茂金属催化剂催化丙烯聚合的β-Me消除选择性研究  

Selectivity towardsβ-Me Elimination of Metallocene Catalysts in Catalytic Propylene Polymerization

作　　者：肖凌云 马海燕[1] XIAO Lingyun;MA Haiyan(Laboratory for Organometallic Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学与分子工程学院金属有机化学研究室,上海200237

出　　处：《华东理工大学学报（自然科学版）》2020年第3期393-403,共11页Journal of East China University of Science and Technology

基　　金：国家自然科学基金(21274041)。

摘　　要：合成及表征了一系列亚乙基桥联取代茚-芴锆、铪络合物{C2H4(5,6-cyclopenta-Ind)(Flu)}ZrCl2(C1),{C2H4(5,6-cyclopenta-Ind)(2,7-t Bu2-Flu)}ZrCl2(C2),{C2H4(3-Bn-5,6-cyclopentaInd)(2,7-t Bu2-Flu)}ZrCl2(C3),{C2H4(3-Bn-5,6-cyclopenta-Ind)(2,7-t Bu2-Flu)}HfCl2(C4),并研究了其与甲基铝氧烷(MAO)组成催化体系催化丙烯聚合的行为。结果表明,在MAO活化下络合物C1~C4均以中等至高等的催化活性催化丙烯聚合,得到以亚乙烯基端基或烯丙基端基为主的丙烯齐聚物或高聚物。在40~100℃,茚环3-位苄基取代的C3具有较高的β-巯基乙醇(β-Me)消除选择性(80%~83%),显著高于茚环3-位没有苄基取代的锆络合物C1和C2,且所得聚合物分子量Mn(800~13 600)也明显低于其他锆络合物催化所得聚合物分子量,说明以β-Me消除为主要链转移方式时有利于降低聚合产物分子量。铪络合物C4具有最高的β-Me消除选择性(87%),但催化活性很低。In propylene polymerization catalyzed by transition metal complexes, chain transfer reactions exert crucial influence on the structures of terminal groups as well as molecular weights of the resultant polymers. Among the known chain transfer reactions, β-methyl elimination(β-Me elimination) could lead to the production of ally-terminated polymer chain selectively, thus attracts great attention. Up to data, it is still a great challenge to achieve high β-Me elimination selectivity systematically during propylene polymerization process. In this work, a series of ethylenebridged indenyl-fluorenyl complexes, {C2H4(5,6-cyclopenta-Ind)(Flu)}ZrCl2(C1), {C2 H4(5,6-cyclopenta-Ind)(2,7-t Bu2-Flu)}ZrCl2(C2), {C2H4(3-Bn-5,6-cyclopenta-Ind)(2,7-t Bu2-Flu)}ZrCl2(C3), {C H4(3-Bn-5,6-cyclopenta-Ind)(2,7-t Bu2-Flu)}HfCl2(C4), were synthesized and characterized. Upon activation with methylaluminoxane(MAO), these complexes could catalyze the polymerization of propylene with moderate to high activities to produce propene oligomers or polymers with vinylidene or allyl-dominant chain ends. Complex C3 bearing a benzyl group at the 3-position of the indenyl ring showed significantly higher β-Me elimination selectivities(80%-83%) at 40-100℃ than the other zirconocene complexes C1 and C2, and meanwhile led to the formation of propene oligomers with significantly lower molecular weights(Mn = 800~13 600) than those obtained by the other zirconocene complexes,suggesting that the dominant β-Me elimination chain transfermode led to the decrease of molecular weights of resultant polymeric products. The hafnocene complex C4 also showed the highest β-Me elimination selectivity among these complexes(87%), however its activity was very low.

关 键 词：茂金属催化剂 丙烯聚合 β-Me消除选择性 

分 类 号：O62[理学—有机化学]