4-Fluoro-2,1,3-benzoxadiazole → 4-(Chlorosulfonyl)-7-fluoro-2,1,3-benzoxadiazole

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Reaction Steps

3.0 g of 7-fluoro-2,1,3-benzoxadiazole were dissolved in 10 ml of chloroform and then 11.0 ml of chlorosulfonate at 0° C. were dripped into the solution. After reacting at room temperature for one hour, the solution was stirred and reacted for an additional two hours. Next, the reaction solution was transferred to 200 g of ice water, and extracted with chloroform very quickly. The extract was then water washed and dried with magnesium sulfate before filtering. The filtrate was then reduced pressure concentrated. The remaining extract was subjected to silica gel column chromatography (chloroform as mobile phase; 2 cm×60 cm) in 5 ml fractions. The respective fractions were analyzed using thin layer chromatography (silica gel, chloroform). The fraction having an Rf value of about 0.5 was then collected and reduced pressure concentrated. 4.0 g of a pale brown needle-shaped crystalline substance with a melting point of between 64° and 66° C. were obtained.

Provenance & Evidence