Abstract
The mechanism of specific fragments which give [M—OH]+ in o-methyl and o-ethyl-formanilide was discussed and the paths to the formation of the fragment ion at m/z 106 in methylformanilides and methylacetanilides were investigated using deuterium labeled compounds.
It was ascertained that the [M—OH]+ ion was produced by the hydrogen-transfer from the ortho-methyl or ethyl group to the acyl oxygen, followed by the OH elimination and that the intensity of [M—OH]+ in o-methylformanilides was enhanced strongly by the nitro group at para position to the methyl group.
It was suggested that the simple cleavage of the —NH—CO— bond which is a route to produce an ion at m/z 106 was more prominent in o-methylformanilide than those in p-methylformanilide and o- or p-methylacetanilide.
