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

20 g (153 mMol) 6-Amino-hexanoic acid was mixed with 80 ml of 2N Sodium Hydroxide (NaOH). 18 ml (221 mMol) of Chloro-acetylchloride and 6N NaOH were added to the mixture at Room Temperature (RT). The pH of the reaction mixture was maintained between 10 and 11 during the addition of Chloro-acetylchloride and 6N NaOH by using a burette to control the addition. The mixture was stirred for 30 mins at this constant pH. Ethyl acetate (EtOAc) was then added to the reaction mixture and the pH was adjusted to 2 with 2N Hydrochloric Acid (HCl). To work up the product, the EtOAc-layer was separated and the aqueous phase was extracted with EtOAc. The organic layers were dried and the solvent was evaporated. The residue was then re-crystallized from diisopropylether/EtOAc (1:1, v:v).