Study On Synthesis Of Benzotriazoles Light Stabilizer

The serie of 2-(2-hydroxyphenyl)-2H-benzotriazoles is an important additive which is used in synthetic materials. 2-(2'-hydroxy-5'- methylphenyl)-2H- benzotriazoles(UV-P)is a representative product. For it has the disadvantage of complex process and environment pollution, method of zinc powder reduction which was commonly used is greatly limited. Thus developing a non-contaminative and high efficiency synthesize process will be of great industrial value.The two steps reduction method to synthesize UV-P was studied in this thesis, Compared with different reductants, hydrazine hydrate and rongalite were the suitable reductants in the reaction system. Firstly azole compound was almost completely reduced to intermediate N-oxide by hydrazine hydrate. Then intermediate N-oxide was reduced to the product by rongalite. The reduction processing condition of intermediate N-oxide reducing to UV-P was optimized: n(N-oxide):n(solvent) n(rongalite): n(NaOH) =1: 34.4: 1.6: 5, the concentration of NaOH solution 18% (wt), the temperature 81℃, the reaction time 1h, in which the yield of UV-P was up to 92~93%. The structure of UV-P, azole compound and intermediate N-oxide was confirmed by IR and MS.A novel benzotriazole stabilizer 2-[2-hydroxy-3-tert-butyl-5-(3-methoxy -carbonylethyl)-phenyl]-2H-benzotriazole(UV-MBHPP)was synthesized.The structure of products UV-MBHPP, azole compound and intermediate N-oxide were qualitatively confirmed by IR and MS.The possible reaction mechanism of benzotriazole stabilizer was also discussed in this thesis.