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Quantum yields in the photolysis of trichlorobenzenes in cyclohexane, 2-propanol and methanol
Article
Date:
1989Publishing House and Editing Place:
ELSEVIER SCIENCE SAMagazine:
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, vol. 47 (pp. 337-344) ELSEVIER SCIENCE SASummary *
The photolysis of 1,2,3,- 1,2,4- and 1,3,5-trichlorobenzene was studied in cyclohexane, 2-propanol and methanol. The main photoreaction observed was reductive dechlorination. Quantum yields were determined for HCl and the corresponding dichlorobenzenes; they were independent of concentration, with the exception of meta-dichlorobenzene photolysis of 1,2,4- and 1,3,5-trichlorobenzene in cyclohexane where the quantum yield decreased when the concentration of the trichlorobenzenes was increased. The HCl quantum yields for 1,2,3,- and 1,2,4-trichlorobenzene were around 0.4 in the three solvents. For 1,3,5-trichlorobenzene the quantum yield was lower, 0.1 - 0.2. A good mass balance between the dechlorination products and HCl was obtained only in 2-propanol. The relative yields of the dichlorobenzenes reflect the reactivity of the different positions in the ring in 2-propanol. Triplet quenching experiments with anthracene showed no effect on the HCl quantum yields. The results suggest that the excited singlet is the intermediate in the primary process. © 1989. Information provided by the agent in SIGEVAKey Words
solvent effectstrichlorobenzenesphotoinduced electron transfer