KR840001723B1 - Process for the preparation of carboxylic peracids - Google Patents

Abstract

The H2O2 oxidn. of alkanoic acids to peralkanoic acids was catalyzed by H2SO4, RSO3H(R=alkyl, aryl, aralkyl, alkaryl), H3PO4, acid phosphate esters, and MeCOCH(SO3H)CO2H. Thus, EtCO2H was treated with 70% H2O2 and 45% H2SO4 in ClCH2CHClMe at 39oC to yield EtC(0)OOH.

Description

Method for producing percarboxylic acid

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of an apparatus for continuously implementing the method of the present invention.

The present invention relates to a process for continuously producing percarboxylic acid by reacting a corresponding carboxylic acid with hydrogen peroxide in the presence of a catalyst.

It is known to produce percarboxylic acids by reacting the corresponding carboxylic acids in the presence of a small amount of catalyst, such as sulfuric acid, with hydrogen peroxide, usually used in the form of an aqueous solution.

This reaction produces water. In order to obtain percarboxylic acid directly in anhydrous form, US Pat. No. 2,814,614 performs this reaction in the presence of a solvent capable of forming the lowest boiling azeotropic mixture with water. In addition, by the midstream of the azeotrope, a method of removing water generated by the reaction or removing water for dilution of reactive components has been proposed.

This known method has some serious drawbacks. In practice, the proportion of peroxide compounds (hydrogen peroxide and percarboxylic acid) present in the reaction mixture is very large and increases as the reaction and azeotropic distillation proceeds. This poses a risk of explosion when carrying out the reaction.

In addition, in the known method, since the catalyst is present in the organic solvent of peracid at the end of the process, it is necessary to remove such a catalyst, which is extremely difficult. The presence of the spent catalyst in the organic solution of peracid can be seen to have a very bad effect on the next use of this solution, such as using this solution as an epoxidation agent. In addition, this method increases the consumption of the catalyst because the catalyst cannot be recovered. Therefore, in order to limit the drawbacks due to the catalyst present in the organic solution of peracid, relatively small amounts of catalyst can be used without exceeding 5% of the carboxylic acid weight used, but this results in a bad effect of reducing the reaction rate. do.

Since the formation reaction of peracid occurs mainly in the aqueous phase, and this aqueous phase is promoted by azeotropic distillation, the production rate of peracid involves loss of aqueous phase and at the same time the time actually decreases. Therefore, in order to obtain a high conversion rate, the response time must be extended. It is also very difficult to carry out the known method in a device which operates continuously.

The method of the present invention can be carried out very easily and continuously, and a method of eliminating all the above-mentioned drawbacks has been found.

The present invention continuously produces percarboxylic acid by reacting a corresponding carboxylic acid with hydrogen peroxide in an inert organic solvent which is a solvent of percarboxylic acid in the presence of a catalyst and can form a heterogeneous azeotrope with water. The method relates to a process in which the resulting water present in the reaction mixture is removed by distillation of a water / organic azeotrope mixture and reacted with an amount of water sufficient to produce an aqueous phase separated from the organic phase containing the organic liquid. By retaining in the mixture. In general, the amount of water retained in the reaction mixture is sufficient when the weight ratio of the organic phase to the aqueous phase in the reaction mixture is 0.05 or more, preferably 0.1 or more, and the best results are obtained when this ratio is 0.2 or more.

In most cases it is not necessary to retain the amount of water in the reaction mixture with a weight ratio of the aqueous phase to the organic phase of 20 or more. This ratio should be less than 10, with the best results being less than 5.

The aqueous phase generally comprises 5 to 95%, preferably 10 to 70%, of the weight of the aqueous phase, with the remainder consisting essentially of the components of the reaction mixture, mainly when the catalyst is soluble or not in a solid suspension. Consists of hydrogen peroxide and a catalyst. The aqueous phase also contains a portion of the carboxylic acid and a portion of the percarboxylic acid.

The water present in the water phase arises, in particular, from the reaction or from the introduction of certain components of the reaction mixture, generally hydrogen peroxide, and also from the catalyst when the catalyst is used in the form of an aqueous solution. Water may be added as needed.

The organic phase generally contains 30 to 98%, preferably 40 to 95% of the organic liquid of the weight of the organic phase and the remainder consists of the components of the reaction mixture, mainly carboxylic and percarboxylic acids.

The organic phase contains a small amount of hydrogen peroxide and, if a catalyst is used, may contain a small amount of catalyst.

In general, the proportion of hydrogen peroxide in the organic phase does not exceed 5% of the weight of the organic phase, and the proportion of catalyst in the organic phase does not exceed 1%. Preferably the proportion of hydrogen peroxide and catalyst in the organic phase does not exceed 2% and 0.4% of the weight of the organic phase, respectively.

The organic liquid used in the reaction mixture should be inert to the various components of the reaction mixture under the reaction conditions. The organic liquid must be formed with water to have a boiling point lower than the boiling point of other components in the reaction mixture or of any other azeotropic mixture that can be produced in the reaction mixture under the same pressure conditions.

Finally, the organic liquid should be capable of dissolving the percarboxylic acid produced during the reaction, preferably under reaction conditions, the concentration of the percarboxylic acid in the organic phase expressed in water / liter is at least 0.05 times, preferably Should dissolve to an equivalent degree of 0.2 times.

According to a preferred practice of the process of the invention, a portion of the reaction mixture is taken out continuously and the aqueous phase in the taken out portion is separated from the organic phase by decantation. The aqueous phase separated in this way is introduced into the reaction mixture, and the organic phase separated in this way constitutes the product.

This embodiment is particularly beneficial when using organic liquids that dissolve very well in water or dissolve in water. Preferably, the selected organic liquid is an organic liquid in which the ratio of the organic phase content is smaller than the ratio of the water / organic liquid azeotrope mixture under the same temperature and pressure conditions, and in most cases, the amount of water in the organic phase is 5% or less, preferably 1 It is less than%. On the other hand, the amount of organic liquid dissolved in the water phase is rarely critical, and in general, the organic liquid should be selected so that the amount does not exceed 10%, especially 5%. In addition, the organic liquid should be selected such that the density of the aqueous phase and the density of the organic phase are sufficiently different so that the aqueous phase and the organic phase can be separated by decantation.

According to a preferred variant of the above embodiment, the organic phase obtained by decantation is used to prepare the epoxide from the olefin according to a method known per se, without separating in advance into the main component.

This organic phase generally contains 5-40% by weight of percarboxylic acid. The organic phase can be subjected to various treatments before being used for epoxidation, for example to remove up to the final traces of water and catalyst. However, this treatment is not essential. During the epoxidation reaction, the molar ratio of the percarboxylic acid to the epoxidizable olefin is generally 0.01 to 20, preferably 0.1 to 10. Various additives such as small amounts of polymerization inhibitors, stabilizers of percarboxylic acids, metal ion sequestrants and the like can be added to the reaction mixture.

The epoxidation reaction is generally carried out at a temperature of 0 to 150 占 폚, preferably when the ionicity is 15 to 120 占 폚. The reaction pressure is sufficient pressure to have at least one liquid phase, and is generally 0.05 to 80 kg / cm ² . In practice, the reaction temperature and pressure depend on the nature of all the olefins to be epoxidized. The epoxidation of propylene uses a temperature of 20-100 ° C. and a pressure of 0.8-30 kg / cm ² . The epoxidation of aryl chloride and aryl alcohol uses a temperature of 20-150 ° C. and a pressure of 0.1-10 kg / cm ² . The reactor used to carry out the epoxidation reaction is a reactor that helps heat exchange to easily control the reaction temperature.

Therefore, it is possible to use a tubular reactor, autoclave, or a cascade type single or multiple reactors.

The reaction mixture obtained by epoxidation is mainly composed of organic liquid, olefin oxide, carboxylic acid and unconverted reactive component, and may contain a small amount of by-products and small amounts of various additives. The mixture is recovered on the one hand with an unconverted olefin, and on the other hand, a first separation step is carried out to recover a first organic solution composed of an organic liquid, an olefin oxide, a carboxylic acid and an unconverted percarboxylic acid.

In the case of volatile olefins, for example propylene, the separation can be advantageous by rapidly reducing the pressure to normal pressure. In the case of low volatile olefins such as aryl chloride or aryl alcohol, the first separation can be carried out by distillation. The collected olefins are recycled to keep them in the epoxidation reaction, and in order to recycle them, the olefins can be absorbed in the gas phase in the organic phase containing percarboxylic acid and then sent to the epoxidation reaction. The olefin can also be condensed and then simply sent to the epoxidation reaction.

