Quantum yields of the photocoloration of the title spiropyran for the direct and benzophenone sensitized photolysis in methanol were 0.38 and 0.53, resp. Biacetyl quenches mainly the triplet photocoloration and to a smaller extent the singlet reaction. From kinetic anal. in the sensitized and quenched reactions, quant. estimation was made of the quantum yields of the primary reactions involved in the direct photolysis. The data suggest that both singlet and triplet of the title spiropyran react to form the colored form. The triplet parameters are as follows: 3t = 2.2 ?10-3 ms; kr = 9.13 ?104 s-1; kd = 8.27 ?104 s-1. Also, the excited triplet state, once populated, is about 2 times more efficient in the formation of the colored form than the excited singlet state.

Key words: INDOLE P, PHOTOCHEMICAL REACTION, BENZENE P, KINETIC ANALYSIS, KETONE, SENSITIZATION, QUANTUM YIELD, QUENCHING, INDOLINOSPIROBENZOPYRAN PHOTOCHROMICS