bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photolysis of N‐nitrosamines in neutral media
Authors: Fiz Nemesio , Usero José L. , Casado Julio 
Published: January 2005

AbstractThe photolysis of N‐nitrosamines in solutions of acetonitrile follows a first‐order reaction with respect to the concentration of nitrosamine. Quantum yields are very low (≈ 0.1) and depend on the concentration of nitrosamine, with the observation of a linear correlation between the reciprocal of quantum yield and the reciprocal of nitrosamine concentration. For all the nitrosamines studied, the final product of the photolysis appears to be unique, alkylidenimine, which in the case of nitroso methyl benzyl amine undergoes a relatively rapid hydrolysis, giving rise to benzaldehyde, following second order kinetics. A provisional model consistent with the experimental results obtained in this work is proposed. © 1993 John Wiley & Sons, Inc.
Kinetic investigation of the collisional behavior of ground state atomic carbon, C(2p2(3PJ)), with halogenated olefins and aromatic compounds studied by time‐resolved atomic resonance absorption spectroscopy in the vacuum ultra‐violet
Authors: Haider Nazre , Husain David 
Published: January 2005

AbstractA kinetic investigation is described of the reaction of ground state atomic carbon, C(2p2(3PJ)), monitored by time‐resolved atomic resonance absorption spectroscopy, with a wide range of halogenated olefins and aromatic compounds. Atomic carbon was generated by the repetitive pulsed irradiation (λ > ca. 160 nm) of C3O2 in the presence of excess helium buffer gas and the added reactant gases in a slow flow system, kinetically equivalent to a static system. C(23PJ) was then monitored photoelectrically by time‐resolved atomic resonance absorption in the vacuum ultra‐violet (λ = 166 nm, 33PJ ← 23PJ) with direct computer interfacing for data capture and analysis. The following absolute second‐order rate constants for the reactions of C(23PJ) with the following reactants are reported:

Reactant
kR/cm3 molecule−1 s−1 (300 K)

C2F4
(1.9 ± 0.1) × 10−10

C2Cl4
(10.6 ± 0.5) × 10−10

CH2CF2
(4.3 ± 0.2) × 10−10

CHClCCl2
(7.9 ± 0.4) × 10−10

C6H6
(4.8 ± 0.3) × 10−10

C6F6
(4.9 ± 0.3) × 10−10

C6HF5
(5.0 ± 0.3) × 10−10

C6H2F4
(4.4 ± 0.2) × 10−10

C6H5—CH3
(5.5 ± 0.3) × 10−10

C6F5—CF3
(5.4 ± 0.3) × 10−10

These results, constituting the first reported body of absolute rate data for reactions of ground state carbon with these reactants, are compared with the analogous body of absolute rate data for atomic silicon in its Si(3p2(3PJ)) ground state, also determined hitherto by time‐resolved atomic resonance absorption spectroscopy and demonstrating similar kinetic behavior. © 1993 John Wiley & Sons, Inc.
Kinetics and mechanism of ninhydrin reaction with copper(II) complexes of glycine and α‐alanine. Elucidation of the template mechanism
Authors: Gupta Dileep , Khan Zaheer , Khan A. Aziz 
Published: January 2005

AbstractNinhydrin has been found to react with Cu(glycine)+ and Cu(alanine)+ in the ratio of 1:1. The kinetic studies of the reaction were carried out at different concentrations of the reactants at 80°C (pH = 5.0). The reaction proceeds through the formation of a ternary labile complex of ninhydrin with Cu(II) complexes of glycine and alanine. The kinetics were found to follow pseudo‐first‐order reaction path with respect to Cu(II)‐complex in presence of excess [Ninhydrin]. Formation of a ternary labile complex indicates a template reaction mechanism based on the reactions with coordinated ligands. The variation of pseudo‐first‐order rate constants with [ninhydrin] was found to be in good agreement with equation

where B1 and B2 are the unknown empirical parameters. The [acetate ion] has no significant effect on the rate constants. On the basis of observed data a probable mechanism has been proposed. © 1993 John Wiley & Sons, Inc.
Reactions of [NiIII(cyclam)] with aqueous sulfur dioxide: Exhibition of a deuterium isotope effect and catalysis by chloride and bromide
Authors: Linn Donald E. , Rumage Scott D. , Grutsch John L. 
Published: January 2005

