A METHOD OF ISOLATING A N-(3-NITROBENZOYL)SULFAMIDE

The presently claimed invention relates to an improved method of isolating 3-nitrobenzenesulfonamide of formula IIn the 3-nitrobenzenesulfonamide of formula I, R1and R2each independently of one another substituted or unsubstituted, linear or branched C1-C8-alkyl; substituted or unsubstituted C3-C8-cycloalkyl; or R1and R2together with the atom to which they are bonded form a 5-, 6-, 7- or 8-membered substituted or unsubstituted, saturated or unsaturated heterocyclic ring which contains 1 or 2 further heteroatoms selected from the group consisting of O and S. The isolation of the 3-nitrobenzenesulfonamide of the formula I from a reaction mixture is performed by acidifying the reaction mixture, separating and washing an organic phase from the acidified reaction mixture to obtain a washed organic phase, obtaining a concentrated organic phase by concentrating a washed organic phase, cooling the concentrated organic phase to obtain a suspension and isolating the 3-nitrobenzenesulfonamide of the formula (I) from the suspension.