Study On The Synthetic Technologies Of Hindered Phenol Type Of Additives UV-2908 And Antioxidant 245

With the development of synthetic materials, the additives that can inhibit the synthetic material ageing are also developing rapidly. Among them, UV absorber and hindered phenol antioxidant are widely used to inhibit material ageing.3,5-di-tert-butyl-4-hydroxybenzoic acid hexadecyl ester(UV-2908) is an excellent light stabilizers, which has the advantages of low volatility, low colorability, good chemical stability, as well as good resistance to acid and alkali. The key step to synthesis UV-2908 is the esterification of 3,5-di-tert-butyl-4-hydroxybenzoic acid with 1-hexadecanol. So, the esterification over a series of ion-exchange resins was investigated, in which resin D072 exhibited excellent catalytic performance. The influence of water on the reaction was also investigated and it was surprisingly found that water would improve the selectivity and yield of target product. Treatment of resins with aqueous sodium hydroxide could improve the selectivity of the target product but remarkably decreased the conversion of 3,5-di-tert-butyl-4-hydroxybenzoic acid. This result indicated that strong Br?nsted acid sites played an important role on this reaction. The optimal reaction conditions were obtained: the catalyst loading was 20 wt.%, the mole ratio of 3,5-di-tert-butyl-4-hydroxybenzoic acid with 1-hexadecanol was 1:1.5, the reaction time was 11.5h with 17 wt.% water added in the beginning of the reaction. Furthermore, D072 was efficiently recycled for four runs by simple treatment with mineral acid. Finally, a series of hindered phenolic esters were successfully synthesized under the optimal reaction conditions.Triethylene glycol bis [3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate](Antioxidant 245) is a kind of hindered phenol antioxidant, which has many advantages such as tasteless, low volatile, high color fastness, high resistance to extraction, and so on. The synthesis process of Antioxidant 245 was studied in this paper. The first step is the Michael addition reaction between 2-tert-butyl-6-methylphenol and methyl acrylate to synthesize 3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate(intermediate of XH-245). The second step is the ester exchange reaction between the intermediate and triethylene glycol to get target product. In this paper, the reaction conditions of the two steps were optimized and the yield of target product was 80%, detected by HPLC. At last, recrystallization conditions of product were studied. The recrystallization solvent and proper solute and solvent weight ratio were determined, and after recrystallization, the yield of target product was 66%.