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Multi-step reaction with 2 steps
1.1: N-ethyl-N,N-diisopropylamine / toluene / 0.17 h / 20 °C
1.2: 0.17 h / 20 °C
1.3: 4 h / 20 °C
2.1: O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate / toluene / 3 h / Reflux
With choline chloride; oxalic acid at 30℃; for 7h;
3 Synthesis of 2-n-octylbenzimidazole
To the eutectic solvent (70g) composed of choline chloride and oxalic acid (molar ratio 1:2), add o-phenylenediamine (54g, 0.5mol) and n-nonanal (85g, 0.6mol) at 30°C React at constant temperature for 7 hours (use silica gel chromatography (TLC) to monitor the reaction).After the reaction is completed, cold water (400 mL) is added, the precipitated solid is filtered, washed with water, and dried.The crude product was recrystallized with ethanol to obtain off-white crystals (90 g) with a yield of 86%.
51.7%
With sodium hydrogensulfite In N,N-dimethyl acetamide at 100℃; for 2h;
Stage #1: 1-nonyne; 1,2-diamino-benzene With copper(l) iodide; 4-toluenesulfonyl azide; triethylamine In acetonitrile at 20℃; for 6h; Inert atmosphere;
Stage #2: With sulfuric acid In acetonitrile for 4h; Reflux;