CS202425B1 - Method of preparing stable solutions of mixture of cyclohexanone peroxides and methyl-cyclohexanone peroxides - Google Patents

Description

The invention relates to a process for the production of stable ketone peroxide solutions from a mixture of cyclohexanone, methylcyclohexanone and hydrogen peroxide. The solutions obtained are used primarily as polymerization initiators in the processing of unsaturated polyester resins and compositions based thereon.

The production of ketone peroxides is based on conventional aliphatic or cycloaliphatic ketones such as methyl ethyl ketone, methyl isobutyl ketone, methylcyclohexanone or oyclohexanone. Individual ketones are reacted with hydrogen peroxide as a rule under mineral acid catalysis and, depending on the nature of ketone peroxide, the organic peroxide is separated from the aqueous phase by filtration or other means, optionally dried and modified with Si plasticizers to pastes or solutions. reaction, which entails problems and difficulties in the preparation and further processing of crystalline products, including the actual application in polyester compositions. Crystalline cyclohexanone peroxides are difficult to dissolve, readily precipitate from solutions and are explosive when dry. Methylcyclohexanone types of peroxides are almost always poorly defined mixtures of individual isomers of quite different properties, which is one of the causes of different initiation activity and different stability of these peroxides.

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The present invention is directed to a process for preparing stable solutions of a mixture of oyclohexanone peroxides and methylcyclohexanone peroxides by reacting cyclohexanone and methylcyclohexanone with hydrogen peroxide. The principle of the present invention is that at an initial temperature of -5 to 30 [deg.] C. and, optionally, up to 8 wt. % of concentrated sulfuric acid and / or nitric acid and / or phosphoric acid, based on the aspen weight of the feed, to the mixture of oyclohexanone and methylcyclohexanone in wt. a ratio of 0.2 to 3: 1 adds a 25 to 40% aqueous hydrogen peroxide solution over a period of 10 to 60 minutes in an amount such that the molar ratio of ketones to hydrogen peroxide is 1: 2 to 4: 1 so that the temperature does not exceed Deň: 32 ° C. After delivery of the hydrogen peroxide solution, the reaction mixture is optionally maintained at a temperature between 25 ° C and 45 ° C for a maximum of 120 minutes. 5 to 15 wt. % of mineral acid salt with a minimum solubility of 5 g / l, the separated organic phase is mixed and 0.5 to 5 wt. The solid particles are removed and either the peroxides isolated / are not diluted with a trialkyl phosphate and / or cycloaliphatic ketones to a 20-80% solution, or that these solvents are already added in corresponding amounts to the mixture of the starting ketones before reacting with the solids. hydrogen peroxide. The final product ee is then optionally stabilized by the addition of up to 3 wt. %, based on xj and the weight of the solution, hydrogen peroxide (calculated as 100%) and / or 0.05 to 0.5 wt. % of heterooyclic substances β 1 to 3 of the Duo atoms per molecule and / or tertiary aliphatic amines. Preferably, a hydrogen peroxide solution of pH 7 and a mixture of its isomers containing not more than 10 wt. % ortho-isomer.

In preparing ae, it usually uses a reaction boiler with the possibility of cooling or heating the reaction mixture with a suitable medium. The inner walls of the boiler are preferably enamelled as well as the surface of the agitator. The agitator is propeller, but other shapes of agitators may be used to provide sufficient agitation of the reaction mixture. The actual peroxidation is preferably carried out at temperatures of 30 to 35 ° C. For the preparation of stable solutions of ketone peroxides, it is appropriate to use a mixture of methylcyclohexanone having a low ortho-isomer content, the ketone content being determined to be not less than 75%. Peroxidaol can be carried out in the above-mentioned solvents such as triethyl phosphate, thus eliminating the additional dilution of the ketone peroxides to the desired consistency.

In this way, ee will prepare stable solutions of ketone peroxides suitable as curing initiators of unsaturated polyester resin compositions, which solutions maintain a constant initiation activity for a long time and are easy to dispense. This eliminates the difficult isolation and eucleation of crystalline types of cyclohexanone peroxides, which also increases the safety of the handling of these substances.

