Spectrophotometric study of photosensitized dechlorination of isomeric mono- and dichloronitrobenzenes

The photosensitized dechlorination of isomeric mono- and dichloronitrobenzenes has been studied in the presence of naphthoxide ion in alkaline medium. The 100 W tungsten lamp was used for irradiation. The effects of pH, concentration of sensitizer, substrate, intensity of light, and temperature on the rate of the dechlorination have been studied. The quantum efficiency of the dechlorination has been evaluated using potassium ferrioxalate actinometer. The removal of chlorine from the substrate was tested with silver nitrate and the formation of nitrobenzene has been confirmed by λmax in UV spectrum. The mechanism of the photodechlorination has been suggested and the rate of the dechlorination follows the order p- > m- > o-chloronitrobenzene.