Substituent effects on the ultraviolet absorption properties of 2,4-dihydroxy dibenzophenone were investigated experimentally. Nine compounds of 2,4-dihydroxy dibenzophenone with different substituents were prepared by a solvent-free reaction of benzoyl chloride. The maximum absorption wavelength (λmax) of these samples was measured, and their UV resistance properties in cotton fabric as well as in polyester were determined. The results show that the λmax is dependent on the substituents at the benzylidene ring, and both electron donating substituents and electron withdrawing substituents cause a bathochromic shift. The UV resistance of fabric increases with the increase in compound concentration. The dyeing rate of each compound on polyester was higher than that of cotton. On cotton fabric, the dyeing rate of 2,4-dihydroxybenzophenone was the highest, 77.8%. On polyester, that of 2,4-dihydroxy-4'-ethyl dibenzophenone was the highest, 84.1%. The study provides new insights into the effect of substituents on the properties of 2,4-dihydroxy dibenzophenone that are related to the whitening of cotton and polyester materials.
Keywords: 2,4-dihydroxy dibenzophenone; UV resistance; substituent effects; ultraviolet absorbent.