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Central Report Index (CRI) Report

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Title

Extrapolation of Vapor Pressure Data Using the Antoine Equation

Author(s) and Userid(s)

Crosthwaite, Jacob (JM) (U393454); Srivastava, Rakesh (R) (U081611)

Final Reviewer and Userid Date Issued Lab Report Code

Pasztor Jr, Andew (AJ) (U075055); Killebrew, Tina 

(TM) (U366965) January 3, 2012

Abstract 

The original toxicity work on divinylbenzene dioxide (DVBDO or Epoxide 12) and associated 

characterization was done on an 80% purity product, where the primary impurities were 

ethylvinylbenzene oxide (EVBO) and divinylbenzene monoxide (DVBMO). The vapor pressure of the 

80% product at 25 °C was measured by an external contract laboratory using a vapor pressure balance. 

However, the value reported for the sample was 4.3 Pa (0.032 mmHg) at 25 °C, which is higher than 

expected based on the extrapolated vapor pressure data for the three major components DVBDO, EVBO, 

and DVBMO from an earlier Dow study. Vapor pressure data had been measured for these three 

components for regressing Antoine equation parameters, which were used for extrapolating vapor 

pressure data at 25 °C. To address this issue, this study was conducted to evaluate the use of Antoine 

Equation constants from vapor pressure data of high boiling compounds (normal boiling points greater 

than 200 °C) for extrapolating vapor pressure data at lower temperatures such as 25 °C from 

measurements conducted at higher temperatures. Vapor pressure data were obtained for three test 

components, tetradecane, 1-dodecanol, and sulfolane, which have comparable volatility to DVBDO and 

experimental vapor pressure data at temperatures near 25 °C. The vapor pressure data of these three 

compounds were measured and the data correlated to the Antoine and Wagner equations for 

extrapolation to lower temperatures near ambient. Predicted vapor pressure data using the correlation 

parameters were compared to experimental data for evaluating the accuracy of the extrapolated vapor 

pressure data. The Antoine equation constrained by the Thomson’s Rule provided the best fit compared 

to the experimental data near 25 °C, with an expected deviation of ±25%. 
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NOTIFICATION LIST 

This list indicates people to be notified by the authors when this report is available from CRI. 

See the RIC website for more information on the notification list. 

Crosthwaite, Jacob (JM) 

Srivastava, Rakesh (R) 

Pasztor, Andrew (AJ) 

Killebrew, Tina (TM) 

Jean, David (DL) 

Krieg, David (DW) 

Treble, Imogene (IE) 

.DL AS R&D-LT

Databook: 200900916 

TABLE OF CONTENTS 

INTRODUCTION ........................................................................................................................................... 3

EXPERIMENTAL .......................................................................................................................................... 3

Materials .................................................................................................................................................... 3

Vapor Pressure .......................................................................................................................................... 3

RESULTS & DISCUSSION ........................................................................................................................... 5

CONCLUSIONS & RECOMMENDATIONS .................................................................................................. 6

REFERENCES .............................................................................................................................................. 6

APPENDIX A. EMAIL CONVERSATIONS WITH HARLAN ........................................................................ 8

LIST OF TABLES 

Table 1. Vapor Pressure of Tetradecane ..................................................................................................... 5

Table 2. Vapor Pressure of 1-Dodecanol ..................................................................................................... 5

Table 3. Vapor Pressure of Sulfolane .......................................................................................................... 5

Table 4. Antoine Equation Parameters (Unconstrained and Constrained by Thomson’s Rule) for 

Tetradecane, 1-Dodecanol, and Sulfolane ................................................................................................... 5

Table 5. Wagner Equations Parameters for Tetradecane, 1-Dodecanol, and Sulfolane ............................ 5

Table 6. Comparison of Predicted Vapor Pressure from Antoine and Wagner Equation Regressions to 

Experimental Data (DIPPR) .......................................................................................................................... 6

LIST OF FIGURES 

Figure 1. Photograph of the Stirred Vapor Pressure Ebulliometer .............................................................. 4
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INTRODUCTION 

The original toxicity work and associated characterization on divinylbenzene dioxide (DVBDO or Epoxide 

12) was done on an 80% purity product, where the primary impurities were ethylvinylbenzene oxide 