AbstractOne unit of S(IV) (SO2 or SHO3−) is oxidized per 2 units of [NiIII(cyclam)] species to obtain sulfate. Kinetic analyses have been done by varying the acidities (0.013 ⩽ [H+] ⩽ 1.0 M) and halide concentrations (0.000 ⩽ [X−] ⩽ 0.012 M; X=Cl and Br) at constant ionic strength (μ = 1.0 M). The rate law that incorporates the [X−] and [H+] dependence is −d[NiIII]T/dt=2k[NiIII]T[S(IV)]T where 2k={ka[H+] + kbK + kK′X[H+] [X−] + kK′XK[X−]} {[H+] + K}−1 {1 + K′X[X−]}−1, here ka=87 ± 7 M−1 s−1, kb=(2.5 ± 0.5)×103 M−1 s−1 and pK = 1.8 ± 0.2. Rate constants ka and kb are attributed to the reactions of [NiIII(cyclam) (H2O)2]3+ with SO2 and SHO3−, respectively. Monohalo species apparent equilibrium constants K′Cl=(1600 ± 400) M−1 and K′Br=(190 ± 20) M−1 and rate constants k=80 ± 8 M−1 s−1 and k = 140 ± 15 M−1 s−1 are ascribed to the protonated pathway, involving the [NiIII(cyclam) (H2O)X]2+ and SO2(aq) reaction pairs. The other two rate constants of k=(5 ± 1)×103 M−1 s−1 and k=(3.1 ± 0.5)×104 M−1 s−1, refer to the deprotonated pathway and are assigned to the [NiIII(cyclam) (H2O)X]2+ /SHO3− redox couple. A deuterium H2O / D2O isotope effect of 2.1–2.8 can be attributed partially to an equilibrium isotope effect at low acidity though a small kinetic isotope (2.5 ± 0.5) effect is evident for the dihydrogen sulfito pathway, ka. The kinetic isotope effect and the absence of sulfite radical scavenging effects are explained by a mechanism entailing migration of a hydride from sulfur to the NiIII center to produce a NiIII—H species, which rapidly comproportionates, and S(VI). © 1993 John Wiley & Sons, Inc.
Kinetics of the BrO + NO2 association reaction. Temperature and pressure dependence in the falloff regime
Authors: Thorn R. P. , Daykin E. P. , Wine P. H. 
Published: January 2005

AbstractA laser flash photolysis‐long path absorption technique has been employed to study the kinetics of the reaction products as a function of temperature (248–346 K), pressure (16–800 torr), and buffer gas identity (N2, CF4). The reaction is found to be in the falloff regime between third and second‐order over the entire range of conditions investigated. This is the first study where temperature‐dependent measurements of k1(P, T) have been reported at pressures greater than 12 torr; hence, our results help constrain choices of k1(P, T) for use in models of lower stratospheric BrOx chemistry. Approximate falloff parameters in a convenient form for atmospheric modeling are derived. © 1993 John Wiley & Sons, Inc.
High pressure fast‐flow technique for gas phase kinetics studies
Authors: Seeley John V. , Jayne John T. , Molina Mario J. 
Published: January 2005

AbstractA fast‐flow technique suitable for measuring elementary rate constants over a wide range of pressures has been developed. The method operates under turbulent flow conditions, in contrast to laminar flow which characterizes the conventional low pressure technique. Flow visualization, velocity profile measurements, and tracer pulse studies have been carried out in a flow tube reactor to investigate the dynamics of both laminar and turbulent flow for chemical kinetics purposes. Furthermore, the wall collision frequency for the reactants has been determined: at the higher pressures it is greatly reduced in comparison with the frequency characteristic of the conventional low pressure laminar flow technique. Also, to test and validate the technique the bimolecular rate constants for the reactions H+Cl2 and H+O3 have been measured at total pressures in the 3–300 torr range; at pressures below 5 torr, as well as above 50 torr in the turbulent flow regime the agreement with the recommended literature values is excellent. © 1993 John Wiley & Sons, Inc.
UV absorption spectrum, and kinetics and mechanism of the self reaction of CF3CF2O2 radicals in the gas phase at 295 K
Authors: Sehested Jens , Ellermann Thomas , Nielsen Ole John , Wallington Timothy J. , Hurley Michael D. 
Published: January 2005

