JPS5839140B2 - Method for producing ethylene glycol monoethyl ether acetate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ethylene glycol monoethyl ether acetate (ethylene glycol monoethyl ether acetate) by a transesterification reaction between ethyl acetate and ethylene glycol monoethyl ether. It is characterized by using a resin and using ethylene glycol monoethyl ether in excess of ethyl acetate as a raw material.

The transesterification reaction between ethyl acetate and ethylene glycol monoethyl ether is a reaction that produces ethylene glycol monoethyl ether acetate, which is important as a solvent for acrylic resin paints, and at the same time produces ethanol as a by-product.
This ethanol has attracted attention for its advantages, such as its ability to be used in the first step of the reaction, i.e., the reaction to produce ethylene glycol monoethyl ether (by addition of ethylene oxide).
Recently, 2.3 methods of carrying out this reaction have been proposed.

For example, in Japanese Patent Publication No. 43-16966, using phosphoric acid, halatoluenesulfonic acid, aluminum alcoholade, isopropyl titanate, etc. as a catalyst, excess ethyl acetate is used relative to ethylene glycol monoethyl ether, and the by-produced ethanol is converted into ethyl acetate. A method is described in which the reaction is carried out while distilling off the azeotrope with.

Furthermore, in JP-A-47-29312, in the presence of a homogeneous catalyst such as aluminum alcolade or titanium alcolade, ethyl acetate is used in excess in the same manner as the method of the above-mentioned Japanese Patent Publication Sho, and under pressurized conditions. , describes a method in which the reaction is carried out while distilling off ethanol as a by-product as an azeotrope with ethyl acetate.

However, these methods all use homogeneous catalysts.
However, since an excess of ethyl acetate is used relative to ethylene glycol monoethyl ether, there are some difficulties in industrial implementation.

For example, when using an acidic homogeneous catalyst such as phosphoric acid or para-toluenesulfonic acid, it is necessary to neutralize the catalyst before purifying the product ethylene glycol monoethyl ether acetate, and an aqueous alkaline solution is added to the reaction product liquid. Adding it causes many disadvantages.

Namely, ethanol, which is completely soluble in water, ethylene glycol monoethyl ether, and ethylene glycol monoethyl ether acetate, which has a fairly high solubility.
Not only is ethyl acetate lost during water repellency, but a considerable amount of water is dissolved in the organic layer containing ethyl acetate, resulting in water-ethanol (boiling point 78.2°C), water-ethyl acetate (boiling point 70.4°C)
), water-ethanol-ethyl acetate (boiling point 70.2°C),
Due to the formation of an azeotrope such as ethyl acetate-ethanol (boiling point 71.8°C), the recovery operation of ethyl acetate and ethanol becomes very complicated.

In addition, when metal alcoholade is used as a catalyst, post-treatment,
There are problems such as variations in activity.

In other words, metal alcoholade catalysts usually need to be hydrolyzed with water or acid and removed as hydroxides, or separated under reduced pressure using an evaporator, etc., prior to distillation of the product liquid, and there are also differences between catalyst preparation lots. Due to the influence of moisture in the raw materials, variations in activity are often seen, making it difficult to handle (
There are some drawbacks.

Furthermore, these methods use ethyl acetate in excess of the amount required for the reaction with ethylene glycol monoethyl ether, and the by-product ethanol is distilled out of the system as an azeotrope with ethyl acetate. A special distillation operation is required to completely separate the ethanol used as a raw material for the reaction from this azeotrope.

For example, a method can be considered in which the distillate from the reactor is distilled under pressure and then the azeotrope from the top of the column is subjected to atmospheric or reduced pressure distillation.

The above-mentioned Japanese Patent Application Laid-Open No. 47-29312 describes a method in which ethanol is recovered by reactive distillation under pressure using an excess of ethyl acetate, followed by distillation under reduced pressure. It is difficult to smoothly carry out such operations using catalysts such as Alcolade and titanium Alcolade.