(EVBO) and divinylbenzene monoxide (DVBMO). The vapor pressure of the 80% product at 25 °C was 

measured by Harlan, an external contract laboratory, using a vapor pressure balance1. The value 

reported for the sample was 4.3 Pa (0.032 mmHg) at 25 °C, which is higher than expected based on the 

extrapolated vapor pressure data for the three major components DVBDO, EVBO, and DVBMO2. The 

method used by Harlan is good for pure components, but will be inaccurate for mixtures. Based on 

conversations with Harlan personnel (see Appendix A for more details), the value reported for the sample 

would be the vapor pressure of the least volatile component in the mixture and not be representative of 

the vapor pressure of the test sample, providing misleading data for risk assessment on environmental 

emissions3. This observation was confirmed as the extrapolated vapor pressure of DVBMO (an impurity 

in the 80% sample) at 25 °C is 0.029 mmHg, which matches the reported value by Harlan. This study 

was conducted to evaluate the use of Antoine Equation constants for extrapolating vapor pressure data at 

lower temperatures such as 25 °C from measurements conducted at higher temperatures. 

Vapor pressure data for DVBDO, EVBO, and DVBMO were measured internally using either an 

ebulliometric or GC method at higher temperatures (70 to 200 °C) and fit to the Antoine equation 

(constrained by the Thomson’s Rule)2. The Antoine equation parameters were then used to calculate the 

vapor pressure at 25 °C. To assess the accuracy of extrapolating vapor pressure data at 25 °C using 

Antoine equation parameters, vapor pressure data were obtained for three test components using the 

stirred-flask ebulliometer. Tetradecane, 1-dodecanol, and sulfolane were chosen as test materials based 

on comparable volatility to DVBDO and the availability of vapor pressure data at temperatures near 25 

°C. The vapor pressure of these three compounds was measured and the data correlated to the Antoine 

and Wagner equations for extrapolation to low temperatures near ambient. Predicted vapor pressure 

data using the correlation parameters were compared to experimental data for evaluating the accuracy of 

the extrapolated vapor pressure data. 

EXPERIMENTAL 

Materials 

Tetradecane (puriss., olefin free, Lot# BCBF0800V, 99.5%), 1-dodecanol (ACS Reagent, Lot# 

MKBF9576V, 99.3%), and sulfolane (Lot# MKBD8843V, 99.9%) were supplied by Aldrich. 

Vapor Pressure 

Vapor pressure data were measured using ASTM method E17194

 in the glass still shown in Figure 1. 

This still consists of a 250- filter flask attached to a condenser. The temperature of the liquid in the 

flask was measured by a platinum resistance thermometer inserted into the liquid with an accuracy of ± 

0.05 °C. The temperature was recorded by a computerized data acquisition system. The still was 

charged through the top of the flask. After charging, the still was evacuated and refilled with dry nitrogen 

to remove moisture and oxygen. The base of the still was then immersed in a silicone bath and the oil 

bath was heated. 

The liquid in the still was stirred vigorously by a large magnetic stirrer located beneath the oil bath. As the 

bath was heating, the pressure was set at the first desired value for the vapor pressure measurements. 

The pressure was controlled and measured by a Mensor pressure controller with an accuracy of ± 

0.025%. The bath was heated until the material in the still began to reflux. The bath temperature was 

then increased until the reflux rate was approximately one drop per second. After the material in the still 

was refluxing at steady state conditions, the bath temperature was raised or lowered by one degree at 

constant condenser pressure. The temperature of the liquid in the still should remain constant even if the 

bath temperature changes when the system is operating at equilibrium. The usual cause for non-
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equilibrium operation is insufficient stirring or not enough reflux. If the temperature in the still responded 

to a change in the bath temperature, the agitation in the still was increased or the bath temperature was 

increased until equilibrium conditions were reached. For this work, the temperature of the oil bath was 

controlled by a Hart Model 2100 temperature controller at approximately 10 °C above the boiling 

temperature of the sample. The temperature in the still was monitored until it was stable. An average 

temperature from several minutes of operation was then recorded in the lab book. After the 

measurement, the pressure was increased to the next desired value, the bath temperature was 

increased, and the system was allowed to re-equilibrate. 