AbstractThe ultraviolet absorption spectrum, kinetics, and mechanism of the self reaction of CF3CF2O2 radicals have been studied in the gas phase at 295 K. Two techniques were used; pulse radiolysis UV absorption to measure the spectrum and kinetics, and long‐path length FTIR spectroscopy to identify and quantify the reaction products. Absorption cross sections were quantified over the wavelength range 220–270 nm. At 230 nm, σ = (2.74 ± 0.46) ×10−18 cm2 molecule−1. This absorption cross section was used to derive the observed self reaction rate constant for reaction (1), defined as, −d[CF3CF2O2]/dt = 2k1obs[CF3CF2O2]2:
equation image
k1obs = (2.10 ± 0.38) ×10−12 cm3 molecule−1 s−1 (2σ).The observed products following the self reaction of CF3CF2O2 radicals were COF2, CF3O3CF3, CF3O3C2F5, and CF3OH. CF3O2CF3 was tentatively identified as a product. The carbon balance was 90–100%. The self reaction of CF3CF2O2 radicals was found to proceed via one channel to produce CF3CF2O radicals which then decompose to give CF3 radicals and COF2. In the presence of O2, CF3 radicals are converted into CF3O radicals. CF3O radicals have several fates; self reaction to give CF3O2CF3; reaction with CF3O2 radicals to give CF3O3CF3; reaction with C2F5O2 radicals to give CF3O3C2F5; or reaction with CF3CF2H to give CF3OH.
As part of this work a rate constant of (2.5 ± 0.6) ×10−16 cm3 molecule−s−1 was measured for the reaction of Cl atoms with CF3CHF2 using a relative rate technique.
Results are discussed with respect to the atmospheric chemistry of CF3CF2H (HFC‐125). © 1993 John Wiley & Sons, Inc.
The possible resurrection of the Chapman mechanism for atmospheric sodium chemiluminescence and ruminations on NaO reaction dynamics
Authors: Schofield Keith 
Published: January 2005

AbstractA critical reappraisal and kinetic modeling is presented of a sodium/N2O system. The analysis provides a compelling argument that previously reported kinetic decay rates may refer not to the reaction of O with NaO but rather to that of O with Na2O. The system shows pronounced propensity for a significant portion of the NaO to be quantitatively converted to Na2O on a time scale commensurate with that of the Na/N2O titration reaction. The O atom in the system does appear to originate from the photolysis of a residual level of NaO. The observed Na(2P) chemiluminescence, used to track the O atom decay rates, can be consistent with the O + NaO reaction as previously surmised. It is unlikely that the alternate O + Na2 and O + Na2O chemiluminescent channels can generate the observed intensity levels. This reanalysis, which provides for the observed first order dependences on N2O(Na2O) and O atom concentrations has significant implications for the Chapman atmospheric mechanism of the sodium airglow. Its conclusions resurrect the viability of the original scheme which requires efficient branching of the O + NaO reaction to Na(2P). Recent suggestions invoking the participation of NaO(A2Σ+) require the latter to have a metastable nature with respect to its radiative and collisional quenching (N2, O2) channels, for which there is no current evidence.An additional evaluation of the rate constant measurements for the fast reactions of NaO with NO or CO indicates that these most probably are kinetically complex and involve longlived transition states. Their rate constants are predicted to have small negative activation energies and pressure dependences. In the case of NaO with CO this may explain its low Na(2P) chemiluminescent efficiency. For the NaO + O reaction, a rate constant of about 4 ×10−11 cm3 molecule−1s−1 is predicted at room temperature. This is similar to that used in earlier atmospheric models. Its magnitude circumvents the consequences of the reaction's large entropy decrease which otherwise implies too large a cross‐section for the reverse reaction. A smaller value also is more likely to be consistent with a normal short‐lived collisional transition state, which will allow for a more significant Na(2P) quantum efficiency. © 1993 John Wiley & Sons, Inc.
Reduction of toluidine blue by stannous ion at low pH: Kinetics and simulations
Authors: Jonnalagadda S. B. , Dumba M. 
Published: January 2005

