Catalytic hydroformylation and hydroxymethylation of high molecular weight CIS-1, 4-Polybutadiene

Abstract

Catalytic hydroformylation and hydroxymethylation of unsaturated polymers is a post polymerization process to introduce reactive functionalized groups such as aldehyde groups or hydroxyl groups, onto backbone polymers. This reactive polymer can be used for grafting, crosslinking or further modification reactions. The hydroformylation of high molecular weight cis-1,4-polybutadiene in the presence of HRh(CO)(PPh[subscript3])[subscript3] as catalyst and monochlorobenzene as solvent was studied. The degree of conversion was examined using [superscript1]H-NMR spectroscopy. From a 2[superscript4] factorial experimental design, temperature, catalyst concentration and total pressure appear to be significant factors. A detailed kinetic study was carried out in a Parr batch reactor and a computer controlled batch reactor by monitoring the amount of synthesis gas consumed during the reaction time. The kinetic results indicate that the hydrofomylation is first order with respect to each of catalyst concentration, and carbon-carbon double bond concentration and H[subscript2]/CO pressure (1:1 ratio) in the pressure range of 13.8 and 30 bar. Effects of CO concentration in synthesis gas, added triphenylphosphine, and stirring speed were also studied. Mechanistic aspects of the catalytic process are discussed.Hydroxymethylation was achieved by subsequent hydrogenation of hydroformylated polybutadiene using Ru(CH=CH(Ph))Cl(CO)(PCy[subscript3])[subscript2] under fairly severe conditions. The thermal properties of the hydroformylated and hydroxymethylated polybutadiene were characterized. The results show that the hydroformylation can increase the glass transition temperature of the polymer. However, the thermal stability of hydroformylated and hydroxymethylated polybutadiene does not significantly change.