7-trihydroxyxanthone, is found in the form of its methyl ether (gentisin) in gentian root; it is obtained synthetically by condensing phloroglucin with hydroquinone carboxylic acid.
OH 0 CI N, C1 CI ??C1 01-1 0 (t) (2) (3) (4) (5) Phloroglucin (I.3.5-trioxybenzene) (i) behaves similarly to resorcin, hexachlor [1.3.5] triketo-R-hexylene (2) being first formed.
Oak tannin; whilst others yield protocatechuic acid and phloroglucin, e.g.
Moringa-tannin or maclurin, C1,H1006 H20, found in Morus tinctoria, hydrolyses on fusion with caustic potash to phloroglucin and protocatechuic acid.
The bark of the horse-chestnut contains a greenish oil, resin, a yellow body, a tannin, C26 H 24012, existing likewise in the seeds and various parts of the tree, and decomposable into phloroglucin and aesciglyoxalic acid, C 7 H 6 O 3, also aesculetin hydrate, and the crystalline fluorescent compound aesculin, of the formulaC21H24013 (Rochleder and Schwarz), with which occurs a similar substance fraxin, the paviin of Sir G.