Study On New Methods Of Synthesis Of Benzotriazole Ultraviolet Absorbents

The 2-(2'H-benzotriazol-2'-yl) phenols are widely used as excellent ultraviolet absorbers in industry for the protection of commercially important synthetic fibres, plastics and coatings against light. As the rapid development of application, the quality requirement on the ultraviolet absorbers has been increasing and the demand for clean and 'green' chemical syntheses has been growing, so the new preparation techniques for ultraviolet absorbers have been paid more and more attention. In this paper, new synthetic methods about benzotriazole ultraviolet absorbers and their intermediates were investigated according to commercial application and environmental protection. It was proved that the benzotriazole ultraviolet absorbers prepared by new methods were efficient.Two intermediates 2-nitro-4-chloro-2'- hydroxy-3'-t-butyl-5'-substituted-azoben zenes were synthesized by the solid phase reaction of 4-chlor-2-nitroaniline and 2-t-butyl-4-substituted phenol at room temperature. The reactions were completed for 15~20min, which gave the product in 93% yield and 86% yield respectively and higher than 99% purity (by HPLC). Both the compounds were characterized by IR spetra, UV-Vis spetra. The main advantages of solid phase method are clean, rapid reaction rate, high yield and convenient for industrial product of azo dye.The same intermediates were synthesized by solvent-free microwave irradiation, which gave the product in 86% yield and 78% yield respectively, with purity of higher than 99% (by HPLC). We discussed the different factors such as power, irradiation time and components molar ratio which affect the yield and quality. The optimum conditions were obtained.With rongalite as reduction agent, three benzotriazole ultraviolet absorbers were synthesized by reduction. All the compounds were characterized by IR spetra, UV-vis spetra or Ms spetra. The effects on the reaction yield and product quality were studied. Under the optimum conditions, the UV-Visible absorption capacity of these products were superior, the transmittance at wavelengths of 500nm is higher than...