Phthalazine undergoes the photoreduction and the photo-reductive dimerization simultaneously to give 1, 2-dihydrophthalazine and its dimer (1H, 1′ H, 2H, 2′ H-1, 1′- biphthalazine), respectively, upon ultraviolet light irradiation in 2-propanol. It has been
[Inoue, Hiroyasu; Sakurai, Tadamitsu; Tomiyama, Koichi; Sano, Ryo; Oshio, Masahiro; et al. Bulletin of the Chemical Society of Japan, 1988 , vol. 61, p. 893 - 898]