Hydrogenation of cis-1,4-poly(isoprene) catalyzed by OsHCl(CO)(O2)(PCy3)2

✍ Scribed by Kitikorn Charmondusit; Pattarapan Prasassarakich; Neil T. McManus; Garry L. Rempel

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 146 KB
• Volume: 89
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.12133

✦ Synopsis

Abstract

The quantitative hydrogenation of cis‐1,4‐poly(isoprene) (CPIP) provides an easy entry to the alternating copolymer of ethylene–propylene, which is difficult to prepare by conventional polymerization. The homogeneous hydrogenation of CPIP, in the presence of OsHCl(CO)(O~2~)(PCy~3~)~2~ as catalyst, has been studied by monitoring the amount of hydrogen consumed during the reaction. The final degree of olefin conversion measured by computer‐controlled gas uptake apparatus was confirmed by infrared spectroscopy and ^1^H nuclear magnetic resonance analysis. Kinetic experiments for CPIP hydrogenation in toluene solvent indicate that the hydrogenation rate is first order with respect to catalyst and carbon–carbon double bond concentration. A second‐order dependence on hydrogen concentration for low values and a zero‐order dependence for higher values of the hydrogen concentration was observed. The apparent activation energy for the hydrogenation of CPIP over the temperature range of 115–140°C was 109.3 kJ/mole. Mechanistic aspects of this catalytic process are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 142–152, 2003