Hydrochloric Acid → 4,6-Diaminoresorcinol Dihydrochloride

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Reaction Conditions

Reaction Steps

The crude diaminoresorcinol (57.0 g), from Step A, containing the Pd/C catalyst, is dissolved in 400 g of 6% aqueous HCl at 80° C. The catalyst is removed by filtration. An additional 50.0 g of concentrated HCl containing 1.5 g of stannous chloride dihydrate is added to the diaminoresorcinol mixture along with 5.0 g of activated carbon. The solution is heated at reflux for 15 minutes and then the carbon is removed by filtration. The filtrate is cooled to 0° C. to allow crystallization of the product. The resulting white precipitate is isolated by filtration under a purge of dry nitrogen. This filter cake is then dried in vacuo at 40° C. to a constant weight to yield 48.7 g of essentially pure (99.8%) 4,6-diaminoresorcinol dihydrochloride having a m.p. of >300° C. Elemental Anal. calc'd for C6H10Cl2N2O2 (213.0643): C, 33.82; H, 4.73; Cl, 33.28; N, 13.15; 0, 15.02, found: C, 33.6; H, 4.64; N, 13.20.

Provenance & Evidence