Continuous generation, in-line quantification and utilization of nitrosyl chloride in photonitrosation reactions

Abstract

Herein, we describe a continuous flow protocol for the generation, purification and quantification of nitrosyl chloride (NOCl). The generation of this useful but hazardous reagent is based on the reaction of aqueous NaNO2 with HCl as readily available starting materials. The reagent, which is formed immediately upon mixing of the reactants, is rapidly extracted into a suitable organic phase, such as CHCl3 or CH2Cl2, and separated using a continuous flow liquid-liquid membrane separator. A convenient method for the in-line monitoring of reagent concentration, based on flow UV/vis analysis, has also been developed and implemented. The synthetic utility of the nitrosyl chloride generator was demonstrated by integrating a continuous flow photochemical reactor downstream to perform the synthesis of cyclohexanone oxime from cyclohexane, an important industrial process.