Chemical Degradation of Condensed Tannin with Phloroglucinol in Acidic Solvents

抄録

In order to easily prepare water-soluble polymers and oligomers investigated the optimum conditions under which kaki-tannin, purified from young and immature persimmon fruit, could be treated with a polyphenol in acidic solvents. Finally, we established the following conditions; ethanol containing 0.5 M acetic acid or formic acid is used as a solvent, the ratio ofphloroglucinol to kaki-tannin is 1 to 1, the tannin concentration is about 0.2 to 1.0%, and the incubation is performed with refluxing under a nitrogen stream. Then, various polymers and oligomers can be prepared by changing the incubation time (for example, 3 to 50 hr).
Four polyphenolic degradates were isolated from kaki-tannin after such phloroglucinol treatment of longer duration. Their chemical structures suggested that phloroglucinol acts as a unitcatching agent in the reaction, as well as toluene-α-thiol.