摘要:

AbstractThe rate constant of the reaction of OH with DMS has been measured relative to OH + ethene in a 420 l reaction chamber at 760 torr total pressure and 298 ± 3 K in N2+ O2buffer gas using the 254 nm photolysis of H2O2as the OH source. In agreement with a recent absolute rate determination of the reaction the measured effective rate constant was found to increase with increasing partial pressure of O2in the system, for 760 torr air a rate constant of (8.0 ± 0.5) × 10−12cm3s−1was obtained.Product studies have been performed on the reaction in air using FTIR absorption spectrometry for detection of reactants and products. On a molar basis, SO2was formed with a yield of 70% and dimethyl sulfone (CH3SO2CH3) with a yield of approximately 20%. These results are considerably different to those obtained in other product studies which were carried out in the presence of NOx. These differences are compared and their relevance for the atmospheric oxidation mechanisms of DMS is dis

ISSN:0538-8066    

DOI:10.1002/kin.550200602

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractAt 298 K the rate constant for the decomposition of N‐chloroleucine has the constant value 3.20 × 10−4s−1over the range pH 5–12, increases with increasing acidity at pH12. A mechanism is put forward which explains these

ISSN:0538-8066    

DOI:10.1002/kin.550200603

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe first‐order rate constants,k1, for 1,2‐ethanediolysis (within the content of 1,2‐ethanediol of 5% to 90%,v/v) and 2‐ethoxyethanolysis (within the 2‐ethoxyethanol content of 5% to 60%,v/v) of phenyl salicylate, PSH, in alkaline aqueous mixed solvents, fit to a relationship:k1=k[ROH]T/(1 +K[ROH]T) wherekandKrepresent the secondorder rate constant for the reaction of alkanol, ROH, with ionized phenyl salicylate, PS−, and association constant for the dimerization of ROH, respectively, and [ROH]Tis the total concentration of ROH. Similar relationship betweenk1and [ROH]Thas been found for 1,2‐ethanediolysis of PS−studied in mixed solvents containing 1,2‐ethanediol and MeCN. In the alkaline aqueous mixed solvents containing 2‐ethoxyethanol, thek1‐[ROH]Tprofile reveals the change in the solvent structure of the reaction medium at>60% (v/v) of ROH content. It is proposed that alkanols exist in polymeric form, (ROH)n, and the alkanolysis of PS−involves the pre‐equilibrium formation of monomeric ROH from (ROH)n, followed by an intramolecular general base‐catalyzed nucleophilic attack at carbonyl carbon of ester. A slight negative KCl salt‐ and slight positiven‐Bu4NI salt‐effect are obtained for 1,2‐ethanediolysis while a significant positiven‐Bu4NI salt‐effect is

ISSN:0538-8066    

DOI:10.1002/kin.550200604

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA new estimate is derived for the group additivity contribution ΔH ƒ∘[O—(O)2] = 55 ± 6 kJ mol−1, based upon recent experimental data, which enables heats of formation and bond dissociation energies to be estimated for species ROnR and RO n¨(R = H, CH3, and CF3). Semi‐empirical MNDO calculated heats of formation, for these species, provide independent support for the new thermochemical estimates. The results are also consistent with other theoretical and experi

ISSN:0538-8066    

DOI:10.1002/kin.550200605

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200606

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200607

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200608

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200601

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY