Response surface-optimized synthesis of cis-9, trans 11 octadecadienoic acid through dehydration of castor oil

Cis-9,trans-11-octadecadienoic acid (9c,11t-18:2), is the most abundant and biologically active isomer of conjugated linoleic acid that is of interest due to its anticarcinogenic and anticholesterolemic properties. To further study the metabolic pathways and physiological effects of 9c,11t-18:2, it is desirable to obtain substantial amounts of this compound in a relatively pure form, ideally by simple methods from readily accessible materials. The optimization of reaction conditions (including reaction temperature, time and amount of catalyst) for 9c,11t-18:2 production by dehydration of castor oil as starting material was investigated using response surface methodology (RSM). This optimization process was done by application of KOH as an inexpensive dehydrating reagent. It was found that the temperature of dehydration and amount of catalyst were the most effective factors in CLA isomer composition and yield. When the reaction temperature was increased, the yield of 9c,11t-18:2 decreased whereas with increasing in catalyst amount, it was increased. Time had a moderate impact on CLA production and with increasing in time, CLA yield was affected slightly. The temperature, 50^◦C; catalyst amount, 1.8 g and reaction time, 5.25 h were found to be the optimum points to achieve the maximum yield of 9c,11t-18:2 (53.93%).