Nitrogen Dioxide Catalyzed Aerobic Oxidative Cleavage of C(OH)-C Bonds of Secondary Alcohols to Produce Acids.

Abstract

Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation and separation procedures. Herein, we reported for the first time that NO2 in DMSO could effectively catalyze the aerobic oxidative cleavage of C(OH)-C bonds to form carboxylic group, and NO2 was in-situ generated by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted to acids in excellent yields in this transition metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail study revealed that NO2 from nitrates promoted the reaction, and NO2 served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.