Process Study On Synthesis To Benzotriazole Ultraviolet Absorber

UV-P(2-(2'-hydroxyl-5'-methyl-phenyl)-2H-benzotriazole), UV-329(2-(2'-hydroxyl-5'-tert-octylphenyl)-2H-benzotriazole)and UV-326(2-(2'-hydroxyl-3'-tertbutyl-5'-methylphenyl)-5-chloro-2H-benzotriazole) were synthesized by diazotization, coupling, glucose reduction and zinc powders reduction. The target compounds and intermediate products were characterized by 1H NMR, MS and IR, and the reaction mechanism was discussed in this paper.UV-P and UV-326 azo intermediates were synthesized in water with 0.5% SDBS, UV-329 azo intermediate was synthesized in ethanol. Under optimized conditions, i.e. at 0-5℃, pH 7-9, the yield of UV-P azo intermediate was up to 95% and higher than 97% purity(by HPLC). Under optimized conditions, i.e. at 0-5℃, pH 7-9, the yield of UV-329 azo intermediate was up to 96% and higher than 98% purity(by HPLC). Under optimized conditions, i.e. at 10-15℃, pH 7-9, the yield of UV-326 azo intermediate was up to 91% and higher than 98% purity (by HPLC).UV-P, UV-329 and UV-326 azo intermediates were reduced to target products by second reduction with glucose and zinc powders. Under optimized conditions, i.e. molar ratio of azo intermediate, glucose and zinc powders 1:1.15:1.15, lOmL ethanol in glucose reduction, 20mL mixed solvent (chlorobenzene and ethanol) in zinc powders reduction,0.06mol H2SO4(14%). UV-P azo intermediate was reduced to nitrogen oxides intermediate by glucose in 10g NaOH solution(20%), the yield of UV-P was up to 96% and higher than 98% purity, and amplification was carried out with good results. UV-329 azo intermediate was reduced to nitrogen oxides intermediate by glucose in 30g NaOH solution(20%), the yield of UV-329 was up to 94% and higher than 95% purity. UV-326 azo intermediate was reduced to nitrogen oxides intermediate by glucose in 20g NaOH solution(10%), the yield of UV-326 was up to 90% and higher than 98% purity.