Catechins(catechin) are widely distributed in plant kingdom, the Acacia catechu, gambir bark abounds with tannins.
Catechins and their oxidation products are hydrocarbon oxygen ternary compound, is made from sugar through a series of enzymes, shikimic acid, by the formation of benzene compounds, the synthesis of catechin.
Catechins has obvious characteristics of phenol, can cause the heavy metals and protein precipitation, therefore, is a kind of phenol content. Phenol content because can make the protein to precipitate, has the size of raw hides tanning into leather performance, so also called tannins or tannin substances.
Catechin and some typical plant tannins (gallic tannin, etc.), compared the performance of the tanning is weaker.
Flavan derivatives. Widely exists in plants, including crystallization water from water/acetic acid needle crystal. Melting point of 93 ~ 96 ℃; Instead of containing water of crystallization of crystalline melting point of 175 ~ 177 ℃. Polarimetric + 16 ° ~ + 18.4 °. Its raceme also assumes the needle crystal, melting point of 212 ~ 216 ℃. Slightly soluble in cold water, ether, soluble in hot water, ethanol, glacial acetic acid and acetone, insoluble in benzene, chloroform and petroleum ether. Catechu essence of cis stereo heterogeneous surface catechu (epicatechin) also widely exists in plants, melting point 242 ℃, polarimetric [alpha] D - 68 ° (ethanol).
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