AbstractA detailed kinetic study of the reaction between toluidine blue (tolonium chloride) (TB+Cl−) and stannous chloride is carried out in aqueous hydrochloric acid. The depletion kinetics of toluidine blue were spectrometrically monitored at 626 nm. The reaction had fractional order with respect to toluidine blue (one half), three halves with respect to Sn2+, and first‐order dependence on H+ ion. Stoichiometric ratio between reductant and oxidant is 1:1. During the reaction Sn2+ is oxidized to Sn4+ and toluidine blue is reduced to colorless base in two univalent steps. © 1993 John Wiley & Sons, Inc.
Kinetics of benzonitrile nitration with mixed acid under homogeneous conditions
Authors: Andreozzi R. , Insola A. , Aquila T. , Caprio V. 
Published: January 2005

AbstractChemical kinetics of benzonitrile nitration with mixed acid is investigated in the temperature range 283–299 K. Pseudo‐first‐order rate constants are evaluated by means of rate experiments on homogeneous reacting mixtures having large stoichiometric excesses of nitric acid.The second‐order kinetic constants for nitronium ion attack to the aromatic substrate are derived on the basis of the assessed nitration mechanism. An activation energy of 604 ± 37 kJ mol−1 is calculated for this reaction step. © 1993 John Wiley & Sons, Inc.
The kinetics of the nitrate radical self‐reaction
Authors: Biggs P. , Canosa‐Mas C. E. , Monks P. S. , Wayne R. P. , Benter Th. , Schindler R. N. 
Published: January 2005

AbstractThis article describes the first direct determination of the rate coefficient for the self‐reaction between two NO3 radicals. A laser photolysis technique was used to generate NO3, and time‐resolved decays of NO3 were followed after stopping the photolysis. The products of the reaction are inferred to be NO2 and O2. The derived rate coefficient at room temperature for the self‐reaction of (2.3 ± 0.8) ×10−16 cm3 molecule−1s−1 is in excellent agreement with the only other data, which were obtained in an indirect study. Consideration is given to the magnitude and influence of secondary chemistry and to the participation of FO in the chemistry of the NO3 buildup phase. The studies were conducted over a pressure range of 8 to 100 torr in helium. No clear pressure dependence was observed, and some tentative inferences are drawn both from this result and from the absolute magnitude of the rate coefficient about the mechanism of the reaction. There is apparently no role for the reaction in the chemistry of the atmosphere. © 1993 John Wiley & Sons, Inc.
Kinetics of liquid phase synthesis of methyl tert‐butyl ether from tert‐butyl alcohol and methanol catalyzed by ion exchange resin
Authors: Matouq Mohammed H. , Goto Shigeo 
Published: January 2005

AbstractSynthesis of methyl tert‐butyl ether (abbreviated as MTBE) from methanol (MeOH) and tert‐butyl alcohol (TBA) in the liquid phase was studied by using Amberlyst 15 in the H+ form as an acid catalyst. Experiments were carried out in a stirred batch reactor at different temperatures (313, 318, and 323 K) under atmospheric pressure.It was found that catalyst sizes and rotation speeds had no significant effects on reaction rates. Mechanism studies showed that three reactions took place simultaneously. It was also found that dehydration of TBA could not be neglected. The experimental concentration profiles with time could be simulated well by simple kinetics. Finally, rate constants could be expressed by Arrhenius equations. © 1993 John Wiley & Sons, Inc.
Kinetics of coupling of diazotized sulfanilamid with 1‐naphthylamine
Authors: Demircioḡlu N. , Bayramoḡlu M. , Topcu N. 
Published: January 2005

