In a 1 l flask with paddle stirrer, internal thermometer and reflux condenser, 142.6 g (1 mol) of 2-azacyclononanone and 110 g (1 mol) of about 36 wt.-% sodium hydroxide solution are boiled under reflux for 4 hours. The solution is subsequently cooled to about 80 °C and mixed with Lewatit SP-112?. After one hour, the acidic ion exchanger is filtered. 500 g of 2-Propanol is added dropwise to the mixture at 80 °C, and the homogeneous solution is slowly cooled to -5 °C. The precipitated solid is filtered and washed with 50 g of 2-propanol. After drying at 85 °C and 20 mbar, 8-Aminooctanoic acid is obtained as a fine colorless powder. A colorless powder. Yield: 127 g (80%). Melting point: 191-193 °C (Lit.: 194 °C).