1-Amino-dihydroresorcine (III): Compound (II), 20g, is treated with 50 mL of conc. hydrochloric acid by heating on a boiling water bath for 10 minutes. An orange coloured precipitate formed. The hydrochloric acid is removed by heating at 50-60+ under vacuum. The residue is dried over NaOH and P2O5 and re-crystallised from glacial acetic acid. Obtained are a orange-yellow prisms with MPt. 235-2440°C. The compound is very soluble in water and alcohol, slightly soluble in ether, chloroform and insoluble in glacial acetic acid. Beilstein test positive. To obtain an analytical sample it was treated with with refluxing glacial acetic acid.
Found C49.26 H 5.7 N 8,79.
The amine hydrochloride precipitates out as almost colourless needles from the filtrate. These are collected by filtration, washed with glacial acetic acid and ether to give 7.6g, 40% of the theoretical yield. In small scale experiments the yield was 50-55%.
The hydrochloride is very soluble in water and alcohol; difficult to dissolve in cold glacial acetic acid and insoluble in ether. In moist air a pink colouration rapidly forms. Furthermore the dry compound is only stable for short periods and cannot be titrated. To obtain an analytical sample it was recrystallised from glacial acetic acid containing HCl. The hydrochloride begins to sinter (bubble) at 180° and melts with decomposition at formation of a red colour at 229-230°C.