Reactivity of H atoms and hydrated electrons with chlorobenzoic acids

H radicals react with chlorobenzoic acids and chlorobenzene (k(H-center dot + substrates) = (0.7-1.5) x 10(9) dm(3) Mol(-1) s(-1)) by addition to the benzene ring forming H adducts with characteristic absorption bands in the range of 310-360 nm. The rate constants for their second-order decay are 2k = (3.5-6) x 10(8) dm(3) Mol(-1) S-1.

By reduction with e(-)(aq) fragmentation and chloride release was established for 2- and 4-chlorobenzoic acid, for 3-chlorobenzoic acid the addition of electrons to the carboxylate group was observed by pulse radiolysis. By gamma radiolysis could be proved that these radical anions undergo intramolecular electron transfer and quantitave dechlorination.

The efficiency in degradation was 4-chlorobenzoic acid > 3-chlorobenzoic acid > 2-chlorobenzoic acid. Benzoic acid was found as final product for all substrates.