DEGRADATION OF -DIMETHYL-TETRAHYDRO-2H-1,3,5-THIADIAZINE-2-THIONE IN AQUEOUS AEROBIC MEDIA

Decomposition of -dimethyl-tetrahydro-2H-1,3,5-thiadiazine-2-thione (D TTT) has been studied by UV-visible spectroscopy (UV-VIS), high-perfor mance liquid chromatography (HPLC), gas chromatography-mass spectromet ry (GC-MS), and fast atom bombardment-mass spectrometry (FAB-MS). Hydr olysis rate constants for DTTT and rate constants for product formatio n were measured. The partially hydrolyzed and aged DTTT solutions have been separated and analyzed by GC-MS. Formaldehyde, 1,3-dimethyl-2-th iourea, N-methyl dithiocarbamic methyl ester, N-methyldithiocarbamic p erthiomethyl ester, l-5-dihydro-3H-4-thia-1,2-isooxazolidine-3-thione, ,5-trimethyl-hexahydro-2H-1,3,5-triazine-2-thione, ethyl-5-methylimin o-1,2,4-dithiazolidine-3-thione, and 2,4-dimethyl-1,2,4-thiadiazolidin e-3,5-dithione were identified from the hydrolyzed DTTT solution. Meth yl isothiocyanate, which is one of the intermediates formed during the decomposition of DTTT, was also monitored by UV-VIS and HPLC for the formation of common products and characterized by GC-MS. The decomposi tion pathways for DTT are presented and are in accord with the limited literature data. Environmental impact assessment of the DTTT and its metabolites is summarized.