SINGLE RUN BENZOPHENONE BENZHYDROL ACTINOMETRY IN AN EXPONENTIAL DILUTION PHOTOCHEMICAL MICROREACTOR

The photoreduction of benzophydrol was investigated in a continuous flow stirred photochemical microreactor. In this system photoreduction can be carried out in combination with the exponential dilution of benzhydrol. The rate of consumption of benzophenone in the photochemical reaction is matched to its rate of input to the microreactor. The effect of benzhydrol concentration on the quantum yield of the photoreduction can be obtained from kinetic analysis of the slow transient behaviour during dilution; also the system can be used for actinometry. In contrast to the classical method in which the concentration of benzhydrol and the irradiation time must be varied incrementally, the reaction parameters vary continuously giving accurate results in a single run. The method is general and can be employed in other areas of photochemistry when a study of concentration effect is needed.