银离子配位色谱法分离香茅次油中β-榄香烯的研究

Isolation of β-Elemene from Citronella Oil by Silver Ion Coordination Chromatography

目的:对比硅胶与硝酸银硅胶层析介质对β-榄香烯的吸附及分离效果,从香茅次油中分离得到β-榄香烯。方法:测定β-榄香烯银离子配位化合物的稳定常数,考察不同极性溶剂中β-榄香烯在硅胶及硝酸银硅胶表面的静态吸附情况,香茅次油在两种层析介质中的薄层分离情况,并采用柱层析方法分离β-榄香烯。结果:β-榄香烯与硝酸银能够形成π配位化合物,稳定常数为5.12×10-5L·mol-1;当硅胶作为层析介质时,β-榄香烯静态吸附量较小,符合单分子层吸附模型,溶剂极性增大有利β-榄香烯柱层析的分离,含量为97%的β-榄香烯回收率为11%;当硅胶经硝酸银改性后,增强了β-榄香烯静态吸附能力,吸附行为与BET多分子吸附模型相近,中等极性的溶剂有利于β-榄香烯柱层析的分离,含量为98%的β-榄香烯回收率为60%。结论:硅胶经硝酸银改性后对不饱和化合物具有选择性吸附能力,倍半萜π配位化合物的稳定性与其化合物结构及溶剂环境等相关;常规硅胶层析法很难将β-榄香烯从倍半萜化合物中分离出来,而硝酸银硅胶柱层析法却能很好地实现,且分离效率高。

Aim： To separate β-elemene from other sesquiterpenes, and compare the effect of silica gel chromatography with/without silver nitrate modification. Methods： Detecting the complex constant of β-elemene-Ag^＋ coordination compound, and investigating the static adsorption of ^-elemene on silica gel before and after treated with silver nitrate in different polar solution and the thin layer chromatography of citronella oil when silica gel and silver nitrate modified silica gel are used for chromatography medium, and separating β-elemene from other sesquiterpenes by silica gel and silica gel column chromatography modified with silver nitrate. Results：β-Elemene- Ag^＋ pi coordination compound will be formed with stability constant 5.12×10^-5 when silver nitrate is added to β- elemene solution. When silica gel is treated as medium, the adsorption of β-elemene conforms to the Langmuir monomolecular adsorption theory and the adsorbility is weak. The polar solvent is available to separate β-elemene from other sesquiterpenes, but the separating result is not good. The 97% content of β-elemene accounts for 11 percent of recovery. While silica gel modified with silver nitrate is treated as medium, the adsorption of β-elemene conforms to BET adsorption theory and the adsorbility is strong. The middling polar solvent is acceptable, and the 98% content of β-elemene accounts for 60 percent of recovery. Conclusions： The selective adsorption of β-elemene will be increased when silica gel is modified by silver nitrate, and the stability of different structure sesquiterpenes- Ag^＋ coordination compounds is related to their molecular structure and solvents. Conventional silica gel chromatography can not be available to separate sesquiterpenes. However,β-elemene can be isolated high efficiently from sesquiterpenes mixtures by silica gel chromatography modified with silver nitrate.