Chlorosuccinimide → Alpha-chlorobenzaldoxime

Participants

Reaction Steps

To a colorless, homogeneous solution of (E)-benzaldehyde oxime (24.4 g, 201 mmol) in N,N-dimethylformamide (60 mL) at room temperature was added N-chlorosuccinimide (26.9 g, 201 mmol) portion-wise over 30 min. During each addition, the reaction mixture became yellow and then gradually returned to near colorlessness. Additionally, an exotherm was noted with each portion added. (It was extremely important to make sure the reaction initiates after the addition of the first ˜⅕ of the NCS; an ice-bath was readily available.) After the addition was complete, the homogeneous reaction mixture was stirred overnight at room temperature. The reaction mixture was diluted with 250 mL of water and extracted with ether (3×100 mL). The organic layers were combined, washed with water (2×100 mL), washed with a 10% aqueous solution of lithium chloride (2×100 mL), and washed with brine (100 mL). The aqueous layers were back extracted with ether (100 mL), and the combined organic layers (400 mL) were dried over anhydrous sodium sulfate. Concentration under reduced pressure afforded (Z)—N-hydroxybenzimidoyl chloride (30.84 g, 198 mmol, 98% yield) as a fluffy, pale yellow solid. The product had an HPLC ret. time=1.57 min.—Column: CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=155.8. 1H NMR (500 MHz, DMSO-d6) δ ppm 7.30-7.64 (m, 3H), 7.73-7.87 (m, 2H), and 12.42 (s, 1H).

Provenance & Evidence