Polymerization behavior of electron‐accepting substituted quinodimethanes

This article describes the polymerization behavior of electron‐accepting substituted quinodimethanes. Chlorine‐substituted quinodimethanes ( 1a–c ) behave differently depending on the number of chlorine substituents. Strong electron‐accepting substituted quinodimethanes like 2a–c and 4 are not homopolymerizable, but copolymerizable with donor monomers like styrene in an alternating fashion. 7,7,8,8‐Tetrakis(alkoxycarbonyl)‐quinodimethanes ( 3a and 3b ) and 7,7,8‐tris( tert ‐butoxycarbonyl)‐8‐cyanoquinodimethane ( 5a ) show amphoteric behavior in their alternating copolymerizations and in their charge‐transfer complex formation. Some substituted quinodimethanes with two different substituents on their exocyclic carbons ( 5b, 6a–c, 7a–e, 8a and 8b , and 9a–e ) are homopolymerizable; for instance anionic polymerization of 7,8‐bis(butoxycarbonyl)‐7,8‐dicyanoquinodimethane ( 6c ) takes place in a living way and gives a polymer with a molecular weight above 10 6 . The homopolymerizations are equilibrium polymerization reactions and the thermodynamic parameters were determined. Their copolymerizations with styrene occur in a random fashion. The cross‐propagation step was studied by means of a linear free energy relationship and a new concept of radical alternating copolymerization is proposed.