Hydrochloric Acid → 4,6-Diaminoresorcinol Dihydrochloride

Participants

Reaction Steps

A one-liter Hastelloy C autoclave equipped with a gas dispersion stirrer and cooling coil is charged with 100.0 g (0.5 mole) of the 4,6-dinitro-1,3-benzenediol, 500 ml of n-propanol, ~7.0 g of 10 percent Pd/C and 10.0 ml of H2O. The sealed reactor is charged with 50 psi of H2 and the temperature is brought to 40° C. and maintained between 40° C.-50° C. during the course of the reaction. After a brief induction period, the uptake of hydrogen becomes extremely rapid and H2 pressure is maintained at about atmospheric pressure during the reaction. Upon completion, no further uptake of H2 is observed. The reactor is cooled to room temperature, opened and 300 ml of concentrated HCl containing ~10 g of SnCl2.2H2O is added to the reaction mixture. The crude product with the catalyst is isolated by filtration. This material is dissolved in 200 g of H2O at 85° C. and the catalyst is removed by filtration. H2O (100-300 ml) is added to the filtrate along with 500 ml of HCl and the catalyst-free material is precipitated from the brown solution. Recrystallization may be carried out in the existing solvent or the semi-pure material can be isolated and air dried to afford 100 g of crude diamino resorcinol dihydrochloride (predominantly 4,6-diamino-1,3-benzenediol dihydrochloride in 95.0 mole percent yield based on the 4,6-dinitro-1,3benzenediol.

Provenance & Evidence