Example 1

190 wt. parts of cyclohexanone and 250 wt. parts of methylcyclohexanone.

While stirring, ee adds 372 wt. of hydrogen peroxide (35%) and concentrated sulfuric acid (1.8 ml) to maintain the reaction mixture temperature at 25-30 ° C.

After the hydrogen peroxide dosing is complete, the reaction mixture is stirred for a further 1 hour and then the mass is added. of sodium sulfate, stirred vigorously for 10 minutes and formed

The organic phase is dried by adding 53 wt. parts of calcined sodium sulfate for 15 minutes. After filtration, the filtrate is diluted with 500 parts by weight of triethylfoaphate and 150 ml of 80% hydrogen peroxide and 0.2% by weight of ethyl acetate are added. % piperazine.

Example 2 /

100 wt. parts of cyclohexanone and 300 wt. 200 parts by weight of methylcyclohexanone are added and stirring is continued. parts of 35% hydrogen peroxide previously neutralized to pH > 7 such that the reaction temperature of the mixture was maintained at 30-35 ° C. After the addition of hydrogen peroxide, the reaction was stirred for a further 2 hours, maintaining the temperature between 30 and 35 ° C. 10 wt. parts of sodium sulfate and 5 wt. parts of potassium chloride, the organic phase is separated and further dried by addition of 46 wt. parts of kaleinated sodium sulfate. After separation of the organic peroxide, this is diluted with 300 wt. parts by weight of cyclohexanone and 100 wt. parts of triethyl phosphate in which 1.6 wt. % of 2- (2-hydroxymethyl) benztriazole.

Example 3

150 wt. parts of cyclohexanone and 50 wt. parts by weight of methylcyclohexanone and 100 wt. parts of triethyl phosphate. The mixture was cooled to 10 ° C and a mixture of 400 ml of 35% hydrogen peroxide and 48 wt. of concentrated nitric acid such that the temperature of the reaction mixture did not exceed 35 ° C. After the dosing is complete, the mixture is allowed to react for 20 minutes and 40 wt. parts of sodium sulfate. After separation of the layers, 100 wt. 2.5 parts by weight of organic layer were added. After stirring, the ketone peroxide solution is separated and treated with 5 wt. parts of 35% hydrogen peroxide.

Claims (3)

Process for the preparation of stable solutions of a mixture of cyclohexanone peroxides and methylcyclohexanone peroxides by reaction of a mixture of cyclohexanone and methylcyclohexanone with β hydrogen peroxide, characterized in that at an initial temperature of -5 to 30 ° C and up to 8 wt. % of concentrated sulfuric acid and / or nitric acid and / or phosphoric acid, based on the total weight of the batch, to a mixture of cyclohexanone with methylcyclohexanone in a wt. a ratio of 0.2 to 3 s 1 adds a 25 to 40% aqueous hydrogen peroxide solution over a period of 10 to 60 minutes in an amount such that the molar ratio of ketones and hydrogen peroxide is 1: 2 to 4: 1 so that the temperature does not exceed 50 ° C, whereby after the hydrogen peroxide solution is supplied, the reaction mixture temperature is maintained between 25 and 45 ° C for a maximum of 120 minutes, then 5 to 15 wt. % of the mineral acid salt β with a minimum solubility of 5 g / l, the separated organic phase being mixed with 0.5 to 5 wt. 50% of the solid dehydratinating agent, after a maximum of 50 minutes, the solid particles are removed and either the peroxides thus isolated are diluted with trlalkyl phosphate and / or cycloaliphatic ketones to a 20 to 80% solution or these solvents are added to the mixture in corresponding amounts. Of the 42 ketones prior to reaction and hydrogen peroxide, the final product is optionally stabilized by the addition of up to 3 wt. %, based on the weight of the solution, of hydrogen peroxide per 100% concentration, and / or 0.05 to 0.5% by weight of the heterooyl and 1 to 3 nitrogen atoms per molecule and / or tertiary aliphatic amines. 2. Process according to claim 1, characterized in that a hydrogen peroxide solution, preferably pH 7, is used for the reaction. 3. A process according to claim 1, wherein the methylcyclohexanone is preferably a mixture. its isomers containing not more than 10 wt. % ortho-isomer.