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分别以钨酸和对-甲苯磺酸为催化剂,在以水为介质的系统中,用 H_2O_2将丙烯醇羟化合成甘油。在40—80℃范围内,甘油生成反应对 H_2O_2与丙烯醇分别为一级,同时存在一个与主反应同级的平行副反应方向。对于磺酸催化系统,在反应后期尚呈现一个对于 H_2O_2为1/2级,对丙烯醇为零级的副反应方向。反应速度常数为催化剂种类与浓度、温度、水含量的函数。钨酸的活性高于磺酸。温度对速度常数的影响可用阿累尼乌斯关系表示,磺酸系统的视活化能高于钨酸;在这两个系统中副反应的视活化能均高于主反应,而在磺酸系统中相差更大。反应速度常数与催化剂浓度间呈直线关系,钨酸系统的浓度效应远高于磺酸。在磺酸系统中,反应速度常数与水浓度的倒数间呈线性关系。在上述两系统中,催化剂浓度与水浓度的改变均不影响视活化能值。研究了分子态磺酸与磺酸根的催化作用系数,得知80℃时前者的催化作用系数八倍于后者。动力学数据的分析表明,在丙烯醇与催化剂过氧酸间的反应是动力学控制步骤。
Respectively, tungstic acid and p-toluenesulfonic acid as catalyst in water as a medium system, with H_2O_2 hydroxylation of propylene glycol glycerol. In the range of 40-80 ℃, the reaction of glycerol generation is one order for H 2 O 2 and allyl alcohol respectively, and there exists a parallel side reaction direction with the same level of main reaction. For the sulfonic acid catalytic system, a side reaction direction of 1/2 level of H 2 O 2 and zero order of level of propylene alcohol appears in the late stage of reaction. The reaction rate constant is a function of catalyst type and concentration, temperature, and water content. Tungstic acid is more active than sulfonic acid. The effect of temperature on the velocity constant can be described by the Arrhenius relationship and the apparent activation energy of sulfonic acid system is higher than that of tungstic acid. The apparent activation energy of side reactions in both systems are higher than that of the main reaction, In the difference between the larger. There is a linear relationship between the reaction rate constant and the catalyst concentration. The concentration effect of the tungstic acid system is much higher than that of the sulfonic acid. In sulfonic acid system, the reaction rate constant and the reciprocal of water concentration showed a linear relationship. In both systems, no change in catalyst concentration or water concentration affected apparent energy of activation. The catalytic coefficient of molecular sulfonic acid and sulfonate was studied. The catalytic coefficient of the former at 80 ℃ was eight times that of the latter. Kinetic data analysis shows that the reaction between the allyl alcohol and the catalyst peroxyacid is a kinetic control step.