ULTRASONICALLY STIMULATED ELECTRON-TRANSFER IN ORGANIC-CHEMISTRY - REACTION OF NITROBENZENE WITH TRIPHENYLMETHANE AND ITS DERIVATIVES

Triphenylmethyl chloride dissolved in nitrobenzene was either heated a t 210 degrees C for 8 h or submitted to a sonochemical promoted reacti on at the equilibrium temperature of the ultrasonic cleaning bath (40 degrees C) for 30 h. A practically quantitative conversion of organic halide was achieved in the thermal process, whereas in the ultrasound activated process the conversion was 60%. An activation of the thermal reaction by the ultrasound promotion of the reaction of about 10(7) w as approximated. The most significant differences between the two reac tions are: (i) triphenylcarbinol is the main product in the sonochemic al reaction (69.87%), whereas in the thermal process it represents onl y 1.53%. (ii) Hydrochloric acid is produced in the thermal process, bu t molecular chlorine in the sonochemical reaction. (iii) In contrast t o the thermal process, only minor reduction products of nitrobenzene a re observed in the sonochemical reaction. The electron transfer mechan ism is discussed, in direct connection with the sonochemical activatio n of the transfer.