Effect of microwave radiation on the acetate-catalyzed hydrolysis of phenyl acetate at 25°C

In this paper we present the experimental results obtained from phenyl acetate hydrolysis in a microwave-irradiated environment and in water solutions containing catalytic acetate ions. The kinetics of the reaction were studied in an irradiated environment where radiation, at a frequency of 2.45 GHz, was given to the reacting system at a power of 0.500 +/- 0.025 W. The energy absorbed by the reacting system was measured using a directional coupler, which can separate the radiation directed to the reactor from any reflected one. The system was irradiated with a power greater than that required to run the reaction; however, any energy in excess of that absorbed by the reaction was quite easily taken up by a thermostatic system. In this way the reaction system could run without any thermal effect due to radiation. The temperature was set at 25 degreesC and was kept constant during the reaction by using carbon tetrachloride as the thermostating fluid. The results obtained show that the kinetics of the reaction studied were greatly enhanced with respect to those of the reaction running in a nonirradiated environment. The kinetic constant at zero concentration of the catalytic species rises from 1.92 x 10(-4) h(-1) in a nonirradiated environment to the value 27.58 x 10(-4) h(-1) found here. The observed kinetic constant retains the same value for all of the studied catalytic acetate ion concentrations. This fact suggests that microwave radiation produces something like a catalytic effect which can replace that given by acetate ions in nonirradiated environments.