JPS5855233B2 - Method for producing sebacic acid dimethyl ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for obtaining dimethyl sebacate from adipic acid monomethyl ester by an electrolytic condensation method, and purifying this to efficiently and easily produce dimethyl sebacate with high purity. It is related to.

The electrochemical condensation reaction of carboxylic acids is generally called the Kolbe reaction.

This reaction produces sebacic acid dimethyl ester from adipic acid monomethyl ester in methanol solution.

Methods for separating dimethyl sebacate from an electrolytic solution containing dimethyl sebacate include distillation, crystallization, extraction, and the like.

However, the distillation method cannot be used as a separation method because dimethyl sebacate and monomethyl adipic acid form an azeotrope.

Furthermore, crystallization methods require operations to be carried out at low temperatures;
There is a drawback that contamination of hairdipic acid monomethyl ester in the crystals of sebacic acid dimethyl ester is unavoidable.

Therefore, conventionally, a method of adding water, hexane, heptane, etc. to an electrolytic solution and performing extraction and separation has been carried out.

The main purpose of this extraction and separation is to separate the product dimethyl sebacate from the raw material monomethyl adipic acid.

However, in conventional methods, if water is used as an extractant, a large amount of water must be used, and the difference in specific gravity between the oil layer and water layer after extraction is extremely small, making it difficult to separate the two layers. was there.

Furthermore, when an organic solvent such as n-hebutane is used as an extractant, there is a drawback that a certain amount or more of adipic acid monomethyl ester is inevitably entrained in the n-hebutane layer.

The most recent production method (Publication of Patent Publication No. 50-89317) involves adding water and an organic solvent that dissolves sebacate dimethyl ester but not water to an electrolytic solution, and separating after a predetermined contact time. succeeded in separating highly pure sebacic acid dimethyl ester using a relatively small amount of extraction solvent, but this method also does not fundamentally solve the conventional drawbacks.

That is, it is unavoidable to introduce new water and organic solvent into the system, and in order to separate high purity dimethyl sebacate, a certain amount of extraction solvent must be used. there were.

As a result of intensive research to overcome these drawbacks, the inventors of the present invention discovered that after removing methanol from the electrolyte, the remaining liquid was transferred to an anion column filled with an anion exchange resin under conditions that contained as little methanol as possible. It has been found that adipic acid monomethyl ester can be adsorbed onto the resin by passing a liquid through the resin.

Furthermore, not only adipic acid monomethyl ester is adsorbed to the resin, but even alkali metal salts of adipic acid monomethyl ester, which were previously thought not to be adsorbed to anion exchange resins, can be adsorbed to the resin in the coexistence of adipic acid monomethyl ester. It has been found that the compound can be adsorbed to the resin either alone or alone.

It has also been found that adipic acid monomethyl ester and the alkali metal salt of adipic acid monomethyl ester adsorbed on the resin can be very easily recovered with methanol and the resin can be regenerated.

As a result, extremely high purity dimethyl sebacate can be extracted from the electrolyte without introducing additional water or organic solvent into the system.

The present invention was made based on this knowledge, and an object of the present invention is to provide an industrially advantageous method for producing highly pure dimethyl sebacate.

That is, the method for producing dimethyl sebacate of the present invention involves electrolytically condensing adipic acid monomethyl ester to obtain an electrolytic solution containing dimethyl sebacate, and separating dimethyl sebacate from this electrolytic solution. After removing methanol from the liquid, the remaining liquid is passed through an anion column filled with an anion exchange resin, and the resin adsorbs and separates adipic acid monomethyl ester and the alkali metal salt of adipic acid monomethyl ester. The method is characterized in that the adsorbed monomethyl adipic acid ester and the alkali metal salt of monomethyl adipic acid are recovered by passing methanol through an anion column, and the resin is regenerated.

The electrolytic solution of the present invention comprises adipic acid monomethyl ester, its alkali metal salt, sebacate dimethyl ester, adipic acid dimethyl ester which is a minute amount of by-product thereof, n
- A methanol solution containing methyl valerate, ω-hydroxy methyl valerate, and methyl allyl acetate.

Alternatively, the electrolytic reaction may be carried out in a batch manner rather than in a continuous manner, and the electrolytic solution may be obtained by completely reacting the raw material, adipic acid monomethyl ester.

The anion exchange resin used in the present invention is a strongly basic anion exchange resin having a quaternary ammonium group as an exchange group, and a weak or medium basic anion exchange resin having a primary to tertiary amine as an exchange group. In consideration of regeneration efficiency and heat resistance of the resin, weakly or medium-basic anion exchange resins are industrially advantageous.

To specifically illustrate them, for example, Diaion WA
-10, WA-11, WA-20, WA-21, WA-
30 (=Product name manufactured by Z Ryokabo Industries Co., Ltd.), Amberlite IRA-68, IR-45, I RA-47, I
RA-93, IRA-94, Amberlyst A-21,
(trade name manufactured by Rohm and Haas), etc.

