Ultrasonically stimulated electron transfer in organic chemistry. Reaction of nitrobenzene with triphenylmethane and its derivatives

Abstract

Triphenylmethyl chloride dissolved in nitrobenzene was either heated at 210°C for 8 h or submitted to a sonochemical promoted reaction at the equilibrium temperature of the ultrasonic cleaning bath (40°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 was approximated. The most significant differences between the two reactions are: (i) triphenylcarbinol is the main product in the sonochemical reaction (69.87%), whereas in the thermal process it represents only 1.53%. (ii) Hydrochloric acid is produced in the thermal process, but molecular chlorine in the sonochemical reaction. (iii) In contrast to the thermal process, only minor reduction products of nitrobenzene are observed in the sonochemical reaction. The electron transfer mechanism is discussed, in direct connection with the sonochemical activation of the transfer.