GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC STUDY OF PHOTODEGRADATION OF CARBAMATE PESTICIDES

The photodegradation of seven carbamate pesticides (bendiocarb, isopro carb, promecarb, ethiofencarb, furathiocarb, fenoxycarb and pirimicarb ), in aqueous solution, has been examined by GC-MS. The most general r esult was formation of the corresponding phenols. Irradation of isopro carb and promecarb also resulted in photo-Fries rearrangement to ortho - and para-hydroxybenzamides. In the case of ethiofencarb photocleavag e of the carbon-sulfur bond gave 2-methylphenyl methylcarbamate as mai n product. Likewise, N-S bond cleavage occurred upon irradiation of fu rathiocarb, to allow the formation of the carbamate insecticide carbof uran, butyl methylcarbamate and carbofuranphenol. Under similar condit ions, fenoxycarb gave p-phenylphenol and 2-hydroxydibenzofuran, throug h primary homolysis of the aryloxy-methylene bond. Finally, pirimicarb gave rise to 2-formylamino-5,6-dimethylpyrimidin-4-yl dimethylcarbama te.