Titanium dioxide - photocatalysed degradation of some anilides

The TiO2 catalysed degradation of N-(3,4-dichlorophenyl)propanamide (the herbicide Propanil) and some other anilides has been studied in water. Both UV-A and solar light effectively degrade these compounds. Kinetic and product studies show that the reaction involves ring hydroxylation and cleavage to give chloride, ammonia, and, presumably, β-ketoacids which are further decomposed to acetic acid and eventually to CO2. 3,4-Dichloroaniline and 1,2-dichlorobenzene are also studied for the sake of comparison. Direct irradiation (254 nm) of the anilides, on the other hand, leads to the products of photo-Fries rearrangement and not to mineralization.