Among these, tertiary amine type anion exchange resins are particularly preferred in terms of exchange capacity.

In the present invention, when adipic acid monomethyl ester and an alkali metal salt of adipic acid monomethyl ester are adsorbed on a weak or medium basic anion exchange resin in an anion column, the presence of methanol prevents the adsorption, so as much methanol as possible is used. Usually, it is preferable to suppress the methanol concentration in the liquid passing through the anion column and the residual liquid in the anion column to 5 weight φ or less, respectively.

The resin regenerant used in the present invention includes water or an organic solvent having an affinity for water, such as methanol, ethanol, acetone, and tetrahydrofuran.

Methanol is industrially advantageous because it has the advantage that it can be used after being removed from the electrolyte.

In the case of methanol, the regeneration temperature is preferably in the temperature range of room temperature to 60°C, considering the boiling point of the regenerant, the regeneration efficiency, the heat resistance of the resin, and the like.

The liquid to replace the resin after regeneration used in the present invention includes water or an organic compound that has no affinity with water and does not adsorb to the resin, such as dimethyl adipic acid and dimethyl sebacate.

However, when post-treatment and the like are taken into consideration, an electrolytic solution from which methanol, adipic acid monomethyl ester, and its alkali metal salts are removed is industrially advantageous.

Next, the present invention will be explained with reference to a flow sheet of drawings showing an example of the present invention. 1 is an electrolytic solution tank, 2 is an electrolytic cell, and the electrolytic solution is circulated between the electrolytic solution tank 1 and the electrolytic cell 2. be done.

A portion of the electrolyte in the electrolytic cell 2 is extracted and sent to the distillation column 3.

In the distillation column 3, methanol is removed, and the residual liquid is sent from the lower part of the column 3 to the lower part of the anion column 4.

In the anion column 4, adipic acid monomethyl ester and the alkali metal salt of adipic acid monomethyl ester are adsorbed onto the resin, and a liquid containing dimethyl sebacate as the main component is extracted from the upper part of the column 4. Further distillation is performed to obtain highly pure sebacic acid dimethyl ester.

The methanol distilled off from the upper part of the distillation column 3 is sent to the upper part of the anion column 4, and the adipic acid monomethyl ester and the alkali metal salt of adipic acid monomethyl ester adsorbed on the resin are recovered in methanol, and then transferred to the electrolyte tank 1.
It is circulated and subjected to an electrolytic reaction.

As detailed above, according to the method of the present invention, by using an anion exchange resin, dimethyl sebacate can be separated from the electrolyte without entrainment of monomethyl adipic acid and the alkali metal salt of monomethyl adipic acid. Furthermore, dimethyl adipic acid ester, n-valeric acid methyl ester, ω-hydroxyvaleric acid methyl ester, allyl acetate methyl ester, etc., which are by-products accompanying sebacic acid dimethyl ester, can be separated, for example, by distillation. I can do it.

Thus, in the conventional method, highly pure dimethyl sebacic acid ester cannot be obtained unless a certain amount or more of water and an organic solvent not present in the system are used, whereas in the method of the present invention, water and an organic solvent are completely newly used. Sebacic acid dimethyl ester of extremely high purity can be obtained without any oxidation.

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

Example 1 24% by weight of sebacic acid dimethyl ester as electrolyte,
Adipic acid monomethyl ester 4 weight cake, potassium salt of adipic acid monomethyl ester 2.1 weight list Other trace amounts of by-products adipic acid dimethyl ester, n-valeric acid methyl ester, ω-hydroxyvaleric acid methyl ester, allyl acetic acid Using a methanol solution containing methyl ester and the like, methanol was removed from this electrolytic solution by distillation to reduce its concentration to 3.0 weight φ.

Also, the water concentration in the electrolyte after removing methanol is 2.
The weight was φ5.

Next, the tertiary amine type weakly basic anion exchange resin DIAION WA-30 (manufactured by Mitsubishi Chemical Industry Co., Ltd., trade name) 12011Ll (water basis) regenerated into the OH type was mixed with methanol, adipic acid monomethyl ester and The potassium salt was replaced with the electrolyte solution from which it was removed, and the column (inner diameter 12 m
m' x 1500 mmh, jacket + lJ).

While passing warm water at 55°C through the jacket of this anion tower, 250 gr of the electrolyte from which methanol has been removed was previously heated to 55°C, and the liquid was passed in an upward flow at a flow rate of SV1. O
The liquid was passed through.

The concentration of adipic acid monomethyl ester is 0.05% by weight
(This concentration is defined as the concentration at the flow-through point of adipic acid monomethyl ester) or less, and the concentration of the potassium salt of adipic acid monomethyl ester is 0.05% by weight (this concentration is defined as the concentration at the flow-through point of the potassium salt of adipic acid monomethyl ester). The amount of effluent below (defined as the concentration at a point) was 175 gr.

