Facile Synthesis of Primary Amines via Nitrogen Fixation in Charged Microdroplets
摘要
Primary amines are one of the most versatile synthetic intermediates, but current methods rely on protecting groups in multistep reactions or corrosive reducing agents. Herein, we report an innovative synthetic method for primary amines based on accelerated microdroplet chemistry. The electrospray process allows in-situ ammonia generation from atmospheric nitrogen, reacting with alcohols of various properties (aliphatic and aromatic) to produce the corresponding amine. The alcohol to amine conversion rate improves (> 10×) when hydrazine is introduced as an ammonia source. Electronic and steric effects are also investigated. Overall, three spray conditions are investigated: (1) co-axial spray with hydrazine, (2) single emitter spray without hydrazine at high flowrates, and (3) single emitter spray without hydrazine at low flowrates. Material collection allowed NMR characterization of products, confirming ipso substitution. Our results suggest this method is a useful alternative to bulk synthesis, achieving primary amines under mild reaction conditions without corrosive reagents and exotic catalysts.