Formation in anhydrous medium of the acyl halide (II) of dl-2-(4?isobutylphenyl)propionic acid (I) with phosphorous or sulfur halides or oxyhalides, and the subsequent reaction in anhydrous medium with beta-hydroxyethylamine (III) to give N-(beta-hydroxyethyl)-dl-2-(4?isobutylphenyl)propionamide.