 34.3s 11.1 11.2Indan (2,3-DihydroiH-indene) 9.2 9.2t 9.71 9.09 Fluorene (9H-Fluorene) 13.0 13.Ou 9.42 9.37

810-73-fi 1,4-Benzodioxin 25.2 25.2 33.0 33.0 2,3-Dihydrobenzo_fura 36.6 36.6 38.0 36.3

r 

### ~ 1, 4

- Naphthoqiino 

### ~ e 3.1 3.1 2.75 2.75

-117-w

s z 

### Table 28. continued
a Experimental data from Atkinson (1989) and the literature. b Experimental data from Ohta and Ohyama (1985). c Experimental data from Bignozzi et al. (1981). d Experimental data from Chiorboli et al. (1983). e Experimental data from Wahner and Zetzsch (1983). f Experimental data from Rinke and Zetzsch (1984). g Experimental data from Ravishankara et al. (1978a). h Experimental data from Atkinson et al. (1985a). 1 

### Experimental data from Atkinson and Aschmann (1985).

~ 

### Experimental data from Atkinson and Aschmann (1989). k Experimental data from Nolting et al. (1987). 1 

### Average of the experimental data of Witle et al. (1986) and Zetzsch (1982) as reported in Atkinson (1989). m Experimental data from Atkinson et al. (1987).. n Experimental data from Wahner and Zetzsch (1983). o Experimental data from Becker et al. (1988). p Experimental data from Nolting et al. (1987) and Atkinson (1989) . 

### q Experimental data from Barnes et al. (1986). r For the thiol group on an aromatic ring, it was assumed that k(4)=k(-SH)=0 [Meylan (1990)]. s Experimental data from Atkinson and Aschmann (1988a). t Experimental data from Baulch et al. (1986) as reported by Atkinson (1989). u Experimental data from Kldpffer et al. (1986) and Becker et al. (1984) as reported in Atkinson (1989). * Recommended value by Atkinson (1989) with the rationale for the recommendation and the uncertainty for the 

### recommendation.

-118-v~

Atkinson (1989) recommends a value of lil*. In 

### a few cases, AOP

lists fewer significant figures than the values reported in the literature. For example, for 4-chlorobiphenyl, AOP reports a value of 3.9 while Atkinson and Aschmann (1985) and Atkinson report a value of 3.86. It should be noted that for 1,4-benzodioxi: n, AOP lists the erroneous name 1,4-dibenzodioxin; and finally, for aniline, AOP first lists the experimental value for iodobenzene and when a key is pressed, the correct experimental value for aniline is displayed.

IV.F.l.b. Evaluation of the Estimated Data A comparison of the estimated values of k OH by AOP and HC in Table 28 indicates that they are the same except for some differences. First, consider the compounds 3,5-dimethylphenol, N,N-dimethylaniline, and 2,4-toluenediamine. In all three cases, AOP lists a maximum value of the rate constant for OH addition to an aromatic ring [i.e., k(7) = kadd,ar, equation 20] as 200 x 10 -12 cm 3 molecule

- is -1 whereas IiC lists a maximum value of k O H [equation 9] as 200 x 10 -12 cm 3 molecule

- ls -1 . Since the maximum allowed collision rate is 200 x 10 -12 cm 3 molecules -1 [Atkinson (1987)], this boundary condition must be invoked on the estimation of kOH and not on the estimation of k(7) = kadd,ar• It should be noted that this is only applicable to aromatic compounds and not to other compounds (e.g., dimethyl disulfide, a-terpinene, a-phellandrene, etc.) For the compounds tetralin, indan, and fluorene, AOP makes an error in calculating k(7) = kadd,ar• For these three

-119-compounds, AOP uses the incorrect value of v 

### ~ (-CH2-) = 0.06**



### instead of the correct value of -0.064** [see Section IV.A., page 40, Table 9, No. 41 and Leifer (1992a), Table 22, page 109]. Furthermore, for the compounds tetralin, indan, fluorene, and 2,3-dihydrobenzofuran, which contain five membered rings, AOP calculates k(ic) erroneously. That is, for these compounds, AOP makes an error by omitting the ring strain factor F(5) for the five membered ring. As a result, the values of k OH for these compounds are erroneous. Finally, for the compounds 0-methylstyrene, chlorobenzene, n-propylpentafluorobenzene, benzylchloride, and phenol, the small differences between the estimated k OH from AOP and HC are a result of the method of rounding off the last digit.
IV.F.2. Heterocyclic Aromatic Compounds IV.F.2.a. Evaluation of the Experimental kOH Data Table 29 summarizes the pertinent k OH data for the reaction of hydroxyl radicals with heterocyclic aromatic compounds as reported in Atkinson (1989), in AOP, and in the literature. Inspection of the experimental kOH data in columns 2 and 3 indicate that there are a few differences. For pyrrole, the recommended value by Atkinson (1989) is 110* whereas AOP reports a value of 110.0 which contains one more significant figure than is warranted from the experimental data; and for 1,3,5-triazine, the value from Atkinson et al. (1987) and Atkinson (1989) is 0.145 whereas AOP rounds off the data to 0.15. For imidazole and

