CS239400B1 - Process for producing potassium phthalimide - Google Patents

Abstract

The subject of the invention is a method for producing potassium phthalimide by reacting crystalline phthalimide with a heated saturated solution of potassium hydroxide in a polar solvent, e.g. at a temperature of Θ0 °C, while the reaction mixture is further refluxed, then cooled, potassium phthalimide is isolated from the solvent, which, after regeneration, is used again in the production of potassium phthalimide.

Description

One of the basic raw materials in various organic syntheses is potassium phthalimide. For example, it is used as an intermediate in the production of N-substituted thiophthalimides which are used as vulcanization retarders.

Potassium phthalimide is prepared by treating potassium phthalimide with potassium hydroxide or as a Gabrile reaction. The Gabriel reaction can also be used in the preparation of 1,4-diaminobutane, where potassium phthalimide is obtained as an intermediate.

Potassium phthalimide can also be obtained as an intermediate in the production of procainamide hydrochloride, or as a condensation product of a primary amine and phthalic anhydride.

In addition to the above mentioned methods of preparation, Landsberg discloses the preparation of the sodium and potassium salts of phthalimide by the action of sodium or potassium ethanolate on phthalimide.

Said methods of preparation do not give satisfactory yields. The use of ethanolic hydroxide solutions of said metals leads in each case to the use of large volumes of solvents, which is a considerable energy-intensive process for their regeneration.

It has now been found that the above disadvantages can be overcome according to the present invention, which is based on dissolving potassium hydroxide in a minimum amount of a polar solvent, preparing a saturated solution, for example at 60 ° C. Solid crystalline phthalimide in molar is added to the saturated solution thus prepared

0 to KOH 1 to 1.0 to 1.2. The reaction mixture was refluxed for 10 to 120 minutes, further cooled. The potassium phthalimide is isolated from the solvent, dried and analyzed.

After regeneration, the solvent is used to produce potassium phthalimide. The polar solvent may be, for example, methanol, ethanol, isopropanol, n-propanol, isobutanol, amyl alcohol, cyclohexanol, cyclohexanone and the like.

The following examples illustrate the invention.

EXAMPLE

4.6 g of KOH was charged to 130 ml of isobutanol and heated to 60 degrees Celsius. 8 g of phthalimide were added with stirring over 60 minutes, and the lukewarm mixture was refluxed at boiling point. After cooling, potassium phthalimide was filtered off, washed with pure isopropanol and dried. 9.9 g of potassium phthalimide were obtained, which represents a 96.5% yield.

Example 2

4.6 grams of KOH were charged to 130 mL of isobutanol, the mixture was heated to 60 ° C, and 8 g of phthalimide was added with stirring. The reaction mixture was refluxed at the boiling point of the solvent for 1-2 hours. After cooling, potassium phthalimide was isolated by filtration. After drying, 9.95 g of potassium phthalimide was obtained, which is 100% yield.

Claims (1)

SUBJECT Process for producing potassium phthalimide by reacting phthalimide and potassium hydroxide, characterized in that the potassium hydroxide is dissolved in a minimum amount of a polar solvent and forms a saturated solution at a temperature close to the boiling point of the solvent. 1.0 to 1.2, the reaction mixture is refluxed for 10 to 120 minutes and after cooling, potassium phthalimide is isolated from the solvent, which is used after regeneration