Figure 1. Photograph of the Stirred Vapor Pressure Ebulliometer 

The vapor pressure data were correlated to the Antoine equation and Wagner equation for extrapolation 

of vapor pressure data to 25 °C. The Antoine and Wagner equations are shown in equations 1 and 2, 

respectively. 

 

Ct

B

P mmHg A



log 

(1) 

         

r

r r r r

r

T

TCTCTCTC

P

6

4

3

3

5.1

1 1 2 1 1 1

ln 

(2) 

c

r

P

P

P 

 (3a) 

c

r

T

T

T 

 (3b) 

where: P = vapor pressure 

 t = temperature (°C) 

 T = temperature (K) 

 Pc = critical pressure 

 Tc = critical temperature (K) 

 A, B, C = Antoine equation parameters 

 C1, C2, C2, C3 = Wagner equation parameters 
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RESULTS & DISCUSSION 

Vapor pressure data for tetradecane, 1-dodecanol, and sulfolane are shown in Tables 1-3, respectively. 

The data match the expected vapor pressure data within the listed uncertainty from the DIPPR database5

for all three components. The measured vapor pressure data were correlated to the Antoine equation 

using the Thermal ANTOINE program and to the Wagner equation using AspenPlus. The details of the 

Antoine equation fitting program can be found on the Dow Intranet6. For the Antoine equation regression, 

two regressions were made: 1) an unconstrained fit and 2) using the Thomson’s rule to constrain the C 

value. The Thomson rule constrains the C value in the Antoine equation based on the normal boiling 

point of the sample, providing an approximately correct curvature for the data. Antoine equation 

constants from both regressions for the three components are shown in Table 4, and Wagner equation 

parameters and constants are shown in Table 5. The critical temperature and pressure for the three 

components were obtained from the DowPure Database using DowPPDS7. 

Table 1. Vapor Pressure of 

Tetradecane 

T (°C) P (mmHg)

109.918 5

123.041 10

143.104 25

160.491 50

171.63 75

180.023 100

186.834 125

192.639 150

197.567 175

Italized data not used in 

Correlations 

Table 2. Vapor Pressure of 

1-Dodecanol 

T (°C) P (mmHg)

127.298 5

139.517 10

153.389 20

169.229 40

179.411 60

187.098 80

193.36 100

198.558 120

Table 3. Vapor Pressure of 

Sulfolane 

T (°C) P (mmHg)

127.907 5

142.528 10

159.058 20

169.681 30

177.651 40

184.089 50

189.536 60

194.268 70

198.335 80

Table 4. Antoine Equation Parameters (Unconstrained and Constrained by Thomson’s Rule) for 

Tetradecane, 1-Dodecanol, and Sulfolane 

Compound Unconstrained Constrained by Thomson's Rule

A B C A B C

Tetradecane 6.55072 1434.67 135.303 7.55531 2069.46 192.45

1-Dodecanol 6.14666 1147.48 83.3671 8.22934 2393.57 191.323

Sulfolane 6.45813 1538.77 139.307 7.25353 2055.73 186.02

Table 5. Wagner Equations Parameters for Tetradecane, 1-Dodecanol, and Sulfolane 

Compound C1 C2 C3 C4 Tc (K) Pc (mmHg)

Tetradecane -2.91963 -13.89285 20.36029 -83.3998 693.15 12166

1-Dodecanol 6.004256 -34.97373 52.098 -175.489 719.4 14956.2

Sulfolane 19.89514 -58.34899 66.02761 -91.9523 855 37694.3
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Table 6. Comparison of Predicted Vapor Pressure from Antoine and Wagner Equation 

Regressions to Experimental Data (DIPPR) 

Component T (°C) Pexp

(mmHg)

