Benzoic acid, 2-hydroxy-3,5-dinitro- → 3,5-Diamino-2-hydroxybenzoic acid

Participants

Reaction Conditions

Reaction Steps

In an autoclave, 20 g of the crude DNSA produced in the above Production Example 4 was dissolved in 150 mL methanol. The solution was degassed by purging nitrogen for 10 minutes, and slowly added with 19.5 g of 98% conc. sulfuric acid and then added with 250 mg of catalyst Pd/C. The autoclave was sealed and bubbled with hydrogen at a pressure of 7 kg/cm2 for further reacting about 12 to 16 hours. After hydrogen was no longer consumed, the pressure in the autoclave was released to normal pressure and the suspended solid in the autoclave was taken out and filtered. The resultant solid was mixed with 600 g of pure water and heated at 85° C. to allow solid dissolving completely. The resultant solution was hot filtered to filter the hydrogenation catalyst off. The filtered solution was distilled under reduced pressure with recovery pure water until all solids were solidified. The solid was added with 450 mL iso-propanol to subject to recrytalization to obtain 17.3 g of product 3,5-diaminoalicylic acid (DASA), m.p.=246.7° C.

Provenance & Evidence