Mechanism of Stereospecific Alcohol Elimination from Cyclohexane trans-1,3-Dicarboxylates Under Electron Impact Ionization

Article abstract of DOI:10.1002/oms.1210290703

Diesters of cyclohexane trans-1,3-dicarboxylic acid give rise to major (+.) ions under electron impact ionization.A mass spectral study of the isomeric mixed methyl ethyl esters of the diacid, substituted by a methyl group at position 1 and deuterium labelled at position 3, indicates a stepwise mechanism for this alcohol elimination; the 3-hydrogen (or deuterium) is transferred to the carbonyl of the 1-ester group in the initial step.Subsequent migration of that hydrogen (or deuterium) to the alkoxyl of position 3 results in the highly site- and stereospecific alcohol elimination.CID spectra of the (+.) ions obtained from the stereoisomeric diesters clearly show that they have different structures (or are different mixtures of structures).