Polymerization behavior of electron‐accepting substituted quinodimethanes

Abstract

This article describes the polymerization behavior of electron-accepting substituted quinodimethanes. Chlorine-substituted quinodimethanes ( l a -c ) behave differently depending on the number of chlorine substituents. Strong electron-accepting substituted quinodimethanes like 2 a-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(terf-butoxycarbonyl)-8-cyanoquinodimethane (5 a) 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 lo6. 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.

Equilibrium Polymerization of 7-(Alkoxycarbonyl)-7-cyano-1,4-benzoquinone Methides, Substituent Effect on Polymerizability, and Copolymerization with Styrene

“…Therefore, it is worth noting that the difference in the copolymerization fashion is determined depending on whether 3a is homopolymerizable or not. That is, it indicates that this polymerization behavior could also be explained well in terms of the alternating copolymerization mechanism , proposed for the copolymerization of the substituted quinodimethanes with styrene. The mechanism is explained on the basis of the following scheme: Substituted 1,4-benzoquinone methides (BQM) are much more conjugative (reactive) than styrene (St).…”

Synthesis of 2,5-Bis(1,3-dithiolan-2-ylidene)- 2,5-dihydrothiophene and Its Novel Polymerization in the Presence of Oxygen

“…17,18 On the polymerizations of these isolable electronaccepting substituted quinonoid compounds, we have found interesting polymerization behaviors such as equilibrium polymerizations, 12,16,18 alternating copolymerizations, [5][6][7][8]13,14,18 and changes in the polymerization mode 8,10,12,16 from random copolymerization to alternating copolymerization depending upon polymerizability. 19 In contrast to many studies of the electron-accepting substituted quinonoid compounds with regard to their polymerization behavior, very little is known about the polymerization behavior of the electron-donating substituted quinonoid compounds except for 7,7,8,8-tetrakis(ethylthio)quinodimethane 20 and 2,5-bis[di(ethylthio)methylene]-2,5-dihydrothiophene, 13 which are neither homopolymerizable with any initiator nor copolymerizable with styrene. From the standpoint of exploring the chemistry of quinonoid compounds in the polymerization, many novel electron-donating substituted quinonoid compounds should be prepared and investigated for their polymerization behavior.…”

“…Crystals allowed us to easily study the chemistry of quinonoid compounds in the polymerization. To date, our studies have been mainly focused to the polymerizations of electron-accepting substituted quinonoid compounds such as p -quinodimethanes, − p -quinone methides, − and p -quinone methide imines. , On the polymerizations of these isolable electron-accepting substituted quinonoid compounds, we have found interesting polymerization behaviors such as equilibrium polymerizations, ,, alternating copolymerizations, − ,,, and changes in the polymerization mode 8,10,12,16 from random copolymerization to alternating copolymerization depending upon polymerizability and 2,5-bis[di(ethylthio)methylene]-2,5-dihydrothiophene, which are neither homopolymerizable with any initiator nor copolymerizable with styrene.…”

Polymerization behavior of 2,5-bis(dicyanomethylene)- 2,5-dihydrofuran

“…Therefore, we have prepared some new substituted QMs as quinonoid monomers and investigated their polymerization behaviors. 8 The alternating copolymerizations between the substituted QMs and styrene, their equilibrium polymerization behaviors, and change in the polymerization mode depending upon the substitution mode were found, and a new concept of an alternating copolymerization mechanism based on the polymerization behaviors of the substituted QMs was also proposed. 8 -10 However, the number of the substituted QMs isolable as pure crystals at room temperature is limited and their properties are not necessarily known well.…”