The first organic solution collected from the first separation step, on the one hand, recovers the desired olefin oxide, and on the other hand, the second organic solution by distillation to recover the second organic solution of the carboxylic acid in the organic liquid. The separation step is performed. Olefin oxide may be used in the form obtained, or may be used after the following purification process to remove trace by-products such as aldehydes. According to a variant of the method described above, an organic liquid solution of carboxylic acid, which may contain unconverted percarboxylic acid or may additionally contain by-products and additives as described above, is sent directly to the production of percarboxylic acid. .

This solution should be preheated prior to introduction into the reaction zone to provide some of the heat required for azeotropic distillation.

When using this modification, the organic liquid is selected from organic liquids having boiling points higher than those of olefins and olefin oxides. In addition, the organic liquid should not form an azeotrope with olefins and olefin oxides.

If the organic liquid can form an azeotrope with a carboxylic acid or a percarboxylic acid, the boiling point of such an azeotrope should be higher than that of the olefin and the olefin oxide.

Any organic compound that is a liquid under the reaction conditions corresponding to the reaction conditions described above is suitable for carrying out the method of the present invention. Such liquids are generally selected from carboxylic acid esters, ethers, halogenated hydrocarbons, unsubstituted hydrocarbons, hydrocarbons substituted with nitro groups, nonacidic esters of nitric acid and phosphoric acid, and mixtures thereof.

Generally preferred carboxylic acid esters are aliphatic, substituted or aromatic esters of mono- or poly carboxylic acids with monohydric or polyhydric alcohols containing 4-20, preferably 4-10 carbon atoms in the molecule. . Particularly suitable among these carboxylic acid esters are isopropyl, formic acid and acetic acid, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl and sec-amyl esters, mono- and polychloroacetic acid, propionic acid, Methyl, ethyl, propyl, isopropyl, butyl, isobutyl and isoamyl esters of butyric and isobutane, valerate, isovalerate and methyl, ethyl and propyl esters of caproic acid, methoxyethyl and ethoxy of acetic acid Chel and cyclohexyl esters, methyl pivalate and diethyl esters of propanoic acid and adipic acid.

Generally suitable ethers are symmetrical or asymmetric aliphatic esters containing 4 to 12 carbon atoms, for example 2,2'-dichloro diethyl ether, butylethyl ether, tert-butyl ethyl ether, tert-amylmethyl ether , Diisopropyl ether, dipropyl ether, dibutyl ether, ethylhexyl ether and diiso butyl ether.

Suitable halogenated hydrocarbons also include aromatic, aliphatic and substituted halogenated hydrocarbons containing from 1 to 8 carbon atoms in the molecule and substituted with at least one halogen selected from chlorine, fluorine and cancellation. Particularly suitable halogenated hydrocarbons are carbon tetrachloride, chloroform, methylene chloride, di-, tri-, tetra and pentachloro ethane, trichlorotri fluoroethane, tri- and tetra-chloro ethylene, mono-, di- and tri-chloropropane, mono Chloro- or polychloro-butane, -methylpropane, -pentane, -hexane, mono- and di-chlorobenzene and chlorotoluene.

Hydrocarbons substituted with suitable nitro groups include aromatic, aliphatic or substituted hydrocarbons containing 3 to 8 carbon atoms such as nitropropane, nitrobenzene and nitrocyclohexane.

Also suitable unsubstituted hydrocarbons are aliphatic, aromatic or alicyclic containing 5 to 14 carbon atoms such as ben, toluene, xylene, pentane, hexane, heptane, octane, diisobutyl, cyclohexane, methylcyclohexane and tetralin There is a hydrocarbon.

Generally preferred carbonates include aliphatic esters containing 3 to 9 carbon atoms in the molecule, such as dimethyl, diethyl, diisobutyl, dibutyl, di-tert-butyl, dipropyl and diisopropyl esters of carbonic acid. There is. Suitable nitric acid esters are selected from aliphatic esters containing 1 to 5 carbon atoms in the molecule, for example methyl, propyl, butyl and isoamyl esters of nitric acid. Most preferred phosphate esters include esters corresponding to the following general formulas, and examples of particular phosphate esters are trimethyl, tributyl, trioctyl and dioctyl kenyl esters.

