摘要:

AbstractThe slow gas‐phase oxidation of tetrahydrofuran was studied under static conditions at 220°C. The relative amounts of each product, if extrapolated to zero reaction time, show which are the primary reaction products, and the reaction stoichiometry was thus established. Rate constants for hydroperoxides production and consumption were calculated; these hydroperoxides are responsible for chain branching. Carbon monoxide and carbon dioxide have been shown to be formed in the early stages of the reaction and not simply as end products of oxidative degradation processes. It has been found that at reaction times close to zero one tetrahydrofuran molecule may be attacked in one or several carbon atoms. 65.9% of tetrahydrofuran consumed in the first stages of the reaction forms succinic acid through a mechanism in which one molecule of fuel is attacked by two molecules of oxygen. More than 20% of the tetrahydrofuran molecules are attacked at least by three molecules of oxyg

ISSN:0538-8066    

DOI:10.1002/kin.550200902

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe kinetics of the reaction between nitric acid and formaldehyde have been studied by spectrophotometry. The reaction is autocatalytic. A two‐step mechanism is proposed, which accounts for this behavior and describes the effect of reactant concentrations on the characteristics of the kinetic curves: the length of the induction period,ti, the maximum rate,rmaxof nitrous acid production and the final product concentration,c

ISSN:0538-8066    

DOI:10.1002/kin.550200903

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe kinetics of the interactions of the Keggin type heteropolyanion [CoW12O40]5−, with all the molecular and anionic forms of citric acid have been investigated spectrophotometrically in the pH range 0.60–5.45 at 60°C. With the exception of the molecular form of the acid (H3L), all the other species (H2L−, HL2−, and L3−) undergo oxidation through an alkali metal ion catalyzed path in addition to the uncatalyzed one. The catalytic power increases with increasing size of the alkali metal ion. The contributions of each path have been evaluated from the kinetic data with the help of the measured dissociation constant values of citric acid. A plausible mechanism involving the formation of a bridged outer‐sphere complex of the reacting species with the alkali cation, has been suggested. The observed limiting dependence ofkobson [citrate] at high concentrations owing to an equilibrium between the reactants preceeding the electron transfer step supports the proposed mechanism. The pH‐rate profile gives an excellent fit with the evaluated kine

ISSN:0538-8066    

DOI:10.1002/kin.550200904

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA kinetic analysis of the thermal decomposition of methylamino and aminomethyl radicals into methyleneimine, reactions (1) and (2):leads to ΔH f0(CH2NH) = 25.0 ± 3 kcal/mol in excellent agreement with ion cyclotron resonance spectroscopy measurements and to a pi bond energy of Eπ= 55.0 kcal/mol in CH2NH which is comparable but smaller than to the corresponding value in CH2CH2(63.7 kcal/mol). Assuming that Eπ(CH2NH) = 0.5 [Eπ(CH2CH2) + Eπ(NHNH)] then requires that Eπ(NHNH) = 46.8 kcal/mol in diimine and BDE(N2H3‐H) = 87.5 kcal/mol i.e. about 11.5 kcal/mol larger than current data for hydrazine but otherwise consistent with additional evidence.The entropy and heat capacity of methyleneimine, calculated from recent infrared and microwave spectroscopic data using the rigid rotor harmonic oscillator approxim

ISSN:0538-8066    

DOI:10.1002/kin.550200905

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractEthylene at concentrations of 2.7 × 10−3to 1.0 × 10−2mol L−1has been pyrolyzed at 900 K in a flow system. The products ethane and hydrogen have been analyzed by gas chromatography. The results are consistent with a mechanism in which these products are initially formed as follows:Reaction [1] occurs only 1 to 2% as often as the addition reaction,The latter reaction is close to equilibrium. Taking the rate constant,k4, and the equilibrium constant,K2, from the literature and making small adjustments for minor processes,k1is found to be (9 ± 3) × 107L mol−1s−1. Here the uncertainty is intended to encompass errors in the present work and in the literature parameters.A secondary source of hydrogen was also observed. Its dependence on ethylene concentration was consistent with formation from an intermediate with six carbon atoms, such a

ISSN:0538-8066    

DOI:10.1002/kin.550200906

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of 1,2 butadiene has been studied behind reflected shock waves over the temperature and total pressure ranges of 1300–2000 K and 0.20–0.55 atm using mixtures of 3% and 4.3% 1,2 butadiene in Ne. The major products of the pyrolysis are C2H2, C4H2, C2H4, CH4and C6H6. Toluene was observed as a minor product in a narrow temperature range of 1500–1700 K. In order to model successfully the product profiles which were obtained by time‐of‐flight mass spectrometry, it was necessary to include the isomerization reaction of 1,2 to 1,3 butadiene. A reaction mechanism consisting of 74 reaction steps and 28 species was formulated to model the time and temperature dependence of major products obtained during the course of decomposition. The importance of C3H3in the formation of benzene is dem

ISSN:0538-8066    

DOI:10.1002/kin.550200907

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractESR equilibrium measurements in radical buffer systems yield a value of 76.0 kcal/mol for the OH bond energy in α‐tocoph

ISSN:0538-8066    

DOI:10.1002/kin.550200908

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550200901

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY