Light-induced and related reactions of quinones. Part V. Substituent effects in light-induced reactions between p-quinones and aldehydes

Abstract

Irradiation of 1,4-benzoquinone with visible light in the presence of terephthaldehyde, p-cyanobenzaldehyde, and p-trifluoromethylbenzaldehyde yields the corresponding quinol monoaroyl esters as the major addition products. Similarly, naphthazarinquinone, 1,4-benzoquinone-2,3-dicarboxylic anhydride, and 2,3-dicyano-1,4-benzoquinone in acetaldehyde give the corresponding quinol monoacetates. 1,4-Benzoquinone gives quinol monoacrylate exclusively when it is irradiated in benzene containing acraldehyde, but in the presence of crotonaldehyde it yields both quinol monocrotonate and crotonylquinol. The significance of these results is discussed.