All four mono-hydroxyxanthones are known, and are prepared by heating salicylic acid with either resorcin, pyrocatechin or hydroquinone; they are yellow crystalline solids, which act as dyestuffs.
Orthophenylene diamine, C 6 H 4 (NH2)2, crystallizes from water in plates, which melt at 102 -103° C. and boil at 256-258° C. When heated with io% hydrochloric acid to 180° C. it yields pyrocatechin (Jacob Meyer, Ber., 1897, 30, p. 2569).
Jour., 1901, 26, p. to) attempted to prepare this compound by the action of iodine on the lead salt of pyrocatechin suspended in chloroform.
Vorlander); when fused with caustic potash, resorcin yields phloroglucin, pyrocatechin and diresorcin.
PYROCATECHIN, or Pyrocatechol, ortho-dioxybenzene, C 6 H 4 (OH) 2, first prepared in 1839 by H.