Hydrochloric Acid → 4,6-Diaminoresorcinol Dihydrochloride

Participants

Reaction Steps

A one-liter Hastalloy C autoclave equipped with a gas dispersion stirrer and cooling coil is charged with 117.3 g (0.5 mole) of 2-chloro-4,6-dinitroresorcinol, 400 ml of glacial acetic acid, 41 g (0.5 mole) of NaOAc, 7.0 g of 10 percent palladium over carbon and 100 mL of H2O. The sealed reactor is charged with 400 psi of H2 and the temperature is brought to 40° C. and maintained between 40° C. and 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 between 100-400 psi during the reaction. Upon completion, no further uptake of H2 is observed. The reactor is cooled to room temperature, opened and 400 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. H2 (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 is carried out in the existing solvent or the semi-pure material can be isolated and air dried to afford 100 g of crude diaminoresorcinol dihydrochloride, (96.8 mole percent yield based on the 2-chloro-4,6-dinitroresorcinol.

Provenance & Evidence