Manganese(III) acetate-catalyzed synthesis of polyguaiacol

Polyguaiacol was synthesized in the mixtures of water and various organic solvents using manganese(III) acetate as a new catalyst for radical polymerization and a biomimetic model for manganese peroxidase. Aqueous solutions of 30-70% (v/v) acetonitrile, 1,4-dioxane, and methanol were used as model solvent mixtures. The polymer yield in the methanol (<30%) solution was lower than that in the acetonitrile or 1,4-dioxane solution (60-90%). The average molecular weight of the polymer was also lowest in the methanol solution. Difference UV absorption spectroscopy analysis revealed that nonhydrated guaiacol clusters were found to be dominant in acetonitrile and 1,4-dioxane solutions, especially when the content of 1,4-dioxane was 50% (v/v) or higher. In the methanol solution, only the hydrated guaiacol clusters were observed. From the comparison of 1 H NMR data for polyguaiacol and products of guaiacol oxidation by manganese(III) acetate, 3-(4-hydroxy-3-methoxy-phenyl)-5,3'-dimethoxy-4,4'-biphenol and a mixture of 5-(4-hydroxy-3-methoxyphenyl)-3,3'-dimethoxy-4,4'-biphenoquinone and 3-(4-hydroxy-3-methoxyphenyl)-5,3'-dimethoxy-4,4'-biphenoquinone were found to be the major structural units of polyguaiacol. Water molecule is not involved in the formation of these compounds. Therefore, the polymerization should take place readily not in methanol but in acetonitrile and 1,4-dioxane solutions.