Antoine

Constrained by 

Thomson's Rule

Antoine

Unconstrained Wagner

P (mmHg) % Diff P (mmHg) % Diff P (mmHg) % Diff

Tetradecane 6.4 2.00E-03 1.41E-03 -29.7 2.67E-04 -86.7 8.28E-05 -95.9

Tetradecane 12.7 4.00E-03 2.94E-03 -26.6 7.20E-04 -82.0 2.65E-04 -93.4

Tetradecane 16.5 6.00E-03 4.48E-03 -25.3 1.26E-03 -79.0 5.10E-04 -91.5

Tetradecane 19.3 8.00E-03 6.06E-03 -24.3 1.87E-03 -76.7 8.08E-04 -89.9

Tetradecane 21.6 1.00E-02 7.71E-03 -22.9 2.55E-03 -74.5 1.16E-03 -88.4

Tetradecane 28.8 2.00E-02 1.59E-02 -20.4 6.43E-03 -67.8 3.40E-03 -83.0

Tetradecane 36.4 4.00E-02 3.25E-02 -18.6 1.57E-02 -60.8 9.50E-03 -76.3

1-Dodecanol 30 2.10E-03 2.60E-03 23.7 1.06E-04 -95.0 3.20E-05 -98.5

1-Dodecanol 40 5.86E-03 7.62E-03 30.1 7.00E-04 -88.0 2.71E-04 -95.4

Sulfolane 27.4 5.57E-03 4.18E-03 -25.0 1.69E-03 -69.7 4.65E-04 -91.6

Sulfolane 55.02 5.53E-02 5.31E-02 -4.0 3.46E-02 -37.4 1.98E-02 -64.1

Table 6 contains vapor pressure data for tetradecane, 1-dodecanol, and sulfolane extrapolated to 

temperatures near 25 °C. The extrapolated data were compared with experimental data obtained from 

the DIPPR Diadem database5, using only the “Accepted” data points. The parameters from the three 

regressions were used to predict the vapor pressure at the experimental temperatures for comparison to 

the experimental vapor pressure data (in terms of percent deviation). The Antoine regression constrained 

using the Thomson’s rule provided the best fit of the experimental data near 25 °C, with percent 

deviations around ± 25% between the experimental and extapolated data near 25 °C. The deviation of ± 

25% would be expected when extrapolating down to 25 °C for similar high boiling components using 

vapor pressure data between 100 to 200 °C, while the expected uncertainty within the experimental data 

set would be considerable lower (typically less than 5%). The better fit was expected since constraining 

the vapor pressure data with Thomson’s rule helps provide a better curvature of the pressure-temperature 

dataset over a larger range up to the normal boiling point. The other two fits were both unconstrained 

and had significantly higher deviations at lower temperatures, with percent deviations of 75 to 100%. 

Based on the results on this study, it is recommended that the Antoine equation constrained by 

Thomson’s rule be used for all regressions of vapor pressure data below 200 mmHg. 

CONCLUSIONS & RECOMMENDATIONS 

Vapor pressure data for tetradecane, 1-dodecanol, and sulfolane were measured and regressed to the 

Antoine and Wagner equations. The regression parameters were then used to predict vapor pressure 

data for comparison to experimental data near 25 °C. The Antoine equation regression constrained by 

the Thomson’s rule provided the best fit relative to the experimental data, with deviations of ± 25%. The 

vapor pressure data for DVBDO, EVBO, and DVBMO in the original report were regressed using the 

Antoine Equation constrained by Thomson’s rule. So, the uncertainty in the predicted vapor pressure for 

these components (4.23*10-4 mmHg for DVBDO; 4.69*10-3 mmHg for EVBO; 2.93*10-2 mmHg for 

DVBMO) in the original report is expected to be about ± 25%. 

REFERENCES 

1. Atwal, S. S.; Tremain, S. P., “Reaction mass of bis(epoxyethyl)benzene and (ethylphenyl)oxirane: 

Determination of Hazardous Physico-chemical Properties”, Project Number 0044/1411, Harlan 

Larboratories, Shardlow, Derbyshire, United Kingdom (2009). 
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2. Alkhawaldeh, A., Fowler, T., Jean, D., Pham, K., Solis, J., Srivastava, R., “Distillation and Physical 

Properties Measurements for Divinylbenzene Dioxide, Divinylbenzene Monoxide, and 

Ethylvinylbenzene Oxide”, CRI Report# EPI N-2010-022 (2010). 

3. Anna Lojakowska, email communication, Oct. 19, 2011. 

4. ASTM E 1719, “Standard Test Method for Vapor Pressure of Liquids by Ebulliometry”, Annual Book 

of ASTM Standards, Vol. 14.02, American Society for Testing and Materials International, West 

Conshohocken, PA, (2004).

5. DIPPR Diadem, Version 5.2.2.

6. http://analytical.intranet.dow.com/rctapp/programs/antoine.htm.

7. Dow PPDS, Version 4.1.0.1.
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