Sulfuric Acid → 1-Chloroisoquinoline-5-sulfonic acid

Participants

Reaction Steps

145 g of 1-Chloroisoquinoline was dropwise added to 500 g of 60% fuming sulfuric acid while cooling with ice. Then, the temperature was elevated to 80° C. and the reaction was effected while stirring for 18 hours. The obtained reaction mixture was added to 1 kg of ice water, followed by stirring for 2 hours at 5° C. to precipitate crystals. The thus obtained crystals were separated by filtration, washed with 100 ml of methanol and then with 100 ml of ether, and dried under reduced pressure to obtain 126 g of 1-chloro-5-isoquinolinesulfonic acid. The compound was analyzed to give the following data.

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