Light-induced and related reactions of quinones. Part VII. Cleavage and isomerisation of some (1-hydroxyalkyl)-1,4-benzoquinones
The synthesis is described of 1,4-benzoquinones carrying, severally, the following side-chains: CH(OH)·CH2Ph,CD(OH)·CH2Ph, CMe(OH)·CH2Ph, CH(OH)·CHPh2, CH(OH)·CH2·CH:CH2, and CMe(OH)·CH2·CH:CH2. When irradiated with visible light all the secondary alcohols yield 2,5-dihydroxybenzaldehyde, and all the tertiary alcohols give 2,5-dihydroxyacetophenone, probably via fragmentation of the derived alkoxyl radicals. The tertiary alcohols also yield isomers in which reorganisation of the side-chain has occurred. Mechanisms are suggested.