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聚酯反应象单元酸与单元醇的酯化反应一样,都是氢离子催化机构。这种机构与现在公认的聚酯反应的氢离子催化机构的区别在于氢离子的来源和氢离子参与反应的详细历程,肯定了氢离子不仅由外酸供给,而且也可由二元酸本身供给。另外,二元酸与二元醇均可作为氢离子的载体。聚酯反应的动力学方程与二元酸与二元醇的起始克分子比有密切关系,应由前篇(3)式表示。当酸与醇以等克分子比起反应,又无外酸存在时,聚酯反应是2(1/2)级反应;若有外酸作催化剂时,当外酸的量加得适当多,由二元酸本身供给的氢离子的贡献可以忽略时,是二级反应,与以往结论相一致:当外酸的量加得少,必须考虑氢离子的同离子效应,它就不再是简单的二级反应,当酸与醇以不等克分子比起反应我们的实验结果亦与理论一致。
Polyester reaction as monomeric acid and esterification of the same alcohol, are hydrogen ion catalytic mechanism. The difference between this mechanism and the currently accepted polyester-catalyzed hydrogen ion catalysis mechanism lies in the details of the source of hydrogen ions and the participation of hydrogen ions in the reaction, confirming that the hydrogen ions are supplied not only from the external acid but also from the diacid itself. In addition, dibasic acid and dihydric alcohol can be used as hydrogen ion carrier. The kinetic equation of polyester reaction is closely related to the initial molar ratio of dibasic acid and diol, which should be expressed in the previous article (3). When the acid and alcohol to react with equal molecular weight, and no external acid exists, the polyester reaction is 2 (1/2) grade reaction; if the external acid as a catalyst, when the amount of external acid plus more appropriate, The contribution of the hydrogen ions supplied by the dibasic acid itself is negligible and is a second order reaction, consistent with previous conclusions: when the amount of external acid is added less, the same ion effect of hydrogen ions must be considered and it is no longer simple The second-order reaction, when the acid and the alcohol to react with different molecular weight, our experimental results are also consistent with the theory.