Polymerization of 1,4-butadiene over MgCl2-supported cobalt catalysts combined with trimethylaluminium

✍ Scribed by Masaki Takeuchi; Takeshi Shiono; Kazuo Soga

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 570 KB
• Volume: 197
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1996.021970226

✦ Synopsis

Abstract

MgCl~2~‐supported Co catalysts with different loading amounts were prepared from the reaction of CoBr~2~[P(C~6~H~5~)~3~]~2~ or CoBr~2~(C~5~H~5~N)~2~ and MgCl~2~ in toluene solution. Polymerization of 1,3‐butadiene was conducted with them using Al(CH~3~)~3~ as cocatalyst, which gave polybutadiene composed of 1,2 and cis‐1,4 units. The content of 1,2 units could easily be regulated from approximately 0% up to 90% by controlling the loading amount of Co as well as by changing the amount of suitable Lewis base added. The sequence distribution of each unit was determined by means of ^13^C NMR using hydrogenated polybutadiene. Addition of ethylene to the polymerization system caused a marked decrease in the molecular weight of polybutadiene, but ethylene was incorporated neither in the main chain nor at the chain ends. The chain end analysis of very low‐molecular‐weight polybutadiene by ^13^C NMR suggested that 1,2 and 2,1 insertion reactions predominantly proceed at the initiation and propagation steps, respectively.