Study On The Preparation Of Bis (2,4-Di-Tert-Butylphenyl) Pentaerythritol Diphosphite

With the development of macromolecule material industry, it is increasing for the demand of phosphite esters antioxidant with good processing stability.Bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite is named antioxidants 626, which is a main variety of phosphite esters auxiliary antioxidants and has several advantages. For example, it has strong decomposition hydrogen peroxide ability, high levels of antioxidants available P and can meet the trend of polymer quantification, especially; it can improve product processing stability, weather resistance and good color, etc. In particular, when the main products and hindered phenolic antioxidant used in conjunction, they can be widely used in polyolefin, polyester, polycarbonate and other polymeric materials, and in the machining process to improve the heat-resisting stability, color and weather resistance, so that it has along aging resistance and UV stability. Therefore, it is a very broad application prospects as a new and high efficient phosphate ester antioxidizing agents, and the product is received by the market.At present, the antioxidants 626 synthesis of literature cost too much and have low yield of synthesis products (yield of product is less than 85%). Therefore, the subjects of antioxidants 626 synthesis technology conducted a study, and design a better process to improve the yield of antioxidants 626, the average yield of product was about 88.1%, higher than the yield reported in the domestic and foreign literature (60% ~ 85%).This paper on the synthesis of antioxidants 626 presents a new process route, and researched influence on the experiment results caused by various factors of preparation, including: (1) influence on the experiment results caused by the reaction solvent; (2) influence on the experiment results caused by the dropping temperature; (3) influence on the experiment results caused by the catalyst and its amount; (4) influence on the experiment results caused by the molar ratio of pentaerythritol, phosphorus trichloride and 2,4-di-tert-butylphenole; (5) influence on the experiment results caused by the the reaction temperature in the first step; (6) influence on the experiment results caused by the reaction time in the first step; (7) influence on the experiment results caused by the reaction temperature in the second step; (8) influence on the experiment results caused by the reaction time in the second step; (9) influence on the experiment results caused by the crystallization solvents. Results of the study are as follows:Choosing toluene as solvent and tetrabutylammonium bromide as the catalyst, and the catalyst amount should be 0.97% of 2,4-di-tert-butylphenole in quality. At about 25oC, 41.3g 2,4 - di-tert-butyl phenol and 25.0g toluene was added to the reaction mixture of 0.4g tetrabutylammonium bromide, 25.0g toluene and 29.1g phosphorus trichloride with stirring about half an hour while maintaining the reaction mixture. In the first step, the reaction temperature was increased to 50oC and held for three hours; in the second step, the reaction solution was added 13.6g pentaerythritol, and the reaction temperature was increased to 125oC and held for five hours, isopropanol as solvent crystallization. At the optimized experimental conditions, the average yield was 88.1%, higher than the yield of literature about 3%.This paper has done characterization and quality analysis on antioxidants 626, such as infrared spectroscopy, melting point, high-performance liquid chromatography, NMR, etc. The Antioxidant 626 products conform to the chemical industry standards HG/T3974-2007.Features and innovations of this paper: (1) 2,4 - di-tert-butyl phenol toluene solution was added to the reaction mixture of the phosphorus trichloride and toluene to avoid the incidence of side effects process; (2) in the bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite synthesis of literature is generally selected three triethylamine as catalyst, the paper selected tetrabutylammonium bromide as catalyst; (3) in post-processing of the product, the paper added a certain amount of triethylamine, and basically solved the problem of the hydrolysis; (4) the paper optimize the process conditions, the yield of the product was increased compared with literature.