Polymerization of conjugated diolefins by homogeneous aluminum alkyl‐titanium alkoxide catalyst systems. I. Cis‐1,4 isotactic poly (1,3‐pentadiene)

The polymerization of 1,3‐pentadiene by soluble aluminum alkyl‐titanium alkoxide catalysts is reported. Both the cis and trans isomers of 1,3‐pentadiene are polymerized by these catalysts to polymers prevalently constituted of cis ‐1,4 units. By fractionating the crude products obtained from the trans isomer, amorphous and crystalline fractions were isolated; the latter were found to have a cis ‐1,4 isotactic structure on X‐ray examination. By fractionating the crude products obtained from the cis isomer, polymers having only a very weak crystallinity could be isolated. A characterization of the crystalline cis ‐1,4 isotactic polypentadiene by X‐ray and IR examination is also reported.