Hydrochloric Acid → 2-(Aminosulfonyl)-4-iodobenzoic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

1000 g (4.34 mol) of methyl 4-amino-2-aminosulfonylbenzoate and 3400 ml of H2O are admixed rapidly with 3700 ml of concentrated hydrochloric acid (37% strength). 10 ml of toluene are added to this mixture. The mixture is cooled to 15° C. and a solution of 315 g of NaNO2 (4.56 mol) in 1740 ml of H2O is added within a period of 1 h (h=hour) at 15-20° C. Stirring is continued for 1 h and the excess of nitrite is destroyed using amidosulfonic acid. In a second vessel, 1082 g of potassium iodide (6.51 mol) and 7000 ml of H2O are initially charged. At 15 to 20° C., the diazonium salt solution is added over a period of 1 to 2 h. The resulting suspension is diluted with 10 liters of H2O and the precipitate is filtered off with suction. The filter cake is then washed free of iodine using a mixture of 435 g of Na2S2O5 in 8.5 liters of H2O, and then washed neutral with 25 liters of H2O. The compound of the formula (IV) is obtained in a quantity of 1771 g (moist). After drying at 50° C. in vacuo (=under reduced pressure), 1403 g (94.8% of theory) of methyl 4-iodo-2- aminosulfonylbenzoate (sulfonamide of the formula IV) of a melting point of 175-177° C. are obtained.

Provenance & Evidence