Versatile Regioselective Friedel–Crafts Hydroxyalkylation Polycondensation toward Linear Polymers Containing Triphenylmethane Backbone Structures

Abstract

Polycondensations play a significant role in the synthesis of polymer materials. However, most traditional polycondensation reactions suffer from slow reaction rates, low efficiency, non-negligible reaction equilibrium and side reactions, low atom economy, and stringent conditions. Previously, we have found the unique regioselective Friedel–Crafts hydroxyalkylation polycondensation between 1,4-disubstituted benzenes and 4-substituted benzaldehydes to produce high molar mass polymers with triarylmethane backbone structures. In this study, we first found the regioselective Friedel–Crafts hydroxyalkylation type small molecule model reaction between 4-methylanisole and 4-nitrobenzaldehyde. By density functional theory calculations, we elucidated the mechanism of this model reaction to quantitatively give a single product with the structure that two 4-methylanisoles were linked together by one 4-nitrobenyl group at the ortho position of the methoxy group. Finally, we show that this model reaction can be successfully developed as a versatile, facile, mild, nonstoichiometric, highly efficient, and atomic economic polycondensation reaction that can produce linear polymers with different backbone structures. This type of Friedel–Crafts hydroxyalkylation polycondensation enriches the collection of polycondensation reactions and is of great significance for overcoming the drawbacks of traditional polycondensation reactions.