1,3,6-Naphthalenetrisulfonic acid, 8-amino-, sodium salt (1:?) → 8-(3-Nitro-2-sulfobenzamido)-1,3,6-naphthalene trisulfonic acid tetrasodium salt

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Reaction Steps

To a solution of 20.0 g of 8-amino-1,3,6-naphthalenetrisulfonic acid trisodium salt and 8.75 g of sodium acetate trihydrate in 180 ml of water at room temperature is added 12.0 g of 3-nitrosulfobenzoic anhydride with stirring. A 400 ml portion of water is added. The mixture is stirred at room temperature for 21/2 hours and then filtered. The filtrate is cooled, acidified with 2-3 ml of concentrated hydrochloric acid an diluted with ethanol. The pink solid is collected by filtration, washed with 85% ethanol, ether and dried. The filtrate is concentrated to a low volume and diluted with ethanol giving a second crop which is collected and combined with the first crop giving a total of 27.6 g of 8-(3-nitro-2-sulfobenzamido)-1,3,6-naphthalene trisulfonic acid tetrasodium salt.

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