Preparation Of Cholesterol By Transesterification Of Lanolin Using Different Catalysts

In this paper, preparation of cholesterol by transesterificatiom of lanolin with different catalysts, i.e., sodium methoxide, formic acid, and two kinds of basic anion exchange resin, was investigated.First of all, the lanolin was transesterificated to yield cholesterol, with methanol as reaction solvent and sodium methoxide as catalyst. The stability of cholesterol during the reaction, the influencing factors such as the water content in raw lanolin, the ratios of methanol and sodium methoxide to raw material, the reaction temperature and time were considered. Results showed that the optimal reaction conditions were: 1:1 of methanol to raw lanolin, 6.4% of sodium methoxide to total cholesterol, reaction temperature 60°C and reaction time 1 h. Under such operation conditions, the yield of cholesterol reached 99%.Then, the paper studied the transesterification process of lanolin with formic acid as catalyst in subcritical alcohol (methanol and ethanol). We studied the stability of cholesterol. It is stable between 150°C and 215°C in the solution of methanol or ethanol. The process of transesterification was affected by water content, type of alcohol, reaction temperature, reaction time, and amount of catalyst. The optimal conditions were: pH 2.5～3.5, methanol/lanolin (v/wt) of 10/1, temperature 200°C, time 8 h. The yield of cholesterol reached 81.7%.Finally, the preparation of cholesterol by transesterification of lanolin with methanol over basic anion exchange resin was investigated. The catalysts were 5# strong basic resin (macroporous resin) and 3# strong basic resin (gel resin). The static adsorption of cholesterol on two resins at reaction temperature were studied. The results showed that two resins did not adsorb cholesterol. The influencing factors to transesterification in fixed bed were focused on feed flow rate, type and ratio of solvent, reaction temperature and contact time. The suitable conditions were as follows: 3# strong basic resin as catalyst, reaction temperature 60℃, the ratio of lanolin (wt) / methanol (v) / petroleum ether (v) 1/2/1, flow rate 1.5 ml/min, the cholesterol yield up to 63.1%.