-120-or

F + ~ 

### Table 29. Comparison of the Estimated Values of kOH at 298 K for

Heterocyclic Aromatic Compounds from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the Literature Versus the Experimental k O H Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Furan / 10--00-9 40.5 40. 5* 40. 5b (c) 3-Methy1furan 9-

: ko - 2 - :9 93.5 93.5d 106. 7(+14 ) h (c) Thiophene ~ ~ V -r
~ 2 ~ 9.53 9.53* 9. 53b (c) Pyrrole Imidazole 2$$'" 3 2 ` 110.0 36.0 110*

35.9e 1.10.0b

36.0b (c)

(c) Oxazole Zg

~ - Z/Z-60 9.1 9. le 9. lOb (c) Thiazole ! 1.40 1. 41 e 1. 40b (c) Pyridine 0.37 0.37f 0.370b (c) 1,3,5-Triazine 0.15 0.1459 0.150b (c)


### a Experimental data from Atkinson (1989) and the literature. b Experimental data for this compound. c Cannot be calculated by HC since Atkinson did not develop S/R relationships for these types of compounds. d Experimental data from Atkinson et al. (1989b). e Experimental data from Witte and Zetzsch (1986) and Atkinson (1989). f Average value from the data of Atkinson et al. (1987) and Witle and Zetzsch (1986) as reported by Atkinson (1989). g Experimental value from Atkinson et al. (1987) as reported by Atkinson (1989). 

### h Percent Error from the value of k O H in column Experimental/(a).

-121-, f



### thiazole, the correct values of k O H obtained from Witte and Zetzsch (1986) and Atkinson (1989) are 35.9 and 1.41, respectively, and not 36.0 and 1.40 as listed in AOP.

IV.F.2.b. Evaluation of the Estimated kOH Data Atkinson did not develop S/R relationships for heterocyclic aromatic compounds whereas Meylan (1990b) did develop S/R relationships for this class of compounds. Meylan used an approach similar to the one used by Atkinson for aromatic compounds (equations 20, 21, and 22). Thus, Meylan postulated that equations 23 and 24 are applicable to heterocyclic aromatic compounds where: (1) Ai is a constant which is equal to the experimental value of k O H for the parent heterocyclic aromatic ring; and (2) the second term is identical to the one used by Atkinson for substituents on the aromatic ring [i.e., -1.35 Min

in equation 21]. The values of Ai are given in Table 10 for a number of parent heterocyclic aromatic rings. The only available experimental kOH data for this class of compounds is for 3-methylfuran, a substituted furan. Atkinson (1989b) reported a value of 93.5 for this compound. The estimated value of kOH obtained from equations 23 and 24 is 106.7 which gives a percent error of +14 which is excellent. However, more experimental kpg data are needed for a number of substituted heterocyclic aromatic compounds listed in Table 29 to confirm the validity of equations 23 and 24.

-122-

# _

t~ 

### IV.F.3. Fused Ring Polyaromatic compounds

IV.F.3.a. Evaluation of the Experimental kOH Data Table 30 summarizes the pertinent experimental kOH data for the reaction of hydroxyl radicals with fused ring polyaromatic compounds (i.e., fused ring polyaromatic hydrocarbons (PAH)). Inspection of the data in columns 2 and 3 indicate that they are the same except for a few differences. For anthracene, the correct value is 112 as reported by Biermann et al. (1985) and Atkinson (1989) and not 110.0 as reported by AOP: For phenanthrene, the recommended value by Atkinson (1989) is 31* and not 31.0 as reported by AOP. Unfortunately, there are no available experimental kOg data for fused ring polyheteroaromatic compounds published in the literature. Hence, there are no entries in Table 30 for this class of compounds.

IV.F.3.b. Evaluation of the Estimated kOH Data A comparison of the estimated values of kOH in columns 4 and 5 of Table 30 indicate that they are the same except for a few differences. The differences are related directly to the dissimilarity between the S/R relationships of Atkinson [equations 26, 27 and 28] and Meylan [equation 29]. First of all, AOP uses the experimental value of kOH for the parent PAH (which is Bi in equation 29) while Atkinson uses the ionization potential of the parent PAH. For naphthalene, both methods give essentially the same results; however, for anthracene and

-123-"V

,

~ Table 30. Comparison of the Estimated Values of k OH at 298 K for

Fused Ring Polyaromatic Compounds (PAH) from the Atmospheric Oxidation Program (AOP) and from a Hand Calculation (HC) and the Experimental kOH Data Reported in the.Literature Versus the Experimental k OH Data in AOP

10 12 k (cm 3 molecule

- ls -1 ) Experimental Estimated Chemical AOP (a) AOP HC Naphthalene 91-.2 O- 3 21.6 21. 6* 21. 6b 21.4 1-Methylnaphthalene 90-/2-v 53.0 53 . Oc 56.9 56.3 2-Methylnaphthalene9i-S7-U 52.3 52.3d 56.9 56.3 2,3-Dimethylnaphthalene 76.8 76.8d 70.0 69.5

