DISSOCIATIVE ELECTRON-CAPTURE OF PROPYLENE-OXIDE - MATRIX-ISOLATION ESR STUDY

A dissociative electron capture process of ethylene oxide yielding the anion radical of the ring-ruptured form, O--CH2-CH2., has been demonstrated recently. A similar electron capture process was examined for propylene oxide, 1,2-epoxybutane, and glycidyl methyl ether in an effort to determine which C-O bond would cleave, if any. The epoxy molecules of interest and Na atoms were cocondensed in argon matrices, and the electron transfer between them was effected by mild radiation (lambda > 580 nm). ESR examination of the matrices revealed that, in each case, the anion had the ring-opened structure resulting from cleavage of one of the C-O bonds. The external C-O bond cleaved preferentially. A concerted, S(N)2-type process is suggested between the epoxy molecule and the approaching electron. The conformations of the anion radicals were deduced from the observed alpha- and beta-proton coupling tensors.