(Wherein R ₁ , R ₂ and R ₃ are the same or different and represent an alkyl, aryl, aryl alkyl or alkylaryl group containing 3-30 carbon atoms in the molecule)

Suitable organic liquids for the production of peracetic acid and gutropionic acid are benzene, toluene, 1,2-dichloropropane, 1,1,2,2-tetrachloroethane, pentachloroethane, tetrachloroethylene, 1-nitropropane , Chlorobenzene, -chlorotoluene, methyl chloroacetate, diethyl carbonate, dichloroethane, butyl acetate, cyclohexane and tributyl phosphate. Particularly good results can be obtained from 1,2-dichloro propane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and mixtures thereof.

The azeotrope collected by distillation is generally condensed and the water is separated from the organic liquid by decantation. The organic liquid thus collected can be used for reflux in at least a portion of the distillation zone.

This organic liquid can be evaporated and then reintroduced into reaction reactions to form an organic phase. Such introduction into the vapor form may provide at least some of the heat required for the evaporation of the water / organic liquid azeotrope.

The process of the invention can be applied to the preparation of a large number of percarboxylic acids, and the process of the invention can also be used to prepare percarboxylic acids starting from mono-napoly-carboxylic acids. In the process of the invention polycarboxylic acids can be used in the form of the corresponding anhydrides. The process of the present invention comprises, for example, aliphatic, alicyclic or aromatic carboxylic acids such as formic acid, acetic acid, chloroacetic acid, propionic acid, butyric acid, maleic acid or maleic anhydride, benzoic acid, cyclohexane, carboxylic acid, phthalic acid and phthalic anhydride. Particularly suitable for the preparation of percarboxylic acids from carboxylic acids containing ˜10 carbon atoms. Particularly advantageous results are obtained here when preparing peracetic acid and perpropionic acid starting from acetic acid and propionic acid.

The catalyst used is generally an acid catalyst suitable for the esterification reaction, for example sulfuric acid, alkylsulfonic acid, arylsulfonic acid, arylalkylsulfonic acid and alkylarylsulfonic acid, phosphoric acid, acidic acid phosphate, acidic aryl phosphate, acidic acid phosphate alkyl Aryl and acidic arylalkyl, trifluoroacetic acid, acetylsulfoacetic acid, and sulfonated polymer or copolymer type ion exchange resins. More suitable catalysts are sulfuric acid and methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, butanesulfonic acid, propanesulfonic acid and naphthalenesulfonic acid.

Among these catalysts, those which are soluble in water and insoluble or slightly soluble in the organic liquid may be used. Under the reaction conditions, the best results are obtained with a water soluble catalyst having a concentration in the organic phase of 3% by weight or less, preferably 1% by weight or less. Especially good results are obtained from sulfuric acid.

The concentration of catalyst in the reaction mixture can vary over a wide range. In order to obtain a fast reaction rate, a high concentration of catalyst is used. The amount of catalyst used is generally at least 5% of the total weight of carboxylic acid and percarboxylic acid present in the reaction mixture. The weight ratio of the catalyst is preferably 0.1 to 30 times the total weight of the carboxylic acid and the percarboxylic acid present in the reaction mixture. The best results are obtained when this weight ratio is 0.2 to 10 times the total weight of carboxylic acid and percarboxylic acid.

The catalyst can be used in a pure state, but when the catalyst is water-soluble it is preferably used in the form of an aqueous solution. In this case, the catalyst can be advantageously used by adding an additional amount of catalyst as necessary to the aqueous phase obtained by decantation and then reintroducing the reaction mixture into the reaction mixture. Generally, the concentration of the water-soluble catalyst in the water phase is 10 to 60% by weight.

Carboxylic acids can be used in the pure state in the process of the invention, but are generally used in the form of solutions in organic liquids. It is advantageous to introduce a solution containing 2 to 70% by weight, preferably 5 to 60% by weight, of carboxylic acid into the reaction mixture. To prepare such a solution, an organic liquid or fresh organic liquid obtained by separation by decantation of the azeotrope mixed out may be used, or the recovered organic liquid may be used after using an organic solution of percarboxylic acid. have. The hydrogen peroxide used for the reaction may be in a pure state or in the form of an aqueous solution.