~~ /- yv-8 1-Nitronapht2Salene

&0-SF' * 2-Nitronaphthalene

58I 

### ~ &y-S 1,4-Dichloronapht alene 5.4 5.6 5.8 5.4e

5.6e 5.8f 2.66

2.66 4.38 2.63

2.63 4.37 Anthracen e '

, Q
~~ z, ~ Phenanthrene 110.0 31.0 1129

31* 110. Ob

31.0b 91.2

22.9 

### as`'G7/" E N a Experimental data from Atkinson (1989) and the literature. b Experimental data for this compound. c Experimental data from Atkinson and Aschmann (1987). d Experimental data from Atkinson and Aschmann (1986). e Experimental data from Atkinson et al. (1989d). f Experimental data from Klt3pffer et al. (1986) and Becker et al. (1984) as reported in Atkinson (1989). g Experimental data from Biermann et al. (1985). * Recommended values by Atkinson (1989) with the rationale for the recommendation, and the uncertainty for the recommendation.

-124-p

."


### phenanthrene, AOP gives the most reliable results. For the

substituted naphthalenes, AOP and Atkinson (HC) give essentially the same results. However, more experimental kOH data are needed for considerably more substituted polyaromatic hydrocarbons to see how reliable both methods are. Since there are no experimental kOH data for fused ring heterocyclic polyaromatic compounds (i.e., quinoline, isoquinoline, quinoxaline, quinazoline, and acridine), Meylan's S/R method cannot be evaluated. Thus, experimental kOH data is needed on a number of compounds in this class of compounds to confirm and refine the AOP method (i.e., equation 30).

IV.G. Evaluation of the Estimated Half-Life for the Reaction of Hydroxyl Radicals with Organic Chemicals in the Troposphere Meylan (1990b), in AOP, estimated the half-life [t(1/2)E] for the reaction of hydroxyl radicals with organic chemicals in the troposphere by assuming that the average OH radical concentration was 5 x 10 5 radicals cm -3 and a 24-hour daylight day. The assumption of a 24-hour daylight day is incorrect. On the average, a 12-hour daylight day is more reasonable. [Leifer (1992a)]. In addition, based on the literature data (Leifer (1992a)], the average OH radical concentration is closer to 1.5 x 10 6 radicals 

### cm 3 . Therefore, it was recommended that the AOP computer program be changed to the atmospheric conditions described above. This has been done by Meylan in a later version of AOP.

-125-i

~

9


### For olefins and acetylenes, which can react with hydroxyl radicals and ozone, it is desirable to have knowledge of the overall oxidative half-life in the troposphere. Therefore,

k OX = k OH + k0 3 (66)



### where k 'OH and k 

### ~ 3 are the first-order rate constants for reaction of an organic chemical in the troposphere with respect to hydroxyl radicals and ozone, respectively, as calculated under the atmospheric conditions (OH) = 1.5 x 10 6 radicals cm -3 and a 12-hour daylight day and (03) = 7 x 10 11 molecules cm -3 ; and the overall oxidative half-life is given by the equation 

# I t(1/2),OX = 0.693/kOX (67)



### Thus, AOP should add

SUNIIKARY : OXIDATION

kOX = (68)

t ( 1 / 2 )OX = (69)

-126-.~

s

J. a V . Ref erences

Anderson, L.G.; Stephens, R.D. (1988). Int. J. Chem. Kinet. 20, 103-110. Kinetics of the Reaction of Hydroxyl Radicals with 2-(Dimethylamino)ethanol from 234-364 K. Anastasi, C.; Smith, I.W.M.; Parkes, D.A. (1987). J. Chem. Soc. Faraday Trans. 1, 74, 1693. Arey, J.; Atkinson, R.; Zielinska, B.; McElroy, P.A. (1989). Environ. Sci. Technol. 2a, 321-327. Diurnal Concentrations of 

### Volatile Polycyclic Aromatic Hydrocarbons and Nitroarenes During a Photochemical Air Pollution Episode in Glendora, California. Arrhenius, S. (1887). Z. Physik Chem. _X, 110. Atkinson, R. (1986). Chem. Rev. 85, 69-201. Kinetics and Mechanisms of the Gas Phase Reactions of the Hydroxyl Radical with Organic Compounds under Atmospheric Conditions. Atkinson, R. (1986a). Int. J. Chem. Kinet. 11, 555-568. Estimation of OH Radical Rate Constants for H-Atom Abstraction from C-H and O-H Bonds over the Temperature Range 250-1,000 K. Atkinson, R. (1987). Int. J. Chem. Kinet. 12, 799-828. A Structure-Activity Relationship for the Estimation of Rate Constants for the Gas-Phase Reactions of OH Radicals with Organic 

### Compounds. Atkinson, R. (1987a). Environ. Sci. Technol. 11, 305-307. Estimation of OH Radical Reaction Rate Constants and Atmospheric Lifetimes for Polychlorobiphenyls, Dibenzo-p-dioxins, and Dibenzofurans. Atkinson, R. (1988). Env. Toxic. and Chem. 7, 435-442. Estimation of Gas-Phase Hydroxyl Radical Rate Constants for Organic Chemicals.

