Photochemical study of tris(benzotriazol-1-yl)methane.

Photodecomposition of tris(benzotrizol-1-yl)methane (1) in benzene gives [1-benzotryazol-1-yl-methylidene]-biphenyl-2-ylamine (2) resulting from the loss of the benzotriazolyl radical and nitrogen followed by addition of benzene. Elimination of the second benzotriazolyl radical from 2 provides the biphenyl-2-ylmethyleneamine radical, which affords phenantridine (3) after ring closure. In contrast, the photolysis of 1 in methanol gives a high yield of benzotriazole (4).