It is preferable to use hydrogen peroxide in the form of an aqueous solution, and it is preferable to use a rich solution of hydrogen peroxide containing 20 to 90% by weight of hydrogen peroxide. Other concentrations of hydrogen peroxide may also be used but are less suitable than the above concentrations. At lower concentrations of hydrogen peroxide, the amount of water that can be removed by azeotropic distillation is significantly higher, whereas higher concentrations of hydrogen peroxide solution are difficult to industrially manufacture.

The proportion of reactive components in the reaction mixture can vary widely relative to one another in absolute value, in particular depending on the chosen rate of introduction of the reactive components. The amount of hydrogen peroxide is 0.1 to 10 mol, preferably 0.2 to 5 mol, per mol of the functional group of the carboxylic acid. The most favorable results are usually obtained when the amount of hydrogen peroxide and carboxylic acid introduced into the reaction mixture is at or near the stoichiometric ratio or slightly less than the stoichiometric ratio. Therefore, the hydrogen peroxide and the carboxylic acid are preferably 0.2 to 1 mole, preferably 0.4 to 1.2 mole of hydrogen peroxide per mole of the functional group of the carboxylic acid.

Hydrogen peroxide may be introduced directly into the reactor or, if the catalyst is water soluble, may be introduced into an aqueous solution of the catalyst sent to the reactor. Hydrogen peroxide is advantageously introduced into the aqueous solution of the catalyst sent to the reactor. Hydrogen peroxide is usually collected by separation by decantation and introduced into the aqueous phase which is continuously recycled to the reactor. Such introduction is advantageously carried out in several steps in order to prevent the local concentration of hydrogen peroxide from becoming high. The flow rate of the continuously recirculating water phase should be sufficient to achieve the composition of the hydrogen peroxide-rich water phase obtained within the limits at which the reaction mixture will not explode.

The temperature of the reaction mixture is selected to 100 ° C or less, preferably 20 to 70 ° C. Higher temperatures are not good because there is a risk of rapid decomposition of the peroxide compound. The pressure is adjusted as a coefficient of temperature to maintain boiling. The pressure can vary widely, preferably 0.01 to 1.2 kg / cm ² .

The heat required to maintain boiling can be provided according to known conventional methods. The reaction mixture (aqueous phase and organic phase) can be heated by contacting the exchange surface heated by an electrothermal fluid such as water vapor. Organic liquids, carboxylic acids or mixtures thereof may also be introduced into the reaction mixture in the form of steam.

In order to practice the method of the present invention, a device suitable for a liquid reaction mixture solution can be used, in particular a Vat reactor equipped with a stirrer. Especially during the reaction, it is preferable to use a known reactor capable of distilling one component of the liquid reaction mixture. The reactor generally used should be one capable of intimate mixing between the aqueous phase and the organic phase and good exchange between liquid and gas phases to assist the evaporation of the water / organic liquid azeotrope.

Such a reactor is preferably connected with a known distillation column such as a plate column or packed column.

The reaction mixtures of the reaction column and distillation column are in contact with stainless steel, INCONEL alloy, HASTELLOY alloy, NICOLOY alloy, NIMONIC alloy, ni-resist (NI). (RESIST) alloys, CHLORIMET alloys and enamel coated steels are recommended.

Separation of the reaction mixture taken out from the reactor by decantation and separation of the water / organic liquid azeotrope collected at the top of the distillation column are carried out by the action of gravity or centrifugal force or on one or the other side of the phase. It can be carried out in accordance with various known methods, such as by passing through the porous membrane selectively squeezed by.

Various types of devices known for this purpose can be used, and florentine separators, centrifuges, separating fiters with membranes, electrical separators and the like can be used. Separation by decantation may be facilitated by pre-operation for bonding droplets in known devices such as pads or shells of fibrous material that are better wetted by the disperse phase.

The method of the present invention relates to a particular practical implementation, which can be carried out continuously with a device as shown in the accompanying drawings.

In the figure, a reactor equipped with a distillation column 2 is provided with a solution of hydrogen peroxide and a catalyst 23 obtained by mixing the aqueous hydrogen peroxide solution introduced in (3) and the catalyst introduced in (8) in a mixer 22. The organic liquid solution of carboxylic acid obtained by (1) and the carboxylic acid introduced in (4) and the organic liquid introduced in (7) in the mixer (6) was mixed through (5) in the reactor. It is introduced in (1).

During the reaction, the water / organic liquid azeotrope starts from the distillation column (2) through (9), condenses in the condenser (10), and passes through (11) to the separator (12). If the organic liquid is denser than water, water is collected through (3) at the top of the separator, and organic liquid is collected through (14) at the bottom of the separator. In the opposite case, the taken out is reversed. The organic liquid is recycled to the distillation column via (15) and refluxed in the column. In some cases, part of this organic liquid is sent to mixer 6 via (16) where it acts as a solvent of carboxylic acid.

A portion of the reaction mixture from the mixing reactor is continuously taken out through (17) and sent to separator (18). The organic phase containing percarboxylic acid produced when the density of the organic phase is lower than the density of the aqueous phase is taken out through the top 20 of the separator 18 and the aqueous phase is taken out at the bottom of the separator 18, (19) Recycle to the reactor through. A portion of the byproducts generated in the water phase can be removed from the bleed 21. The organic phase collected via (20) can be used directly and can be purified, in particular for carrying out the epoxidation reaction or to remove the last traces of the level or catalyst.

The method of the present invention has proved to be advantageous because it is possible to continuously obtain an organic solution which is mainly anhydride and contains a concentration of percarboxylic acid. In addition, since the total concentration of the peroxide compound is maintained at a constant level and the concentration point of the peroxide compound is not observed, the risk of explosion due to decomposition of the peroxide compound in the reaction medium is significantly reduced. The ratio of peroxide compounds in the reaction mixture remains at a relatively low level, and the conversion rate of the reactive component is excellent. The process of the present invention does not cause breakage of the catalyst and does not require any complicated method for the recovery of the catalyst, and in particular does not require any distillation. The process of the present invention allows the selection of reaction conditions for obtaining extremely fast reaction rates.

The percarboxylic acids obtained according to the process of the invention can be used as active carbon sources in a number of chemical reactions, in particular for the preparation of epoxides from olefins.

For this purpose, optionally substituted organic compounds containing at least one unsaturated carbon-carbon bond in the molecule, in particular containing 2-20 carbon atoms, can be used.

Such olefins include, for example, propylene, aryl chloride, aryl alcohol and styrene.

The present invention will be described with reference to the production of percarboxylic acid by way of examples, which do not limit the scope of the invention.

EXAMPLE

The device used is similar to the device shown in FIG.

0.2 kg of sulfuric acid with an initial concentration of 45% was added to a reactor with a capacity of 1 liter, the reactor temperature was maintained at 39 ° C. and the pressure was 100 mmHg.

The aqueous solution of hydrogen peroxide at a concentration of 70% by weight was 0.12 kg / hr, and a 1,2-dichloropropane solution of propionic acid at 27% by weight was continuously introduced into the reactor at 1.07 kg / hr. The weight ratio of water phase to organic phase present in the reactor is 1.04. The water phase and the organic phase are maintained in the emulsion zone by a stirring device.

A portion of the reaction mixture is taken out continuously. The extracted portion is separated by decantation, and then 1.1 kg per hour of organic solution having the following composition is obtained.

From the results obtained in the examples, it can be seen that by the method of the present invention, an organic solution containing high concentration (20%) of perpropionic acid and practically not containing water and a catalyst can be obtained.

The concentrated organic solution obtained in this way can be used directly, for example to epoxidize propylene. In this way, a 1,2-dichloropropane solution of propylene oxide additionally containing propionic acid and unreacted propylene is collected. By the first distillation of this solution, unreacted propylene can be collected from the top of the column, and by the second distillation, propylene oxide is obtained from the top of the column, and 1,2-dichloropropane solution of propionic acid is collected from the bottom of the column. Get

Claims (1)

In a method of continuously producing percarboxylic acid by reacting carboxylic acid with hydrogen peroxide in the presence of an inert organic liquid which forms a heterogeneous azeotrope with water as well as a solvent of percarboxylic acid, hydrogen peroxide, water and catalyst are prepared. The mixture of the aqueous phase containing and the organic phase containing carboxylic acid, percarboxylic acid, organic liquid and trace amount of water is phase-separated while maintaining the weight ratio of the aqueous phase to the organic phase at 0.1 to 10, and the water and reaction produced by the reaction. A method for producing a percarboxylic acid, characterized in that the water present in the mixture is removed by azeotropic distillation with an inert organic liquid.

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