The methyl ester is saponified and converted into 1 l-bromo- undecanoic acid by peroxide-catalyzed HRr addition. This important step can easily be carried out on a commercial scale. A solution of the unsaturated acid in toluene benzene flows down the column-shaped reactor countcrcurrent to a HHr and air stream from below. Approximately 96% of the resulting bromide has the bromine in a terminal position. The product is reacted with NH, to form the ammonium salt of w-aminoundecanoic acid, which is released by acidification: