Electrosynthesis of a nylon-6 precursor from cyclohexanone and nitrite under ambient conditions

Abstract

Cyclohexanone oxime, an important nylon-6 precursor, is conventionally synthesized through cyclohexanone-hydroxylamine (NH₂OH) and cyclohexanone ammoxidation methodologies. These strategies require complicated procedures, high temperatures, noble metal catalysts, and toxic SO₂ or H₂O₂ usage. Here, we report a one-step electrochemical strategy to synthesize cyclohexanone oxime from nitrite (NO₂⁻) and cyclohexanone under ambient conditions using a low-cost Cu-S catalyst, avoiding complex procedures, noble metal catalysts and H₂SO₄/H₂O₂ usage. This strategy produces 92% yield and 99% selectivity of cyclohexanone oxime, comparable to the industrial route. The reaction undergoes a NO₂⁻ → NH₂OH→oxime reaction pathway. This electrocatalytic strategy is suitable for the production of other oximes, highlighting the methodology universality. The amplified electrolysis experiment and techno-economic analysis confirm its practical potential. This study opens a mild, economical, and sustainable way for the alternative production of cyclohexanone oxime.

The sustainable synthesis of cyclohexanone oxime, the precursor of nylon-6, without toxic SO₂ or H₂O₂ usage is desirable. Here, the electrosynthesis of cyclohexanone oxime from nitrite and cyclohexanone under ambient conditions is reported.