摘要:

AbstractThe kinetics of the oxidation of cyclopentanol, cyclohexanol, 2methylcyclohexanol, and cycloheptanol by hexacyanoferrate(III) ions in mild alkaline medium has been studied in the presence of traces of ruthenium(VI) ≈ 10−7Mat constant ionic strength (0.26M). The results suggest that the oxidation of the studied cyclic alcohols proceeds via the formation of a complex between Ru(VI) and the substrate which slowly decomposes, giving the reduced form of ruthenium which was reoxidized to Ru(VI) in a fast step by alkaline hexacyanoferrate(III) ions. The product study shows the production of the corresponding k

ISSN:0538-8066    

DOI:10.1002/kin.550160302

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe rate constants for the quenching of O2(1Δg) with carbon disulfide, dimethyl sulfide, dimethyl disulfide, diallyl disulfide, ethyl mercaptan, and thiophene have been determined in a discharge flow system in the absence of oxygen atoms. The rate constants are found to be (6.5 ± 0.6) × 104, (1.8 ± 0.2) × 104, and (3.5 ± 0.6) × 103L/mol · s for dimethyl sulfide, ethyl mercaptan, and thiophene, respectively. The other compounds have rate constants<9.9 × 102L/mol · s. In the case of dimethyl sulfide, even when NO2concentration is more than what is required to remove oxygen atoms completely, the rate constants are found to vary with different amounts of NO2. No correlation is found to exist between the logarithm of the rate constants and the ionization potentials of the

ISSN:0538-8066    

DOI:10.1002/kin.550160303

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractEnergetic H atoms produced by photolysis of gaseous HI react with CD3Br by D abstraction (1) and Br abstraction (2) and possibly also by the substitution reactions (4) and (5).Yields of HD and CD3H have been determined for several defined initial translational energies of H*. The phenomenological threshold energy of reaction (1) is 53 ± 5 kJ/mol. Over the range of initial energies of 76–109 kJ mol the integral probability of reaction (1) increases substantially, but the sum of the integral probabilities of reactions (2) and (5) shows little change. The ratio of the sum of the integral yields of reactions (2) and (5) to the integral yield of reaction (1), when normalized to equal numbers of Br and D atoms, is 69 ± 33 at an initial energy of 76 kJ/mol and 31 ± 6 at 109 kJ

ISSN:0538-8066    

DOI:10.1002/kin.550160304

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe kinetics of the reactions of iron(III) with diglycolic, tartaric, and citric acids have been studied in aqueous acid solutions by the temperature‐jump method at 25.0°C and at ionic strengths 1.0 (for tartaric and citric acids) and 0.50 mol/dm3(for diglycolic acid). The experimental data indicate that iron(III) monochelate formation occurs by the same reaction mechanism for all three ligands examined and that only pathways involving the FeOH2+ion contribute to the chelation process. The reacting species for citric acid is the undissociated ligand. For tartaric and diglycolic acids both the neutral ligands and the corresponding monoanions react significantly under the experimental conditions used. Kinetic evidence for the contribution of intermediate steps to the limiting rate in the overall chelate‐formation process has been obtained and discu

ISSN:0538-8066    

DOI:10.1002/kin.550160305

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractMixtures of cyanogen and nitrous oxide diluted in argon were shock‐heated to measure the rate constants ofA broad‐band mercury lamp was used to measure CN in absorption at 388 nm [B2Σ+(v= 0) ←X2Σ+(v= 0)], and the spectral coincidence of a CO infrared absorption line [v(2 ← 1),J(37 ← 38)] with a CO laser line [v(6 → 5),J(15 → 16)] was exploited to monitor CO in absorption. The CO measurement established that reaction (3) produces CO in excited vibrational states. A computer fit of the experiments near 2000 K led to\documentclass{article}\pagestyle{empty}\begin{document}$$ k_2 \, = \,10^{11.70\left( { + 0.25, - 0.19} \right)} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ k_3 \, = \,10^{13.26 \pm 0.26} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s} $$\end{document}An additional measurement of NO via infrared absorption led to an estimate of the ratiok5/k6:withk5/k6≃ 103.36±0.27at 2150 K. Mixtures of cyanogen and oxygen diluted in argon were shock heated to measure the rate constant ofand the ratiok5/k6by monitoring CN in absorption. We found near 2400 K:\documentclass{article}\pagestyle{empty}\begin{document}$$ k_4 \, = \,10^{12.68\left( { + 0.27, - 0.19} \right)} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s} $$\end{document}and\documentclass{article}\pagestyle{empty}\begin{document}$$ {{k_5 } \mathord{\left/ {\vphantom {{k_5 } {k_6 }}} \right. \kern-\nulldelimiterspace} {k_6 }}\, = \,10^{2.68 \pm 0.28} $$\end{document}The combined measurements ofk5/k6lead tok5/k6≃ 10−3.07exp(+31,800/T) (±6

