摘要:

AbstractThe reaction Cl + H2CO → HCl + HCO has been studied at 295 K. Chlorine atoms were produced via the infrared laser induced dissociation of CCl3F, using a pulsed CO2TEA laser. Using HCl infrared chemiluminescence as the diagnostic, we find the rate constant to be 7.4 ± 0.7 × 10−11cm3/molecule sec, in good agreement with several recent studies. An evaluation of TEA laser photolysis as a technique for the generation of chlorine atoms is made, and the relationship of this experiment to recent theories of infrared laser induced chemistry is disc

ISSN:0538-8066    

DOI:10.1002/kin.550130402

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractModels for the energy profile along the reaction coordinate are utilized to determine the barrier's height and location as a function of ΔG. These form the basis for structure–reactivity correlations and afford a unified formulation for various postulates in the field of physical organic chemistry. Current experimental evidence is examined for the resulting correlations, and some of their applications as an aid to the chemical kineticist are present

ISSN:0538-8066    

DOI:10.1002/kin.550130403

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe flash photolysis of azo‒n‒propane and of azoisopropane has been studied by kinetic spectroscopy. Transient absorption spectra in theregion of 220–260 nm have been assigned to then‐propyl and isopropyl radicals. For then‐propyl radical, ϵmax= 744 ± 39 l/mol cm at 245 nm and the rate constants for the mutual reactions were measured to bekc= (1.0 ± 0.1) × 1010l/mol sec (combination) andkd= (1.9 ± 0.2) × 109l/mol sec (disproportionation). For the isopropyl radical, ϵmax= 1280 ± 110 l/mol cm at 238 nm, withkc= (7.7 ± 1.6) × 109l/mol sec andkd= (5.0 ± 1.2) × 109l/mol secThe rate constant for the dissociation of the vibrationally excited triplet state of the azopropanes into radicals was measured from the variation in the quantum yield of radicals with pressure. For azo‐n‐propanek dT= (6.6 ± 1.3) × 107sec−1, and for azoisopropanek dT= (1.6 ± 0.4) × 108sec−1. Collisional deactivation of the vibrationally excited singlet and triplet states was found to occur on every collision forn‐pentane; but nitrogen and argon were inefficient with a rate constant of 1.1 × 1010l/mol sec.Spectra observed in the region of 220–260 and 370–400 nm areattributed to thecisisomers of the parenttrans‐azopropanes. These are formed, as permanent products, in i

ISSN:0538-8066    

DOI:10.1002/kin.550130404

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe kinetics of the reactionhave been investigated in H2SO4medium under different conditions. The observed bimolecular rate constantkobs, has been found to depend on [H+]−0.55and to increase with the initial concentration ratio of the reactantsR0= [H2O2]0/[U (IV)]0above 0.49. The activation energy of the overall reaction has been determined as 13.79 and 14.3 kcal/mol atR0= 1 and 0.35, respectively. Consistent with experimental data, a detailed reaction mechanism has been proposed where the hydrolytic reaction (4) followed by the rate‐controlling reaction (10) and subsequent fast reactions of U (V) and OH radicals are involved:A kinetic expression has been derived from which a graphical evaluation of (kK4)−1andk−1has been made atR0= 1 as (12.30 ± 0.09) × 10−3Mmin, (6.23 ± 2.19) × 10−4Mmin; and atR0= 0.35 as (12.63 ± 2.13) × 10−3Mmin, (8.32 ± 6.62) × 10−4Mmin, respectively. Indications of some participation of a chain reactionatR0= 1 have been obtained without affecting thesecond‐o

ISSN:0538-8066    

DOI:10.1002/kin.550130405

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe rates of pyrolysis of 4‐chloro‐2‐butanone in the gas phase have been determined in a static system seasoned with the products of decomposition of allyl bromide. The reaction is catalyzed by hydrogen chloride. Under maximum catalysis of HCl, the kinetics were found to be of order 1.5 in the substrate suggesting that a complex elimination is involved. The reaction, when maximally inhibited with propene, appears to undergo a unimolecular elimination and follows a first‐order law kinetics. The products are methylvinyl ketone and hydrogen chloride. The kinetics have been measured over the temperature range of 402.0–424.4°C.The rate coefficients are given by the Arrhenius equation\documentclass{article}\pagestyle{empty}\begin{document}$ \log k_1 (\sec ^{ - 1}) = (13.67 \pm 0.69) - (225.2 \pm 8.6)\,{\rm kj}/{\rm mol}/2.303RT\angle $\end{document}. Thepyrolysis of 4‐chloro‐2‐butanone is 31 times greater in rate than that of ethyl chloride at 440°C. This large difference in rate may be attributed to the ‐M effect of the acetyl substituent in the pyrolysis of the f

ISSN:0538-8066    

DOI:10.1002/kin.550130406

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe entropy of activation for the hydrolysis of pentaphenoxyphosphorane in 25% aqueous dioxane is −188 J/mol deg. The enthalpy of activation is 22.5 kJ/mol, which is small for the relatively slow reaction. This suggests that the reaction is a multistep process having a preliminary equilibrium with a negative heat of reaction. This conclusion is supported by the results obtained for the hydrolysis of C6H5[OCH(CF3)2]2. A kinetic isotope effectkH2O/kD2Oof 3.46 was found for the latter reaction. Orders in water were obtained, and a mechanism of hydrolysis is propose

ISSN:0538-8066    

DOI:10.1002/kin.550130407

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractRate constants and activation parameters for the isotopic exchange reactions between (PhO)2PSCl and M36Cl (M = Me4N+, Et4N+,n‐Bu4N+, Et3HN+, EtH3N+, Li+) in acetonitrile were measured in order to find the effect of the cation nature onthe kinetics of the reaction. The rate constants measured for a range of concentrations of Et3HN36Cl, EtH3N36Cl, and Li36Cl were analyzed using the Acree equation. The equivalent conductance of LiCl in acetonitrile was determined. The nature of the cation has no effect on the mechanism of the reaction. The cation changes only the experimental rate constant proportionally to the dissociation degree of the salt. Smaller values of the rate constant and smaller activation parameters ΔH‡ and ΔS‡ for the reaction with Li36Cl indicate the existenceof the intermolecular interaction between lithium ions andO,O‐diphenylphosphorochlorid

ISSN:0538-8066    

DOI:10.1002/kin.550130408

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe reactionshave been studied competitively over the range of 28–182°C by photolysis of mixtures of Cl2+ C2F5I+ CH4. We obtain\documentclass{article}\pagestyle{empty}\begin{document}$$ \log {\rm }k_1 /k_2 = (0.96 \pm 0.06) + (1210 + 440)/\theta $$\end{document}where θ = 2.303RTJ/mol. The use of published data on reaction (2) leads to log (k1cm3/mol sec) = (13.96 ± 0.2) − (11,500 ±

ISSN:0538-8066    

DOI:10.1002/kin.550130409

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550130401

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY