通过乙醚和乙酸乙酯萃取可得到极性不同的组分。分析表明，各级分的分子量分布范围不同，且相对较窄。
Various fractions of tannins with different polarities and relatively narrow molecular weight distribution were obtained by extractions using ether and ethyl acetate sequently .
在氟化钾催化下， 芳香醛与氰乙酸乙酯发生克脑文格尔缩合反应，得到高产率的缩合产物。且只得到E式异构体。
The knoevenagel condensation of aromatic aldehydes with ethyl cyanoacetate proceeds smoothly in the presence of potassium fluoride giving products in high yield. Only the E isomers could be isolated.
结果：以60%丙酮为溶剂进行提取，以乙酸乙酯为溶剂进行纯化，鞣质纯度可达到75%左右，且重复性较好。
Results: the purity of tannins can be as high as reach 75% when it's extracted with 60% acetone and purified with ethyl acetate, and the process has good reproducibility.
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