Abstract: | Under electron impact dimethyl and diethyl mesaconates give rise to abundant [M ? MeOH]+ and [M ? EtOH]+ ions, respectively. The geometrically isomeric citraconates yield [M ? MeO]+ and [M ? EtO]+ ions. Mixed methyl ethyl mesaconates eliminate both methanol and ethanol. These findings, together with the results of a deuterium labelling study, indicate that the elimination of alcohol from the molecular ions of the mesaconates is partially preceded by a hidden hydrogen transfer step. |