摘要:

AbstractA steady‐state system involving the photolysis of NO2in an excess of I2as a source of IO radicals has been used to study the reaction IO + DMS in 760 Torr N2at 296 K. IO radicals were found to react rapidly with DMS, one molecule of DMSO being produced for each molecule of DMS consumed. Numerical analysis of the experimental results yielded a rate constant of (3.0 ± 1.5) × 10−11cm3s−1for the reaction IO + DMS →

ISSN:0538-8066    

DOI:10.1002/kin.550190602

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reaction IO + CH3SCH3→ products (3) was studied at room temperature and near 1 Torr pressure of He, using the discharge flow mass spectrometric technique. The rate constant was found to bek3= (1.5 ± 0.5) × 10−11cm3molecule−1s−1. CH3S(O)CH3was detected as a product suggesting the following channel: IO + CH3SCH3→ CH3S(O)CH3+ I. The rate constant of the reaction IO + IO → products (1) was also measured:k1= (3 ± 0.5) × 10−11at 298 K and 1 Torr pressure. The atmospheric implication of reaction (3) is discussed. The results indicate that this reaction could be a potential important sink of CH3SCH3in

ISSN:0538-8066    

DOI:10.1002/kin.550190603

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractRates of acidic hydrolysis of hexano‐, octano‐, and decanohydroxamic acids and of 4‐bromophenylaceto‐ and phenylacetohydroxamic acids have been determined in aqueous perfluorooctanoic acid—a reactive counterion surfactant system. Typical micellar catalysis was observed for the hydrolyses of then‐alkyl hydroxamic acids but not for the arylacetohydroxamic acids. The Arrhenius activation energy for hydrolysis of octano‐hydroxamic acid is smaller above the cmc of the surfactant than it is

ISSN:0538-8066    

DOI:10.1002/kin.550190604

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe kinetics of the direct synthesis reaction (Si + 2CH3Cl → (CH3)2SiCl2) were measured on a Cu3Si alloy containing 1.2 atom % Zn. Reaction was carried out in a differential reactor (520–595 K, 1 atm) attached to an ultrahigh vacuum (UHV) system. Auger spectroscopy was used to characterize the surface before and after reaction. Zinc does not significantly change the overall rate of reaction, but it changes selectivity to dimethyldichlorosilane (the desired product), surface composition, activation energies, and induction times. The rate of silicon diffusion to the surface is not limiting in the presence of zinc. Zinc is found to be a promoter for improved selectivity only in low concentrations, and only a fraction of the surface appears to be active for reaction. The kinetics appear relatively insensitive to the surface composition or the form of surface carbon. A Cu3Si surface with Zn is shown to be a good model catalyst for the direct synthesis react

ISSN:0538-8066    

DOI:10.1002/kin.550190605

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe surface reaction of NO2and H2O vapor to emit HONO into the gas phase was studied in the evacuable and bakeable photochemical chamber under the irradiation of UV‐visible light (≳ 290 nm). Kinetic analysis of the NO, NO2, and HONO with the aid of computer modeling strongly suggested that the formation of HONO by the surface reaction is photoenhanced. When a linear regression was assumed, the photoenhancement factor defined by {(k′21/k21) − 1} was expressed as (6.8 ± 2.5)k1under our experimental conditions, wherek1is the primary photolysis rate of NO2, andk21,k′21are the second‐order‐equivalent rate constants of the HONO formation reaction in dark and under irradiation, respectively. The discussion was made that this photocatalitic enhancement of HONO formation would explain the nature of the extra OH radical flux in the smog chamber experiments, which has been discussed as “unknown radical source” and has still been unexplained by the surface dark reaction of NO2an

ISSN:0538-8066    

DOI:10.1002/kin.550190606

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractWe examine the kinetic modelD. The differential equations describing this reaction scheme are cast in a nondimensional form and analyzed in four basic approximation regimes: a ‘pseudo‐first order’ approximation valid for small values of the ratio of the initial concentrations of the reactants; an asymptotic solution valid for large values ofk3; the standard steady state (Bodenstein) approximation; and an approximation to a second order system without intermediate. Interconnecting relationships between the various approximations derived are examined, and the approximations are compared to numerical solutions to the full equations. The results are assessed from the standpoint of the experimental kineticist, and it is suggested that the reaction studied, and consequently many other more complex reactions, may under certain circumstances be subject to non‐unique interpr

ISSN:0538-8066    

DOI:10.1002/kin.550190607

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe kinetic study of the gas‐phase thermal elimination reactions ofN‐ethyl‐3,5 dimethyl‐pyrazole (I),N‐ethyl‐pyrazole (II),N‐sec‐butyl‐pyrazole (III), andN‐tert‐butyl‐pyrazole (IV) using a flow system is reported. After obtaining activation parameters forIwe carried out competitive reactions withII, IIIandIVusingIas internal standard to obtain theirEa. The values of Δ(ΔH fo) calculated forII, IIIandIVagree with the little differenc

ISSN:0538-8066    

DOI:10.1002/kin.550190608

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550190601

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY