Exchange of aryl groups in Friedel — Crafts alkylation of arenes in superacid by 2-halogeno- 2-trifluoromethylstyrenes. Mechanism and ways of suppression

Abstract

The protonation of 2-halogeno-2-trifluoromethylstyrenes in superacids leads to formation of benzyl carbocations that are capable to take part in Friedel — Crafts reaction with arenes to afford 1,1- diaryl-2-halo-3,3,3-trifluoropropanes. The reaction with strong π-nucleophiles (xylenes, anisole or veratrole) can be complicated by exchange of aryl groups. The mechanism and ways of suppression of this additional process were proposed.