CS239399B1 - Process for producing potassium phthalimide - Google Patents

Abstract

The subject of the invention is a method of producing potassium phthalimide by the reaction of dissolved phthalimide in a polar solvent at the boiling temperature of the solvent, and potassium hydroxide or its saturated solution at the boiling temperature of the solvent is added to this saturated solution at the boiling temperature of the solvent, benzene is then added, and the mixture is refluxed for 1 to 2 hours while azeotropically removing the reaction water together with benzene. Further, after cooling, the potassium phthalimide is isolated from the solvent, which is recycled back into the production process.

Description

The present invention provides a process for producing potassium phthalimide by reacting dissolved phthalimide in a polar solvent at the boiling point of the solvent and adding potassium hydroxide or a saturated solution thereof to the saturated solution at the boiling point of the solvent, further adding benzene, refluxing the mixture. up to 2 hours under azeotropic removal of the reaction water together with benzene. Further, after cooling, potassium phthalimide is isolated from the solvent that is recycled to the production process. 239399 239399

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

Potassium phthalimide is prepared by the action of potassium hydroxide on phthalimide or according to Gabriel's reaction. The Gabriel reaction can also be used to prepare 1,4-diaminobutane where potassium phthalimide is obtained as an intermediate.

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

In addition to the above mentioned processes, Landsberg discloses the preparation of the sodium and potassium salts of phthalimide by the action of sodium or potassium ethanolate on phthalimide. According to Hammick, good yields of sodium and potassium phthalimide were achieved using sodium or potassium amyloxide in the amyl alcohol.

Said preparation methods do not give satisfactory extracts. The use of ethanolic solutions of the hydroxides of the metals in each case leads to the use of large volumes of solvents, which is considerably energy intensive in their regeneration.

It has now been found that the above drawbacks can be overcome by the present invention, wherein the phthalimide is dissolved into a saturated solution in a polar solvent at the boiling point of the solvent. To the thus heated saturated solution is added a solution of KOH in a polar solvent at the boiling point of the solvent or directly KOH. The molar ratio between phthaleneidoin and KOIT is 1 to 1 to 1.2. After mixing, benzene is added to the mixture. The mixture is refluxed for 1-2 hours while azeotroping the reaction water. After cooling, potassium phthalimide is isolated from the solvent that is recycled to sleep in the potassium phthalimide process; The polar solvent may be, for example, ethanol, isopropanol, n-propanol, isobutanol, cyclohexanol, cyclohexanone, n-isobutanol, amyl alcohol. The following examples illustrate the invention. Example 1 17.7 g of phthalimide was dissolved in 225 ml of ethanol at 50 ° C. Next, an ethanolic KOH solution was prepared by dissolving 8.8 grams of KOH in 64 ml of ethanol at 50 ° C. Hot solutions were blended together and 15 ml of benign was added. The reaction mixture was refluxed in a three-necked flask equipped with a thermometer and a sizing column filled with Raschig pads. A binary mixture of water-benzene was collected at the head of the sizing column and the aqueous layer was drained. After removal of the water, the solid phase was isolated, washed with alcohol and dried. 17.65 g of potassium phthalimide was obtained, which represents 95.5% yield. The analyzed potassium phthalimide contained 19.4% potassium and 7.06 nitrogen. Example 2 The same procedure as in Example 1 was followed, only the phthalimide potassium filtrate was used as the solvent for phthalimide: KOIT.

Claims (1)

SUBJECT Process for producing potassium phthalimide by reacting phthalimide and potassium hydroxide, characterized in that the phthalimide is dissolved in a polar solvent to a saturated solution at the boiling point of the solvent, an equivalent amount of KOH or dissolved KOH in the polar solvent is added. benzene, the mixture is refluxed for 1 to 2 hours, while azeotropically removing the reaction water along with benzene from the reaction mixture, after cooling, the potassium phthalimide is isolated from the solvent, which is recycled back to the production process.