芳杂环二腈及其聚合物——Ⅸ.4,4’-联苯二甲腈聚合动力学

本文研究了4,4′-联苯二甲腈在4,4′-联苯二甲腈氯化锌配合物催化下的聚合反应动力学,氰基浓度通过以铁氰化钾为内标的石腊糊法的红外光谱定量分析法测定。结果表明:该聚合反应是二级反应,聚合反应速度和氰基浓度及配合物浓度各成一次方比例。聚合反应表观活化能为12.4千卡/克分子。此外,也研究了不同的4,4′-联苯二甲腈金属氯化物配合物为催化剂对4,4′-联苯二甲腈聚合反应速度的影响,并对聚合反应机理进行了讨论。

THE AROMATIC AND HETEROCYCLIC DINITRILES IX AND THEIR POLYMERS——Ⅸ. The Polymerization Kinetics of 4,4'-biphenyldicarbonitrile

The polymerization kinetics of 4,4'-biphenyldicarbonitrile I catalyzed by complex of 4, 4'-biphenyldicarbonitrile with ZnCl2 was studied. The cyano group concentration was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. The results proved: the polymerization of 4,4'-biphenyldicarbonitrile is a second order reaction. The polymerization rate is directly proportional to concentrations of cyano group and complex. The rate constants of polymerization are 0.808; 1.058; 1.249; 1.632; 1.808 1·mol-1·hr-1. at 260°; 270°;280°;290°;300℃ respectively. The activation energy of the polymerization is 12.4 kcal, mol-1..The polymerization rates of 4, 4'-biphenyldicarbonitrile catalyzed by following eight complexes of 4,4'-biphenyldicarbonitrile with chloride at 280℃ were measured. The rate constants are: I · TiCl4, 1.4.2; t · 2ZnCl2 1.25; I· FeCl3 0.785; I · 2CoCl2 0.706; I · SnCl4 0.418; I · AlCl3 .0.396; I · 2SbCl5 0.169; I · 2BC13 0.0247 I·mol-1·hr-1. The N1s binding energy shifts, measured by XPS(X-Ray Photoelectron Spectroscopy), are as follow: I · 2ZnCl2 1.6; . I · 2CoCl2 1.5; I· SnCl4 1.3; I · TiCl4 1.2; I · FeCl3 1.1; I· 2SbCl5 1.0; I · A1C13 0.7; I · 2BC13, 0.5 (e. v.),. This fact shows that the nitrogen atom in these complexes possesses less electron density than that in the 4, 4'-biphenyldicarbonitrile molecule and then it induces the carbon atom of the cyano group of these complexes to be more positive. This is favourable for the attack of the cyano group by other 4, 4'-biphenyldicarbonitrile molecules therefore the rate of the polymerization is accelerated. The polymerization mechanism may be: