摘要:

AbstractDibenzoylmesitylene undergoes protiodeacylation in 89.8% (w/w) sulfuric acid at ca. 90°C, with subsequent sulfonation, to give mesitylenedisulfonic acid. The reaction involves a single‐path sequence of four first‐order reactions. The corresponding reaction of acetylbenzoylmesitylene can proceed by two possible routes: it is shown that about 94% of the overall reaction at 75° involves initial protiodeacetylation and about 6% initial protiodebenzoylation. The kinetic analyses provide estimates of concentration ratios as functions of time, and of the buildup and decay of intermediates in the reac

ISSN:0538-8066    

DOI:10.1002/kin.550200202

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the rate of the reaction of OH with 2‐(dimethylamino)‐ethanol, (CH3)2NCH2CH2OH (DMAE) was investigated over the temperature range, 234 to 364 K. The reaction was studied using the flash photolysis‐resonance fluorescence technique. The room temperature rate constant determined for this reaction was (10.3 ± 2.0) × 10−11cm3molecule−1s−1, with essentially no temperature dependence evident within the uncertainty in the experiments. A value of (9.0 ± 2.0) × 10−11cm3molecule−1s−1is believed to best describe the reaction over the entire temperature range. The room temperature rate constant is about twice the value reported previously for this reaction. The overall reaction of OH with DMAE was apportioned to the reactivity of OH for abstracting individual H‐ atoms from different types of CH bonds and the OH bond within the molecule. This technique predicts the overall rate constant for the OH‐DMAE reaction to within about 15% of the experimental value and makes it possible to estimate the yields of the initial radical products of the OH attack on DMAE. A mechanism is proposed for the subsequent atmospheric reactions that would occur

ISSN:0538-8066    

DOI:10.1002/kin.550200203

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200204

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractAbsolute rate constants are measured for the reactions: OH + CH2O, over the temperature range 296–576 K and for OH + 1,3,5‐trioxane over the range 292–597 K. The technique employed is laser photolysis of H2O2or HNO3to produce OH, and laser‐induced fluorescence to directly monitor the relative OH concentration. The results fit the following Arrhenius equations:k(CH2O) = (1.66 ± 0.20) × 10−11exp[−(170 ± 80)/RT] cm3s−1andk(1,3,5‐trioxane) = (1.36 ± 0.20) × 10−11exp[−(460 ± 100)/RT] cm3s−1. The transition‐state theory is employed to model the OH + CH2O reaction and extrapolate into the combustion regime. The calculated result covering 300 to 2500 K can be represented by the equation:k(CH2O) = 1.2 × 10−18T2.46exp(970/RT) cm3s−1. An estimate of 91 ± 2 kcal/mol is obtained for the first CH bond in 1,3,5‐trioxane by using a correlation of CH bond s

ISSN:0538-8066    

DOI:10.1002/kin.550200205

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe rate constant for the Br + O3→ BrO + O2reaction was measured by the discharge flow technique, employing resonance fluorescence detection of Br. Over the temperature range 248 to 418 K, in 1 to 3 torr of He, decays of Br in excess O3yield the valuek1= (3.28 ± 0.40) × 10−11e[−944±30]/Tcm3molecule−1s−1. Cited uncertainties are at the 95% confidence level and include an estimate of the systematic errors. The rate constants for the reactions of O3with Br, Cl, F, OH, O, and N correlate with the electron affinities of the radicals suggesting that the reactions proceed through early transition states dominated by transfer of electron density from the highest occupied molecular orbital of ozone to the singly occupied radical MO. The implications of this new measurement ofk1for stratospheric chemistry a

ISSN:0538-8066    

DOI:10.1002/kin.550200206

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe rates of elimination of seven cycloalkyl acetates containing between 5 and 15 ring carbons have been determined in a static system over a temperature range 280–370°C and a pressure range 35–234 torr. The unimolecular reactions, carried out in the presence of the inhibitor cyclohexene, are homogeneous in seasoned vessels and follow a first‐order rate law. The rate coefficients are exemplified by that found for cyclopentyl acetate:\documentclass{article}\pagestyle{empty}\begin{document}$$\log {\rm}k_1 ({\rm s}^{{\rm - 1}}) = (12.68 \pm 0.14) - (179.8 \pm 1.5){\rm \,kJ\,mol}^{{\rm - 1}} {\rm (2}{\rm .303}RT)^{- 1}$$\end{document}The sequence of relative rates is analogous to that found in most solution reactions of these compounds. The contribution of ring strain to energy barriers of these compounds is des

