Synthesis Of UV Absorbers Of Dimeric Benzotriazol Structure By Mannich Reaction

The three target compounds were synthesized by Mannich reaction in this paper, which were 2,2-methylene bis(4-t-octyl-6-benzotriazolyl phenol),2,2-methylene bis(4-methyl-6-benzotriazolyl phenol) and 2,2-methylene bis(4-t-butyl-6-benzotriazolyl phenol). Their optimum reaction conditions were studied and they were characterized by MS,'H-NMR and IR. The method for the determination of 2,2-methylene bis(4-t-octyl-6-benzotriazolyl phenol) was established, the Mannich base was isolated and characterized and the mechanism was initially discussed.2,2-methylene bis(4-t-octyl-6-benzotriazolyl phenol) was obtained with 90.0%yield and 99.9% purity under the optimum reaction conditions which the raw material molar ratio was n(2-(2-hydroxy-5-t-octylphenyl)benzotriazole):n(Paraformaldehyde):n(di-n-propylamine)= 1:0.56:1.4 and reacted 2h at 140℃. Then the catalyst(NaOH) and solvent(1,2,4-trimethyl--benzene) were added, the molar amount of catalyst was n(NaOH):n(2-(2-hydroxy-5-t-octyl--phenyl)benzotriazole)=1:10, the molar amount of solvent was n(1,2,4-trimethylbenzene): n(2-(2-hydroxy-5-t-octylphenyl)benzotriazole)=3.3:1, the reaction temperature was 170℃and the reaction time was 10h.2,2-methylene bis(4-methyl-6-benzotriazolyl phenol) and 2,2-methylene bis(4-t-butyl-6-benzotriazolyl phenol) were synthesized under the same conditions, the yields were 95.0% and 89.4% respectively, the purity was 99.9%. The target compounds were tested by ultraviolet absorption spectrum and thermogravimetry, the UV test and TG test showed that dimeric benzotriazol compounds were excellect UV Absorbers.