Synthesis and photoinitiating ability of substituted 4,5-di-tert-alkyl-o-benzoquinones in radical polymerization

New tri- and tetraalkyl-substituted o-benzoquinones were synthesized based on 5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2,3-diol derivatives. The new compounds were characterized by spectroscopic and electrochemical methods. The reactivity of o-benzoquinones was evaluated in the photoreduction and initiation of photopolymerization of oligocarbonate dimethacrylate (OCM-2) in the presence of N,N-dimethylcyclohexylamine and in the inhibition of MMA polymerization. The introduction of the methyl substituent into the benzene ring has a weak effect on the inhibitory activity of o-benzoquinone, whereas the (3,5-dimethylpyrazol-1-yl)methyl substituent enhances the inhibitory effect of 4,5-di-tert-alkyl-substituted o-benzoquinone.