| Abstract: | The photostability of pirimicarb, (2-dimethylamino-5,6-dimethylpyrimidin-4-yl dimethylcarbamate) in aqueous media, under natural and artificial sunlight irradiation conditions, is reported. The pH of the irradiated solutions remained constant during degradation time. The photodegradation mechanism seemed to be similar under both conditions, but the half-life was found to be about three times longer under natural than under artificial conditions. Four main photo-products ( 1 , 2 , 3 and 4 ) were isolated and identified by spectroscopic methods. It is proposed that a common photodegradation pathway exists for pirimicarb under both irradiation conditions. The results obtained from the photodegradation of pirimicarb and of its four main products isolated on solid phase permit the construction of a possible photodegradation pathway. Photoproduct 4 (2-methyl-formylamino-5,6-dimethyl-4-hydroxypyrimidine) is here described for the first time. |
