Photochemical studies of a sulphonated derivative of 1,3-Diphenyl-2-pyrazoline

Abstract

The photochemistry of the sulphonated pyrazoline fluorescent whitening agent sodium 4-(3?-phenyl-2?-pyrazolin-1?-yl)benzenesulphonate has been examined in aqueous solution, in films of poly(vinyl alcohol) and in the wool fibre. Photooxidation to give the pyrazole occurs almost quantitatively in solution, but accounts for only half of the photoproducts formed in the polymer. In the wool fibre, pyrazole formation accounts for more than half of the pyrazoline whitener destroyed during exposure to simulated sunlight.