In addition, if ethanol is not purified and used as an azeotrope with ethyl acetate in the previous reaction, that is, the reaction of adding ethylene oxide to ethanol to produce ethylene glycol monoethyl ether, This is not preferable because the yield of the product decreases.

By using a solid strongly acidic cation exchange resin as a catalyst, the present inventors solved problems such as catalyst separation, separation of reaction product liquid due to water contamination, and activity variation. We have conducted various studies focusing on what is possible, but there are many practical problems in using a gel-like strongly acidic cation exchange resin as a catalyst, or in using a strongly acidic cation exchange resin directly in a conventionally known method. It was acknowledged that there were problems.

In other words, in a system where only organic compounds such as ethyl acetate, ethylene glycol monoethyl ether, ethanol, and ethylene glycol monoethyl ether acetate are present, ordinary gel-like resins not only have extremely low catalytic activity, but also contain a large amount of catalytic activity in the reaction raw materials. If various impurities, especially polymerizable organic impurities, are contained, the activity will quickly decrease, and both the raw materials and products mentioned above are generally widely used as "solvents".
This is a substance that is used as a binder, and in such a system, the catalyst resin deteriorates significantly and easily breaks up in the reactor.

Next, a conventionally known method was applied to a strongly acidic cation exchange resin, in which an excess of ethyl acetate was used relative to ethylene glycol monoethyl ether, and the by-product ethanol was distilled off as an azeotrope with ethyl acetate. In some cases, the relatively high reaction temperature causes the problem that the catalyst deteriorates over a short period of time.

In order to maintain a long catalyst life, it is necessary to carry out the reaction at a relatively low temperature. For example, if an excess of ethyl acetate is used to carry out an equilibrium reaction using a fixed bed liquid phase flow method, unreacted ethyl acetate There are problems such as a large amount of heat is required to separate ethanol and ethanol, and the separation itself is extremely difficult.

The present inventors have conducted extensive research in order to overcome the deficiencies of the conventional methods and establish an industrially advantageous transesterification method between ethyl acetate and ethylene glycol monoethyl ether. The catalytic activity and lifetime of transesterification reactions vary greatly depending on the type of acidic cation exchange resin, and if a porous strongly acidic cation exchange resin is used instead of the conventionally known gel-like resin, the space-time yield can be extremely high. In addition, ethylene glycol monoethyl ether is used in excess of ethyl acetate as a raw material, and unreacted ethyl acetate is converted into ethanol in the subsequent separation process. By recovering it as an azeotrope and recycling it as a reaction raw material, most of the by-product ethanol can be avoided from forming an azeotrope with ethyl acetate.
It was discovered that not only can it be recovered very easily and economically in a later separation step, but also that the life of the catalyst can be extended by the above raw material composition, and the method of the present invention has been achieved.

That is, an object of the present invention is to carry out a transesterification reaction between ethyl acetate and ethylene glycol monoethyl ether to obtain ethylene glycol monoethyl ether acetate in an industrially advantageous manner. In the transesterification method with monoethyl ether, ethyl acetate and ethylene glycol monoethyl ether in excess of ethyl acetate,
A crosslinking degree of 2 with a surface area of 0.10 m/11 or more and a porosity (pore volume) of 5% or more, along with ethanol recovered as an azeotrope with ethyl acetate from the subsequent separation step.
This is easily achieved by contacting in the liquid phase with a porous strongly acidic cation exchange resin of ~50%.

According to the present invention, there is no need to separate the catalyst, there is no water contamination, and continuous operation is very easy.A high conversion rate can be obtained with a small amount of catalyst. In addition to the advantages that the reaction can be carried out stably for a long period of time with almost no visible disintegration, ethyl acetate, which is recovered as an azeotrope with ethanol, can be used as a raw material for the reaction, and there are no problems with the target product or by-products. , it is possible to efficiently and economically separate, recover, and reuse unreacted raw materials, and in particular, ethanol, which has conventionally been difficult to separate and recover and requires a large amount of equipment and expense, can be easily and economically processed. The recovery effect is significant, and this makes it possible to economically produce ethylene glycol monoethyl ether acetate.

