Iodine → 4-Isothiocyanatobenzoic acid

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Reaction Steps

A mixture comprising 4-aminobenzoic acid (0.20 g, 1.5 mmol), dioxane (5 mL), a saturated sodium hydrogencarbonate aqueous solution (5 mL) and carbon disulfide (0.37 mL, 6.1 mmol) was stirred in a nitrogen atmosphere at room temperature for 19 hours and then concentrated under reduced pressure to dryness. The obtained residue was dissolved in water (8.0 mL), and 1M sodium hydroxide aqueous solution (1.5 mL) was added. With stirring at room temperature, an ethanol (8.0 mL) solution of iodine (0.38 g, 1.5 mmol) was dropwise added thereto over a period of 8 minutes, followed by stirring at room temperature for further 12 minutes. Then, the insoluble matter was removed by filtration. The filtrate was concentrated under reduced pressure to remove ethanol and dioxane as far as possible. Then, 1M hydrochloric acid (4.5 mL) was added, and the precipitated solid was collected by filtration to obtain 4-isothiocyanatobenzoic acid as a ocher solid (0.20 g, yield: 78%). The HPLC purity was 62%.

Provenance & Evidence