Purification of 2-nitro-4-methylsulphonylbenzoic acid

一种从2-硝基-4-甲磺酰基苯甲酸中除去杂质的方法，所述方法包括至少两个以下任意顺序的步骤：(a)将2-硝基-4-甲磺酰基苯甲酸溶解在pH值约为2至10的水中，随后过滤；(b)在pH值约为2至10下，使2-硝基-4-甲磺酰基苯甲酸的水溶液与活性炭接触；(c)用足量的碱处理2-硝基-4-甲磺酰基苯甲酸的水溶液，水解不需要的硝基和二硝基取代的杂质；随后将所得的含有2-硝基-4-甲磺酰基苯甲酸的水溶液保持在最高可达约95℃的温度下，并且调节所述溶液的pH值至约为在冷却的情况下足于使2-硝基-4-甲磺酰基苯甲酸发生结晶的pH值。 A method for removing impurities from 2-nitro-4-methylsulfonylbenzoic acid which comprises at least two of the following steps, in any order, (a) dissolving 2-nitro-4-methylsulfonylbenzoic acid in water at a pH of about 2 to 10, followed by filtration; (b) contacting an aqueous solution of 2-nitro-4-methylsulfonylberizoic acid with activated carbon at a pH of about 2 to 10; (c) treating an aqueous solution of 2-nitro-4-methylsulfonylbenzoic acid with sufficient base to hydrolyze undesired nitro and dinitro substituted impurities; followed by maintaining the resulting aqueous solution comprising 2-nitro-4-methylsulfonylbenzoic acid at a temperature of up to about 95° C., and adjusting the pH of said solution to about a pH which is sufficient to effect crystallization of 2-nitro-4-methylsulfonylbenzoic acid upon cooling.