Formation of aniline-like ions by electron-impact-induced elimination of CO from formanilide

The metastable peak intensity ratios for elimination of HNC vs DNC from the M ? CO]⁺· ion of deuterium labelled analogues of formanilide show that the formyl hydrogen atom migrates to nitrogen prior to or during CO expulsion to form a C₆H₇N]⁺· ion of aniline-like structure. An examination of metastable peaks does not allow similar conclusions to be reached for methyl substituted formanilides. Low abundance C₆H₆O]_+· ions are formed by HNC elimination from the formanilide molecular ion in a reaction where three covalent bonds to the formyl carbon are broken.