Patent ID: 8080671

Claim:
A process for isolating 4-nitro-N-alkylphthalimide from an aqueous mixture of 4-nitro-N-alkylphthalimide and 3-nitro-N-alkylphthalimide comprising the steps of: (a) providing a first mixture comprising (i) solids comprising 4-nitro-N-alkylphthalimide and 3-nitro-N-alkylphthalimide and (ii) water; (b) adding a salt selected from the group consisting of alkali metal carbonates, alkali metal hydrogen carbonates, alkaline earth metal carbonates, hydrogen carbonates and mixtures thereof to the first mixture, thereby forming a second mixture; (c) stirring the second mixture under conditions sufficient for selective hydrolysis of the imide linkage of 3-nitro-N-alkylphthalimide into a water-soluble acid-amide salt of 3-nitro-N-alkylphthalimide, thereby forming a third mixture; (d) adding an organic solvent to the third mixture, thereby forming a fourth mixture comprising (i) an organic phase comprising 4-nitro-N-alkylphthalimide dissolved in the organic solvent and (ii) an aqueous phase comprising dissolved acid-amide salt of 3-nitro-N-alkylphthalimide; and (e) separating the organic phase from the aqueous phase.