Phospholyl catalysts for olefin polymerization
Phospholyl catalysts for olefin polymerization
复制标题
DOI：
10.1016/s1381-1169(97)00170-2
复制
发表时间：
1998-02-27
影响因子：
--
通讯作者：
Shaw, RW
中科院分区：
文献类型：
--
作者：
de Boer, EJM;Gilmore, IJ;Shaw, RW
以甲基铝氧烷为助催化剂，研究了17种磷酰基配体与（Phos）（2）ZrCl_2、（Phos）（C_5 H_5）ZrCl_2共22种锆配合物的丙烯聚合催化性能。制得的无规聚丙烯分子量为450 ~> 20000，端基为亚乙烯基（CH_2 =C（Me）R），活性高达170 kg/g Zr。H.对于结构（2，5-R2 C4 H2 P）（2）ZrCl 2的11种二磷酰基，催化活性最高，具有与磷相邻的中等体积的取代基（例如，c-Pr，Ph），而具有两个小的（H）或两个大的（CMe 3，SiMe 3）配体取代基的配合物是无活性的。据推测，最佳的活性与MAO需要选择性阻断磷孤对配位铝，同时允许游离丙烯的方法的活性位点。在2，5-二取代磷酰配合物系列中，聚合度稳定增加，二烷基<烷基苯基<二苯基，表明电子因素比空间因素在决定M-n中更重要。(C)1998年Elsevier Science B.V.
Seventeen different phospholyl ligands were incorporated in a total of 22 zirconium complexes, (Phos)(2)ZrCl2, (Phos)(C5H5)ZrCl2, investigated in propylene polymerization catalysis using methylaluminoxane as cocatalyst. Atactic polypropylene with M-n varying from 450 to > 20 000 and vinylidene end groups (CH2=C(Me)R) was obtained with activities up to 170 kg/g Zr . h. For the 11 diphospholyls of structure (2,5-R2C4H2P)(2)ZrCl2, catalytic activity was highest with substituents of moderate bulk adjacent to phosphorus (e.g., c-Pr, Ph), whereas complexes with two small (H) or two large (CMe3, SiMe3) ligand substituents were inactive. It is hypothesized that optimum activity with MAO requires selective blocking of phosphorus lone pair coordination to aluminum, whilst allowing free propylene approach to the active site. The degree of polymerization increased steadily in the series of 2,5-disubstituted phospholyl complexes, dialkyl < alkyl-phenyl < diphenyl, suggesting that electronic factors are more important than steric factors in determining M-n. (C) 1998 Elsevier Science B.V.