乙炔在烯烃歧化催化剂上的聚合

近年来文献中出现了一些以歧化催化剂用于炔烃聚合的尝试^[1-4],例如以WCl₆-ph₄Sn、MoCl₅-ph₄Sn体系进行炔烃聚合反应,均有活性。我们在烯烃均相催化歧化反应的研究中,试探了将此类催化剂用于乙炔聚合,结果是:(1)试验过的7种催化体系均能使乙炔聚合,生成黑色不溶的高分子,红外光谱测定表明,得到的聚乙炔是顺式和反式结构的混合物,此外,部分乙炔尚三聚环化成苯;(2)不同催化剂作用下乙炔聚合和烯烃歧化的活性和选择性没有平行关系;(3)几种催化体系对乙炔高聚和环化三聚的选择性不同(见表1)。

POLYMERIZAT ON OF ACETYLFNE ON OLEFIN METATHESIS CATALYSTS

Polymerization of acetylene was tested on olefin metathesis catalysts.Experiments showed that polymerization and cyclotrimerization of acetylene did occur with all the seven catalysts tested. No correlation in catalyst activity and selectivity was found between olefin metathesis and acetylene polymcrization. Ageing of the Bu₄N[Mo(CO)₅Cl]-EtAlCl₂ system showed a tremendous decay in catalytic activity for olefin metathesis, but a minor effect on the rate of polymerzation of acetylene. It seems likely that although metathesis of olefin and polymerization of acetylenc proceed on the same catalyst, the active species is not identical. The fact that the turn over number in acetylene polymerization is very low and the polyacetylene is formed very rapidly implics the presence of very small amount of Mo or W molecules acted as active species for polymerization.