-127-i '. ~

Atkinson, R. (1987b, 1988a). In OECD (Organization for Economic Cooperation and Development) 

### Test Guideline on Photochemical Oxidative Degradation in the Atmosphere. 1. Draft Final Report Dated January, 1987b. Revision 2, p. 49- 113. 

### 2. Draft Final Report Dated August, 1988a. Revision 3, p. 19-42 and Annex III (Forty-eight examples are given for the estimation of the rate constants kOH). Umweltbundesamt Berlin, Bundesrepublik Deutschland. Estimation of OH Rate Constants. Atkinson, R. (1989). Monograph No. 1. Kinetics and Mechanisms of the Gas-Phase Reactions of the Hydroxyl Radical with Organic Compounds. American Chemical Society, Wash., D.C. and American Inst. of Physics, New York, N.Y. Atkinson, R. (1989a). Unpublished Results. Updating of the Structure/Reactivity Relationships for the Reaction of OH Radicals with Organic Chemicals in the Gas-Phase. Atkinson, R.; Aschmann, S.M. (1984). Int. J. Chem. Kinet. 1¢, 1175-1186. Rate Constant for the Reaction of OH Radicals with a Series of Alkenes and Dialkenes at 295 ± 1 K. Atkinson, R.; Aschmann, S.M. (1985). Environ. Sci. and Technol. 12, 462-464. Rate Constants for the Gas-Phase Reaction of Hydroxyl Radicals with Biphenyl and the Monochlorobiphenyls at 295 ± 1 K.
Atkinson, R.; Aschmann, S.M. (1986). Int. J. Chem. Kinet. 11, 569-573. Kinetics of the Reaction of Naphthalene, 2-Methylnaphthalene, and 2,3-Dimethylnaphthalene with OH Radicals and with 03 at 295 ± 1 K


### . Atkinson, R.; Aschmann, S.M. (1987). Atmos. Environ. al , 2323-2326. Kinetics of the Gas-Phase Reactions of Alkylnaphthalenes with 0 3 , N205, and OH Radicals at 298 ± 2 K. Atkinson, R.; Aschmann, S.M. (1988). Int. J. Chem. Kinet. 2&, 339-342. Rate constants for the Reaction of OH Radicals with Isopropylcyclopropane at 298 ± 2 K: Effects of Ring Strain on Substituted Cycloalkanes. • F ! S

-128-.~

: ~

Atkinson, R.; Aschmann, S.M. (1988a).

Int. J. Chem. Kinet. 2Q, 513-539. 

### Kinetics of the Reactions of Acenaphthalene and Structure-Related Aromatic Compounds with OH and NO 3 radicals, N205, and 0 3 at 296 + 2 K. 

### Atkinson, R.; Aschmann, S.M. (1989). Int. J. Chem. Kinet. ZI, 355-365. Rate Constants for the Gas-Phase Reactions of the OH Radical with a Series of Aromatic Hydrocarbons at 296 ± 2 K. Atkinson, R.; Aschmann, S.M. (1989a). Int. J. Chem. Kinet. ZI, 1123-1129. Rate Constants for the Reaction of the OH Radical with the Propyl and Butyl Nitrates and 1-Nitrobutane at 298 t 2 K. Atkinson, R.; Carter, W.P.L. (1984). Chem. Rev. $4, 437-470 Kinetics and Mechanisms of the Gas-Phase Reactors of Ozone with Organic Compounds Under Atmospheric Conditions. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L. (1983). Int. J. Chem. Kinet. 15, 1161-1177. Effects of Ring Strain on Gas-Phase Rate Constants; 2. OH Radical Reactions with Cycloalkenes. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L. (1983a). Int. J. Chem. Kinet. 11, 37-50. Rate Constants for the Gas-Phase Reactions of OH Radicals with a Series of Bi- and Tricycloalkanes at 299 ± 2 K. Effects of Ring Strain. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L. (1984a) Int. J. Chem. Kin. 1&, 967-976. Kinetics of the Reactions of 03 and OH Radicals with a Series of Dialkenes at 294 ± 2 K. Atkinson, R.; Aschmann, S.M.; Pitts, Jr., J.N. (1986). Int. J. Chem. Kinet. 1$, 287-299. Rate Constants for the Gas-Phase Reactions of the OH Radicals with a Series of Monoterpenes at 294 ± 1 K. Atkinson, R.; Perry, R.A.; Pitts, Jr., J.N. (1977). J. Chem. Phys. 11, 1578-1581. Rate Constants for the Reaction of the OH Radical with CH 3 SH, CH 3 NH 2 over the Temperature Range 299-426 K.

