Microflow Synthesis of Unsymmetrical H-Phosphonates via Sequential and Direct Substitution of Chlorine Atoms in Phosphorus Trichloride with Alkoxy Groups.

Abstract

Unsymmetrical H-phosphonates were synthesized by a rapid (<15 s) and mild (20 °C) process in a microflow reactor as the first example of the sequential direct substitution of the chlorine atoms in PCl3 with alkoxyl/aryloxy groups using equivalent amounts of PCl3 and alcohols. The optimal base concentration differed in each step, presumably attributed to differences in the Brønsted basicity of the electrophilic intermediates. Phosphite hydrolysis was observed, and the structure-hydrolysis relationship was quantitatively evaluated.