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    直接法合成棕榈酰基甲基牛磺酸钠的催化剂筛选和反应动力学

    Catalyst Screening and Reaction Kinetics for Direct Synthesis of Sodium Palmitic Methyl Taurine

    • 摘要: N-酰基氨基酸型表面活性剂具有优良的表面活性、安全性和生物降解性,广泛应用于日化、医药和食品等领域。以棕榈酸和N-甲基牛磺酸钠为原料经直接法合成棕榈酰基甲基牛磺酸钠,对比分析了金属氧化物、金属氯化物和硼酸系催化剂对棕榈酰基甲基牛磺酸钠合成反应的影响,筛选出适宜的催化剂,并进行反应动力学研究。结果表明,2-氯苯硼酸可有效催化棕榈酰基甲基牛磺酸钠的合成反应,当2-氯苯硼酸质量为棕榈酸质量的4%时,棕榈酰基甲基牛磺酸钠的收率达到97.5%,选择性达到98.4%。在棕榈酸过量的情况下,反应活化能为68.0 kJ/mol,指前因子为1.6×1010 h−1

       

      Abstract: In this paper, palmitic acid and sodium N-methyl taurine were used as raw materials to directly synthesize sodium palmitic methyl taurine. The structure of the product was characterized by Fourier-transform infrared spectrometer and liquid chromatograph-mass spectrometer. Series of metal oxides (zinc oxide and magnesium oxide), metal chlorides (magnesium chloride and stannous chloride) and boronic acids (methylboronic acid, phenylboronic acid and 2-chlorophenylboronic acid) were screened for their ability to catalyze the reaction. The effect of catalysts on the yield and selectivity of sodium palmitic methyl taurine was studied systematically. The results showed that the yield of sodium palmitic methyl taurine increased significantly during the early stage of the reaction, and remained barely changed after 4 h. Boronic acids performed better than the other catalysts tested. The reaction kinetics was studied in detail using 2-chlorophenylboronic acid as the catalyst with a loading amount of 4% relative to palmitic acid. The concentration of N-methyl taurine was determined at different time points with different temperatures. According to the experimental data, the reaction rate constant, reaction order, reaction activation energy and pre-exponential factor were calculated to obtain an expression of the reaction rate. Under the optimal condition, a yield of sodium palmitic methyl taurine of 97.5%, and a selectivity of 98.4% were obtained. With an excess of palmitic acid, an activation energy of 68.0 kJ/mol and a pre-exponential factor of 1.6×1010 h−1 were obtained.

       

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