Hydrochloric Acid → 3-((Aminocarbonyl)Amino)Benzoic Acid

Participants

Reaction Steps

Urea (17.5 g, 0.292 mol), m-aminobenzoic acid (Aldrich, 10.0 g, 0.073 mol), water (30 mL), and concentrated HCl (3 mL) were added to a 125-mL Erlenmeyer flask and boiled for 45 min. The brown suspension became a purple solution on boiling and a brown precipitate formed after 15 min. The pH of the solution was 7 after 45 min. The mixture was cooled on ice and a mauve solid was collected by filtration, slurried with water, and again collected by filtration. The solid was added to 50 mL boiling ethanol and dimethylformamide (DMF, 25 mL) was added by drop until the solid dissolved. No precipitate formed on cooling. Water was added with stirring until turbidity and then a few drops of DMF were added to give a clear solution. The solution was cooled on ice and a light-purple solid was collected by filtration. Water was added to the filtrate to precipitate a tan solid which was also collected by filtration. The tan solid was dissolved in 5% sodium bicarbonate and neutralized with a 10% solution of potassium bisulfate. The tan solid was collected by filtration, washed with water, and dried in vacuo. The tan solid was then recrystallized from 700 mL methanol and 300 mL water. After cooling, a purple solid was collected by filtration. The product was precipitated from the filtrate with the addition of 1 L of water. This light-tan solid was collected on a filter and dried in vacuo. The product was dissolved in 175 mL boiling ethanol and the volume was reduced to 75 mL and filtered while hot. This was slowly cooled to room temperature and then on ice to give an off-white solid. This solid was collected on a filter, washed with cold ethanol, and dried in vacuo to give 2.5 g (20%) of the title compound, mp 276°-280° C.

Provenance & Evidence