Mass spectrometric study of resonance electron capture by molecules of 3-substituted myristic acids

Abstract

The formation of (M — H) − ions by resonance capture of electrons of myristic, 3-hydroxymyristic and 3-ketomyristic acids and their methyl esters has been studied. It has been established that non-oxygenated compounds form (M — H) − ions both at low energy (1–3 eV) and high energy (7.0 eV) resonances, whereas the 3-substituted compounds (hydroxy and keto acids and the methyl ester of 3-hydrocy acid) do this only at low energy resonance. At low energy resonance the (M — H) − ions of acids are carboxylate anions, whereas these ions of methyl esters of the acids are carbanions formed by the loss of an H atom from C(2). For the high energy resonance a mechanism for generating (M — H) − ions has been suggested, which is the same for both the acids and their methyl esters. The proposals are based on comparison of the resonance electron capture mass spectra of these compounds with the same data for their deutero analogs as well as on the comparative study of a series of acids encompassing C 3 and C 22 carbonic acids.