桥联茚-芴钛族络合物催化丙烯高选择性二聚研究

Dimers of propylene such as 4-methyl-1-pentene and 2-methyl-1-pentene are important polyolefin comonomers as well as fine chemical raw materials. For improving the quality of polyethylenes, exploiting novel synthetic polyolefinic materials, and better utilization of propylene, it is of great importance to develop highly selective and efficient manufacturing process for propylene dimers..Based on the fact that highly selective propylene dimerization to 2-methyl-1-pentene could be achieved by the catalysis of several group 4 metal complexes bearing ethylene bridged ansa-(indenyl)(fluorenyl) ligands with 3-posititon of indenyl substituted by a pendant aromatic group, this project intends to study firstly the steric and electronic effects of substituent at 3-position of indenyl on the activity and selectivity of corresponding metallocene complexes for propylene dimerization (including the selectivities both for C6 components and a single dimer). Afterwards, the influence of substituents at other positions of indenyl ring, substituents at specific positions of fluorenyl ring, the ansa bridge as well as different metal centers on the catalytic performace of corresponding metallocene complexes for selective propylene dimerization will be studied in combination with the influence of substituent at 3-position of indenyl. Based on obtained structure-performance relationship, the key structural factors govering either belta-H elimination or belta-Me elimination will be explored in order to obtain high performance catalysts for highly selective and efficient prolyenen dimerization to give specific propylene dimers, such as 4-methyl-1-pentene, 2-methyl-1-pentene.

丙烯二聚体如4-甲基-1-戊烯、2-甲基-1-戊烯是重要的烯烃共聚单体及精细化工原料，实现其高效、高选择性合成对于提升我国丙烯深加工水平、聚乙烯产品性能，开发新型聚合物均具有深远的意义。.基于茚环3-位悬垂芳基取代的亚乙基桥联茚-芴锆络合物能催化丙烯高选择性二聚得到2-甲基-1-戊烯，本课题提出系统考察茚环上各取代基电子和空间因素对络合物催化丙烯二聚选择性（包括C6选择性以及单一异构体选择性）、催化活性的影响；在此基础上，考察在芴环上引入取代基、引入不同桥联结构、不同金属中心（Zr, Hf）对络合物催化丙烯二聚选择性和催化活性的影响；找出络合物结构中控制齐聚过程发生belta-H消除、belta-Me消除的关键结构因素，以实现丙烯高活性、高选择性二聚制备单一异构体（如4-甲基-1-戊烯、2-甲基-1-戊烯）的目的。

丙烯二聚体如4-甲基-1-戊烯、2-甲基-1-戊烯是重要的烯烃共聚单体及精细化工原料；丙烯齐聚过程中经选择性belta-Me消除得到的烯丙基端基丙烯齐聚物是优秀的烯烃共聚大单体。实现这些丙烯衍生物的高效、高选择性合成对于提升我国丙烯深加工水平，优化聚烯烃产品性能，开发新型聚合物均具有深远的意义。. 本项目设计合成了三大系列亚乙基桥联型多取代茚-芴、二茚以及茂-芴类型的钛族金属络合物近70个。系统考察了茚环（茂环）、芴环典型位置取代基的电子和空间结构因素、不同配体骨架结构、不同金属中心（Zr、Hf）对络合物催化丙烯齐聚性能的影响，重点研究了影响belta-Me消除选择性的关键结构因素。研究表明，对于茚环3-位悬垂基团取代的亚乙基桥联茚-芴以及二茚钛族络合物体系，茚环3-位取代基团的具体结构是决定其催化丙烯齐聚性能的关键因素。通过调控3-位取代基的结构，实现了：（1）高选择性催化丙烯二聚得到2-甲基-1-戊烯，选择性高达96-99%，催化活性约104-105 g/(mol-Zr·h)；（2）高belta-Me消除选择性得到烯丙基端基的丙烯齐聚物，belta-Me选择性处于80-98%范围，得到聚合度为8-300不同分子量段的齐聚物，且催化剂普遍具有高催化活性，达到106-107 g/(mol-M·h)，是目前已知对丙烯转化具有最高belta-Me消除选择性、兼具高催化活性的体系；（3）以99%的高选择性得到丙烯二聚物，为四种异构体的混合物，其总belta-Me消除选择性为45-58%，催化活性达到105-106 g/(mol-M·h)。通过本项目的研究，对络合物催化丙烯转化过程中“聚合——齐聚——选择性二聚——单一二聚异构体选择性”各环节转化的关键络合物结构因素有了系统深入的认识。