Mass spectrometry in structural and stereochemical problems—CLXXI: Factors governing the preferential loss of small vs. Large radicals in the α-fission of aliphatic amines

A study of the α-cleavage processes of aliphatic amines (using R_LCH₂N(R)CH₂R_s and R_LCH(NR)R_s

1 R_L represents the larger R_s the smaller alkyl group throughout this paper and both, unless indicated to the contrary, have similar degrees of lsubstitution on the α-carbon atom.

as typical substrates) at several ionizing voltages indicates that the loss ratio of large and small alkyl radicals, M ? R_L]/M ? R_s], decreases with ionizing voltage. This ratio, greater than 1·0 at 70 eV, may become less than unity at low voltage (15 eV, 10 eV) in some cases. Comparison of similarly structured compounds with nitrogen or oxygen as the heteroatom suggests that the effects of ionizing voltage are lessened when the fragment is of greater stability (e.g. amine vs. ether or imine vs. ketone). The effects of lowering the ionizing voltage became much less pronounced as the alkyl groups become larger or similar in size.