Hydrochloric Acid → Ethyl 1,3-benzothiazole-2-carboxylate

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Reaction Steps

A solution of 2-aminothiophenol (10.7 mL, 0.1 mol) in diethyl oxalate (27.3 mL, 0.2 mol) is heated at reflux for 4 hr. The solution is cooled to rt and poured into a solution consisting of water (150 mL), conc. HCl (50 mL) and 95% EtOH (70 mL). With stirring, the oil dissolved and a solid formed. The solution is cooled in an ice bath, the solid is collected by vacuum filtration and the solids are washed with a solution consisting of EtOH/water (25/75) to afford a dark solid. This material is purified by crystallization from hot (68° C.) ligroin to yield ethyl 2-benzothiazolecarboxylate (7.5 g, 36%): Elemental analysis for C10H9NO2S: Calc: C, 57.95; H, 4.38; N, 6.76. Found: C, 57.99; H, 4.28; N, 6.78.

Provenance & Evidence