Electron‐transfer polymers. XXX. Preparation of poly(1‐vinyl‐3,4,6‐trimethyl‐2,5‐benzoquinone)

Abstract

Abstract1‐Vinyl‐3,4,6‐trimethyl‐2‐methoxy‐5‐hydroxy‐benzene (I) was prepared in good yield by the Wittig reaction from the corresponding chloromethyl compound. It could be polymerized cationically to low molecular weight material. The polymer could be oxidized to poly(1‐vinyl‐3,4,6‐trimethyl‐2,5‐benzoquinone) (III) and could be reduced to the corresponding hydroquinone. Compound (I) was acetylated at the phenolic hydroxyl group and polymerized. The acetyl group was quantitatively reduced with lithium aluminum hydride, and the resulting polymer could be oxidized quantitatively to (III). Its molecular weight was a little higher than that prepared directly from (I).

Electron‐transfer polymers (oxidation‐reduction polymers)

“…This is an acetal which is very stable to base and which is readily removed by acid (184), but which permits vinyl polymerization. An alternative route to redox polymer was developed by Wegner and Nakabayashi (191)(192)(193)(194)(195)(196)(240)(241)(242)(243). They prepared condensation polymers in which during polymerization the redox function was in the oxidized state, and thus not in need of protection, or else was ingeniously self-protected (193,194).…”

“…) Other protecting groups (each of which has its limitiations (1,156), have been studied: ether (83,118), acetate (140,141), benzoate (82), other acetals such as tetrahydropyranyloxy (1 14,178). A method of some interest uses the Wittig reactions (63,191). This reaction was also used by Manecke and colleagues (1 57,172), to prepare oligomeric and polymeric 2,5-dimethoxyphenylenevinylenes of the general types (V) and (VI), which could later be demethylated.…”

“…This would agree with the observed irreversible precipitation (due to cross-linking) of oxidized polymer. The ring is stabilized by replacing the ring hydrogens with methyl (163,191), but these electron-donating groups lower the redox potential to the point that trimethylated hydroquinonyl polymer is unstable to oxygen of the air. In a-tocopherol, a six-member ether ring engages one of the hydroxyl groups, and gives great stability to the molecule (192).…”

“…In the case of vinyl polymers, the presence of bulky groups ortho to the vinyl group hinders polymerization. Vinyl compounds can undergo radical, anionic, and cationic initiation if the monomer structures are compatible (191).…”