ISSN:0538-8066    

DOI:10.1002/kin.550160306

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe rate of the reaction of aqueous sulfite with theN‐chloropeptideN‐chloroalanylalanylalanine has been studied as a function of pH, temperature, and ionic strength. The results of this work suggest that the mechanism of the reaction involves the interaction of the neutral chloramine with the three ionic forms of sulfite, SO 3−2, HSO 3−, and H2SO3, with the rate of reaction increasing rapidly with increasing protonation. The estimated second‐order rate constants for each ionic species as a function of temperature are\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm H}_{\rm 2} {\rm SO}_{\rm 3} } \hfill & {k_1 \, = \,2.00\, \times \,10^8 \,{\rm exp}\left( {{{ - 1544} \mathord{\left/ {\vphantom {{ - 1544} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {{\rm HSO}_{\rm 3}^ - } \hfill & {k_2 \, = \,4.35\, \times \,10^4 \,{\rm exp}\left( {{{ - 1170} \mathord{\left/ {\vphantom {{ - 1170} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {\,\,{\rm SO}_{\rm 3}^{ - 2} } \hfill & {k_3 \, = 1.58\, \times \,10^{12} \,{\rm exp}\left( {{{ - 12,660} \mathord{\left/ {\vphantom {{ - 12,660} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ \end{array} $$\end{document}where the activation energies are in uni

ISSN:0538-8066    

DOI:10.1002/kin.550160307

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractRate constants for the reactions of O3and OH radicals with acetylene, propyne, and 1‐butyne have been determined at room temperature. The rate constants obtained at 294 ± 2 K for the reactions of O3with acetylene, propyne, and 1‐butyne were (7.8 ± 1.2) × 10−21cm3/molecule · s, (1.43 ± 0.15) × 10−20cm3/molecule · s, and (1.97 ± 0.26) × 10−20cm3/molecule · s, respectively. The rate constants at 298 ± 2 K and atmospheric pressure for the reactions with the OH radical, relative to a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10−12cm3/molecule · s, were determined to be (8.8 ± 1.4) × 10−13cm3/molecule · s, (6.21 ± 0.31) × 10−12cm3/molecule · s, and (8.25 ± 0.23) × 10−12cm3/molecule · s for acetylene, propyne, and 1‐butyne, respectively. These data are discussed and compared wit

ISSN:0538-8066    

DOI:10.1002/kin.550160308

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe rate of the perchloric acid hydrolysis of aqueous ethyl and butyl vinyl ethers at 25.0°C, in the presence of micellar aggregates [anionic, sodium dodecyl sulfate (SDS); cationic, cetyl trymethyl ammonium bromide (CTAB); and nonionic, polyoxyethylen23dodecanol, (Brij 35)], has been studied. Negligible effects were observed in the cases of cationic and nonionic micelles. Anionic micelles produce an enhancement in the reaction velocity, and the rate constants go through maxima with increasing SDS concentration. These maxima disappear in the presence of excess sodium perchlorate. All these facts are interpreted quantitatively by means of the pseudo‐phase ion‐exchan

ISSN:0538-8066    

DOI:10.1002/kin.550160309

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe recent experiments on the chloride‐assisted dealkylation of alkylcobalamins by a variety of oxidants (IrCl 62−, AuCl 4−, Fe(H2O)5Cl2+, and PtCl 62−), which are scattered in several previous publications, and their general kinetic characteristics are summarized. The kinetic studies are also extended to include the dealkylations of (methylaquo)−3,5,6‐trimethylbenzimidazolylcobamide and protonated base‐off ethylcobalamin by IrCl 62−(1.0MCl−) and by Fe(III) ions at 0.1MCl−, and the demethylation of (methylaquo)−3,5,6‐trimethylbenzimidazolylcobamide by AuCl 4−(1.0MCl−). This extension is in an effort to substantiate the general mechanism which has been previously proposed for these oxidative dealkylations. The general kinetic characteristics are described in terms of a preassociation of the reactants, followed by a rate‐determining electron‐transfer process to yield the R‐B 12+radical, which then undergoes further reactions to produce the products observed. The overall reactions are discussed within the framework of chlorine‐br

ISSN:0538-8066    

DOI:10.1002/kin.550160310

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550160301

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY