JPS5845412B2 - Method for producing carboxylic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a carboxylic acid ester having excellent electrical insulation, transparency and thermal stability by removing acidic substances present in an esterification reaction product liquid.

Carboxylic acid esters produced from carboxylic acids and alcohols are mainly used as plasticizers for thermoplastic synthetic resins, and are said to require excellent electrical insulation, transparency, and thermal stability.

The esterification reaction product liquid obtained by reacting carboxylic acid and alcohol contains free carboxylic acid, impurities,
Acid catalysts such as carboxylic acid half esters and unreacted alcohols, insoluble suspension catalysts, entrainers, etc. are present.

Among these impurities, if acidic substances such as free carboxylic acids, carboxylic acid half esters, and acid catalysts remain in the product ester obtained by purifying the esterification reaction product liquid, the electrical insulation and transparency of the product ester will deteriorate. descend.

Moreover, such product esters have low thermal stability, such as further reduction in electrical insulation and transparency when heated during use.

Therefore, in order to produce an excellent carboxylic acid ester, it is necessary to remove acidic substances from the esterification reaction product liquid.

However, if the removed acidic substances are dumped as they are, it is not only uneconomical but also inevitably pollutes the natural environment.

Therefore, if it is possible to remove and recover acidic substances from the esterification reaction product liquid, it is required to reuse them.

Conventionally, various methods have been proposed in which the esterification reaction product liquid is neutralized using an aqueous solution of an alkaline neutralizing agent to remove acidic substances.

For example, the esterification reaction product liquid is neutralized in one stage using an aqueous solution of a strong alkaline neutralizing agent such as an alkali metal hydroxide, and the ester phase obtained by separating the neutralized liquid is subsequently washed with water. There is a method of removing acidic substances from the esterification reaction product liquid by doing so.

However, in this method, due to the use of a strong alkaline neutralizer, a part of the target ester produced not only saponifies and decomposes during the neutralization process, but also after washing with water. Since trace amounts of strong alkaline neutralizing agents or their salts remaining in the ester phase promote saponification and decomposition of the target ester during distillation or heating, the quality of the resulting product ester is lacking.

As a method that does not use a strong alkaline neutralizing agent, there is a method in which the esterification reaction product liquid is neutralized using an aqueous solution of an alkali metal carbonate.

When using this method, the saponification and decomposition of the target ester is suppressed to some extent, but on the other hand, a large amount of carbon dioxide gas is generated during the neutralization process, which reduces the efficiency of liquid-liquid contact and sometimes results in several times during the neutralization process. The drawback is that it is time consuming, making this method unsuitable for large scale processes.

Furthermore, there is a method for producing phthalate esters described in Japanese Patent Publication No. 45-4974.

That is, in the first step, 80 to 90% of the acidic components present in the reaction mixture after esterification are mixed with a caustic soda aqueous solution or caustic potassium having a concentration of 0.5 to 10% by weight, especially 2 to 5% by weight. Neutralize using an aqueous solution with a residence time of up to 3 minutes, especially up to 1 minute, and then in a second step with a residence time of up to 3 minutes, especially up to 1 minute, in a second step with a residence time of up to 3 minutes, especially up to 1 minute.
20% by weight, particularly preferably 4 to 12% by weight of sodium or -potassium carbonate or sodium or -bicarbonate
In this method, neutralization of acidic components in the reaction mixture is completed by adding an aqueous solution of potassium.

In this method, by doing as described above, it has become possible to suppress to some extent both the decrease in the efficiency of liquid-liquid contact due to the generation of carbon dioxide gas and the saponification and decomposition during the neutralization treatment of the target ester.

However, a trace amount of salt generated from an acidic substance and a strong alkaline neutralizing agent such as caustic soda or caustic potash remains in the ester phase after neutralization, causing saponification and decomposition of the target ester during distillation or heating. In this respect, it is essentially the same as the above-mentioned one-stage neutralization method using an aqueous solution of a strong alkaline neutralizer. It had the disadvantage of being complex.

Furthermore, during neutralization using an aqueous solution of an alkaline neutralizing agent, most of the acidic substances are transferred to the neutralized wastewater as salts generated from the acidic substance and the alkaline neutralizing agent.

If such neutralized wastewater is dumped as is, pollution of the natural environment is inevitable, and in order to prevent this from occurring, it is necessary to treat the neutralized wastewater by some method.

Conventionally, acid precipitation treatment has been the only method that can be used industrially to treat neutralized wastewater.

That is, a mineral acid, such as sulfuric acid, hydrochloric acid, or phosphoric acid, is added to the neutralized wastewater, and the salts generated from the acidic substance and the alkaline neutralizing agent are acid-decomposed to liberate the acidic substance, and the acidic substance is separated and recovered. This method involves reusing it in the esterification reaction.

However, when using this method, not only is an amount of mineral acid newly required commensurate with the amount of salt generated from the acidic substance and alkaline neutralizing agent present in the neutralized wastewater, but also the amount of mineral acid must be recycled. In order to obtain an acidic substance that can be used, it is necessary to further purify it by washing with water after recovery, and the dissolution loss during this process is also negligible, making it unsuitable as a method for recovering acidic substances.

The present inventors have made the following new findings in the course of long-term research into a method for decomposing salts generated from acidic substances and alkaline neutralizers present in neutralized wastewater to liberate and recover acidic substances. Obtained.

That is, when an aqueous solution of an ammonium salt of a carboxylic acid or an aqueous solution of an ammonium salt of a carboxylic acid half ester is brought into contact with carbon dioxide gas in the presence of a cation exchange resin, for example, formulas (1) to (2) are obtained [wherein R is a hydrocarbon other than a phenyl group] The reaction represented by [residue]] occurs, and ammonia is eliminated and acidic substances are liberated.

Based on this new knowledge, the present inventors recovered acidic substances, especially free carboxylic acids and carboxylic acid half esters, present in the esterification reaction product liquid with a high recovery rate, and distilled them during neutralization treatment. The present invention was developed as a result of intensive research to provide a method for easily and efficiently producing a carboxylic acid ester that has excellent electrical insulation, transparency, and thermal stability by preventing saponification and decomposition of the target ester during heating or heating. reached.

That is, in the present invention, when producing a carboxylic acid ester by reacting a carboxylic acid and/or a carboxylic acid half ester with an alcohol, the esterification reaction product liquid is neutralized using an aqueous ammonia solution, and this neutralization treatment is performed. This method for producing a carboxylic acid ester is characterized by separating a liquid into an ester phase and neutralized wastewater, and bringing the neutralized wastewater into contact with carbon dioxide gas in the presence of a cation exchange resin.

The esterification reaction product liquid in the present invention may be one obtained by reacting ordinary carboxylic acid and/or carboxylic acid half ester with alcohol, and may include the target ester, unreacted alcohol, and carboxylic acid half ester. Contains free carboxylic acid, catalyst, entrainer, etc.

Although there is substantially no free carboxylic acid in the esterification reaction product solution obtained under normal conditions, the present invention can also be applied when a large amount of free carboxylic acid is present in the esterification reaction product solution. It goes without saying that this method is effective.

The carboxylic acid used in the esterification reaction is not particularly limited, but aromatic carboxylic acids such as benzoic acid, nitrobenzoic acid, aminobenzoic acid, toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and trimethyl are generally used. Benzoic acid, n-propylbenzoic acid, isopropylbenzoic acid, tetramethylbenzoic acid, naphthoic acid and methylnaphthoic acid, aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, nitrophthalic acid, aminophthalic acid, hemimelitic acid aliphatic saturated-carboxylic acids such as formic acid, acetic acid, propionic acid, such as trimellidic acid, trimesic acid, brenidic acid, merophanic acid, pyromellitic acid, benzenepentacarboxylic acid, mellitic acid and naphthalic acid;
n-4 acid, inbutyric acid, n-valeric acid, isovaleric acid, methylethyl acetate, trimethylacetic acid, caproic acid, heptonic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid aliphatic saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, ethylsuccinic acid, pimelic acid,
Aliphatic unsaturated carboxylic acids such as ethylglutaric acid, superric acid, azelaic acid, sebacic acid and brassylic acid, such as acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, undecylic acid, naleic acid, elaidic acid, centreic acid Aliphatic unsaturated polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid, mesaconic acid , citraconic acid and aconitic acid, oxycarboxylic acids such as malic acid, tartaric acid and citric acid, cycloaliphatic carboxylic acids such as hexahydrobenzoic acid and hexahydrophthalic acid, halogenocarboxylic acids such as chlorobenzoic acid, fromobenzoic acid, fluorobenzoic acid, etc. Acetic acid, chloroacetic acid, fromoacetic acid, iodoacetic acid, chloropropionic acid, bromopropionic acid, chlorobutyric acid, fromobutyric acid, chlormalonic acid, chlorconoxphosphate,
Examples include chloroacrylic acid, fromacrylic acid, chlormaleic acid, chlorofumaric acid, chloromalic acid, and chlorocinnamic acid, as well as acid anhydrides of these carboxylic acids.

