Sodium Hydroxide → 3-Aminoazepan-2-one hydrochloride

Participants

Reaction Steps

A stirred mixture of L-lysine hydrochloride 1 (55 g, 300 mmol) and NaOH (12 g, 300 mmol) in 1,2-propanediol (1.2 L) is heated to reflux. A Dean-Stark trap is used to withdraw the first 120 mL of condensed solvent. The reaction solution is refluxed for an additional 2 hours until all starting material is consumed (which maybe determined by 1H NMR). The solution is cooled and is concentrated under vacuum. Ethanol is used to completely dissolve the α-amino-ε-caprolactam 2. Byproduct NaCl is removed by filtration. The filtrate is concentrated and the resulting crude α-amino-ε-caprolactam 2 is dissolved in water. After acidification to pH 6 with addition of concentrated HCl and subsequent partial concentration, crystals maybe formed at room temperature to afford α-amino-ε-caprolactam hydrochloride (36.5 g) in 74% yield.

Provenance & Evidence