Effect of pressure on the photolysis of azo-bis-isobutyronitrile in the presence of diphenylpicrylhydrazyl

Abstract

AIBN was photolyzed in toluene at room temperature at pressures up to 2, 000kg/cm^2 and the rates of the disappearance of DPPH which was used as a radical scavenger were measured spectrophotometrically. The rate was decreased with increasing pressure and the apparent activation volume was +7.6cm^3/mole. In comparison with Ewald's results on the thermal dissociation of AIBN, it was considered that an important contribution to the apparent activation volume was due to the change of "cage efect" by plessure and that the retarding effect of pressure on the photodissociation of AIBN would be smaller than on the thermal dissociation of AIBN.