ISSN:0538-8066    

DOI:10.1002/kin.550200207

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractHighly dilute mixtures of 1,3‐butadiene and 1,3‐butadiene‐1,1,4,4‐d4were pyrolyzed behind reflected and incident shock waves, respectively. Concentrations of H and D atoms were measured by resonance absorption spectroscopy. In the early stages of the reaction, nearly equal amounts of H and D were formed from CD2CHCHCD2, indicating that loss of H from C2followed by loss of D from C1is a more important reaction than breaking of the central CC bond. Overall, rate constants for atom‐forming reactions are much slower than rate constants for disappearance of butadiene in earlier experiments, suggesting that most of the butadiene disappears by processes that do not involve H or D atoms or by radicals that produce t

ISSN:0538-8066    

DOI:10.1002/kin.550200208

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractPyrolysis of a dilute mixture of neopentane (2,2‐dimethylpropane) has been studied behind incident shock waves at an average pressure of 0.35 atm; the reaction was followed by absorption spectroscopy for H atoms. In the temperature range 1230–1455 K, the rate constant for dissociation of neopentane tot‐butyl and methyl radicals is 1.1E13 exp(−62 kcal/RT) s−1. These data and some of the literature results, between 1000 and 1450 K, can be fitted by an RRKM model of the hindered Gorin type, with five active internal rotors in the complex. To match our data with other literature data down to 800 K, a vibrational model was more satisfactory, but this did not fit very low pressure pyrolysis data in the 1000–1100 K range. Apparently, the VLPP data are too high because of heterogeneous processes or chai

ISSN:0538-8066    

DOI:10.1002/kin.550200209

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractAbsolute rate constants were determined for the gas phase reactions of OH radicals with a series of esters using the flash photolysis resonance fluorescence technique. Experiments were performed over the temperature range 240–440 K at total pressures (using Ar diluent gas) between 25–50 torr. The kinetic data for methyltrifluoroacetate (k1) over the complete temperature range, and for methylacetate (k2), and ethylacetate (k3) over the range 296–440 K were used to derive the Arrhenius expressions;\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = (3.0 \pm 0.7) \times 10^{- 13} {\rm \,exp[- (512} \pm {\rm 78)/}T]{\rm \,cm}^{\rm 3}\, {\rm \,molecule}^{{\rm - 1}}\, {\rm s}^{{\rm - 1}}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$k_2 = (8.3 \pm 3.5) \times 10^{- 13} {\rm \,exp[- (260} \pm 150{\rm)/}T]{\rm \,cm}^{\rm 3}\, {\rm \,molecule}^{{\rm - 1}}\, {\rm s}^{{\rm - 1}}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$k_3 = (2.3 \pm 0.2) \times 10^{- 12} {\rm \,exp[- (131} \pm 28{\rm)/}T]{\rm \,cm}^{\rm 3}\, {\rm \,molecule}^{{\rm - 1}}\, {\rm s}^{{\rm - 1}}$$\end{document}At 296 K, the measured rate constants (in units of 10−13cm3molecule−1s−1) were:k1= (0.52 ± 0.08),k2= (3.41 ± 0.29), andk3= (15.1 ± 1.4). Room temperature rate constants for the OH reactions with several other aliphatic esters were also measured. These were (in the above units): methylformate, (2.27 ± 0.34); ethylformate, (10.2 ± 1.4); n‐propylformate, (23.8 ± 2.7);n‐butylformate, (31.2 ± 3.3); n‐propylacetate, (34.5 ± 3.4);i‐propylacetate, (37.2 ± 2.9);n‐butylacetate, (41.5 ± 3.0);s‐butylacetate, (56.5 ± 5.9); methylpropionate, (10.3 ± 0.4); ethylpropionate, (21.4 ± 3.0);n‐propylpropionate, (40.2 ± 3.2); methylbutyrate, (30.4 ± 3.3); ethylbutyrate, (49.4 ± 3.8);n‐propylbutyrate, (74.1 ± 3.2), andn‐butylbutyrate, (106 ± 13), error limits represent 2σ from linear least‐squares analyses. The results are discussed in terms of the reaction mecha

ISSN:0538-8066    

DOI:10.1002/kin.550200210

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to quantitatively measure the concentration of ions produced by a microwave discharge source commonly used in the production of atomic species. Using a double floating probe to monitor the ion content, the results indicate that the flow of ions was less than 1.8 × 10−6times the total flow of particles from the discharge cavity. Due to the low ion mole fraction, it is concluded that ion‐molecule reactions are not competitive with previousry reported atom‐molecule rea

ISSN:0538-8066    

DOI:10.1002/kin.550200211

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY