A series of novel oligo(halobenzoquinoid) compounds have been obtained from the photoinduced self‐substitution of 2,5‐dibromo‐1,4‐benzoquinone (1a), 2,6‐dibromo‐1,4‐benzoquinone (1b), 2‐chloro‐1,4‐benzoquinone (1c), 2‐bromo‐5‐chloro‐1,4‐benzoquinone (1d), 2,3,5,6‐tetrachloro‐1,4‐benzoquinone (1e) and 1,4‐benzoquinone (1f) in the presence of N, N‐dimethyl‐t‐butylamine (2) in acetonitrile. Dimers, trimers and/or pentamers of these haloquinones were found to be the major products.

Photolysis of 4-acetyl-4-ethoxyforrnylcyclohexanone, 4-acetyl4phenylcyclohexanone .and 1-acetyl-l-phenylcyclohexane in deuteriochloroform using a high pressure Hg-Xe lamp showed ,unusual polarizations. The results are explained by the formation of a singlet exciplex of the ketone with deuteriochloroform and the photoaddition of deuteriochloroform to the ketone.