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The vacuum UV photolysis of various C 4 and C 5 olefins: The energy content of the α‐ and β‐methallyl fragments
Author(s) -
Collin Guy J.,
Deslauriers Hélène
Publication year - 1980
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550120103
Subject(s) - chemistry , photodissociation , radical , fragmentation (computing) , bond cleavage , photochemistry , excited state , reaction rate constant , kinetic energy , double bond , decomposition , kinetics , atomic physics , organic chemistry , physics , quantum mechanics , computer science , catalysis , operating system
In recent publications from this laboratory, we have shown that the fragmentation of photoexcited olefinic molecules in the vacuum UV region leads mainly to the cleavage of a C—C bond located in the ß position relative to the double bond. The allyl fragment bears away part of the excess energy of the photon. At low pressure, this excited radical is capable of undergoing further decomposition. From the pressure effect, we were able to measure the first order rate constant for this secondary fragmentation. In this paper we shall use RRKM calculations in order to get a better idea on how the energy is distributed among the primary fragments. In cases where α‐ and β;‐methallyl radicals were involved, the results show that an important part of the excess energy is located in the methallyl fragment in the 7.1 and 7.6 eV photolysis of 3‐methyl‐1‐butene, 2‐methyl‐1‐butene, and cis ‐2‐pentene.