-129-

### Atkinson, R.; Perry, R.A.; Pitts, Jr., J.N. (1978).

J. Chem. Phys., 1850-1853. Rate Constants for the Reactions of the OH Radical with (CH3)2NH, (CH3)3N, and C2H5NH2 over the Temperature Range 298-426 K. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L.; Pitts Jr., J.N. (1982). 

### Int. J. Chem. Kinet. IA, 839-847. Rate Constants for the Gas-Phase Reaction of OH Radicals with a Series of Ketones at 299 + 2 K. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L.; Winer, A.M. (1982a). Int. J. Chem. Kinet. I,4, 919-926. Kinetics of the Gas-Phase Reactions of OH Radicals with Alkyl Nitrates at 299 + 2 K. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L.; Winer, A.M.; Pitts Jr., J.N. (1982b). Int. J. Chem. Kinet:.J„4,, 781-788. Kinetics of the Reactions of OH Radicals with ;}-Alkanes at 299 ± 2 K. Atkinson, R.; Carter, W.P.L.; Aschmann, S.M.; Winer, A.M.; Pitts Jr., J.N. (1984). Int. J. Chem. Kinet. 1,¢, 469-481. Kinetics of the Reactions of OH Radicals with a Series of Alkanes at 297 ± 2 K. Atkinson, R.; Aschmann, S.M.; Carter, W.P.L.; Winer, A.M.; Pitts Jr., J.N. (1984b). Int. J. Chem. Kinet. 1,¢, 1085-1101. Formation of Alkyl Nitrates from the Reaction of Branched and Cyclic Alkyl Peroxy Radicals with NO. Atkinson, R.; Aschmann, S.M.; Winer, A.M.; Pitts Jr., J.N. (1985a). Arch. Environ. Contam. Toxicol. 19, 417-425. Atmospheric Gas Phase Loss Processes for Chlorobenzene, Benzotrifluoride, and 4-Chlorobenzotrifluoride and Generalization of Predictive Techniques for Atmospheric Losses of Aromatic Compounds. Atkinson, R.; Tuazon, E.C.; Wallington, T.J.; Aschmann, S.M.; Arey, J.; Winer, A.M.; Pitts Jr., J.N. (1987). Environ. Sci. Technol. al , 64-72. Atmospheric Chemistry of Aniline, N,N-Dimethylaniline, Pyridine, 1,3,5-Triazine, and Nitrobenzene. r

~

~

! y

-130-~r

~

~• 

### Atkinson, R.; Aschmann, S.A.; Goodman, M.A.; Winer, A.M. (1988).

Int. J. Chem. Kinet. 2,0_, 273-281. Kinetics of the Gas-Phase Reactions with the OH Radical with (C2H S O)3P(0) and (CH30)2P(S)C1 at 296 ± 2 K. Atkinson, R.; Baulch, D.L.; Cox, R.A.; Hampson Jr., R.F.; Kerr, J.A.; Troe, J. (1989a). Int. J. Chem. Kinet. ZI, 115-150. Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry: Supplement III. Atkinson, R.; Aschmann, S.M.; Tuazon, E.C.; Arey, J.; Zillinska, B. (1989b). Int. J. Chem. Kinet. 21, 593-604. Formation of 3-Methylfuran from the Gas-Phase Reaction of OH Radicals with Isoprene and the Rate Constant for its Reaction with OH Radicals. Atkinson, R.; Baulch, D.L.; Cox, R.A.; Hampson Jr., R.F., Kerr, J.A.; Troe, J. (1989c). J. Phys. Chem. Ref. Data 18, No. 2, 881-1097. Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry, Supplement III. Atkinson, R.; Aschmann, S.M.; Arey, J.; Zielinska, B.; Schuetzles, D. (1989d). Atmos. Environ. 21, 2679-2690. Gas-Phase Atmospheric Chemistry of 1- and 2-Nitronaphthalene and 1,4-Naphthoquinone. Barnes, I.; Bastian, V.; Becker, K.H.; Fink, E.H.; Nelson, W. (1986). 

### J. Atmos. Chem. 4, 445-446. Oxidation of Sulfur Compounds in the Atmosphere: I. Rate Constants of OH Radical Reactions with Sulfur Dioxide, Hydrogen Sulfide, Aliphatic Thiols and Thiophenol. Barnes, I.; Bastian, V.; Becker, K.H. (1986a). Ninth International Symposium on Gas Kinetics, University of Bordeaux, Bordeaux France. July 20-25, 1986. D. Riedel Publishinq Co. Dordrecht, Holland (1987). Baulch, D.L.; Campbell, I.M.; Saunders, S.M. (1985). Int. J. Chem. Kinet. 17, 355-366. The rate constants for the reaction of the hydroxyl radical with methyl, n-propyl, and H-butyl nitrites. Baulch, D.L.; Campbell, I.M.; Saunders, S.M. (1986). 9th International Symposium on Gas Kinetics U. of Bordeaux, Bordeaux, France, July 20-25, 1986.

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### Becker, K.H.; Bastian, V.; Klein, T.H. (1988).

