Synthesis
General procedure for the synthesis of 2-acetylaminobutyric acid from ethanoic anhydride and DL-2-aminobutyric acid:
1. dissolve 163 g (1.58 mol) of DL-2-aminobutyric acid in an appropriate amount of acetic acid.
2. 242 g (2.37 mol) of acetic anhydride was added slowly and dropwise to the above solution.
3. the reaction mixture was stirred continuously at 100 °C for 2 hours until the reaction was complete.
4. After completion of the reaction, the solvent was removed by vacuum evaporation to give a solid residue.
5. The solid residue was suspended in ethyl acetate and filtered.
6. The filter cake was washed with ether to remove unreacted raw materials and by-products.
7. The target product 2-acetylaminobutyric acid was obtained after drying in a yield of 220 g (95.9% yield).
Product characterization data: 1H-NMR (methanol-d4) δ/ppm 0.97 (t, 3H), 1.65-1.93 (m, 2H), 1.99 (s, 3H), 4.29 (q, 1H).
References
[1] Patent: WO2003/93268, 2003, A1. Location in patent: Page/Page column 25
[2] Patent: WO2003/93270, 2003, A1. Location in patent: Page/Page column 21
[3] Patent: WO2003/97645, 2003, A1. Location in patent: Page/Page column 26
[4] Biochemical Journal, 1939, vol. 33, p. 1915
[5] Journal of Physical Chemistry, 1984, vol. 88, # 1, p. 86 - 92
