Reactions of nitrophenide and halonitrophenide ions with acrylonitrile and alkyl acrylates in the gas phase: The case of [M−2]− ion formation ☆

Abstract The structure of [M−2] − ions formed in reactions between α,β-unsaturated compounds (acrylonitrile and alkyl acrylates) and nitro- and p -halonitro-phenide ions have been studied both experimentally and theoretically. Although it is not possible to prove the origin of the [M−2] − ions directly clear evidence for intermediate β-adduct formation during reaction was found. More specifically, the mechanism involves transformation of the β-adduct comprising an O-atom transfer via a six-membered intermediate, followed by the loss of an HCOR molecule (R = CN, CO 2 Me, CO 2 Et). This sequence leads eventually to an [M−2] − anion with an o -nitrosobenzylic anion structure. Further transformation of the o -nitrosobenzylic anion to the more stable o -aminobenzaldehyde anion was also considered but was ruled out.