ARS | Publication request: Investigation of congugated soybean oil as drying oils and CLA sources

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2012
Publication Date: August 23, 2012
Citation: Chintareddy, V.R., Oshel, R.E., Doll, K.M., Yu, Z., Wu, W., Zhang, G., Verkade, J.G. 2012. Investigation of congugated soybean oil as drying oils and CLA sources. Journal of the American Oil Chemists' Society. 89:1749-1762.

Interpretive Summary: Soybean oil (SBO) has been modified into an oil with better drying properties. SBO is commonly referred to as a semi-drying oil, which means that it will polymerize slowly but not to an extent necessary for a good coating. Drying oils suitable for coatings, such as tung oil or linseed oil, have limited production and commonly sell at considerably higher prices than SBO. Through a catalytic process, the double bonds in SBO can be altered to give a trans-conjugated structure which will dry in a manner similar to or even better than the more expensive oils. The process reported here uses an iodine catalyst and a simple lamp to achieve reaction at relatively low temperatures. This research is a potential benefit to coating manufacturing, vegetable oil producers and anyone wishing to use low priced natural oil based coatings.

Technical Abstract: A promising pound-scale production method for the conjugation of soybean oil (SBO) using iodine under photochemical reaction conditions is reported. Variations in catalyst loading, SBO concentration, light source, free radical catalyst source, solvent, and temperature were studied. A quantitative conversion of SBO to conjugated soybean oil (CSBO) in hexanes at reflux temperature is achieved. Parameters including catalyst loading, lamp source, and temperature were investigated, and the effect of fatty acid isomer distribution in CSBO on drying properties of the CSBO is discussed. The conjugated dienes formed were predominantly of the trans 9, trans 11 configuration using this method, which contrasts distributions found using other catalysts such as strong base and organometallic compounds. Employing a high pressure sodium lamp gave a significant improvement in the reaction rate. Drying oil properties of some of our CSBOs are superior to that of raw linseed oil. Methods to remove and recover the iodine are also reported.