SYNTHESIS AND POLYMERIZATION OF 2,5-DIMETHYLENE-2,5-DIHYDROTHIOPHENE DERIVATIVES

Novel 2,5-bis(substituted methylene)-2,5-dihydrothiophenes such as 2,5-bis[di(ethylthio) methylene]-2,5-dihydrothiophene [1] and 2,5-bis[cyano(ethylthio)methylene]-2,5-dihydrothiophene [2] were successfully prepared. The first reduction potentials of [1], [2], and 2,5-bis(dicyanomethylene)-2,5-dihydrothiophene [3] were measured in cyclic voltammetry to know the electron-accepting character of each compound. The compounds of [1], [2], and [3] are not homopolymerizable with any initiators and also not copolymerizable with vinyl monomers except for an alternating copolymerization of [3] with styrene. The attempts of copolymerizations of [1], [2], and [3] with 7,8-bis(butoxycarbonyl)-7,8-dicyanoquinodimethane [10] as a highly conjugative comonomer failed and only the homopolymer of [10] was obtained, showing that these thiophene derivatives are as much lower in reactivity than [10].