Hydrogenation of canola oil using chromium catalysts

Homogeneous, supported and precipitated chromium catalysts were prepared from chromium hexacarbonyl in an attempt to selectively hydrogenate canola oil. These chromium compounds showed low activity, lowering the iodine value of the oil by only 10 IV units. The concentration oftrans-isomers, however, was very low (<1% for most runs). Infrared spectroscopy revealed the presence of a Cr(CO)₃(diene) PPH₃ complex in two of the hydrogenated oils. The selectivity and the mechanism by which chromium catalysts hydrogenate unsaturates are discussed.