These carboxylic acids may be used alone or as a mixture of two or more.

Among the carboxylic acids, aromatic carboxylic acids and their anhydrides and aliphatic carboxylic acids are industrially preferred, and benzoic acid, toluic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellidic acid and the acid anhydrides of these carboxylic acids Particularly preferred for things.

The carboxylic acid half ester used in the esterification reaction means a polyhydric carboxylic acid partial ester having at least one carboxyl group that has not yet been esterified, such as phthalic acid monoester, trimellitic acid monoester,
Examples include trimellidic acid diester and adipic acid monoester.

The type of carboxylic acid half ester present in the esterification reaction product liquid is the same as the type of carboxylic acid half ester described above.

There are no particular restrictions on the alcohol used in the esterification reaction, but in general, aliphatic saturated-hydric alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and secondary butyl alcohol. Alcohol, tertiary butyl alcohol, isobutyl alcohol, n-amyl alcohol, secondary amyl alcohol, tertiary amyl alcohol, isoamyl alcohol, secondary isoamyl alcohol, activated amyl alcohol, diethyl carbinol, tertiary butyl carbide aliphatic saturated polyhydric alcohols such as ethylene glycol, diethylene glycol, etc.
Glopylene glycol, trimethylene glycol, tetramethylene glycol, 1,2-butanediol, 1.
3-butanediol, 2,3-butanediol, 2,2
-dimethyl-1,3-propanediol, glycerin,
Alcohols with aromatic rings, such as aliphatic unsaturated alcohols such as allyl alcohol, crotyl alcohol and propargyl alcohol, cycloaliphatic alcohols such as cyclopentanol and cyclohexanol, such as diglycerin, trimethylolpropane, pentaerythritol and dipentaerythritol Heterocyclic alcohols such as furifuryl alcohol and mixtures of these alcohols include tatoehabenzyl alcohol, β-phenylethyl alcohol, methylphenyl carbinol, phthalyl alcohol and cinnamyl alcohol.

Among these alcohols, aliphatic saturated alcohols having 1 to 13 carbon atoms are particularly preferably used.

The esterification reaction proceeds either in the presence or absence of a catalyst.

When a catalyst is used, it may be any conventional esterification catalyst, and examples of known acid catalysts include p-)luenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, sulfuric acid, and phosphoric acid. , as well as insoluble suspension catalysts such as tin oxide, zinc oxide, antimony oxide,
Examples include titanium peroxide, alumina-sodium hydroxide mixed system, magnesium-silicon composite oxide, sodium-aluminum composite oxide, magnesium-aluminum composite oxide, and the like.

During the esterification reaction, water produced by the reaction is removed from the reaction system as an azeotrope with alcohol or other entrainer.

Therefore, substantially no water is present in the esterification reaction product liquid.

The entrainer may be one that is inert to the reaction and forms an azeotrope with water, such as benzene,
Examples include toluene, xylene and n-hexane.

The esterification reaction product liquid is mixed with an ammonia aqueous solution and subjected to neutralization treatment.

The concentration of ammonia aqueous solution used for neutralization treatment is 0.1 to 8.
The weight percent is preferably 0.25 to 6 weight percent.

If the amount is less than o or i% by weight, the neutralization process may take a long time or may be incomplete.

If it exceeds 8% by weight, depending on the type of target ester, the liquid separation between the ester phase and the neutralized wastewater may deteriorate during the liquid separation described below.

There is no particular limit to the amount of ammonia aqueous solution used for neutralization, but in general, if it is too small, the neutralization process will take a long time, and if it is too large, liquid separation tends to be poor.

Therefore, the amount of the ammonia aqueous solution is such that the volume ratio to the esterification reaction product liquid is less than 1/7 or more than 2, but industrially the amount is 1/7 to 2.

Although the combination of concentration and amount of ammonia aqueous solution used for neutralization treatment is generally arbitrary, industrially, at least a stoichiometrically equivalent amount of ammonia to the acidic substance present in the esterification reaction product solution is used. It is preferable to include.

The neutralization temperature can be changed depending on the type of target ester and the concentration of the ammonia aqueous solution, but in general, at low temperatures, the viscosity of the esterification reaction product increases and the neutralization process takes a long time due to poor liquid-liquid contact. At high temperatures, ammonia gas not only escapes and is wasted during the neutralization process, but also causes inconvenience in the neutralization process.

Therefore, industrially, the temperature range is preferably from 20 to 60°C.

The neutralization treatment time depends on the concentration of the ammonia aqueous solution used in the neutralization treatment, the type of apparatus, etc., but is generally 2 to 30 minutes.

The pressure during the neutralization treatment is not an essential requirement, and may be reduced pressure, normal pressure, or increased pressure.

The neutralization treatment is preferably carried out under forced stirring in order to increase the efficiency of liquid-liquid contact.

For esterification reaction product liquids containing insoluble suspended catalysts, the insoluble suspended catalysts should be separated and removed by conventional solid-liquid separation means such as filtration, sedimentation, or centrifugation prior to neutralization. is preferred.

Through the neutralization treatment, acidic substances such as free carboxylic acids, carboxylic acid half esters, and acid catalysts (hereinafter simply referred to as "acidic substances") in the esterification reaction product liquid are converted to their respective ammonium salts, and the neutralized wastewater is converted into the respective ammonium salts. Move inside.

The ammonium salt of a carboxylic acid half ester refers to an ammonium salt produced by adding an ammonia molecule to the unesterified carboxyl group of a carboxylic acid half ester. Examples include diammonium salts of esters, monoammonium salts of trimellidic acid diesters, and monoammonium salts of adipic acid monoesters.

The neutralized solution is allowed to stand and is separated into an ester phase and neutralized wastewater.

The main component of the separated ester phase is the target ester, and this ester phase is washed with water and then purified by distillation to produce a product.

Distillation includes an alcohol removal and recovery process using a conventional method, a removal and recovery process for an initial fraction containing low-boiling substances, a purification process by vacuum distillation, and optionally an entrainer removal and recovery process.

Neutralized wastewater contains acidic substances such as ammonium salts, ammonia, and alcohol.

The neutralized wastewater is deammoniated as it is or after the concentration of the ammonium salt of an acidic substance has been increased, by contacting it with carbon dioxide gas in the presence of a cation exchange resin.

As will be described later, from the viewpoint of efficiently recovering acidic substances from the deammoniated liquid, it is preferable to increase the concentration of the ammonium salt of the acidic substance prior to the deammoniated treatment.

Any method can be used to increase the concentration of ammonium salts of acidic substances, but generally there are sequential accumulation methods, heating concentration methods, vacuum concentration methods, ventilation concentration methods, etc., or a combination of these methods, and the sequential accumulation method is economical. advantageous to

The sequential accumulation method in the present invention means that the neutralized wastewater is mixed with a concentrated ammonia aqueous solution or dissolved ammonia gas as necessary to adjust the ammonia concentration to a range of 0.1 to 8% by weight, and then subjected to the neutralization treatment. This method gradually increases the concentration of ammonium salts of acidic substances in neutralized wastewater by reusing the wastewater.

In addition, in the sequential accumulation method, in addition to mixing or dissolving a concentrated ammonia aqueous solution or ammonia gas whose concentration should be adjusted in the neutralized wastewater whose concentration has not been adjusted in advance and then reusing it for neutralization treatment, An embodiment in which the treated waste water, concentrated aqueous ammonia solution, and ammonia gas are directly added to the esterification reaction product liquid for neutralization treatment is also possible.

There is no restriction on the type of cation exchange resin in the present invention,
Known examples include those having a cation exchange group such as a sulfone group, carboxyl group, phenolic hydroxyl group, phosphonic group or arsone group in a resin matrix such as styrene, phenol or methacrylic.

Among these cation exchange resins, those having a sulfone group in the styrene resin matrix are preferably used because they have a high ammonia elimination rate.

The amount of cation exchange resin used may vary slightly depending on the type and concentration of ammonium salts of acidic substances contained in the neutralized wastewater, but generally the weight ratio to the neutralized wastewater is 11.
The amount is 5 to 1, preferably 1/3 to 1/2.

If the weight ratio is less than 115, contact between the cation exchange resin and the neutralized wastewater will be incomplete, and the objective may not be fully achieved.

If the weight ratio exceeds 1, the recovery of acidic substances from the deammoniated solution, which will be described later, may lack fluidity and the work may become less smooth.

Cation exchange resins can be used as fixed or suspended beds.

There is no particular restriction on the amount of carbon dioxide gas brought into contact.

The common method of contact is to blow carbon dioxide gas into the neutralized wastewater, and the blowing may be continuous, intermittent, or intermittent, but it is substantially continuous throughout the deammonization process. It is preferable that

Generally speaking, when the temperature of the deammonia treatment is low, the desorption rate of ammonia is low, and at a high temperature, the cation exchange resin deteriorates, which in any case leads to a decrease in the efficiency of the deammonia treatment.

Therefore, although it does not prevent the temperature from being below 65°C or exceeding 120°C, industrially it is generally 65 to 120°C.
Preferably it is in the range of 80 to 100°C.

The deammonification treatment time refers to the time during which the neutralized wastewater, the cation exchange resin, and the carbon dioxide gas, that is, the liquid-solid gas, are in contact with each other, and this is related to the temperature of the deammonification treatment. , generally takes a long time at low temperatures;
It only takes a short time at high temperatures.

The time for deammonification treatment can be arbitrarily selected depending on the purpose, but the preferred time is expressed by the formula ■ [where X and y are the temperature ('C) for deammonification treatment]
and time (minutes), respectively].

During the ammonia removal treatment, excess carbon dioxide gas containing ammonia is discharged.

This excess carbon dioxide may be released into the atmosphere as is, but in order to prevent environmental pollution and reduce production consumption, it must be washed with water using conventional methods to recover ammonia and purify carbon dioxide. It is preferable to reuse ammonia and carbon dioxide gas at the same time.

Ammonium salts of acidic substances present in the neutralized wastewater are decomposed by the deammonification treatment, and as a result, acidic substances and ammonia are liberated.

When using a cation exchange resin as a suspended bed, the deammoniation treatment liquid contains the cation exchange resin,
This is separated and removed by conventional solid-liquid separation means such as filtration, centrifugation, sedimentation, etc.

The separated cation exchange resin can be reused for deammonification without any special treatment.

When a cation exchange resin is used as the packed bed, the deammoniation treatment liquid, that is, the effluent from the packed bed does not contain the cation exchange resin, so the above separation step is not necessary.

Note that the packed bed can be continuously reused.

Water is subsequently removed from the deammoniated liquid and acidic substances are recovered.

Methods for removing water include, for example, a static separation method, a solvent extraction method, a concentration method, or a combination thereof, which are rationally selected and adopted depending on the type and concentration of the acidic substance to be recovered.

The stationary separation method is a method in which the deammoniated liquid is left stationary and separated into an oil phase mainly composed of acidic substances and a clean aqueous phase, and the aqueous phase is discharged from the system.

The static separation method is suitable for recovering acidic substances that have relatively low solubility in water.

The solvent extraction method is a method in which acidic substances are extracted from the deammoniated liquid using an extractant with relatively low solubility in water, and the clean extraction residue is discharged outside the system.

The extracting agent is preferably the same alcohol as the raw material alcohol for the target ester.

Solvent extraction is also effective for recovering acidic substances that have relatively high solubility in water.

The concentration method is a method in which the water in the deammoniated liquid is evaporated by heating, reduced pressure, ventilation, etc. without damaging the acidic substances to be recovered, and an oil phase containing acidic substances as the main component is recovered.

Concentration methods are particularly effective for recovering acidic substances with relatively high decomposition temperatures or high vapor pressures.

The clean aqueous phase or extraction residue (hereinafter simply referred to as the "discharged water phase") separated from the deammoniated liquid is discharged outside the system, but water is substantially removed from the deammoniated liquid. The obtained oil phase or extract (hereinafter collectively referred to as "recovered oil phase") can be reused as is for producing the desired carboxylic acid ester.

The method of the present invention can be carried out by a continuous method, a semi-continuous method, or a batch method.

Next, the present invention will be explained in more detail with reference to the drawings.

The drawing shows an example of a system of equipment for continuously producing carboxylic acid esters by the method of the present invention.

In the drawing, the carboxylic acid, alcohol with relatively low solubility in water and the recovered oil phase are routed through routes 1.2 and 3.
These are respectively supplied to the esterification reactor 4.

In the esterification reactor 4, an esterification reaction is carried out.

The water produced by the reaction is distilled off as an azeotrope with alcohol, sent to a cooler 6 via a route 5, condensed, and sent to a liquid separation tank 8 via a route 7, where it is separated into alcohol and water.

The separated alcohol is sent to the esterification reactor 4 via route 9.
and reused in the esterification reaction.

On the other hand, the separated water is discharged from the reaction system through path 10.

The esterification reaction product liquid is extracted from the esterification reactor 4 and sent to the neutralization treatment tank 12 through a path 11, where it is neutralized with an ammonia aqueous solution supplied through a path 13.

The neutralized liquid is sent to a liquid separation tank 15 through a path 14 and separated into an ester phase and neutralized wastewater.

The neutralized wastewater, ammonia gas, and the washing wastewater are supplied to the preparation tank 19 through routes 16, 17, and 18, respectively, and an ammonia aqueous solution for neutralization is prepared.

The ester phase is sent to a washing tank 21 through a path 20 and washed with water supplied through a path 22.

The washing liquid is sent to a liquid separation tank 24 through a path 23 and separated into an ester phase and washing wastewater.

This ester phase is sequentially sent through route 25 to an alcohol removal and recovery process, an initial distillate removal and recovery process, and a purification process by vacuum distillation, and is converted into a product.

On the other hand, part or all of the washing-treated wastewater is sent to the preparation tank 19 via the path 18.

A part of the neutralized wastewater is extracted from the middle of the route 16 through a route 26 and sent to a deammonification treatment tank 27 filled with a cation exchange resin.

In the deammonification treatment tank 27, carbon dioxide gas is blown into the tank through a path 28, and excess carbon dioxide gas containing ammonia is discharged through a path 29.

The deammonification treatment liquid is extracted from the bottom of the deammonification treatment tank 27 and sent to the extraction treatment tank 31 through a path 30, where acidic substances are extracted with alcohol supplied through a path 32.

The extraction processing liquid is sent to a liquid separation tank 34 through a path 33 and separated into a recovered oil phase and a discharged water phase.

The recovered oil phase is returned to the esterification reactor 4 via route 3 and reused in the esterification reaction, while the discharged water phase is returned to the esterification reactor 4 via route 35.
is discharged from the system.

According to the method of the present invention, acidic substances present in the esterification reaction product liquid are removed in a short time, and saponification and decomposition of the target ester during neutralization, distillation, and heating is prevented.

The carboxylic acid ester produced by the method of the present invention does not contain acidic substances and has excellent electrical insulation, transparency, and thermal stability, and is suitable as a plasticizer for thermoplastic synthetic resins.

According to the method of the present invention, when free carboxylic acids, carboxylic acid half esters, and acid catalysts are used, acidic substances such as acid catalysts can be efficiently recovered from neutralized wastewater.

The recovered acidic substance can be reused in the esterification reaction without any treatment.

In the case of the method of the present invention, the wastewater is only the discharged water phase separated from the deammoniated liquid and, if necessary, the water-washed wastewater, and does not substantially contain the target ester, free carboxylic acid, or carboxylic acid half ester. The concentration of alcohol and ammonia is extremely low, so even if it is dumped as is, it will not pollute the natural environment.

Next, the present invention will be explained in more detail with reference to Examples.

In addition, "1 part" and "%" in the examples are respectively "1 part" and "%".
"parts by weight" and "% by weight" are meant.

In addition, the numbers indicating the devices used in Examples 6 and 7 are in accordance with the attached drawings.

In addition, the analysis of the esterification reaction product liquid, ester phase, neutralized wastewater, recovered oil phase, and discharged water phase in Examples was performed by potentiometric titration.

The first quality test for product ester is JIS K675119.
The test was carried out in accordance with 55.

Example 1 148.0 parts of phthalic anhydride and 310.0 parts of 2-ethylhexanol were mixed to 210 to 230 parts without using a catalyst.
Bis(2-ethylhexyl) phthalate) obtained by reacting for 4 hours while removing the reaction product water at 90°C and normal pressure.
19%, mono(2-ethylhexyl)phthalate) 4.2
405.6 parts of esterification reaction product liquid I containing 4% and 5.38% of 2-ethylhexanol were neutralized using 100 parts of a 5.83% ammonia aqueous solution at 60° C. and normal pressure for 10 minutes.

After leaving the neutralized solution for a while, add bis(2-ethylhexyl)
Phthalate 94.40%, 2-ethylhexanol5.
387.0 parts of an ester phase containing 17% and 0.04% of ammonia and 0.25% of bis(2-ethylhexyl)phthalate, 15.31% of monoammonium mono(2-ethylhexyl)phthalate) and 1% of 2-ethylhexanol. .50% and 119.5 parts of neutralized wastewater containing 3.98% ammonia.

Ester phase (2) was washed twice with 200 parts of water at 50°C, 2-ethylhexanol was distilled off at 135°C under 40°Hg, and the mixture was heated at 160-171°C under 0.4mmHg.
The first distillate of
362.0 parts of the fraction at 80 to 193°C was designated as product (■).

Neutralized wastewater ■ is treated with Amberlyst 15 (ROHM).
& Haas cation exchange resin product) 30.0
4 parts at a blowing rate of 143.3 parts/hour at 95°C.
Ammonia removal treatment was carried out by continuously blowing carbon dioxide gas for 0 minutes.

The deammoniated solution was filtered to separate Amberlyst 15, and the filtrate was allowed to stand for a while. Mono(2-ethylhexyl) phthalate 94.71%, 2-ethylhexanol 5.
03%, water 0.20% and ammonia 0.02%
118.0 parts of the recovered oil phase containing 0.29% of bis(2-ethylhexyl)phthalate, and 0.29% of monoammonium mono(2-ethylhexyl)
-ethylhexyl) phthalate) 0.30%, 2-ethylhexanol 0.71% and ammonia 0.0
The effluent was separated into 98.5 parts of aqueous phase I containing 7%.

Recovered oil phase I 18.0 parts, phthalic anhydride 139.0
The esterification reaction was carried out under the same conditions as above except that 310.0 parts of bis(2-ethylhexyl) phthalate and 310.0 parts of 2-ethylhexanol were used as raw materials.
88.64%, mono(2-ethylhexyl) phthalate 4.07% and 2-ethylhexanol 6.94%
414.0 parts of an esterification reaction product solution was obtained.

The esterification reaction product liquid (1) was neutralized under the same conditions as the above-mentioned esterification reaction product liquid (I) to contain 93.04% of bis(2-ethylhexyl) phthalate, 6.75% of 2-ethylhexanol, and 0.0% of ammonia. 396.7 parts of ester phase II containing 0.6% and 0.30% of bis(2-ethylhexyl) phthalate, 15.29% of monoammonium mono(2-ethylhexyl) phthalate, 2
- Ethylhexanol 1.40% and ammonia 4
．． It was separated into 117.0 parts of neutralized wastewater containing 10%.

Ester phase (2) was purified under the same conditions as for ester phase (2) above to obtain 364.7 parts of product (2).

Neutralized wastewater (■) is deammoniated under the same conditions as the neutralized wastewater (■) and filtered to obtain mono(2-ethylhexyl).
Phthalate 95.48%, 2-ethylhexanol 4
．． 18%, water 0.31% and ammonia 0.01
% of recovered oil phase T containing 11.7.7 parts of bis(2-ethylhexyl) phthalate 0.28%, monoammonium mono(2-ethylhexyl) phthalate) 0.16%, 2
- Ethylhexanol 0.40% and ammonia
It was separated into 93.4 parts of a discharged aqueous phase containing 0.04%.

In addition, esterification reaction product liquids ■ and ■, ester phase ■
No free phthalic acid was detected in any of the recovered oil phases ■ and ■ and recovered oil phases ■ and ■.

In addition, no diammonium phthalate was detected in either the neutralized wastewater (■) or (2) or the discharged water phases (■) or (2).

Furthermore, mono(2
-ethylhexyl) phthalate and monoammonium mono(2-ethylhexyl) phthalate were not detected.

The obtained bis(2-ethylhexyl) phthalate products (1) and (2) were of high quality and excellent thermal stability as shown in Table 1.

Example 2 148.0 parts of phthalic anhydride and 310.0 parts of 2-ethylhexanol were mixed into 210-2 parts of phthalic anhydride without using a catalyst.
Bis(2-ethylhexyl) phthalate obtained by reacting at 30°C under normal pressure for 4 hours while removing reaction product water.
90.81% mono(2-ethylhexyl) phthalate
404.1 parts of esterification reaction product liquid I containing 4.06% and 5.10% of 2-ethylhexanol was added to 3.8 parts.
Using 80.0 parts of 9% aqueous ammonia solution at 55°C,
Neutralization treatment was carried out for 5 minutes under normal pressure.

After leaving the neutralized solution for a while, add bis(2-ethylhexyl)
Ester phase I containing 94.33% (2-ethylhexyl), 494% 2-ethylhexanol and 0.06% ammonia 388.5 parts Tobis(2-ethylhexyl)
Phthalate 0.23%, monoammonium mono(2-ethylhexyl) phthalate 17.63%, 2-ethylhexanol 1.42% and ammonia 2.06
It was separated into 98.8 parts of neutralized wastewater I containing %.

The ester phase (2) was washed twice with 200 parts of water at 50°C, 2-ethylhexanol was distilled off at 135°C under 40°Hg, and the mixture was heated at 160-172°C under 0.4 mmHg.
The first distillate of
360.1 parts of the fraction at 80 to 193°C was designated as product (■).

To the neutralized wastewater ■, 35.0 parts of 1R120B (a cation exchange resin product manufactured by Rohm and Haas) was added and carbon dioxide gas was continuously blown at 95°C for 40 minutes at a blowing rate of 177.8 parts/hour. Blow deammonia treatment was performed.

The deammoniated solution was filtered to separate IR-120B, and the filtrate was allowed to stand for a while. Mono(2-ethylhexyl) phthalate) 91.40%, 2-ethylhexanol 5.0
17.5 parts of recovered oil phase I containing 9% water, 0.18% water and 0.01% ammonia and 0.01% monoammonium mono(2-
ethylhexyl) phthalate 0.50%, 2-ethylhexanol 0.31% and ammonia 0.02%
74.6 parts of the discharged aqueous phase I containing:

The esterification reaction was carried out under the same conditions as above except that 117.5 parts of the recovered oil phase, 139.5 parts of phthalic anhydride and 310.0 parts of 2-ethylhexanol were used as raw materials.

Bis(2-ethylhexyl) phthalate 87.56%
, 412.9 parts of an esterification reaction product liquid containing 491% of mono(2-ethylhexyl) phthalate and 7.50% of 2-ethylhexanol was obtained.

The esterification reaction product liquid (■) was neutralized under the same conditions as the above esterification reaction product liquid (■) to obtain 92.04% of bis(2-ethylhexyl) phthalate, 7.54% of 2-ethylhexanol, and 0.05% of ammonia. 392.2 parts of ester phase containing % and 0.23% of bis(2-ethylhexyl)phthalate,
ethylhexyl) phthalate 20.11%, 2-ethylhexanol 1.36% and ammonia 1.77
It was separated from the neutralized wastewater n107.0 parts containing %.

Ester phase (2) was purified under the same conditions as for ester phase (2) above to obtain 355.1 parts of product (2).

The neutralized wastewater (■) was deammoniated under the same conditions as the above neutralized wastewater (■) and filtered to yield 96.60% of simono(2-ethylhexyl) phthalate and 2-ethylhexanol.
3.16%, water 0.21% and ammonia 0.0
Recovered oil phase containing 17.7 parts of Tl and 0.03% of bis(2-ethylhexyl) phthalate, 0.40% of monoammonium mono(2-ethylhexyl)phthalate)
, and 78.2 parts of the effluent aqueous phase containing 0.39% 2-ethylhexanol and 0.02% ammonia.

Recovered oil phase n 17.7 parts, phthalic anhydride 139.3
The esterification reaction was carried out under the same conditions as above except that 310.0 parts of bis(2-ethylhexyl) phthalate and 310.0 parts of 2-ethylhexanol were used as raw materials.
87.60%, mono(2-ethylhexyl)phthalate)
4.90% and 2-ethylhexanol 7.3
412.0 parts of esterification reaction product liquid II containing 0% was obtained.

The esterification reaction product liquid (■) was neutralized under the same conditions as the above-mentioned esterification reaction product liquid (2) to obtain 92.10% of bis(2-ethylhexyl) phthalate, 7.07% of 2-ethylhexanol, and 0.07% of ammonia. ester phase m containing 396.0 parts and bis(2-ethylhexyl) phthalate 0.76%, monoammonium mono(2-ethylhexyl) phthalate 18.14%, 2-
Ethylhexanol 1.77% and ammonia 3
．． It was separated into 1118.0 parts of neutralized wastewater containing 34%.

Ester phase (2) was purified under the same conditions as for ester phase (2) above to obtain 365.2 parts of product (2).

The neutralized wastewater (■) was deammoniated and filtered under the same conditions as the neutralized wastewater (■) above to obtain 95.50% mono(2-ethylhexyl) phthalate and 2-ethylhexanol.
4.18%, water 0.30% and ammonia 0.0
m20.9 parts of recovered oil phase containing less than 1% bis(2-ethylhexyl) phthalate 0.05%, monoammonium mono(2-ethylhexyl) phthalate 0.20%,
It was separated into 110.5 parts of a discharged aqueous phase (1) containing 0.25% of 2-ethylhexanol and 0.02% of ammonia.

In addition, esterification reaction product liquid ■, ■ and ■, ※※ester phase ■, ■ and ■ and recovered oil phase ■, ■ and ■
No free phthalic acid was detected in any of the samples.

In addition, neutralized wastewater ■, ■ and ■ and discharge water phase ■
Diammonium phthalate was not detected in any of , ■, and ■.

Furthermore, mono(
Neither 2-ethylhexyl) phthalate nor monoammonium mono(2-ethylhexyl) phthalate was detected.

The obtained bis(2-ethylhexyl) phthalate products (1), (2) and (2) were of high quality and excellent thermal stability as shown in Table 2.

Example 3 148.0 parts of isophthalic acid and 310.0 parts of 2-ethylhexanol were mixed into 210 to 2 parts of 2-ethylhexanol without using a catalyst.
Bis(2-ethylhexyl)isophthalate 84.07%, mono(2-ethylhexyl)isophthalate 608% and 2-ethylhexanol 7
．． Esterification reaction product liquid I containing 17% 378.0
1 part was neutralized using 110 parts of a 4.86% ammonia aqueous solution at 60°C under normal pressure for 10 minutes.

After leaving the neutralized solution for a while, add bis(2-ethylhexyl)
isophthalic acid) 91.34%, 2-ethylhexanol 7.27% and ammonia 0.02%; -ethylhexyl) inphthalate 17.42%,
It was separated into 141.2 parts of neutralized wastewater I containing 0.78% 2-ethylhexanol and 2.75% ammonia.

Ester phase (2) was washed twice with 200 parts of water at 50°C, 2-ethylhexanol was distilled off at 135°C under 40 nHg, and the first distillation was carried out at 170-175°C under 0.3 hg. The fraction was distilled off and distilled under 0.1 to 0.2 rrartHg to obtain 311.5 parts of the fraction at 190 to 215°C as product (2).

For neutralized and Japanese treated wastewater ■, use Amberlist 1530.0.
6 parts at a blowing rate of 177.8 parts/hour at 95°C.
Ammonia removal treatment was carried out by continuously blowing carbon dioxide gas for 0 minutes.

The deammoniated solution was filtered to separate Amberlyst 15, and the filtrate was allowed to stand for a while. Mono(2-ethylhexyl) inphthalate 94.80%, 2-ethylhexanol 4
．． 88%, water 0.30% and ammonia 0.01
24.0 parts of recovered oil phase I containing less than 0.01% of bis(2-ethylhexyl)isophthalate and less than 0.01% of monoammonium mono(2-ethylhexyl)isophthalic acid).
．． 30%, 2-ethylhexanol 0.08% and ammonia 0.02% (112.7 parts).

The esterification reaction was carried out under the same conditions as above except that 24.0 parts of recovered oil phase I, 1360 parts of inphthalic acid and 310.0 parts of 2-ethylhexanol were used as raw materials to obtain 8640 parts of bis(2-ethylhexyl) inphthalate. %, mono(2-ethylhexyl) inphthalate) 5.27% and 2-ethylhexanol 7.1
377.0 parts of esterification reaction product liquid n containing 8% was obtained.

The esterification reaction product solution (1) was neutralized under the same conditions as the above-mentioned esterification reaction product solution (2), and 92.33% of bis(2-ethylhexyl) inphthalate, 7.35% of 2-ethylhexanol, and 0.9% of ammonia were added. 350.9 parts of ester phase n containing 0.3% and 110% of bis(2-ethylhexyl) inphthalate, monoammonium mono(2-ethylhexyl) inphthalate) 14.
Neutralized wastewater containing 79%, 2-ethylhexanol 0.88% and ammonia 2.89% n143.0
It was separated into two parts.

Ester phase (1) was purified under the same conditions as ester phase I above to obtain 321.8 parts of product I.

Neutralized wastewater (1) was deammoniated and filtered under the same conditions as the above neutralized wastewater (I), containing 95.20% mono(2-ethylhexyl) inphthalate, 4.53% 2-ethylhexanol, and 0.0% water. 25% and ammonia
■ 20.3 parts of recovered oil phase containing less than 0.01% and screws (2
-Ethylhexyl) inphthalate 0.02%, monoammonium mono(2-ethylhexyl) inphthalate 0.20%, 2-ethylhexanol 0.09% and ammonia 0.01% n115.2
It was separated into two parts.

In addition, esterification reaction product liquids ■ and ■, ester phase ■
No free isophthalic acid was detected in any of the recovered oil phases I and II.

Furthermore, no diammonium inphthalate was detected in either the neutralized wastewaters (1) and (2) or the discharged water phases (2) and (2).

Furthermore, mono(2
-ethylhexyl) inphthalate and monoammonium mono(2-ethylhexyl) isophthalate were not detected.

The obtained bis(2-ethylhexyl) isophthalate products (1) and (2) were of high quality and excellent thermal stability as shown in Table 3.

Example 4 148.0 parts of phthalic anhydride and 278 parts of heptatool
．． Diheptyl phthalate 89.33%, monohebutyl phthalate 453% and heptatool 5 .76%
38.8.9 parts of esterification reaction product liquid I containing 1
．． 20°C using 128 parts of 55% ammonia aqueous solution
, neutralization treatment was carried out for 2 minutes under normal pressure.

After allowing the neutralized solution to stand for a while, diheptyl phthalate)93.
91%, heptatool 5.74% and ammonia
369.5 parts of ester phase I containing 0.01% and diheptyl phthalate) 0.11%, monoammonium monoheptyl phthalate 12.47%, heptatool 0.
It was separated into 145.1 parts of neutralized wastewater containing 81% and 0.58% of ammonia.

The ester phase (2) was washed three times with 100 parts of water at 60°C, and then washed at 56-63°C, 6.0-7.01rL71L.
Heptatool was distilled off under Hg, 2.0-3.0 mm
) The first distillate at 160-195°C was distilled off under ig, and the
~3. Distillation was performed under OmmHg, and 341.5 parts of the fraction at 195 to 204°C was designated as product (2).

Neutralized wastewater ■: Amberlis) 200C (Rohm & Co., Ltd.'s cation exchange resin product) 7
0.0 part was added thereto, and carbon dioxide gas was continuously blown in at 110'C for 35 minutes at a blowing rate of 118.6 parts/hour to carry out deammonia treatment.

The deammoniated solution was filtered to separate Amberlyst 200C, and the filtrate was allowed to stand for a while, followed by monohebutyl phthalate 9
7.10%, heptatool 2.48%, water 0.40
% and less than 0.01% ammonia
17.3 parts and diheptyl phthalate) less than 0.01%, monoammonium monoheptyl phthalate 0.25%,
Heptatool less than 0.01% and ammonia 0.
and 126.0 parts of the aqueous phase I containing 0.02%.

The esterification reaction was carried out under the same conditions as above except that 117.3 parts of the recovered oil phase, 1.386 parts of phthalic anhydride, and 278.9 parts of heptatool were used as raw materials to obtain 88.00% diheptyl phthalate. , monohebutyl phthalate 4.98% and heptatool 6.89%
381.7 parts of esterification reaction product liquid (2) containing the following were obtained.

The esterification reaction product liquid (■) is neutralized under the same conditions as the above esterification reaction product liquid (I) to obtain diheptyl phthalate (diheptyl phthalate).
Ester phase I [360.2 parts containing 92.75%, heptatool 7.02% and ammonia 0.02% and diheptyl phthalate 0.12%, monoammonium monoheptyl phthalate 13.79%, heptatool 0 .77% and 146.5 parts of neutralized wastewater containing 0.52% ammonia.

Ester phase (1) was purified under the same conditions as ester phase I above to obtain 329.4 parts of product I.

Neutralized wastewater ■ is deammoniated and filtered under the same conditions as the neutralized wastewater I above to obtain monobutyl phthalate 9.
2-31%, heptatool 7.30%, water 0.37%
and recovered oil phase n2 containing less than 0.01% ammonia.
0.3 parts of effluent aqueous phase II containing 0.10% of diheptyl phthalate, 0.21% of monoammonium (monoheptyl phthalate), 0.20% of heptatool and 0.02% of ammonia. separated.

In addition, esterification reaction product liquids ■ and ■, ester phase ■
No free phthalic acid was detected in any of the recovered oil phases ■ and ■ and recovered oil phases ■ and ■.

In addition, no diammonium phthalate was detected in either the neutralized wastewater (■) or (2) or the discharged water phases (■) or (2).

Furthermore, neither monohebutyl phthalate nor monoammonium monoheptyl phthalate was detected in either of the ester phases (① and ①).

The obtained diheptyl phthalate products ■ and ■ are the fourth
As shown in the table, it was of high quality and had excellent thermal stability.

Example 5 148.0 parts of phthalic anhydride and 395.7 parts of 8-methylnonanol were mixed to 200 to 21 parts without using a catalyst.
Bis(8-methylnonyl) phthalate obtained by reacting for 5.5 hours at 5°C and under normal pressure while removing reaction product water.
88.90%, mono(8 methylnonyl) phthalate 3
．． 474.1 parts of esterification reaction product liquid I containing 50% and 7.40% of 8-methylnonanol was neutralized using 250 parts of 0.49% ammonia aqueous solution at 40° C. and normal pressure for 30 minutes.

After the neutralized solution was allowed to stand for a while, bis(8-methylnonyl)phthalate) 92.51%, 8-methylnonanol 7,4
Esters containing 0% and 0.01% ammonia: [4
55.1 part and 0.1 part of bis(8-methylnonyl)phthalate.
05%, monoammonium mono(8-methylnonyl)phthalate 6.40%, 8-methylnonanol 0.5
3% and 266:0 parts of neutralized wastewater I containing 0.09% ammonia.

The ester phase (2) was washed twice with 200 parts of water at 45°C, and then washed at 90-96°C under Hg for 7.5-9.0 hours.
- Distill methyl nonanol, 0.2-0.4 miHg
The first distillate at 150-170°C is distilled off at 0, 1-0.
Distilled under 2 imHg, 183-199°C fraction 415
．． The 7th part was designated as product ■.

Neutralized wastewater ■ is treated with Amberlith) 15 180.
0 part was added thereto, and carbon dioxide gas was continuously blown in at 80° C. for 110 minutes at a blowing rate of 166.0 parts/hour to carry out deammonia treatment.

The deammoniated solution was filtered to separate Amberlyst 15, and the filtrate was allowed to stand for a while, followed by 967.0% of mono(8-methylnonyl) phthalate and 2.78% of 8-methylnonanol.
, 15.8 parts of recovered oil phase I containing 0.50% water and 0.01% ammonia and bis(8-methylnonyl).
less than 0.01% phthalate, monoammonium mono(8
-methylnonyl)phthalate) 0.42%, 8-methylnonanol less than 0.01% and ammonia 0.03%
and 248.0 parts of the aqueous phase I containing the effluent.

An esterification reaction was carried out under the same conditions as above except that 115.8 parts of the recovered oil phase, 140.9 parts of phthalic anhydride, and 396.0 parts of 8-methylnonanol were used as raw materials to obtain bis(8-methylnonyl). Phthalate 87.3
1%, mono(8-methylnonyl)phthalate) 4.02%
479.0 parts of an esterification reaction product liquid n containing 8.79% of 2-ethylhexanol was obtained.

The esterification reaction product solution (1) was neutralized under the same conditions as the above esterification reaction product solution (2) to obtain 91.10% of bis(8-methylnonyl)phthalate, 8-methylnonanol 8
．． Ester phase containing 70% and 0.05% ammonia;
It was separated into 265.0 parts of neutralized wastewater n containing 0.50% and 0.06% ammonia.

Ester phase (2) was purified under the same conditions as ester phase (2) above to obtain 423.0% of product II.

Neutralized wastewater ■ is deammoniated under the same conditions as the above neutralized wastewater ■ and filtered to obtain mono(8-methylnonyl).
20.8 parts of recovered oil phase n containing 90.86% of bis(8-methylnonyl)phthalate, 0.5 parts of water and less than 0.01% of ammonia and less than 0.01% of bis(8-methylnonyl)phthalate, monoammonium mono(8 - effluent aqueous phase n containing 0.10% of methylnonyl)phthalate, less than 0.01% of 8-methylnonanol and 0.01% of ammonia.
It was separated into 250.0 parts.

In addition, esterification reaction product liquids ■ and ■, ester phase ■
No free phthalic acid was detected in any of the recovered oil phases ■ and ■ and recovered oil phases ■ and ■.

Furthermore, no diammonium phthalate was detected in either the neutralized wastewater I and ① or the discharged water phases ② and ②.

Furthermore, mono (8
-Methylnonyl)phthalate and monoammonium mono(8-methylnonyl)phthalate were not detected.

Obtained bis(8-methylnonyl) phthalate product ■
As shown in Table 5, and ■ were of high quality and excellent in thermal stability.

Example 6 Phthalic anhydride 1400 parts/hour, Lineball 79 (a product of Shell Chemical Co., Ltd., which is a mixed alcohol with a straight chain ratio of 60% of aliphatic alcohol having 7 to 9 carbon atoms)
2988 parts/hour and 114 parts/hour of recovered oil phase were fed to esterification reactor 4 through conduits 1, 2 and 3, respectively.

In the esterification reactor 4, the esterification reaction was carried out without using a catalyst under the conditions of 19° C. to 210° C., normal pressure, and an average residence time of 50 hours.

The reaction product water was distilled off as an azeotropic mixture with alcohol, sent to a cooler 6 through a conduit 5, condensed, and sent to a liquid separation tank 8 through a conduit 7, where it was separated into alcohol and water.

The separated alcohol is passed through conduit 9 to esterification reactor 4.
The separated water was returned to the water and reused in the esterification reaction, and the separated water was discharged from the reaction system through a conduit 10.

Dialkyl phthalate 95.20% and monoalkyl phthalate 3.03% are extracted from the esterification reactor 4.
4330 parts/hour of esterification reaction product liquid containing 1.40% alcohol is sent to the neutralization treatment tank 12 through conduit 11, and 2512 parts/hour of 0.60% ammonia aqueous solution is supplied through conduit 13 at 35°C. Average residence time 5
Neutralized in minutes.

6842 parts/hour of neutralized liquid is transferred from conduit 14 to liquid separation tank 15.
Ester phase 4213 parts/hour and neutralized wastewater 26
29 parts/hour.

Dialkyl phthalate 0.10%, monoammonium monoalkyl phthalate 14.7%, alcohol 0
．． Part of the neutralized wastewater containing 51% and 0.36% ammonia 1800 parts/hour, the total amount of washing wastewater containing 8 parts/hour ammonia gas and 0.08% ammonia 704 parts/hour is the conduit 16°17 and 18 were respectively supplied to the preparation tank 19 to prepare a 0.60% ammonia aqueous solution.

It is separated in a liquid separation tank 15, and dialkyl phthalate 98.
20% Alcohol 1.20% Yohiammonia 0
．． 4213 parts/hour of ester phase containing 0.3% in conduit 20
The sample was then sent to the washing treatment tank 21 and was washed in one pass at 55° C. with 699 parts/hour of water supplied through the conduit 22.

Washing treatment liquid 4912 parts/hour is transferred from conduit 23 to liquid separation tank 2.
4, where it was separated into an ester phase of 4208 parts/hour and a water-washing wastewater of 704 parts/hour.

This ester phase was sent via conduit 25 to a post-treatment step.

In the post-treatment process, the temperature was 120-130°C for 30 mrn.
The alcohol was distilled off under Hg, and the first fraction at 160-170°C was cut under 0.5 mmHg.
Purified by distillation under 31n7ILHg 180-20
4052 parts/hour of the 5°C fraction was commercialized.

On the other hand, 704 parts/hour of washing-treated wastewater was sent to the preparation tank 19 through the conduit 18.

The remaining 829 parts/hour of the neutralized wastewater separated in the liquid separation tank 15 is sent through a conduit 26 to a deammonification treatment tank 27 filled with 250 parts of DOWEX 50W (a cation exchange resin product manufactured by Dow Chemical Company). Deammonification was carried out at 85° C. with an average residence time in the packed bed of 40 minutes.

In the deammonification treatment tank 27, 35.6 parts/hour of carbon dioxide gas was supplied through a conduit 28, and excess carbon dioxide gas containing ammonia was discharged through a conduit 29.

802 parts/hour of the deammonification liquid extracted from the bottom of the deammonification treatment tank 27 is directly sent to the liquid separation tank 34 without passing through the extraction treatment tank, where it is collected into a recovered oil phase of 114 parts/hour and a discharged water phase of 706 parts/hour. / Separated from time to time.

Monoalkyl phthalate 93.30%, alcohol 6
．． 04%, water 0.60% and ammonia 0.02
% was sent to the esterification reactor 4 through the conduit 3 and reused in the esterification reaction.

The discharged aqueous phase containing less than 0.01% dialkyl phthalate, less than 0.01% monoammonium monoalkyl phthalate, less than 0.01% alcohol and less than 0.01% ammonia was discharged out of the system via conduit 35.

In addition, free phthalic acid was detected in any of the esterification reaction product liquid extracted from the esterification reactor 4, the ester phase separated in the liquid separation tank 15, and the recovered oil phase separated in the liquid separation tank 34. It wasn't done.

Moreover, diammonium phthalate was not detected in either the neutralized wastewater separated in the liquid separation tank 15 or the discharge water phase separated in the liquid separation tank 34.

Furthermore, neither monoalkyl phthalate nor monoammonium monoalkyl phthalate was detected in the ester phase separated in liquid separation tank 15.

As a result of continuously producing ester under these conditions for 8 days, the dialkyl phthalate product obtained was of high quality and excellent thermal stability as shown in Table 6.

Example 7 1394 parts/hour of phthalic anhydride, 3035 parts/hour of 2-ethylhexanol and 213 parts/hour of recovered oil phase were supplied to esterification reactor 4 through conduits 1, 2 and 3, respectively.

In the esterification reactor 4, the esterification reaction was carried out without using a catalyst under the conditions of 200 to 225[deg.] C., normal pressure, and average residence time of 4.5 hours.

The reaction product water was distilled off as an azeotropic mixture with 2-ethylhexanol, sent to a cooler 6 through a conduit 5, condensed, and sent to a liquid separation tank 8 through a conduit 7, where it was separated into 2-ethylhexanol and water.

The separated 2-ethylhexanol was returned to the esterification reactor 4 through a conduit 9 and reused in the esterification reaction, and the separated water was discharged from the reaction system through a conduit 10.

The esterification reaction product liquid extracted from the esterification reactor 4 contains 89.30% bis(2-ethylhexyl) phthalate, 5.20% mono(2-ethylhexyl) phthalate, and 5.40% 2-ethylhexanol.
4469 parts/hour was sent to the neutralization treatment tank 12 through the conductor 11 and neutralized with 2839 parts/hour of a 1.22% ammonia aqueous solution supplied through the conduit 13 at 50° C. for 3 minutes.

7308 parts/hour of neutralized liquid is sent to liquid separation tank 1 from conduit 14.
5 and was separated into an ester phase of 4252 parts/hour and a neutralized wastewater of 3056 parts/hour.

Part of this neutralized wastewater contained 0.10% of monoammonium mono(2-ethylhexyl) phthalate, 25.80% of monoammonium mono(2-ethylhexyl) phthalate, 0.41% of 2-ethylhexanol, and 0.74% of ammonia. 1980 parts/hour of ammonia gas, 19 parts/hour of ammonia gas, and a total amount of 840 parts/hour of washing wastewater containing 0.12% ammonia are supplied to the preparation tank 19 through conduits 16, 17, and 18, respectively, and 1.22% ammonia is added. An aqueous solution was prepared.

Separated in liquid separation tank 15, bis(2-ethylhexyl) phthalate) 94.30%, 2-ethylhexanol 5.0%
Ester phase containing 2% and 0.04% ammonia
4252 parts/hour is sent to the washing treatment tank 21 from the conduit 20, and 832 parts/hour of water is supplied from the conduit 22, resulting in a temperature of 55°C.
Washed with water in one pass.

Washing treatment liquid 5084 parts/hour is transferred from conduit 23 to liquid separation tank 2
4, where it was separated into an ester phase and water washing wastewater.

4244 parts/hour of this ester phase was sent via conduit 25 to the post-treatment step.

In the post-treatment process, the temperature was 135-141°C and 40mmH.
2-ethylhexanol was distilled off under 0.5 h
The first distillate at 160-170℃ is cut under 0.2 g.
The product was purified by distillation under mvtHg and 3930 parts/hour of the fraction at 180-190°C was commercialized.

On the other hand, 840 parts/hour of washing-treated wastewater was sent to a preparation tank 19 through a conduit 18.

Remaining part of neutralized wastewater separated in liquid separation tank 15 107
6 parts/hour was sent through a conduit 26 to a deammonification tank 2T filled with 280 parts of Amberlyst 15, and deammoniated at 100° C. for an average residence time in the packed bed of 25 minutes.

In the deammonification treatment tank 27, 29.6 parts/hour of carbon dioxide gas was supplied through a conduit 28, and excess carbon dioxide gas containing ammonia was discharged through a conduit 29.

1012 parts/hour of the deammoniated liquid extracted from the bottom of the deammoniated treatment tank 27 is sent directly to the liquid separation tank 34 without passing through the extraction treatment tank, where it is collected as a recovered oil phase of 213 parts/hour and as a discharge water phase of 799 parts. / Separated from time to time.

mono(2-ethylhexyl)phthalate) 95.80
%, 2-ethylhexanol 3.48%, water 0.7
The recovered oil phase containing 0.0% and less than 0.01% ammonia was sent via conduit 3 to esterification reactor 4 and reused in the esterification reaction.

Bis(2-ethylhexyl) phthalate less than 0.01%, monoammonium mono(2-ethylhexyl) phthalate less than 0.01%, 2-ethylhexanol 0.
The discharged aqueous phase containing less than 0.02% ammonia and less than 0.01% ammonia was discharged out of the system via conduit 35.

In addition, free 7-talic acid is not found in any of the esterification reaction product liquid extracted from the esterification reactor 4, the ester phase separated in the liquid separation tank 15, and the recovered oil phase separated in the liquid separation tank 34. Not detected.

Moreover, diammonium phthalate was not detected in either the neutralized wastewater separated in the liquid separation tank 15 or the discharge water phase separated in the liquid separation tank 34.

Furthermore, neither mono(2-ethylhexyl) phthalate nor monoammonium mono(2-ethylhexyl) phthalate was detected from the ester phase separated in the liquid separation tank 15.

(7) J: Continuously processed for 15 days under 5 conditions (bis(2-ethylhexyl) phthalate, the product obtained as a result of manufacturing the full product) was of high quality as shown in Table 7. It had excellent thermal stability.

Example 8 70% p-toluenesulfonic acid aqueous solution containing 162.0 parts of phthalic anhydride and 304.7 parts of 2-ethylhexanol as a catalyst 4. 140-145°C in the presence of o parts;
90-100 mrttHg, the reaction product water is 2-
Bis(2-ethylhexyl) obtained by reacting for 3 hours with removal as an azeotrope with ethylhexanol
Phthalate 95.2%, mono(2-ethylhexyl) phthalate 0.5%, 2-ethylhexanol 4.2%
and p-) 450 parts of esterification reaction product liquid I containing 62% of luenesulfone Ho was neutralized using 73 parts of 1.5% ammonia aqueous solution at 60° C. and normal pressure for 10 minutes.

3. Leave the neutralized solution to stand still to obtain 96.34% bis(2-ethylhexyl) phthalate and 2-ethylhexanol.
442.0 parts of the ester phase containing 63% and 0.02% ammonia and bis(2-ethylhexyl) phthalate.
) 3.09%, monoammonium mono(2-ethylhexyl)phthalate) 3.16%, ammonium p-)luenesulfonate 3.72%, 2-ethylhexanol 3.46% and ammonia 0.17%. and 80.91 parts of Japanese treated wastewater I.

The ester phase (1) was washed three times with 1,000 parts of water at 50°C, 2-ethylhexanol was distilled off at 135°C and 40 mm Hg, and the ester phase
The initial fraction at 171°C was distilled off and the temperature was 0.1 to 0.2 mmHg.
419.5 parts of the fraction at 180 to 193° C. was designated as product (■).

Neutralized wastewater I was deammoniated by adding 40.0 parts of IR-120B thereto and continuously blowing carbon dioxide gas at 95° C. at a blowing rate of 150 parts/hour for 75 minutes.

The deammoniated solution was filtered to separate IR-120B, and the filtrate was left to stand to yield 32.13% bis(2-ethylhexyl) phthalate, 30.45% mono(2-ethylhexyl) phthalate, and 34% 2-ethylhexanol. ．． ．． 8
4%, water 2.58% ■ 7.75 parts and bis(2-ethylhexyl) phthalate o, oi%,
Monoammonium mono(2-ethylhexyl)phthalate) 0.08% ammonium P-toluenesulfonate 4
．． 0.2% 2-ethylhexanol 0.13% and ammonia 0.01% 74.9 parts of effluent aqueous phase I.

7.75 parts of recovered oil phase ■, 159.72 parts of phthalic anhydride, and 298.86 parts of 2-ethylhexanol as raw materials.
The esterification reaction was carried out under the same conditions as above except that 4.0 parts of an aqueous solution of toluenesulfonic acid (%p-) was used as a catalyst to obtain bis(2-ethylhexyl) phthalate 94
．． 79%, mono(2-ethylhexyl)phthalate) 0.
58%, 2-ethylhexanol 4.01% and p
-Toluenesulfonic acid 446 (65 parts) of esterification reaction product liquid (2) containing 0.62% was obtained.

The esterification reaction product liquid (■) was neutralized under the same conditions as the above-mentioned esterification reaction product liquid (2) to obtain 96.49% of bis(2-ethylhexyl) phthalate, 2-ethylhexanol 3
．． 436.39 parts of ester phase n containing 49% and 0.02% ammonia and 2.76% bis(2-ethylhexyl)phthalate, 3.30% monoammonium mono(2-ethylhexyl)phthalate), ammonium p-toluenesulfonate It was separated into 83.26 parts of neutralized wastewater containing 3.66%, 2-ethylhexanol 3.18% and ammonia 0.18%.

Ester phase (2) was purified under the same conditions as the above-mentioned ester phase (2) to obtain 415.8 parts of product n.

Neutralized wastewater (■) is deammoniated under the same conditions as the neutralized wastewater (■) and filtered to obtain bis(2-ethylhexyl).
Recovery phase n7. containing 29.96% phthalate, 34.35% mono(2-ethylhexyl)phthalate, 33.29% 2-ethylhexanol and 2.40% arsenic water.
51 parts and bis(2ethylhexyl) phthalate 0.0
7%, monoammonium mono(2-ethylhexyl)phthalate [), 03%, ammonium p-toluenesulfonate 4.07%, 2-ethylhexanol 0.20
% and ammonium 0.01% containing effluent aqueous phase n7
It was separated into 5.01 parts.

In addition, esterification reaction product liquid I and ■, ester phase T
No free phthalic acid was detected in any of the recovered oil phases ■ and ■ and recovered oil phases ■ and ■.

In addition, no diammonium phthalate was detected in either the neutralized wastewater (■) or (2) or the discharged water phases (■) or (2).

Furthermore, mono(2
-Ethylhexyl) phthalate and monoammonium mono(2-ethylhexyl) phthalate were not detected.

The obtained bis(2-ethylhexyl) phthalate products (1) and (2) were of high quality and excellent thermal stability as shown in Table 8.

Example 9 Kiyoward 500 (product of Kyowa Chemical Industry Co., Ltd.)

Bis(2-ethylhexyl) phthalate was obtained in the same manner as in Example 1 except that the solid content was separated by filtration after carrying out an esterification reaction using Mg6Al2(OH)16CO3.4H20 as a catalyst. Ta.

The obtained bis(2-ethylhexyl) phthalate was
As shown in the table, it was of high quality and had excellent thermal stability.

Comparative Example 1 In Example 1, the use of Amberlyst 15 and carbon dioxide gas was omitted (other than that, when producing an ester in the same manner as in Example 1, the deammoniated solution from which Amberlyst 15 had been removed was heated to 25°C). Upon cooling, a large amount of scaly crystals precipitated in the liquid.

After purification by recrystallization, the crystals were identified as phthalimide by examining the infrared absorption spectrum and measuring the melting point.

Therefore, the experiment was discontinued.

Comparative Example 2 In producing an ester in the same manner as in Example 1 except that carbon dioxide gas was not used, a deammoniated solution from which Amberlyst 15 had been removed was tested at 25°C.
When the solution was cooled to a temperature of 100%, a large amount of scale-like crystals and needle-like crystals were precipitated in the liquid.

After purification by a recrystallization method, the scale-like crystals were identified as phthalimide and the needle-like crystals were identified as phthalic acid based on an examination of infrared absorption spectra and a melting point of 1+B.

Therefore, the experiment was discontinued. Comparative Example 3 In Example 1, the use of Amberlyst 15 was omitted (other than that, when producing an ester in the same manner as in Example 1,
The esterification reaction product liquid obtained by reacting the recovered oil phase, phthalic anhydride, and 2-ethylhexanol was used as a trial.
When the mixture was cooled to 5° C., a large amount of scale-like crystals and needle-like crystals were precipitated in the liquid.

After purification by the recrystallization method, the scale-like crystals were identified as phthalimide and the needle-like crystals were identified as phthalic acid by examining the infrared absorption spectrum and measuring the melting point.

Therefore, the experiment was discontinued.

[Brief explanation of drawings]

The drawing shows an example of a system of equipment for continuously producing carboxylic acid esters by the method of the present invention. In the drawing, 4 is an esterification reactor, 6 is a cooler, and 8 is an esterification reactor.
, 15, 24 and 34 are liquid separation tanks, 12 is a neutralization tank, 19 is a preparation tank, 21 is a water washing tank, 27 is a deammonification tank, and 31 is an extraction tank.

Claims (1)

[Claims] 1. When producing a carboxylic acid ester by reacting a carboxylic acid and/or a carboxylic acid half ester with an alcohol, the esterification reaction product liquid is neutralized using an ammonia aqueous solution; A method for producing a carboxylic acid ester, which comprises separating a treated liquid into an ester phase and neutralized wastewater, and bringing the neutralized wastewater into contact with carbon dioxide gas in the presence of a cation exchange resin. 2. The method for producing a carboxylic acid ester according to claim 1, wherein the carboxylic acid is an aromatic carboxylic acid, an aromatic carboxylic acid anhydride, or an aliphatic carboxylic acid. 3. The method for producing a carboxylic acid ester according to claim 1, wherein the ammonia aqueous solution has a concentration of 0.1 to 8% by weight. 4. The method for producing a carboxylic acid ester according to claim 1, wherein the neutralization treatment is carried out at 20 to 60°C. 5. The carboxylic acid according to claim 1, wherein the cation exchange resin is a cation exchange resin having a sulfone group, a carboxyl group, a phenolic hydroxyl group, a phosphonic group, or an arsone group in a styrene-based, phenolic-based or methacrylic-based resin matrix. Method for producing esters. 6. The method for producing a carboxylic acid ester according to claim 1, wherein the neutralized wastewater is brought into contact with carbon dioxide gas at a temperature of 65 to 120°C.