3834-39-7Relevant articles and documents
KrF laser induced telomerization of bromides with olefins. Part 1. Self-inhibition and kinetic analysis
Linyang,Fuss,Kompa
, p. 867 - 874 (1990)
The chain reaction of several organic bromides with olefins was induced by a KrF laser. In all cases we found a self-inhibition, leading to a termination of first order in the radical concentration. There is indirect evidence that it is due to molecular bromine, accumulated during the reaction in spite of the presence of olefins. It has not been noticed previously. We show that kinetic analysis is easy also for pulsed excitation, and the example CF3Br + C2H4 is studied in detail. We found rate constants for CF3 + C2H4 → CF3C2H4 (7.2·109 cm3 mol-1 s-1; this is in between two previous values) and for CF3C2H4 + CF3Br → CF3C2H4Br + CF3(1.2·109 cm3 mol-1 s-1) as well as preliminary values for some other reactions.
Fluorine substitution effects on the alkyl coupling reaction on a Ag(111) surface
Paul, Anumita,Gellman, Andrew J.
, p. 9056 - 9066 (2007/10/03)
We have investigated fluorine substitution effects on the rate of coupling of adsorbed alkyl groups on a Ag(111) surface. Alkyl groups are formed by thermal dissociation of the C-I bond in adsorbed alkyl iodides. Variable heating rate temperature programmed reaction (TPR) studies were used to determine the kinetic parameters for the coupling of ethyl groups and propyl groups. They are Ea = 15.1 ± 0.6 kcal/mol, v = 1016.7±0.8 s-1 and Ea = 16.9 ± 0.4 kcal/mol, v = 1017.1±0.4 s-1, respectively. Substitution of fluorine for hydrogen in the adsorbed alkyl groups systematically raises the coupling reaction temperature. For example, trifluoropropyl groups self-couple at temperatures ～70 K higher than propyl groups on Ag(111). Coadsorbed propyl and trifluoropropyl groups cross-couple at temperatures ～10 K higher than the propyl self-coupling reaction. The kinetic parameters evaluated from the results of this study and from results of earlier studies by X.-L. Zhou, J. M. White, and co-workers [Surf. Sci. 1989, 219, 294; Catal. Lett. 1989, 2, 375; J. Phys. Chem. 1991, 95, 5575] are used to plot linear free energy relationships (LFER) which provide insight into the electronic nature of the reaction center. The implication of the LFER plots for the surface alkyl coupling reaction is that the reaction center in the transition state is electron deficient with respect to the initial state.
