CS195775B1 - Method for the separation of mixture of potassium chloride,potassium phthalimide,phthalimide,n-/cyclohexylthio/phthalimide,possibly with n-chlorphthalimide - Google Patents

Description

The invention relates to a process for separating a mixture of potassium chloride, potassium phthalimide, phthalimide, N- (cyclohexylthio) phthalimide, optionally with N-chlorophthalimide, and a solvent.

N- (cyclohexylthio) phthalimide is a vulcanization inhibitor for natural and synthetic rubbers, in the presence of the commonly used sulfenamide-type vulcanization accelerators, already at low concentrations, provides good processability and safety of the mixture by extending processing safety in the vulcanization vulcanization process while maintaining high speed.

N- (cyclohexylthio) phthalimide is prepared according to U.S. Pat. No. 178,735 by condensation of potassium phthalimide and cyclohexylsulphenyl chloride or according to No. 191,385 of potassium phthalimide, dicyclohexyldisulphide and chlorine in a carbon tetrachloride environment, wherein the molar ratio between dlcyclohexyldisulphide and 1 to potassium phthalimide is further selected; introducing into the mixture a chlorine solution in a molar ratio of disulfide to chlorine of 1 to 1 at 5 to 30 ° C for 60 minutes and further allowing the reaction mixture to react with stirring at 20 to 60 ° C for 30 to 180 minutes. The N- (cyclohexylthio) phthalimide is isolated from the reaction mixture by filtering off a solid phase containing predominantly potassium chloride and washing it with pure carbon tetrachloride, whereby N- (cyclohexyltlo) phthalimide is isolated from the filtrate after concentration by precipitation with a non-polar solvent.

The solid phase containing predominantly potassium chloride, which is obtained after filtration by cessation, is not further worked up. Its composition varies depending on the reaction technological conditions of condensation conduction.

It contains potassium chloride, which is the reaction product of the condensation of cyclohexylsulphenyl chloride and potassium phthalimide.

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4 and predominates in a concentration of 20 to 43% by weight. Another component of the solid phase is potassium phthalimide as an unreacted condensation component, which may be poorly soluble in the condensation environment used, its concentration in said mixture being in the range of 8 to 27% by weight. In addition to potassium phthalimide, the solid phase also contains phthalimide which is introduced into the reaction system prior to condensation as an impurity of the raw material - potassium phthalimide, its concentration is 1 to max. 9% by weight.

N-chlorophthalimide is another component of the mixture, which is often found in very small amounts in said mixture and is produced as a by-product of condensation. Its concentration did not exceed 0.3% by weight. The N- (cyclohexylthio) phthalimide formed by the condensation of potassium phthalimide and cyclohexylsulfenyl chloride should be completely dissolved in the solvent used, but some of the product precipitates and passes into the salt. The concentration of N- (cyclohexylthio) phthalimide in the solid mixture is dependent on solubility in the solvent used or in the solvent mixture. No. 191,385 removes N- (cyclohexylthio) phthalimide from this mixture by washing with pure solvent, passing into a solution from where it is isolated by precipitation. The solid phase after washing with pure organic solvent, containing sodium chloride, potassium phthalimide, phthalimide, N-chlorophthalimide and insoluble N- (cyclohexylthio) phthalimide, was not further processed. It also contains a part of the solvent that remains in the form of moisture in the filtered filter cake, its concentration was min. 5, max. 35% by weight.

These disadvantages are eliminated by a method of dividing · potassium chloride, phthalimide, potassium phthalimide, N- (cyclohexylthio) phthalimide, N-chlorophthalimide and a solvent, which is characterized in that a mixture comprising the above ingredients with water Temperature 10 to 40 ^D C. During washing, water the potassium chloride and potassium phthalimide are dissolved and the phthalimide, N-chlorophthalimide and N- (cyclohexylthio) phthalimide remain in the solid phase. Residues of the organic solvent in which the condensation has been carried out and which remain in the form of moisture in the filter cake are displaced into the filtrate. The organic solvent is separated from the filtrate, collected, collected, further dried and, after regeneration, used again for the production of N- (cyclohexylthio) phthalimide. Next, the solid phase obtained after washing with water is washed with a potassium hydroxide solution, where the phthalimide and N-chlorophthalimide are both in the form of both potassium phthalimide and potassium chloride to give a solid N- (cyclohexylthio) phthalimide. The two filtrates, the solutions obtained from the water wash and the potassium hydroxide wash, were combined, and hydrochloric acid was added to the solution until neutral to precipitate the phthalimide, which was further filtered to obtain a chloride solution. potassium.

