Polymerization of phenol derivatives by the reduction of gold ions to gold metal

The phenol derivatives 3-methylcatechol, 4-methylcatechol, 4-ethylcatechol and m-cresol were polymerized through their ability to reduce gold ions. 3-Methylcatechol has the highest susceptibility to oxidation by gold ions, indicating that the location and number of OH groups and hydrophobic groups adjacent to the OH groups in phenol derivatives are crucial. Twenty-five millimoles of trivalent gold ion were completely reduced to the zero-valent state by catechol derivatives in approximately 4 h, with precipitation of gold particles. The oxidized phenol derivatives produced by the reduction of gold ions formed water-insoluble polymers with molecular weight approximately 1000 g mol−1. The polymerization of phenols using a redox reaction between phenol derivatives and gold ions holds possibility as a novel synthetic method for polyphenols.