Benzocaine → 4-[(11-Phenylundecyl)amino]benzoic acid

Participants

Reaction Steps

A mixture of 16.5 g. of ethyl p-aminobenzoate, 16.3 g. of 11-phenylundecanol O-methanesulfonate (prepared as described in Example 7) and 50 ml. of hexamethylphosphoramide are heated in an oil bath at 120° C. for 20 hours. The mixture is poured into ice and water and extracted with chloroform. The extracts are washed with water, 0.1 N NaOH, saturated sodium chloride solution and water. After drying over magnesium sulfate the extract is filtered through silica gel and the silica gel is washed with chloroform. The filtrate is concentrated in vacuo to an oil which is combined with 200 ml. of ethanol-water (9:1), 15 g. of potassium hydroxide and the mixture is refluxed for 3.5 hours. The mixture is acidified with concentrated hydrochloric acid, diluted with 50 ml. of water and chilled. Dilution with 100 ml. of ethanol and 25 ml. of water and filtration gives a gummy solid which is washed with water. The solid is dissolved in hexane:ether:ethyl acetate:acetic acid (40:5:5:2) and filtered through silica gel G. The support is washed with the same solvent (2 fractions). The first fraction is concentrated in vacuo to an oil which is crystallized from hexane to give pale yellow crystals, m.p. 50°-52° C. Recrystallization from ether-hexane (1:1) gives white crystals, m.p. 53°-55° C.

Provenance & Evidence