Cyclization of synthetic cis-1,4-polyisoprene

Cyclization of synthetic cis-1,4-polyisoprene was carried out by using TiCl₄ and p-toluenesulfonic acid catalyst. The average cyclicity and structure of the polymers cyclized to a different degree was studied by infrared and high-temperature NMR spectroscopy. The methods of synthesizing an average mono-, bi-, tri-, or polycyclic polymer that could be distinguished by high-temperature NMR spectroscopy and followed by gel-permeation chromatography are discussed.