Direct plasma synthesis of a high-value C–N–O compound with inert N2 and CH4

Direct co-conversion of earth-abundant N 2 and CH 4 to high-value C–N–O compounds is a promising synthetic method but remains challenging, as the activation of N 2 and CH 4 typically requires high-energy conditions that can cause product decomposition. Here we report a plasma-cascade process for synthesizing cyclohexanone cyanohydrin (Cy(OH)CN) via direct coupling of N 2 and CH 4 plasma with cyclohexanone. This catalyst-free process achieves a Cy(OH)CN formation rate of 0.60 mmol h −1 with a high selectivity of 95.8% towards the cyclohexanone-derived products under mild conditions, concurrently generating ammonia as a valuable coproduct. Comprehensive mechanistic studies reveal that plasma-generated ·CH x and hydrogen radicals enable direct α-carbonyl functionalization of cyclohexanone to α-CH x cyclohexanol intermediates, which then coupled mainly with excited-state N 2 and are further activated by hydrogen radicals to generate Cy(OH)CN. This plasma-cascade strategy decouples the activation of inert molecules from the formation of relatively unstable C–N–O compounds, enabling selective cyanohydrin synthesis that avoids using high-cost NH 3 and toxic HCN. The alternative text for this image may have been generated using AI.