ABSTRACT
Chlorosubstitutions in the aromatic rings can give rise to several isomers. For example, one to eight chlorine atoms can be attached onto different positions in the dibenzo-p-dioxin rings, thus producing a total of 75 isomers. Chlorosubstitution in positions 2, 3, 7, and 8 gives 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), CAS [1746-01-6], occurring in trace amounts in chlorophenoxyacid herbicide, 2,4,5-T. 2,3,7,8-TCDD is an extremely toxic substance that can cause liver and kidney damage, ataxia, blurred vision, and acne-like skin eruption (Patnaik, 2007). is is also a known carcinogen and teratogen. It melts at 303°C and has a vapor pressure of 1.5 × 10−9 torr. Its solubility in water is about 0.3 μg/L and in chloroform about 370 mg/L (Westing, 1984).