J. Photochem. Photobiol.; A: Chemistry 45, 195-205. The Reactions of OH Radicals with Toluene Diisocyanate, Toluenediamine, and Methylenediamine Under Simulated Atmospheric Conditions. Becker, K.H.; Biehl, H.M.; Bruckmann, P.; Fink, E.H.; Ftibr, F.; Kldptfer, W.; Zellner, R.; Zetzsch, C. (November, 1984). Editors Kernforschungs anlage Jiilick Gmblt. Bundesrepublik Deutschland. Report 1980-1983. Behnke, W.; Nolting, F.; Zetzsch, C. (1988). 10= International Symposium on Gas Kinetics (July 24-29, 1988) University of Swansea, Swansea, U.K. Bennett, P.J.; Kerr, A. (1989). J. Atmos. Chem. $, 87-94. Kinetics of the Reactions of Hydroxyl Radicals with Aliphatic Ethers Studied under Simulated Atmospheric Conditions. Biermann, H.W.; Macleod, H.; Atkinson, R.; Winer, A.M.; Pitts Jr., J.N. (1985). Environ. Sci. Technol. 19, 244-248. Kinetics of the Gas-Phase Reactions of the Hydroxyl Radical with Naphthalene, Phenanthrene, and Anthracene. Bignozzi, A.; Maldotti, A.; Chiorboli, C.; Bartocci, C.; Carasitti, V. (1981). Int. J. Chem. Kinet. 11, 1235-1242. Kinetics and Mechanism of Reactions Between Aromatic Olefins and Hydroxyl Radicals. Boodaghians, R.B.; Hell, I.W.; Toby, F.S.; Wayne, R.P. (1987). J. Chem. Soc. Faraday Trans. 12, 2073-

. Absolute Determinations of the Kinetics and Temperature Dependencies of the Reactions of OH with a Series of Alkynes. Brown, H.C. and Okamoto, Y. (1958). J. Am. Chem. Soc. $Q, 4979-4987. Electrophilic Substituent Constants. Campbell, I.M.; Parkinson, P.E. (1978). Chem. Phys. Lett. 12, 385



### - 387. 

### Rate Constants for Reactions of Hydroxyl Radicals with Ester Vapors at 292 K. Chiorboli, C.; Bignozzi, C.A.; Maldotti, A.; Giardini, P.F.; Rossi, A.; Carassiti, V. (1983). Int. J. Chem. Kinet. 15, 579-586. Rate Constants for the Gas-Phase Reactions of OH Radicals with

~ 

### - Dimethylstyrene NO x

- 

### Air Photooxidation. s

~ M_ 9

~ J

-132-f ]~

.

/

~


### Clyne, M.A.A.; Holt, P.M. (1979).

J. Chem. Soc. Faraday Trans. Z, 582-591. Reaction Kinetics Involving Ground X 2 n and Excited A 2 E+ Hydroxyl Radicals. Cox, R.A.; Patrick, K.F.; Chant, S.A. (1981). Environ. Sci. Toxicol. 15, 587-592. Mechanism of Atmospheric Oxidation of Organic Compounds. Reactions of Alkoxy Radicals in Oxidation of n-Butane and Simple Ketones. Crutzen, D.J. (1982). In "Atmospheric Chemistry," D.G. Goldberg, Editor. The Global Distribution of Hydroxyl. pp. 313-328. Springer-Verlag, NY. Dagaut, P.; Wallington, T.J.; Liu, R.; Kurylo, M.J. (1988). J. Phys. Chem. U, 4375-4377. 

### A Kinetics Investigation of the Gas-Phase Reactions of OH Radicals with Cyclic Ketones and Diones: Mechanistic Insights. Da aut, P.; Wallington, T.J.; Liu, R.; Kurylo, M.J. (1988a). 22 International Symposium on Combustion. Aug. 14-19, 1988. Seattle, WA. Darnall, K.R.; Winer, A.M.; Lloyd, A.C.; Pitts Jr., J.N. (1976). Chem. Phys. Letters g,4, 415-418. Relative Rate Constants for the Reaction of OH Radicals with Selected C6 and C7 Alkanes and Alkenes at 305 ± 2 K. Davis, L.I.; James, J.V.; Wang, C.C.; Guo, C.; Morris, P.T.; Fishman, J. (1987). J. Geophys. Res. U, 2020-2024. OH Measurement Near the Intertropical Convergence Zone in the Pacific. 

### Edney, E.O.; Kleindienst, T.E.; Corse, E.W. (1986). Int. J. Chem. Kinet. 11, 1355-1371. Room Temperature Rate Constants for the Reaction of OH with Selected Chlorinated and Oxygenated Hydrocarbons. Felton, C.C.; Sheppard, J.C.; M.J. Campbell (1988). Nature =, 53 (1988). Measurements of the Diurnal OH Cycle by a 14 C-Tracer Method. Gaffney, J.S.; Levine, S.Z. (1979). Int. J. Chem. Kinet. 11, 1197-1209. Predicting Gas Phase Organic Molecule Reaction Rates Using Linear Free Energy Correlations. I.0( 3 P) and OH Addition and Abstraction.

