Photolysis of 4-acetyl-4-ethoxyformylcyclohexanone, 4-acetyl-4-phenylcyclohexanone and 1-acetyl-1-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.
