Acetyl chloride → 2-Methyl-1-phenyl-1H-benzimidazole-5-carboxylic acid

참여 물질

반응 단계

A 2-neck flask was charged with 3-amino-4-phenylaminobenzoic acid (see Synthesis Example 1-2) (1.40 g, 6.35 mmol) and anhydrous toluene (15 mL) and this was refluxed. To this was added dropwise over approx. 15 minutes acetyl chloride (1.00 g, 12.70 mmol) in toluene solution (approx. 2.5 mL), and this was stirred under these conditions for 2.5 hours. This was allowed to cool to room temperature, and was extracted with dilute aqueous sodium hydroxide solution (10%, 200 mL). After separating the dark orange aqueous layer, it was cooled in ice (5 to 10° C.), and concentrated hydrochloric acid (12 M) was added to the liquid to give approx. pH 4. The precipitated crystals were filtered off, washed with distilled water, and dried under reduced pressure with heating to yield the title compound (1.34 g, 83.5% yield) as a light purple solid.

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