The general procedure for the synthesis of isobutylamine hydrochloride from L-valine is as follows: a magnetic stirring bar, 3 mL of n-propanol (n-PrOH), 10 mmol of R-carvone and 5 mmol of L-valine were added to a pressure vessel. The vessel was heated from room temperature to 190 °C in 5 min under stirring conditions. If the reaction mixture was slurry-like, it was continued at 190°C until the solution became clear. After the vessel was cooled below the boiling point of the solvent, it was carefully vented to release the generated CO2. Subsequently, 10 mL of 2M hydrochloric acid (HCl) was added to the vessel and the vessel was again heated to 190 °C in 5 min under stirring and then cooled. The aqueous reaction mixture was washed three times with 25 mL of ether and the aqueous solvent was removed by distillation to give the hydrochloride product. The hydrochloride was transferred to a vacuum oven and dried overnight at 150 °C and 10 Torr pressure. Finally, the hydrochloride product was weighed and analyzed by infrared spectroscopy (IR) and nuclear magnetic resonance (NMR).The NMR data of 2-methylpropan-1-amine hydrochloride were as follows: δH 0.83 (6H, d, J = 4 Hz), 1.79 (1H, m, J = 8 Hz), 2.69 (2H, d, J = 8 Hz); δC 18.8, 26.2, 46.3.