The present invention will be explained in detail below.The porous strongly acidic cation exchange resin with a skeleton made of styrene-divinylbenzene copolymer used as a catalyst in the present invention has many pores with a diameter of several hundred to several thousand holes inside. It is a resin with macropores, and is distinguished from conventional gel-like resins in that it has a large internal surface area and porosity (pore capacity).

The physical properties of the porous strongly acidic cation exchange resin can be changed widely by changing the manufacturing conditions, but as a catalyst used for the transesterification reaction between ethyl acetate and ethylene glycol monoethyl ether, at least 0.1
A resin having a surface area of 0 m''/1 or more and a porosity of 5% or more and a degree of crosslinking of 2 to 50 is used.

If the degree of crosslinking is too low, the catalyst will have a short lifespan and will deteriorate in a relatively short period of time.

In addition, if it is too high, the activity is low and it is not practical.

These porous strongly acidic cation exchange resins can be prepared by various known methods.

For example, by copolymerizing styrene and divinylbenzene,
Non-solvents that do not participate in polymerization and are good solvents for monomers when producing the base material of ion-exchange resins, but have no or small ability to swell the resulting copolymer, such as tertiary amyl alcohol. It can be prepared by introducing a sulfonic acid group into a porous base resin obtained by coexisting an alcohol such as , secondary butyl alcohol, or an aliphatic hydrocarbon such as isooctane or n-heptane.

In addition, when copolymerizing styrene and divinylbenzene, a linear polymer that does not participate in the polymerization, such as polystyrene, is allowed to coexist, and then this linear polymer is eluted from the copolymer. It can be prepared by introducing a sulfonic acid group into a base resin.

In the present invention, it is necessary that the molar ratio of ethyl acetate and ethylene glycol monoethyl ether brought into contact with the porous strongly acidic cation exchange resin is such that the latter is in excess of the former. affects the reaction rate and increases the cost of separating and recovering unreacted components, so the ratio is usually 1:1.1 to 10 in order to obtain an appropriate space-time recovery and to reduce the circulation amount of recovered raw materials. Preferably 1:
The range is preferably from 2 to 5.

In addition, the amount of ethanol to coexist is determined from the subsequent separation process.
There are no particular restrictions as long as it can be recovered azeotropically with ethyl acetate under normal pressure or slightly increased or reduced pressure.
, usually in a molar ratio of 0.05 to 0.8 to ethyl acetate.
It is carried out as appropriate within the range of 5.

In addition, excess ethanol that escaped azeotropy with ethyl acetate is
In a later separation step, it is separated into ethylene glycol monoethyl ether and ethylene glycol monoethyl ether acetate, which are used for the reaction with ethylene oxide in the earlier step.

As the type of reactor in the present invention, it is preferable to use a column that can be filled with a porous strongly acidic cation exchange resin.

The flow of the raw material mixture to the column may be either a forward or reverse piston flow type in a fixed bed, or a complete reverse flow mixing type in a fluidized bed, and the contact time is 0.2 to 5 hours, preferably 0.5 to 3 hours. supply at a rate such that

The temperature of the column is kept below 100°C, usually between 20 and 90°C, preferably between 30 and 80°C.

At high temperatures of 100°C or higher, catalyst deterioration and by-products of ethyl ether and high-boiling substances become significant.

The reaction pressure only needs to be large enough to maintain the liquid phase, and normally normal pressure is fine, but depending on the raw material composition and reaction temperature, the pressure may be increased to 5 kfl/crA (absolute pressure). .

The selectivity of ethylene glycol monoethyl ether acetate in the present invention is extremely high (98% or more), and the practical value of using excess ethylene glycol monoethyl ether and coexisting ethanol in the raw material composition is high.

