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

Abstract

We demonstrated direct conversion of benzene into pyridine and aniline, assisted through exact mass measurements (m/z 80.0494, 93.0574, and 94.0651, respectively), through the interaction of benzene with water/nitrogen vapor plasma produced by corona discharge. Systematic analysis using a series of isotopic standards indicated that formation of pyridine and aniline occurred through the reaction between neutral benzene and reactive N + (OH 2 ) 2 in water/ nitrogen plasma; exact mass measurements of products and intermediates supported this hypothesis. As the proportion of water vapor in plasma increased over time, the reaction proceeded from exclusive formation of protonated pyridine to formation of protonated aniline as the main product; theoretical simulations indicated that the presence of water vapor promoted proton migration to elicit formation of protonated aniline. The reactions we discovered suggest a new mechanism for direct nitrogen fixation.

Observing C–N bond formation in plasma: a case study of benzene and dinitrogen coupling via an arylnitrenium ion intermediate

“…The plasma-driven synthesis of N -containing compounds from N 2 molecules is rare. According to the sparsely reported results, N -containing compounds were observed, mainly including iminium salts, 20 aniline derivatives, 21 and pyridine, 22 when alkanes or benzene were treated in N 2 plasma. On the other hand, those nitrogenous compounds were merely detected at a mass spectrometric scale, rather than for a preparative purpose.…”