Hydrogenation of poly(1,3-cyclohexadiene)

The hydrogenation of poly(1,3-cyclohexadiene)s (PCHDs) with various homogeneous catalysts are reported. The initial screening for hydrogenation catalysts was carried out using cyclohexene as a model compound for the monomeric unit in the polymer chain. High conversion for both cyclohexene and 1,4-linked PCHD were found with carbonylchlorohydridotris(triphenylphosphine)ruthenium(II)[RuHCl(CO)(PPh3)(3)]. The existence of units formed by 1,2-addition (the 1,2-CHD unit) in the polymer chain strongly influenced the extent of hydrogenation of PCHD. Complete hydrogenation of PCHD (polycyclohexane: PCHE) containing 1,2-CHD units was found with the cobalt(III)acetylacetonate[Co(acac)(3)] /triisobutylaluminium[(i-C4H9)(3)Al] system. The PCHE obtained was composed of cyclohexane rings directly connected in the main chain, and had excellent thermal stability.