Stigmasterol, Beta-sitosterol Maleate And Separation Process Research

Phytosterol is a kind of secondary alcohol in steroids compounds, which are widely present in foods of plant origin, especially oils. The most common phytosterols in nature are the 4-desmethylsterols, namely stigmasterol,β-sitosterol, campersterol and brassicasterol.The esterification process of stigmasterol orβ-sitosterol with maleic anhydride was studied and esterified products were characterized. The kinetics of esterification of stigmasterol orβ-sitosterol with maleic anhydride in the presence of p-toluenesulphonic acid as a catalyst and toluene as a solvent has been investigated. The solubilities of the esterified products, stigmasteryl monomaleate andβ-sitosteryl monomaleate in various solvents have been investigated. According to the solubilities of stigmasteryl monomaleate andβ-sitosteryl monomaleate in certain solvents, the esterified products were purified with recrystallization. The works were carried out as follow parts:1. The characterization of esterified products of stigmasterol orβ-sitosterol with maleic anhydrideThe estrification of stigmasterol orβ-sitosterol with maleic anhydride were carried out in the presence of p-toluenesulphonic acid as a catalyst and toluene as a solvent. The esterified products were charterized by elemental analysis, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results showed that the esterified products of stigmasterol andβ-sitosterol with maleic anhydride were stigmasteryl monomaleate andβ-sitosteryl monomaleate.2. The esterification processes and kinetics of stigmasterol orβ-sitosterol with maleic anhydrideThe effects of reaction conditions on stigmasterol esterification process, such as temperatures, reactant ratios of sterol to maleic anhydride and the amount of catalyst using were investigated. It can be concluded that stigmasterol conversionηincreased at the same reation time with increasing temperature, reactant ratio of stero to maleic anhydride and the amount of catalyst using.The kinetics of monoesterification of stigmasterol orβ-sitosterol with maleic anhydride in the presence of p-toluenesulphonic acid as a catalyst and toluene as a solvent has been investigated. The reactions appear to be first order with respect to sterol and first order to maleic anhydride, respectively. The final kinetic equations are as follows: r = kc_sc_B , in which k = 1.21×10⁷ exp (-60300 / RT ) (dm³·mol^-1·min^-1) r = kc_βc_B , in which k = 6.26×10⁶ exp (-57000 / RT ) (dm³·mol^-1·min^-1) The value of activation energy for stigmasteryl monomaleate andβ-sitosteryl monomaleate formation is 60.3 and 57.0 kJ·mol^-1, respectively.3. Solubilities of stigmasteryl monomaleate andβ-sitosteryl monomaleate in various solventsSolubilities of stigmasteryl monomaleate andβ-sitosteryl monomaleate at various temperatures in acetone, ethyl acetate were studied. The solubilities of these steryl esters are represented by equation log(1 /x )= A/T+B for each solvent. The conclusions can be drawn from the measured solubility data: The solubility of stigmasteryl monomaleate andβ-sitosteryl monomaleate increases in ethyl acetate and acetone with increasing temperatures. The solubility of stigmasteryl monomaleate in ethyl acetate is higher than that in acetone at constant temperature. So was theβ-sitosteryl monomaleate. The solubility ofβ-sitosteryl monomaleate is higher than that of stigmasteryl monomaleate in all of two kinds of solvents at constant temperature. The experimental data could be regressed by equation log(1 /x )= A/T+B.4. Purification and separation of stigmasteryl monomaleate andβ-sitosteryl monomaleateThe solvents acetone, ethyl acetate and cyclohexanone were used for separation the mixture stigmasteryl monomaleate andβ-sitosteryl monomaleate separation. The results show that after four stages crystallization in ethyl acetate and cyclohexanone, the content of stigmasteryl monomaleate is up to 80%. As cyclohexanone a solvent, the content ofβ-sitosteryl monomaleate is up to 80% after four stages crystallization. The acetone is not a good kind of solvent in separation mixture of stigmasteryl monomaleate andβ-sitosteryl monomaleate.