Mechanism of the elimination of methyl radical from the [M - H 2O] +· ion of 1,4-butanediol derivatives

Abstract

Upon electron ionization 1,4-butanediol gives a fragment ion, ion k , 1 which is formed by loss of water and methyl radical from the molecular-ion. As the mechanism of the loss of water, leading to ion i , the precursor of ion k , has been discussed previously (ref. 1) this paper deals with the mechanism of the formation of ion k from ion i . The hydrogen rearrangement(s) preceding the loss of the methyl group could be [1,3]- and/or [1,2] migrations. It is shown by investigating appropriate deuterium labelled derivatives of 1,4-butanediol, that a double [1,2] hydrogen rearrangement is mainly operating upon formation of ion k .