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利用分子模拟技术探讨了钛配合物[O,N]CpTiMeCl(其中[O,N]为2-甲基-喹啉-8-氧基[C_10H_8NO])在助催化剂甲基铝氧烷(MAO)作用下催化烯烃聚合过程中形成活性中心的一般反应历程。量子力学计算表明,MAO大阴离子对负电荷的分散作用使形成金属阳离子的过程更加容易;乙烯单体与金属阳离子中心的配位反应是放热反应(-2.76kcal/mol),即乙烯能够稳定金属阳离子,促进分离离子对的形成;AlMe_3更易与MAO中氧原子作用形成加合物,而不是形成二甲基桥加合物;金属阳离子与MAO形成的氯桥加合物比形成与氧原子配位的加合物要稳定。计算结果表明,MAO中含一定量的AlMe_3可以保护助催化酸性位,并对金属阳离子与MAO的加合物起着稳定化作用。
The molecular simulation technique was used to investigate the catalytic activity of the titanium complex [O, N] CpTiMeCl (where [O, N] is 2-methyl-quinoline-8-oxy [C_10H_8NO] Under the action of catalytic olefin polymerization process of the formation of the active center of the general reaction process. Quantum mechanics calculations show that the dispersion of negative charges by MAO large anions makes the formation of metal cations easier. The coordination reaction between ethylene monomer and metal cation centers is exothermic (-2.76 kcal / mol), that is, ethylene can be stabilized Metal cations promote the formation of isolated ion pairs; AlMe 3 more easily forms an adduct with the oxygen atoms in MAO rather than forming a dimethyl bridge adduct; the chloride bridge adduct formed by the metal cations and MAO forms a complex with oxygen atoms Coordination adduct to be stable. The calculated results show that MAO containing a certain amount of AlMe 3 can protect the promoter acidic sites and stabilize the adducts of metal cations with MAO.