An Easy, High-yield Synthesis of Highly Chlorinated Mono-, Di- and Triarylmethanes

Abstract

A simple, direct, high-yield Friedel-Crafts synthesis of highly chlorinated, overcrowded αH-aryl, αH-diaryl, and αH-triarylmethanes is described. The latter compounds are most valuable chemical precursors of inert free radicals, which are frequently obtained through otherwise cumbersome, medium-to-low-yield aromatic chlorination of triphenylmethane derivatives. The condensation is performed with aluminium chloride at temperatures ranging from 70 to 160°C. The substrate is a benzene with all its hydrogens flanked by two ortho chlorines. The alkylating component is chloroform, αH-heptachlorotoluene (2a) or αH-undecachlorodiphenylmethane (3a). For comparison, the condensation with a few non-sterically-hindered substrates has also been performed.