Uracil photoproducts from uracil irradiated in ice.

Two new products were isolated from uracil irradiated with ultraviolet light in frozen aqueous solution. As judged by mass, nuclear magnetic resonance, and ultraviolet and infrared spectra, one is a photopolymer, U(3) and the structure of the other is probably 6-4'-[ pyrimidin-2'-one]-uracil. Formations of these products between pyrimidine bases are apparently common photoreactions, and may be important to the study of the photochemistry and photobiology of nucleic acids.