PHOTOLYSIS OF ALKYL N-ALKYLBENZOHYDROXAMATES

The photochemistry of alkyl N-alkylbenzohydroxamates)PhCONR(1)OR(2)) w as studied. These compounds give both type I (benzaldehyde) and type I I (N-alkylbenzamides) products. Although alkyl benzohydroxamates (PhCO NHOR) undergo the type II process exclusively through the triplet stat e, the alkyl N-alkylbenzohydroxamates have both singlet and triplet co ntributions to the type II process. The type I process for the alkyl N -alkylbenzohydroxamates occurs via the singlet state and has not been observed previously in benzohydroxamate photochemistry. When changing from a more polar to a less polar solvent, the quantum yields of the t ype II product increase. This differs from the type II process of alky lbenzohydroxamates which shows no solvent effect and that of aryl alka nones which shows the opposite effect. The solvent effect observed her e is attributed to intramolecular hydrogen bonding in the hydroxy 1,4- diradical.