Typical examples are shown below, but these are merely illustrative examples to facilitate understanding of the method of the present invention.
It goes without saying that the present invention is not limited to these, and is not limited thereto in any way.

Example 1 Diaion-PX312 (H type), a porous strongly acidic cation exchange resin with a skeleton made of styrene-divinylbenzene copolymer, was thoroughly dried in advance (registered trademark).
Degree of crosslinking 6, surface area 0.15-0, 20 m/f? , porosity 10%) was used as a catalyst for continuous operation.

Made of stainless steel and filled with 100m7 of ethylene glycol monoethyl ether, the catalyst mentioned above.
New ethylene glycol monoethyl ether,
Ethyl acetate at 22.6f/Hr and 22.1f/Hr, respectively.
Ethyl acetate-ethanol azeotropic composition recovered from the latter stage separation step of treating Hr and reaction product liquid 27.4 P/H
r (ethanol 25.8% by weight), ethylene glycol monoethyl ether 107.3'f? /Hr in a mixer and then supplied at a rate of 200ml/hr.

As a result of analyzing the reaction product liquid discharged from the reactor using a gas chromatograph using a conventional method, the composition (based on weight) was found to be 1 part ethylene glycol monoethyl ether acetate.
8.3%, ethanol 10.3%, acetic acid: r-f 11
．． 3%, ethylene glycol monoethyl ether 59.
8%, others 0.3%.

Therefore, the reaction results are ethyl acetate conversion rate of 52.1% and ethylene glycol monoethyl ether acetate selectivity of 99.0 based on ethylene glycol monoethyl ether.
%.

Although this continuous reaction was carried out for three months, almost no deterioration of the catalyst was observed.

Example 2 Porous strongly acidic cation exchange resin Diaion-PX316 (H type) [registered trademark] (crosslinking degree 8, surface area 0.15~ A reactor of the same type as in Example 1 was filled with 100 rr Ll of ethylene glycol monoethyl ether in a state swollen with ethylene glycol monoethyl ether, and continuous operation was carried out.

Fresh ethylene glycol monoethyl ether and ethyl acetate were added to this reactor maintained at 65°C by backflow at 10.0 P/Hr and 9.8% at normal pressure, respectively. Ethyl acetate-ethanol azeotropic composition 11, IS'/Hr recovered from the latter stage separation step of treating the reaction product liquid with /Hr
(-11-tanol 31% by weight), ethylene glycol monoethyl ether 60.9? /Hr in a mixer and then supplied at a rate of 100 mA/Hr.

The reaction product liquid discharged from the reactor was analyzed by gas chromatography using a conventional method, and the composition was found to be 15.8% ethylene glycol monoethyl ether acetate, 9.3% ethanol, 8.3% ethyl acetate, and ethylene glycol monoethyl ether acetate. Recall monoethyl ether was 66.3% and others 0.3%.

Therefore, the reaction volume is ethyl acetate reaction rate of 55.9% and ethylene glycol monoethyl ether acetate selectivity of 98.8 based on ethylene glycol monoethyl ether.
%.

Although this continuous reaction was carried out for three months, almost no deterioration of the catalyst was observed.

Example 3 Porous strongly acidic cation exchange resin Diaion PK-228 (H type) [registered trademark] (degree of crosslinking 14, surface area 0.15~ 0.20 ml?, porosity 10%) was used as a catalyst, and the reactor of the same type as in Example 1 was filled with 100 ml of ethylene glycol monoethyl ether in a state swollen with ethylene glycol monoethyl ether, and continuous operation was performed.

Fresh ethylene glycol monoethyl ether and ethyl acetate were added to this reactor maintained at 90°C and 2 kg/c4 (absolute pressure) at 25.5 y'/Hr and 2
4.7? /Hr and ethyl acetate ethanol azeotropic composition recovered from the latter stage separation step of treating the reaction product liquid 31.5
f/Hr (ethanol 25.8% by weight), ethylene glycol monoethyl ether 97.1? /Hr in a mixer and then supplied at a rate of 200 ml/Hr.

