Sulfuric Acid → 1,3,5,7-Naphthalenetetrasulfonic acid

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Reaction Steps

To 100 ml of 30% fuming sulfuric acid at 200° C., is added 25 g of 1,5-naphthalenedisulfonic acid disodium salt. The mixture is refluxed at 180°-185° C. for 18 hours then cooled to 50°-60° C. and filtered, giving 25.6 g of 1,3,5,7-naphthalenetetrasulfonic acid as a tan solid. The entire 25.6 g is added to 200 ml of thionyl chloride and then 2.0 ml of dimethylformamide are added. The mixture is warmed gently until hydrogen chloride is evolved, then heated until bubbling, then allowed to stand at room temperature for 13/4 hours and finally refluxed for 3 hours. The mixture is filtered while warm and the filtrate is evaporated to 20 ml. The solid is collected by filtration and washed with dichloromethane and ether, giving 3.0 g of 1,3,5,7-naphthalenetetrasulfonyl chloride as a colorless powder.

Provenance & Evidence