Popis: |
Department of Chemistry, School of Sciences, Gujarat University, Navrangpura, Ahmedabad-380 009, India E-mail: ucprl@indiatimes.com, dwivedi_ank@indiatimes.com Manuscript received 20 August 2003. revised 22 November 2004. accepted 2 February 2005 The photosensitized dechlorination of isomeric 5-chloro-o-anisidine (5-C-o-A) and 3-chloro-p-anisidine (3-C-p-A) has been studied using methylene blue (MB) as photosensitizer in alkaline medium. The 100 W tungsten lamp was used for irradiation. The dechlorination products arc identified and formation of a molecular complex between anisidine and methylene blue is observed. The effect of pH, concentration of sensitizer, substrate, intensity of light and temperatureon the rate of the reaction has been studied. The quantum efficiency of the photodechlorination has been evaluated using potassium ferrioxalate actinometer. The removal of chlorine from the substrate was tested with silver nitrate. The dechlorination products of isomeric chloroanisidines have been confirmed by shift in the wavelength. The mechanism of the photodechlorination has been suggested. The rate of the reaction of the dechlorination follows the order : 5-C-o-A > 3-C-p-A. |