The composition of the reaction product liquid is 20.5% ethylene glycol monoethyl ether acetate, 11.7% ethanol,
The contents were 13.1% ethyl acetate, 54.3% ethylene glycol monoethyl ether, and 0.4% others.

Therefore, the reaction volume is 51.2% ethyl acetate conversion and 98.2 ethylene glycol monoethyl ether acetate selectivity based on ethylene glycol monoethyl ether.
%.

Example 4 Amberlyst 15, a porous strongly acidic cation exchange resin with a skeleton made of styrene-divinylbenzene copolymer
registered trademark] (degree of cross-linking 16, surface area 43 m/P, porosity 32%) as a catalyst, 100 ml of the same type of reactor as in Example 1 was filled in a state swollen with ethylene glycol monoethyl ether, and continuous operation was carried out. I did this.

Fresh ethylene glycol monoethyl ether and ethyl acetate were added to this reactor maintained at 70°C and 2 kg/ca (absolute pressure) by backflow at 12.0 P/Hr and 1
1.61/Hr and ethyl acetate-ethanol azeotropic composition recovered from the latter stage separation step of treating the reaction product liquid 17.
4 P/Hr (ethanol 31wt%), ethylene glycol monoethyl ether 484? /Hr in a mixer and then supplied at a rate of 100ml/Hr.

The composition of the reaction product liquid was 19.4% ethylene glycol monoethyl ether acetate, 12.8% ethanol, 13.4% ethyl acetate, 54.1% ethylene glycol monoethyl ether, and 0.3% other. there were.

Therefore, the reaction volume is ethyl acetate reaction rate of 49.3%,
Ethylene glycol monoethyl ether acetate selectivity based on ethylene glycol monoethyl ether: 98.
It is 2%.

Comparative Example As a catalyst, gel-like strongly acidic cation exchange resin Amberlite 1R120B (H type) [registered trademark] (crosslinking degree 8, surface area 0.1 m/f? below, porosity 1.8%) 50 m
1 (in ethylene glycol monoethyl ether) was charged into the same reactor as in Example 1, and 66.4 P of ethylene glycol monoethyl ether was charged by reverse flow at 65°C and normal pressure.
/Hr and ethyl acetate 22.6? /Hr was supplied at a rate of 100 ml/Hr.

The composition of the reaction mixture discharged from the reactor was 5.8% ethylene glycol monoethyl ether acetate, 5.3% ethanol, 641% ethyl acetate, 15.8% ethylene glycol monoethyl ether, and 0.3% others. there were.

Therefore, the reaction volume is ethyl acetate reaction rate of 43.1% and ethylene glycol monoethyl ether acetate selectivity of 98.1 based on ethylene glycol monoethyl ether.
%.

When this continuous reaction was carried out for one month, the ethyl acetate reaction rate decreased to 37.3% and the outflow differential pressure increased.

In addition, some of the resin taken out after the reaction was found to be cracked or crushed.

Claims (1)

[Claims] 1. Ethylene glycol characterized by reacting ethyl acetate and ethylene glycol monoethyl ether in excess of ethyl acetate under liquid phase conditions in the presence of a porous strongly acidic cation exchange resin. Method for producing monoethyl ether acetate. 2. The method of item 1 above, wherein the porous cation exchange resin is a resin in which a sulfonic acid group is bonded to a skeleton made of a styrene-divinylbenzene copolymer with a degree of crosslinking of 2 to 50. 3 The porous cation exchange resin has a surface area of 0.1 rrl/
? The method according to the above item 1 or 2, wherein the resin has a long pore capacity of 5% or more. 4. The method of item 1 above, wherein the molar ratio of ethyl acetate and ethylene glycol monoethyl ether at the beginning of the reaction is within the range of 1:1.1 to 10. 5. The method according to item 1 above, wherein in the step of separating bioforms after the reaction, the reaction is carried out in the coexistence of unreacted ethyl acetate and ethanol recovered as an azeotrope.