Photodecomposition of DDA

The photodecomposition of aqueous solutions of 2,2-bis (p-chlorophenyl) acetic acid (DDA) was slow in sunlight and rapid in the laboratory, producingp,p-dichlorobenzophenone (DCB),p-chlorobenzaldehyde,P-chlorophenol, and several unidentified polar products.p,p-Di-chlorobenzilic acid, andp,p-dichlorobenzhydrol gave rise to the same photoproducts, while bis-(p-chlorophenyl) methane (DDM) and chlorobenzilate were converted only to DCB. DCB andp-chlorobenzaldehyde proved to be resistant to photodegradation but gradually producedP-chlorobenzoic acid which, in turn, formedp-hydroxybenzoic and benzoic acids, probably the last environmentally detectable links in the long chain of DDT degradation to CO₂ and water.High pressure liquid chromatography (HPLC) proved to be ideal for separating and quantitating the parent compounds and their photoproducts directly from the aqueous photolysates or from methanol solutions of the isolates and standards.Contribution to Regional Project W-45, Environmental Distribution, Transformation, and Toxicological Implications of Pesticide Residues. University of Arizona Agricultural Experiment Station journal series No. 2931.