Nitrogen incorporation in saturated aliphatic C6-C8 hydrocarbons and ethanol in low-pressure nitrogen plasma generated by a hollow cathode discharge ion source

摘要

Ion/molecule reactions of saturated hydrocarbons (n-hexane, cyclohexane, n-heptane, n-octane and isooctane) in 28-TorrN(2) plasma generated by a hollow cathode discharge ion source were investigated using an Orbitrap mass spectrometer. It was found that the ions with [M+14](+) were observed as the major ions (M: sample molecule). The exact mass analysis revealed that the ions are nitrogenated molecules, [M+N](+) formed by the reactions of N-3(+) with M. The reaction, N-3(+) + M[M+N](+) + N-2, were examined by the density functional theory calculations. It was found that N-3(+) abstracts the H atom from hydrocarbon molecules leading to the formation of protonated imines in the forms of RRCNH2+ (i.e. C-H bond nitrogenation). This result is in accord with the fact that elimination of NH3 is the major channel for MS/MS of [M+N](+). That is, nitrogen is incorporated in the C-H bonds of saturated hydrocarbons. No nitrogenation was observed for benzene and acetone, which was ascribed to the formation of stable charge-transfer complexes benzeneN(3)(+) and acetoneN(3)(+) revealed by density functional theory calculations. Copyright (c) 2016 John Wiley & Sons, Ltd.