n an ice-bathed round bottom flask were introduced glutamic acid (2.93 g, 20 mmol), NaBr (0.21 g, 10 mol%), and 50 mL H2O. NaOCl solution (15 wt% in
H2O, 24.8 mL, 60 mmol) was added dropwise under a good stirring (for each drop of NaOCl solution, the reaction mixture turned orange and
a strong CO2 evolution was observed while the coloration disappeared). After 1 hour stirring at 4 oC the reaction mixture was carefully
quenched with Na2S2O3.5H2O. NaCl was then added till saturation and the reaction mixture was extracted with Et2O (4 x 30 mL). The
collected organic layers were dried over MgSO4 and evaporated to dryness. 1H NMR analysis of the crude showed 3-cyanopropanoic acid (5,
850 mg, 43% yield) as the major product and the corresponding aldehyde as a minor product (85% purity). A 94% purity towards 3-cyanopropanoic acid (5)
was obtained after one recrystallisation in Et2O. An alternative work-up procedure consisted in evaporating the water after reaction and
quenching. The resulting paste was extracted with Et2O (4 x 30 mL), the collected organic layers were dried over MgSO4 and evaporated to
dryness. NMR analyses of the crude showed 3-cyanopropanoic acid (5, 1.39 g, 70% yield, 90% purity). |
