Hydrochloric Acid → 6-(2-Chloroacetamido)hexanoic acid

18 mL (221 mMol) chloracetylchloride was added dropwise to 20 g (153 mMol) 6-aminohexanoic acid dissolved in 80 mL cold NaOH solution (2 N) at RT. The reaction mixture was stirred for 30 minutes while the pH of the solution was kept between 10 and 11 with occasional addition of NaOH solution (6 N). The pH of the reaction mixture was then altered to pH 5 with HCl (2 N) and the residue was filtered. The residue was then washed with water until the pH of the water was neutral. The product, dried over phosphorus pentoxide, was re-dissolved in 300 ml chloroform and filtered to remove the undissolved residue. Heptane was added to the filtrate and a syrup was obtained by stirring under cooling. The product was filtered, dried and was then crystallized from water.