AbstractIn this study, the coupling kinetics of sulfanilamid diazonium salt with 1‐naphthylamine has been studied by spectrophotometric method. In the experiments conducted at constant temperature, 25°C, pH has been varied between 2.2−3.4, reactant concentration between 1.25 × 10−5 − 5 × 10−5 M, and ionic strength between 0.1−1 M. The reaction has been confirmed to be of second‐order and rate constants and the dissociation constant of 1‐naphthylamine have been calculated. © 1993 John Wiley & Sons, Inc.
Decomposition kinetics of the N‐bromoaminoacids, N‐bromoalanine, N‐bromo‐2‐aminobutyric acid, and N‐bromonorvaline
Authors: Antelo Juan M. , Arce Florencio , Crugeiras Juan , Armesto José L. 
Published: January 2005

AbstractA kinetic study of the decomposition reactions of N‐bromoalanine, N‐bromo‐2‐aminobutyric acid, and N‐bromonorvaline shows them to be first‐order with respect to N‐bromoaminoacid concentration and independent of both excess aminoacid and pH over the interval pH 9–11. In this pH range the mean rate constants at 298 K were 1.20 × 10−3 s−1, 1.37 × 10−3 s−1 and 1.28 × 10−3 s−1, respectively. © 1993 John Wiley & Sons, Inc.
Mono‐complex formation kinetics of iron(III) with nonsubstituted octane and nonane 2,4‐dicarbonyl ligands in aqueous solution
Authors: Blanco Carlos A. , Romero Jose M. , Verdu Jesus 
Published: January 2005

AbstractThe kinetics and mechanism of the reaction of complexation of iron(III) with 2,4‐octanedione and 2,4‐nonanedione have been investigated spectrophotometrically in aqueous solution at 10°C and ionic strength 0.5 mol dm−3 NaClO4. The equilibrium constants of the mono‐complexes have been determined. The mechanism proposed to account for the kinetic data involves a double reversible pathway where both Fe3+ and Fe(OH)2+ react with the enol tautomer of the ligand. 2,4‐Octanedione reacts with Fe3+ and Fe(OH)2+ with rate constants of 0.65 dm3 mol−1 s−1, and 14.07 dm3 mol−1 s−1, respectively. For 2,4‐nonanedione complexation the rate constants determined are 0.49 dm3 mol−1 s−1, and 11.39 dm3 mol−1 s−1, respectively. Some discussions are made on the basis of Eigen‐Wilkins theory considering the effect of solvent exchange on the complex formation. © 1993 John Wiley & Sons, Inc.
The kinetics of thermal dimerization of hexatriene
Authors: Bulatov V. , Oref I. 
Published: January 2005

AbstractThe thermal isomerization ofcis‐hexatriene (cHT) to cyclohexadiene (CHD) and the dimerization of CHD andtrans‐hexatriene (tHT) in the liquid phase in the temperature range 380 K‐473 K are reported.The rate coefficients are: for thecHT to CHD isomerizationfortHT dimerizationlogand for CHD dimerization; endo formexo form© 1993 John Wiley & Sons, Inc.
Errors associated with nonuniform concentrations upon rate constants using absorption techniques
Authors: Fahr Askar , Laufer Allan H. 
Published: January 2005

AbstractKinetic absorption spectroscopy is a commonly used technique in the experimental determination of rate constants. Here we consider the effect of nonuniform reactant concentrations upon the measured results and the errors associated with the final determination of second‐order rate constants in particular. We conclude that the errors associated with nonuniformity of reactant, while significant, are comparable or less than other common systematic or random errors. © 1993 John Wiley & Sons, Inc.
High temperature pyrolysis of 1,5‐cyclooctadiene and 4‐vinylcyclohexene in shock waves
Authors: Hidaka Yoshiaki , Ninomiya Natsuhiko , Oshita Hidekazu , Kawano Hiroyuki , Koike Tohru 
Published: January 2005

Abstract1,5‐cyclooctadiene or 4‐vinylcyclohexene mixture diluted with argon was heated to temperatures in the range 880–1230 K behind reflected shock waves. Profiles of IR‐laser absorption were measured at 3.39 μm. From these profiles, rate constants k1 and k2 for the decyclization reactions 1,5‐cyclooctadiene → biradical and 4‐vinylcyclohexene → biradical were evaluated as k1 = 5.2 × 1014 exp(−48.3 kcal/RT) s−1 and k2 = 3.5 × 1014 exp(−55.3 kcal/RT) s−1, respectively. © 1993 John Wiley & Sons, Inc.
Kinetics of CN radical reactions with formaldehyde and 1,3,5‐trioxane
Authors: Yu Tao , Yang David L. , Lin M. C. 
Published: January 2005

AbstractAbsolute rate constants were measured for the reaction CN + CH2O over the temperature range 297–673 K and CN + 1,3,5‐trioxane over the range of 297–600 K by the laser photolysis/laser induced fluorescence technique. The rate constants for these reactions can be effectively represented, in units of cm3/s, by: k(CH2O) = 2.82 × 10−19 T2.72 exp(718/T), and k(1,3,5‐trioxane) = 1.39 × 10−23 T4.26 exp(1333/T), respectively. Transition state theory calculations were able to fit the temperature dependence of the CN + CH2O rates relatively well. We attempted to correlate the CN reaction rate with CH2O and other molecules which occur through simple abstraction with the corresponding OH reaction rates, yielding only a qualitative linear correlation for a majority of the processes. The reactions which deviated significantly from linearity include those which contain strong dipoles, highlighting the significant role long‐range attractive forces play in CN and OH reactions. Using a simple electrostatic potential, cross‐sections were determined for reactions with CN. No linear correlation was found between the calculated and experimental cross sections for the majority of the reactions studied. © 1993 John Wiley & Sons, Inc.
Rate constants for the gas‐phase reactions of O3 with a series of cycloalkenes and α,β‐unsaturated ketones at 296 ± 2 K
Authors: Greene Chipper R. , Atkinson Roger 
Published: January 2005

AbstractThe kinetics of the gas‐phase reactions of O3 with a series of alkenes and two α,β‐unsaturated ketones have been investigated at atmospheric pressure (ca. 740 torr) of air and 296 ± 2 K, using a relative rate method in the presence of sufficient cyclohexane to scavenge OH radicals generated in these reactions. Combined with our previous relative rate measurements (Int. J. Chem. Kinet., 24, 803 (1992)), the rate constants obtained relative to k(O3 + propene) = 1.00 were: 3‐penten‐2‐one, 3.62 ± 0.16; 2‐cyclohexen‐1‐one, <0.19; bicyclo[2.2.2]‐2‐octene, 7.44 ± 0.48; 1,3‐cycloheptadiene, 16.1 ± 1.1; cycloheptene, 23.7 ± 1.6; 1,3‐cyclohexadiene, 134 ± 13; bicyclo[2.2.1]‐2‐heptene, 170 ± 16; and bicyclo[2.2.1]‐2,5‐heptadiene, 390 ± 36. The resulting rate constants then lead to a self‐consistent set of room temperature data for the reactions of O3 with these alkenes and α,β‐unsaturated ketones. These rate constants are compared with the literature data, and the effects of ring size discussed. © 1994 John Wiley & Sons, Inc.
Synthesis and pyrolysis of perfluoroazo‐2‐propane
Authors: Scherer K. V. , Batt L. , Stewart P. H. 
Published: January 2005

AbstractAn improved method has been used to synthesize perfluoroazo‐2‐propane. Pyrolysis over the temperature range 450–514 K in a static system has been shown to be a homogeneous, first‐order process. No pressure dependence was observed in the presence of excess inert gas (SF6). The only products were nitrogen and perfluoro‐2,3‐dimethylbutane. The rate constant (k) for the decomposition process is given by:

These results lead to a straightforward mechanism for the decomposition process
equation image
The results are compared with those for other azo compounds. © 1994 John Wiley & Sons, Inc.