二价氯化稀土催化丁二烯聚合的活性

<正> 稀土催化聚合双烯烃的研究表明,不同稀土元素的催化活性极不一样,对此虽有不同的解释,但通常公认Sm、Eu等活性骤低,可归之于它们在制备催化剂过程中极易被烷基铝从三价还原到二价,又根据大部分具活性的其它稀土元素在催化体系中总是三价的事实,进而推断:只有在体系中能保持三价的稀土化合物方有产生活性的可能,二价化合物则不具活性。然而,由于二价稀土化合物,特别是除Sm、Eu之外的二价化合物难以制得,迄今为止并无直接的实验事实来判断这些推断是否正确。

ON CATALYTIC ACTIVITY OF BIVALENT RARE EARTH CHLORIDES FOR BUTADIENE POLYMERIZATION

Bivalent rare earth chlorides——NdCl2-nTHF and SmCl2——have been synthesizedthrough the reduction of corresponding trivalent chlorides with Lithium/Naphthaline in THF. Their catalytic activity for butadiene polymerization was studied. The system composed of NdCl2.nTHF and Et3Al showed a moderate catalystic activity while that composed of SmCl2 and Et3Al was inactive. The difference in activity between NdCl2. nTHF and SmCl2 was discussed.