Chinese gall extract

Figure 3 The major component of Chinese gall extract (tannic acid)...

To ground Chinese nut galls (120 g.) and methyl isobutyl ketone (60 mL.) mixture was stirred at the reflux temperature for one and one-half hours and then cooled. Sufficient 60° Be sulfuric acid was added to neutralize the alkali and liberate the gallic acid and its salts. Gallic acid was extracted with three successive 1500 mL. portions of methyl isobutyl ketone which were separated from the reaction mixture by decantation. The ketone extract was steam distilled and the hot residual extract was then treated with iron-free activated carbon and allowed to cool. Crude gallic acid which crystallized from the aqueous solution was filtered off and dried. Yield 59 g. 

The tannin or tannic acid employed can be any hydrolyzable tannin such as that obtained by extraction thereof from such tannin-containing materials as tara pods, Chinese nut galls, Aleppo galls, sumac-leaves, etc. Taratannin (i.e., tannin obtained by extraction from tara pods) is preferred. 

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