4-Hydroxybenzoic Acid → 4-hydroxy-N-phenylbenzamide

Participants

Reaction Conditions

Reaction Steps

p-Hydroxybenzoic acid (96.68 grams, 0.70 mole), sodium ethoxide catalyst (0.218 gram, 0.225% wt. of the p-hydroxybenzoic acid used) and N,N'-dimethylacetamide solvent (550 grams) are added to a reactor equipped with a reflux condenser and stirred under a nitrogen atmosphere at 23° C. to provide a solution. Phenyl isocyanate (87.55 grams, 0.735 mole) is added inducing a maximum exotherm of 46° C. four minutes later. Three minutes after the maximum exotherm temperature is achieved, heating of the reactor commences and a 160° C. reaction temperature is achieved 94 minutes later. After three hours at the 160° C. reaction temperature, the reactor is cooled to 50° C. then the contents poured into 4 liters of deionized water. A precipitated product is recovered via filtration of the aqueous slurry, washed with deionized water (500 milliliters) then dissolved into boiling methanol (850 milliliters) and refluxed therein (67° C.). After cooling the methanol solution to room temperature (23° C.) and maintaining therein for sixteen hours, a white crystalline product is filtered off, washed with methanol (100 milliliters) and dried in a vacuum oven at 80° C. and 1 mm Hg to a constant weight of 99.49 grams. Fourier transform infrared spectrophotometric analysis of a potassium bromide pellet of a portion of the product revealed the presence of the expected hydroxyl group O--H and secondary amide (solid state) N--H stretching at 3336 cm31 1 (sharp) with a shoulder at 3409 cm-1 and the secondary amide carbonyl stretching (solid state) at 1656 cm-1 (sharp).

Provenance & Evidence