The general procedure for the synthesis of 5-chloro-1-methylimidazole from N,N'-dimethyl oxalamide was as follows: phosphorus pentachloride (383.2 g, 1.8 mol) was added to N,N'-dimethyl oxalamide (116.1 g, 1.0 mol), and heated to 60 °C to form a melt with foam generation. Subsequently, the reaction mixture was stirred at 85-95 °C for 2 h, and then distilled to remove the resulting POCl3. The dark brown residue was dissolved in 700 mL of water and adjusted to pH 8 with 915 g of 12.75% KOH solution. The aqueous phase was extracted four times with 500 mL of dichloromethane (DCM), and the organic extracts were combined and dried over sodium sulfate. After concentration under reduced pressure, the resulting reddish brown liquid was vacuum distilled to give 5-chloro-1-methylimidazole (53.1 g, 46% yield) as a colorless liquid. The product properties were as follows: flash point 85-86 °C (22 mbar); 1H NMR (400 MHz, d6-DMSO) δ 7.33 (s, 1H, 4-H), 6.80 (s, 1H, 2-H), 3.47 (s, 3H, CH3); 13C NMR (100 MHz, d6-DMSO) δ 137.4 (C-2), 126.0 (C -4), 118.4 (C-5), 31.6 (CH3).
