Identification of UV photoproducts and hydrolysis products of butachlor bymass spectrometry

The photoproducts and hydrolysis products of butachlor in water were identi fied by gas chromatography/mass spectrometry. When exposed to UV light, but achlor in aqueous solution was rapidly degraded, giving at least 11 photo p roducts as a result of dechlorination with subsequent hydroxylation or cycl ization processes. The chemical structures of nine degradation compounds we re identified on the basis of mass spectrum interpretation and literature d ata. Major photoproducts are identified as 8-ethyl-1-butoxymethyl-4-methyl- 2-oxo-1,2,3,4-tetrahydro-quinoline, 2-hydroxy-2 ' ,6 ' -diethyl-N-(butoxyme thyl) acetanilide, and a compound related to butachlor. Minor photoproducts are identified as 2,6-diethylaniline; 1-acetyl-7-ethylindole; N-(2,6-dieth ylphenyl)-N-lbutoxymethyl)acetamide; 2-oxo-N-(2,6-diethyl-phenyl)-N-(butoxy methyl)acetamide; 1-hydroxyacetyl-2-butoxyl-3-methyl-7-ethylindole; 1-acety l-2butoxyl-3-methyl-7-ethylindole; and two compounds with the chemical stru cture unknown. The half-lives of butachlor UV photolysis were 7.54, 10.56, and 12.22 min in deionized water, river water, acid paddy water, respective ly. The half-lives of butachlor hydrolysis at pH 4, 7, and 10 were 630, 115 5, and 1155 days at 25 +/- 1 degreesC, respectively. A hydrolysis product a t pH 4 was identified by GC/MS to be 2-hydroxy2 ' ,6 ' -diethyl-N-(butoxyme thyl) acetanilide.