Photolysis of Chlorophenylacetic Acids

The herbicide fenac is a mixture of chlorinated phenylacetic acids in which the 2,3,6-trichloro isomer predominates. Aqueous solutions of the sodium salt were photolyzed in ultraviolet light to complex mixtures. Similar irradiation of the three isomeric sodium monochlorophenylacetates as models produced phenylacetic acid, benzyl alcohol, benzaldehyde, and benzoic acid in one sequence of reactions, and the corresponding hydroxyphenylacetic acids, hydroxybenzyl alcohols, and humic acid in a simultaneous series. Detection of phenolic compounds and the isolation of dichlorobenzaldehyde, dichlorobenzyl alcohol, and trichlorobenzaldehyde illustrate that the photolysis products of fenac include the many different reduced and hydroxylated compounds suggested by the models.