Abstract: The photochemistry of 4-acetylbenzoyl azide (ABA), 4-acetyl-4'-biphenoyI azide (ADA), and 4-acetylphenoxycarbonyl azide (APA) shows unusual wavelength and structural effects. Irradiation of ABA or ADA into their air* bands with deep-UV light leads to formation of 4-acetylbenzoylnitrene (ABN) and 4-acetyl-4'-biphenoylnitrene (ADN), respectively, in competition with photo-Curtius rearrangement to form isocyanates. Irradiation of these ...