Gas-phase amination of aromatic hydrocarbons by corona discharge-assisted nitrogen fixation

Abstract

This paper reports on the gas-phase amination reaction of aromatic hydrocarbons occurring under corona discharge conditions with N2 gas as the nitrogen source. The corona discharge device within an atmospheric pressure chemical ionization source was employed to achieve the plasma-assisted N2 fixation, and the coupled ion trap mass spectrometer (IT-MS) was used to detect positively charged product ions. In the model case, under APCI conditions, unusual product ions, [M + 16]+ and [M + 14]+, were observed. Based on the high resolution MS data and tandem mass spectrometric information, [M + 16]+ was confirmed to be protonated p-toluidine and [M + 14]+ was confirmed to be p-methylphenylnitrenium ion. According to the experimental results of the isotopic labelling and substituent effect, one feasible mechanism is proposed as follows. Firstly, N2 is activated by plasma caused via the corona discharge and then electrophilically attacks toluene, yielding the key intermediate, p-methylphenylnitrenium; secondly, the intermediate undergoes double-hydrogen transfer reaction to give rise to the final product ion, protonated p-toluidine. This study may provide a novel idea to explore new and green method for the synthesis of anilines.

Nitrogen Fixation by Benzene into Pyridine and Aniline in Water/Nitrogen Plasma

“…Recently, Shen et al reported on the gas-phase amination reaction of aromatic hydrocarbons occurring under corona discharge conditions with dinitrogen gas as the nitrogen source and one feasible mechanism is proposed. 15 Herein, in contrast to the aforementioned studies, 14,15 we observed pyridine generation in the early stage of the reaction and formation of aniline as the dominant product in the late stage upon exposure of neutral benzene vapor to water/ nitrogen plasma. We demonstrated, for the first time, that trace water in dinitrogen gas could promote formation of an aniline product and aid direct synthesis of value-added nitrogencontaining compounds with the C−N bond from benzene.…”

“…Herein, in contrast to the aforementioned studies, , we observed pyridine generation in the early stage of the reaction and formation of aniline as the dominant product in the late stage upon exposure of neutral benzene vapor to water/nitrogen plasma. We demonstrated, for the first time, that trace water in dinitrogen gas could promote formation of an aniline product and aid direct synthesis of value-added nitrogen-containing compounds with the C–N bond from benzene.…”

“…Zhang et al proposed a mechanism involving carbon replacement with nitrogen-containing species and ring-opening and ring-closing reactions. Recently, Shen et al reported on the gas-phase amination reaction of aromatic hydrocarbons occurring under corona discharge conditions with dinitrogen gas as the nitrogen source and one feasible mechanism is proposed …”

Ortho C–H Bond Activations in an Atmospheric Microwave Plasma Ion Source

“…Ultrafast time-resolved spectroscopy is an early way to realize spectral observation . In the gas-phase amination reaction of aromatic hydrocarbons, p -methylphenylnitrenium ions are captured as reaction intermediates using MS. − In the plasma tip, PhNH + can be easily and continuously produced and detected, but it remains unstable. In addition to its own signal observed in MS, the solvent adduct signal is obvious, indicating that the PhNH + is easily captured by the solvent molecule.…”

Gas-Phase Alcoholysis of Benzylic Halides in the Atmospheric Pressure Ionization Source

“…In the case of APCI, the degradation of all the studied neonicotinoid pesticides took place; by contrast, the degradation of the neonicotinoid pesticides studied in ESI was not significant, which was attributed to the accelerated in-source pyrolysis caused by the higher auxiliary gas heater temperature in the APCI source. Our group recently reported the interesting gas-phase amination reactions of aromatic hydrocarbons under APCI condition with N 2 gas as the nitrogen source . In addition, other kinds of unexpected in-source reactions during APCI process, such as redox reactions, , association reactions, − dissociation reactions, − and so on, have been recognized and documented.…”