L'isomérisation de radicaux insaturés. II. Les radicaux α-éthallyles et α,γ-diméthallyles formés dans la photolyse de l'hexène-3 et du méthyl-4-pentène-2 à 147,0 et 184,9 nm

Abstract

The photolysis of cis-3-hexene and 4-methyl-cis-2-pentene has been studied at 147.0 and 184.9 nm. The fragmentation pattern of the photoexcited molecule is normal: it requires, mainly, the split of a C—C bond located in the β position relative to the double bond [Formula: see text]. Some α(C—C), β(C—H), and α(C—H) primary splits complete this mechanism. The formation of α-ethallyl and α,γ-dimethallyl radicals is important in 3-hexene and 4-methyl-2-pentene, respectively. An isomerization process, involving these two radicals, is necessary to explain the formation of part of the 1,3-pentadiene in the 3-hexene system and of all the 1,3-butadiene in the 4-methyl-2-pentene system. This process involves a 1,4-hydrogen atom transfer.