Formation of conjugated double bonds in soybean oil with iodine as a catalyst

Abstract

A method for the iodine-catalyzed conjugation of soybean oil was developed, and the conjugated product was analyzed by UV, IR, and 1H NMR. The results indicated that the optimal conditions for conjugation included a temperature of 180°C, a catalyst loading of 0.5 wt.% and a reaction time of 3 h, at which the concentration of conjugated linoleic acid was 1.51 mol L-1, with 92 % conversion, the CLNA reached 0.225 mol L-1 when the temperature was 130°C, a catalyst loading of 0.5 wt.%, and a reaction time of 3 h with a conversion rate of 99.9 %. The reaction predominantly produced trans-trans, trans-cis and cis-trans isomers. It was also revealed that the conjugation of linolenic acid was much faster than that of linoleic acid. The method possessed the advantages of a short procedure, a high conversion rate, and no methyl esterification of the raw material, and it was an environmentally friendly technology that does not use solvents.

Keywords

• soybean oil
• conjugation
• iodine
• linoleic acid
• linolenic acid