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~ a 

### Gaffney, J.S.; Fajer, R.; Senum, G.I.; Lee, J.H. (1986). Int. J. Chem. Kinet. ,U, 399-407. Measurement of the Reactivity of OH with Methyl Nitrite: Implications for Prediction of Alkyl Nitrate -OH Reaction Rates. Goodman, M.A.; Aschmann, S.M.; Atkinson, R.; Winer, A.M. (1988). Arch. Environ. Contam. Toxicol. 1,7, 281-288. Kinetics of Atmospherically Important Gas-Phase Reactions of a Series of Trimethyl Phosphorothioates. Goodman, M.A.: Aschmann, S.M.; Atkinson, R.; Winer, A.M. (1988a). Env. Sci. Technol. 22, 578-583. Atmospheric Reactions of a Series of Dimethyl Phosphoroamidates and Dimethyl Phosphorothioamidates. Gorse, R.A.; Volman, D.H. (1974). J. Photochem. 2, 115-122. Photochemistry of the Gaseous Hydrogen Peroxide-Carbon Monoxide System. II. Rate constants for Hydroxyl Radical Reactions with Hydrocarbons and for Hydrogen Atom Reactions with Hydrogen Peroxide. Gorse, R.A.; Lii, R.R.; Saunders, B.B. (1977). Science Ul, 1365-1367. 

### Hydroxyl Radical Reactivity with Diethylhydroxylamine. Hard, T.M.; O'Brien, R.J.; Chan, C.Y.; Mehrabzadeh, A.A. (1984). Environ. Sci. Technol. 1$, 768. Tropospheric Free Radical Determination by FAGE. Hard, T.M.; Chan, C.Y.; Mehrabzadeh, A.A.; Pan, W.H.; O'Brien, R.J. (1986). Nature 2U, 617 (1986). Diurnal Cycle of Tropospheric OH. Hansch, C.; Leo, A. (1979). Substituent Constants for Correlation Analysis in Chemistry and Biology. J. Wiley and Sons, New York, NY. Harris, G.W.; Atkinson, R.; Pitts Jr., J.N. (1979). J. Phys. Chem. $a, 2557-2559. 

### Kinetics of the Reactions of the OH Radical with Hydrazine and Methylhydrazine. Harris, G.W.; Kleindienst, T.E.; Pitts Jr., J.N. (1981). Chem. Phys. Lett. $Q, 479-483. Rate Constants for the Reaction of OH Radicals with CH3CN 1 C2H5CN, and CH2=CHCN in the Temperature Range 298-424 K.

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Int. J. Chem. Kinet. 2S, 339. 

### Hartmann, D.; Gedra, A.; Rhasa, D.; Zellner, R. (1987). Proceedings, 4th European Symposium on the Physio-Chemical Behavior of Atmospheric Pollutants (1986). D. Riedel Publishing Co., Dordrecht, Holland. p. 225. Hatakeyama, S.; Honda, S.; Washida, N.; Akimoto, H. (1985). Bull. Chem. Soc. Jpn. a, 2157-2162. Rate Constants and Mechanism for Reactions of Ketenes with OH Radicals in Air at 299 ± 2 K. Hatakeyama, S.; Washida, N.; Akimoto, H. (1986). J. Phys. Chem. 2Q, 173-178. Rate Constants and Mechanisms for the Reaction of OH (OD) Radicals with Acetylene, Propyne, and 2-Butyne in Air at 297 ± 2 K. Hendry, D.G.; Mi11,

- T.; Davenport, J.E. (August 1988). In OECD (Organization for Economic Cooperation and Development). OECD Test Guideline on Photochemical Oxidative Degradation in the Atmosphere. Draft Final Report, p. 14-43. January 1987. Umweltbundesamt Bundesrepublik Deutschland, Berlin. Hewitt, C.W.; Harrison, R.M. (1985). Atmos. Environ. U, 545-554. Tropospheric Concentrations of the Hydroxyl Radical -- A Review. Howard, C.J. (1976). J. Chem. Phys. §

~ 

### , 4303-4306. Rate Constants for the Reactions of OH with Ethane and Some Halogen Substituted Ethanes at 296 K. Howard, C.J.; Evenson, K.M. (1976). J. Chem. Phys. §g,, 4303. Rate Constants for the Reactions of OH with Ethane and Some Halogen Substituted Ethanes at 296 K. Hiibler, G.; Perner, D.; Platt, U.; Tonnissen, A.; Ehkalt, (1984). J. Geophys. Res. 12, 1309-1319. Ground level OH Radical Concentration: New Measurements by Optical Absorption. Hynes, A.J.; Wine, P.H.; Semmes, D.H. (1986). J. Phys. Chem. 90, 4148-4156. Kinetics and Mechanisms of OH Reactions with Organic Sulfides. 

