A Safe and Efficient Route for the Preparation of Nitro-, Dinitro-, and Trinitrophenyl Chloroformates

Abstract

A safe and simple method has been developed for synthesis of chloroformates derived from 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, and pentafluorophenol, the yields being in the range of 72–96%. The method is based on a heterogeneous reaction of the substituted phenol with phosgene dissolved in dichloromethane catalyzed with solid anhydrous potassium carbonate. The synthesis of 2,4,6-trinitrophenyl chloroformate takes place only in the presence of a phase-transfer catalyst, in this case the easily recovered α,ω-dimethoxy poly(ethylene glycol) (PEG; M = 2 kDa). The only waste products of the suggested synthesis of the mentioned esters are sodium chloride and potassium chloride. The method markedly reduces the explosion risk connected with drying and handling of salts of mono-, di-, and trinitrophenols and is much more environmentally friendly than the currently used methods. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.