Phthalimide, after crystallization, is used abbot in the technology of producing N- (cyclohexylthio) phthalimide.

The advantage of the process is that from the mixture consisting of potassium chloride, potassium phthalimide, phthalimide, N-chlorophthalimide and N- (cyclohexylthiophthalimide and part of the organic solvent, washing with water and further washing with potassium hydroxide solution gives N- (cyclohexylthio) phthalimide which was losses in the waste salt mixture.

Further, the phthalimide is recovered from the filtrate obtained from the washing of the mixture, which is reused after purification in the N- (cyclohexylthio) phthalimide production technology.

A further advantage is that waste hydrochloric acid produced in the process of producing N- (cyclohexylthio) phthalimide at the stage of oxidation of cyclohexylthiol by chlorine to dicyclohexyldisulphide can be used to neutralize the filtrate, possibly by direct chlorination of cyclohexylthiol in the production of cyclohexylsulphenyl chloride. a disulfide preparation step of phthalimide isolation and recovery.

The invention is applicable in the field of N- (cyclohexylthio) phthalimide production.

The process according to the invention is illustrated by the following non-exhaustive examples and the following scheme.

Example 1

After condensation of cyclohexylsulphenyl chloride and potassium phthalimide, a solid phase of 7.8 g of potassium phthalimide, 16.64 g of potassium chloride, 2.6 g of phthalimide, 11.7 g of N- (cyclohexylthio) phthalimide and 21 g of carbon tetrachloride was filtered off. The mixture was washed with water at 25 ° C with stirring, and both potassium chloride and potassium phthalimide were dissolved in the aqueous layer. At the same time, carbon tetrachloride was displaced from the solid phase. After washing with water, the organic layer containing wet carbon tetrachloride is separated from the filtrate for 2 hours. Solid Phase. and washed further with 300 ml of a 3% KOH solution while dissolving the phthalimide into the solution and leaving the wet frit of N- (cyclohexylthiophthalimide) which was further dried to give 11.2 g of N- (cyclohexylthio) phthalimide, mp 91-93 ° C.

The water wash filtrate was combined with the wash solution with potassium hydroxide solution and dilute hydrochloric acid was added to the resulting solution until the pH was neutral. Next, the filtrate was cooled to 10-14 ° C, phthalimide crystallized within 3 hours, filtered and dried. 7.8 g of phthalimide of m.p. 234 DEG C. were obtained.

6

Example 2

After the condensation was complete, the solid was filtered from the reaction mixture and dried by evaporating the solvent. The composition of the mixture was as follows: 13 g of potassium phthalimide, 21.5 g of potassium chloride; 3.35 g of phthalimide and 15 g of N- (cyclohexylthio) phthalimide, 0.1 g of N-chlorophthalimide. The mixture was washed with heated water at 35 ° C, whereupon potassium chloride and potassium phthalimide dissolved. The solid phase was further washed with 4% potassium chloride solution. The wet N- (cyclohexylthio) phthalimide remained on the filter and was dried (14 g, mp 91-93 ° C). The filtrate from the water wash and the filtrate from the wash with potassium hydroxide solution were combined and neutralized with dilute hydrochloric acid. After cooling and 3 hours, phthalimide was filtered off. 10.5 g of phthalimide of m.p. 234 DEG C. were obtained.

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Claims (3)

SUBJECT Process for separating a mixture of potassium chloride, potassium phthalimide, phthalimide, N- (cyclohexylthio) phthalimide, optionally with N-chlorophthalimide and a solvent, characterized in that a mixture of potassium phthalimide, phthalimide, potassium chloride, N- (cyclohexylthio) phthalimide and N- the chlorophthalimide is washed with water at 10 to 40 ° C, with potassium phthalimide and potassium chloride going into solution and the phthalimide, N-chlorophthalimide is further washed with potassium hydroxide solution to give a solid N- (cyclohexylthio) phthalimide and the phthalimide is passed into the solution and N-chlorophthalimide in the form of potassium phthalimide and potassium chloride, and the two solutions obtained from washing the mixture with water and washing with a solution of the potassium hydroxide solution of the invention, and thereafter adding hydrochloric acid to this solution until the phthalimide is precipitated. is filtered off and a potassium chloride solution is obtained. 2. A method according to claim 1, wherein washing the mixture with water displaces the organic solvent remaining in the form of moisture in the mixture after filtration, phase separation from the filtrate and regenerating. 3. A process as claimed in claim 1 or claim 2, wherein the filtrate is neutralized by using waste hydrochloric acid, preferably from the production of N- (cyclohexylthio) phthalimide and cyclohexylsulphenyl chloride, respectively.