CATECHU 295 



twigs of Uncaria gamhier contains as its chief constituents 

 catechin and catechu tannic acid. 



2. Acacia catechu derived from the heart-wood of Acacia 

 catechu contains, according to Perkin, a substance acacatechin 

 which is isomeric with the catechin occurring in gambier, 

 and presumably catechu tannic acid. 



3. Areca catechu, obtained by extracting the fruits of 

 Areca catechu, the Betel nut palm, contains a substance re- 

 sembling catechu tannic acid, but there is some question as 

 to its containing a catechin. 



It will be seen from the above that the composition of 

 the above products is somewhat similar ; they all contain 

 catechu tannic acid as the active tanning agent and also 

 catechins which are not of themselves tanning materials, but 

 may apparently be converted into such by the process of ex- 

 traction and evaporation. 



The work of Perkin, of Kostanecki, and of Freudenberg has 

 shown that at least two * catechins exist, namely catechin [h) 

 contained in gambier and acacatechin, or catechin [a), from 

 Acacia catechu ; these two substances would appear to be 

 stereo-isomers, the former being dextro-rotatory while the 

 latter is laevo-rotatory. 



Gambier catechin {b) may be prepared by extracting 

 powdered catechu with ether ; the crude material obtained 

 on evaporating off the ether may be purified by crystalHza-, 

 tion from water. 



Catechin forms colourless glistening needles, which, when 

 dry, melt at 175-177°. If is readily soluble in alcohol and 

 ethyl acetate, not so readily soluble in ether, and only slightly 

 soluble in cold water. 



With ferric chloride alone it gives a green colour, but with 

 ferric chloride and sodium acetate a dark violet. 



It gives the phloroglucin reaction with pine wood shaving 

 and hydrochloric acid. 



Potash fusion gives protocatechuic acid and phloroglucinol. 



* A third Catechin, (c). melting at 235-237°, is contained in the mother 

 liquors of the above Gambier catechin (Perkin : "J. Chem. Soc," 1905. 

 87, 398). 



