HYDROLYSIS AND PHOTOLYSIS OF HEXACHLOROCYCLOPENTADIENE

The radioactivity on adding C-14-Hexachlorocyclopentadiene (Hex) to wa ter (7 mu g/L) decreased by 18% on Day 2 and by 31 to 55% by Day 42. O n Day 42, the radioactivity remaining in water consisted of apolar (pe troleum ether-extractable), polar (ethyl acetate-extractable), and hyd rophilic hydrolysis products with Hex amounting to only 8% of the tota l radioactivity. The time for Hex to reach 50, 10, and 5% of its initi al concentration was estimated to be about 4, 27, and 40 days, respect ively. The hydrolysis rate constant compared to 4 X 10(3) hr(-1) as re ported in literature. The apolar radioactivity (25% of total) consiste d of Hex and a major product as judged by gas chromatography (GC). The polar products resolved into 10 and hydrophilics into 14 different co mpounds as examined by thin-layer chromatography. The photolysis of He x in acetone occurred very rapidly (t(1/2) = <1 day) with no trace of Hex after 15 days. Most of these products were more polar than Hex as examined by GC. These products on thin-layer chromatography (TLC) sepa rated into two major zones. Further TLC of each of these zones showed products of one zone to resemble those of aqueous hydrolysis. The othe r zone represented apolar products which resolved into three peaks by HPLC, the major one of these appeared to have an empirical formula of C6Cl7O (m/e = 408) as analyzed by GCMS. The 8-h photolysis products' m ixture had an LT(50) to goldfish Carassius auratus of 22 h compared to 15 h for Hex. The 96-h LT(50) value of the 15-day photolysis products ' mixture was 2,300 compared with 119 mu g/L for Hex. Thus, Hex in wat er as well as on exposure to light breaks down to less toxic products.