## •

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; Tuazon, E.C.; Atkinson, R.; Carter, W.P.L. (1985). Environ. Sci. Technol. U, 265-269. Atmospheric Chemistry of cis- and trans-3-Hexene-2,5-dione. Tuazon, E.C.; Atkinson, R.; Aschmann, S.M.; Arey, J.; Winer, A.M.; Pitts Jr., J.N. (1986). Environ. Sci. Technol. 2,Q, 1043-1046. Atmospheric Loss Process of 1,2-Dibromo-3-chloropropane and Trimethyl Phosphate. Tuazon, E.C.; Atkinson, R.; Aschmann, S.M.; Goodman, M.A.; Winer, A.M. (1988). J. Chem. Kinet. 2Q, 241-265. Atmospheric Chemistry of Chloroethenes with the OH Radical. Wahner, A.; Zetzsch, C. (1983). J. Phys. Chem. $7, 4945-4951.Rate Constants for the Addition of OH to Aromatic (Benzene, pChloroaniline, and Q-, M-, and p-Dichlorobenzene and theUnimolecular Decay of the Adduct. Kinetics into QuasiEquilibrium). Wallington, T.J.; Kurylo, M.J. (1987). J. Phys. Chem. 11, 5050-5054.Flash Photolysis Resonance Fluorescence Investigation of the GasPhase Reactions of OH Radicals with a Series of Aliphatic Ketones over the Temperature Range 240-440K. Wallington, T.J.; Kurylo, M.J. (1987a). Int. J. Chem. Kinet. 12, 1015-1023. The Gas Phase Reactions of Hydroxyl Radicals with a Series of Aliphatic Alcohols Over the Temperature Range 240-440 K. Wallington, T.J.; Dagaut, P.; Liu, R.; Kurylo, M.J. (1988). Int. J. Chem. Kinet. 2,Q; 177-186. The Gas Phase Reactions of Hydroxyl Radicals with a Series of Esters Over the Temperature Range 240-440 K. Wallington, T.J.; Liu, R.; Dagaut, P.; Kurylo, M.J. (1988a). Int. J. Chem. Kinet. 2&, 41-49. The Gas Phase Reactions of Hydroxyl Radicals with a Series of Aliphatic Ethers over the Temperature Range 240-440 K. Wallington, T.J.; Dagaut, P.; Liu, R.; Kurylo, M.J. (1988b). Int. J. Chem. Kinet. ZQ, 541-547. Rate Constants for the Gas Phase Reactions of OH with C5 through C7 Aliphatic Alcohols and Ethers. Predicted and Experimental Values.

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### "Handbook of Chemistry and Physics" E-74. 57tth Edition. Ionization Potentials of Molecules. CRC Press, Cleveland, Ohio. Winer, N.M.; Lloyd, A.C.; Darnall, K.R.; Pitts Jr., J.N. (1976). J. Phys. Chem. 80, 1635-1639. Relative Rate Constants for the Reaction of the Hydroxyl Radical with Selected Ketones, Chloroethenes, and Monoterpene Hydrocarbons. Witte, F.; Urbanik, E.; Zetzsch, C. (1986). J. Phys. Chem. 90, 3251-3259. 

### Temperature Dependence of the Rate Constants for the Addition of OH to Benzene and Some Monosubstituted Aromatics (Aniline, Bromobenzene, and Nitrobenzene) and the Unimolecular Decay of the Adducts. Kinetics into a Quasi-Equilibrium. Wu, C.H.; Japar, S.M.; Niki, H. (1976). J. Environ. Sci. Health - Environ. Sci. Eng., A11 (2), 191-200. Relative Reactivities of HO-Hydrocarbon Reactions from Smog Reactor Studies. Zabarnick, S.; Fleming, J.W.; Lin, M.C. (1988). Int. J. Chem. Kinet. 2Q, 117-129. Kinetics of Hydroxyl Radical Reactions with Formaldehyde and 1,3,5-Trioxane between 290 and 600 K. Zabarnick, S.; Fleming, J.W.; Lin, M.C. (1988a). Chem. Phys. 120, 319-325. The Reaction of OH and OD with Nitromethane. Zetzsch, C. (1980). Bunsen Colloquium, Gdttingen, W. Germany, October 9, 1980. Zetzsch, C. (1982). Report to Bundesminister fUr Forschung und Technologie, Projektrager fUr Umweltchemikalien. Bundesrepublik Deutschland. ~

-141-.. 

### _~pEPOR7 DOCUMEN7ATION 1. REPORT NO. 2. 3. Recipient's Accession No. PAGE EPA-744R-93-001 S. Report Date 4, TIfM end Subtitle DETERMINATION OF RATES OF REACTION IN THE GAS-PHASE IN THE Jenuary 1993 

# 1 A~ ('DN ~~~ i THEORY AND PRACTICE. S Rate of i esearch Corporetion for Estimadng thea 6. ^ YI rem ot yracuse R ro R

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### OX

~ d a pop Cumputar Prog Or anic Cheroical with Hyd ~ M p~ pi ~h 8 ~~~ ~ oRS tept for the Raac ~ o"
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