Methyl cyanide, molecular structure

The mass spectrum of quinoxaline shows fragment ions resulting from the loss of one and two molecules of hydrogen cyanide. Where structurally possible, loss of hydrogen cyanide from the molecular ion is found to be the major fragmentation process for many nitrogen heteroaromatic compounds. Similarly in the case of 2-alkyl- and 2-arylquinoxalines, (M—HCN)" and (M—RCN)" ions are observed. A notable feature of the spectrum of 2-methyl-3-phenylquinoxaline is the formation of an intense (M-1)- - ion. ° i... 

Wallwork. S.C. Powell. H.M. The structure of molecular compounds. XI. Crystal structure of the addition complex of quinol and methyl cyanide. J. Chem. Soc. 1956. 4855-4858. 

Quite unexpected was the recently reported ring-closure reaction associated with Cl loss from the molecular ion of a-methyl-) -chloropropionitrile (132), which yields 30% C4H6N ions which have the structure of N-protonated cyclopropyl cyanide (134). The intermediacy of 133 was suggested (Scheme 21). 

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