Iodine → 2,4-Dichloro-5-iodobenzoic acid

Beteiligte Stoffe

Reaktionsschritte

Sodium iodate (4.4 g) and iodine (11.1 g) were added to 90% sulfuric acid (330 ml) and stirred at room temperature for 8 hours. Commercially available 2,4-dichlorobenzoic acid (21 g) was added and stirred at the same temperature for 24 hours. The reaction solution was poured onto ice water (3 l), and the precipitated solid material was separated by filtration. The solid material was then washed with water, and dried under reduced pressure. 2,4-Dichloro-5-iodobenzoic acid (16.8 g) was obtained by recrystallization (acetic acid-water). 2,4-Dichloro-5-iodobenzoic acid (2 g) was dissolved in dichloromethane (20 ml) and methanol (20 ml), and trimethylsilyldiazomethane (2 M; n-hexane solution) was added dropwise thereto until the solution became yellow. After a small amount of acetic acid was added, the mixture was concentrated under reduced pressure. The resulting residue was recrystallized from n-hexane to yield the title compound 2,4-dichloro-5-iodobenzoic acid methyl ester (2 g) as a white solid.

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