SYNTHESIS AND POLYMERIZATION OF 7-(ALKOXYCARBONYL)-7-CYANO-1,4-BENZOQUINONE METHIDES

7-(Alkoxycarbonyl)-7-cyano-1,4-benzoquinone methides 4 with four kinds of alkoxy groups, methyl, ethyl, isopropyl, and butyl, were successfully prepared as pure, isolable crystals. Acid-catalyzed 1,6-addition reactions of 7-cyano-7-(ethoxycarbonyl)-1,4-benzoquinone methide (4a) with phenol and N,N-dimethylaniline each gave 1:1 adducts in quantitative yield. Compound 4a reacted with hydrogen chloride to give a 1,6-addition product in situ in quantitative yield, but it did not react with acetic acid. When dissolved in basic aprotic polar solvents such as acetone, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide, 4a spontaneously polymerized to give an oligomer with a molecular weight of 400-6000. Compounds 4 were homopolymerizable with 2,2'-azobis(isobutyronitrile) (AIBN), pyridine, and even boron trifluoride etherate. Pyridine afforded poly-4a with a high molecular weight of 1.1 x 10(5). Both anionic and radical poly-4a consisted of 1,6 or head-to-tail monomer unit placement. Compound 4a was copolymerizable with styrene in a random fashion in the presence of AIBN to obtain the monomer reactivity ratios: r4a = 3.4 +/- 0.2 and r(St) = 0.01 +/- 0.08 at 60-degrees-C to allow Q and e values for 4a to be 23 and 1.04, respectively, indicating that it is highly conjugative (highly reactive) and electron-accepting.