摘要
合成了 3种不同结构的 Cn H2 n桥联双核茂钛配合物 ( CH3 ) 2 C[( C5H4) Ti Cl2 ( C5H5) ]2 ( 3 ) ,( CH2 ) n[( C5H4) Ti Cl2 ( C5H5) ]2 ( 6,n=3 ;7,n=4) ,并用 1H NMR进行了表征 .发现以甲苯为溶剂时 ,不仅提高了产率 ,而且有效地避免了副产物 Cp2 Ti Cl2 的生成 .研究了化合物 7/MAO(甲基铝氧烷 )催化乙烯聚合的反应 ,考察了反应条件对催化体系的影响 .结果表明 ,催化活性随着 n( Al) /n( Cat.)比的增大而提高 ,聚乙烯的分子量在 n( Al) /n( Cat.) =5 0 0和 5 0℃时达到最高值 9.0 1 0 2× 1 0 4;随着聚合时间的延长 ,催化活性下降 ,而产物分子量不断升高 ;随着温度的上升 ,5 0℃时催化活性和聚乙烯的分子量最高 ,分别为 2 .40 74×1 0 5g PE/( mol Ti· h)和 6.8679× 1 0 4.随着桥联双核茂钛配合物碳桥的增长 ,催化活性增加 ,所得聚乙烯的分子量降低 .
Three different dinuclear titanocene complexes (CH 3) 2C 2(3), (CH 2)·n 2(6, n=3; 7, n=4) were synthesized by the reaction of the corresponding dilithiumed salts with two equivalents of CpTiCl 3 in toluene. The yield of the corresponding dinuclear titanocene complex in toluene is higher than that in THF, in which CpTiCl 3 may be disproportionated to form Cp 2TiCl 2. All titanocenes are characterized by 1H NMR. The catalytic properties of the dinuclear titanocene complexes for ethylene polymerization were investigated in the presence of MAO(methylaluminoxane). For the ethylene polymerization catalyzed by compound 7/MAO, the catalytic activity increases with the increase of n(Al)/n(Cat.), the moleculer weight of polyethylene reaches 9.010 2×10 4. With the prolongation of the polymerization time, the catalytic activity declines while the molecular weight of polyethylene increases. At 50 ℃, the molecular weight of the polymer reaches up to 7.77×10 4. However, it decreases rapidly along with rising reaction temperature. When the length of the bridged ligand increases, the polymerization activity increases with the increase of the bridge length while the molecular weight decreases accordingly.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第12期2304-2307,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金 (批准号 :2 0 0 740 2 8)
中国石化总公司 SIN OPEC(批准号 :X5 0 0 0 3 0 )资助
