Uncatalyzed N-Alkylation of Amines in Ionic Wind from Ambient Corona Discharge

Ionic wind comprising of the drag of bulk air in the presence of electrical discharge enabled N-alkylation reactions under ambient conditions. By introducing reactant vapor as part of the discharge gas during the stages of electron acceleration, both neutral and charged species of the selected organic reactant gain energy through ion-neutral collisions, which is identified to facilitate chemical reactions. By performing this experiment in front of a mass spectrometer, chemical reactions occurring in the ionic wind were examined in real time. Reaction energetics were characterized via the use of benzylamine, which freely dissociates at a critical energy of 3.6 eV to give the resonance-stabilized benzyl cation as reaction intermediate. Benzylamine and many other primary amines were observed to undergo N-alkylation reactions by engaging in self-cross-coupling ion-molecule reactions. Because of the high energies of species involved and the fact that the ionic wind is generated at atmospheric pressure, it was straightforward to collect the ensuing reaction products without the use of complicated instrumentation. Water served as an effective collecting solvent allowing >0.1 mg of intact N-alkylated products to be collected under ambient conditions using a single plasma emitter. A novel N-alkylation reaction pathway involving the synthesis of N-benzyl-1-(methyleneamino)-1-phenylmethanaime was discovered through this offline product collection experiment, providing new insight into benzylamine dissociation in the ionic wind.