The flow exchange capacity of adipic acid monomethyl ester is 0.5
5 meq/ml of resin, and the flow-through exchange capacity of the potassium salt of adipic acid monomethyl ester is 0.23 m
eq/ml-resin.

The average yields of sebacic acid dimethyl ester and adipic acid monomethyl ester in this effluent are shown in Table 1.

Note that the flow-through exchange capacity is the amount of liquid WA that has flowed out up to the flow-through point.
gr, amount of resin replacement liquid WB gr, concentration of adipic acid monomethyl ester or potassium salt of adipic acid monomethyl ester in the influent to the anion tower CA Weight list Adipic acid monomethyl ester and its potassium salt in the influent to the anion tower Difference between the total concentration of potassium salts and the total concentration of both in the effluent up to the flow-through point C8 Weight range, resin amount (water standard) V
m4 It was determined by the following formula from the molecular weight M of adipic acid monomethyl ester or its potassium salt.

(Hereafter, other cases were obtained in the same manner.

) Next, while hot water at 55°C is passed through the jacket of the anion tower, 300 mA' of methanol previously heated to 55°C is passed through the anion tower in a downward flow at a flow rate of SV 1.5.
The remaining liquid in the anion column was extruded and the adipic acid monomethyl ester and its potassium salt adsorbed on the resin were desorbed.

The amount of adipic acid monomethyl ester recovered in the effluent was 18.9 gr, and the recovery rate was 81φ.

In addition, the amount of potassium salt of adipic acid monomethyl ester recovered in the effluent was 10.7 gr, and the recovery rate was 9.
It was 3φ.

Note that the recovery rate is the amount of adipic acid monomethyl ester or its potassium salt recovered in the effluent, WCg r ,
The amount of adipic acid monomethyl ester or its potassium salt in the residual liquid in the anion column VVI) The amount of adipic acid monomethyl ester or its potassium salt adsorbed on the gr s resin was determined from the amount WEgr by the following formula.

(Hereafter, other cases were obtained in the same manner.

) Next, while passing hot water at 55°C through the jacket of the anion tower, 180% of the electrolyte from which methanol, adipic acid monomethyl ester, and its potassium salt, which had been previously heated to 55°C had been removed, was poured downward into the anion tower. Flow rate S
Liquid was passed through the tank at V1.5 to extrude methanol.

The concentration of metal vine in the effluent decreased to 4.5 weight φ.

Next, while hot water at 55°C was passed through the jacket of the anion tower, 250 gr of the electrolyte from which methanol had been removed and previously heated to 55°C was passed through the anion tower in an upward flow at a flow rate of SV 1.0 again. The liquid was passed through.

Both adipic acid monomethyl ester and its potassium salt reached the flow-through point at the same time, and the amount of liquid flowing out up to the flow-through point was 170 gr.

The flow exchange capacity of adipic acid monomethyl ester is 0.5
2 meq/ml resin, and the flow-through exchange capacity of potassium salt of adipic acid monomethyl ester is 0.22 meq/ml resin.
q/rnl resin.

The concentrations of sebacic acid dimethyl ester and adipic acid monomethyl ester in the effluent are shown in Table 1.

Note that the purity is determined by the concentration C of adipic acid monomethyl ester.
c. It was determined from the concentration CD of sepa-shioic acid dimethyl ester using the following formula.

Further, adipic acid monomethyl ester and sebacic acid dimethyl ester were analyzed by gas chromatography, and potassium salt of adipic acid monomethyl ester was analyzed by atomic absorption spectrometry of potassium ions.

Example 2 The same operation as in Example 1 was carried out except that the electrolyte composition of Example 1 and the electrolyte composition after methanol removal were changed, and the amount of liquid flowing into the anion tower in the adsorption process and re-adsorption process was changed. I did it.

Sebacic acid dimethyl ester 27 weight cake as electrolyte,
Adipic acid monomethyl ester 0.4 weight list Potassium salt of adipic acid monomethyl ester 0.9 weight φ, a minute amount of by-product adipic acid dimethyl ester, n-
Using a methanol solution of valeric acid methyl ester, ω-hydroxyvaleric acid methyl ester, allyl acetate methyl ester, etc., methanol was removed from this electrolytic solution by distillation, and the concentration was lowered to 4.5 weight φ.

Also, the water concentration in the electrolyte after removing methanol is 3.
It was 3% by weight.

The results obtained using the electrolytic solution from which methanol has been removed are shown below.

(1) In the adsorption process, 1000 g of an electrolytic solution from which methanol had been removed was passed through an anion tower.

The amount of liquid flowing out to the flow-through point of adipic acid monomethyl ester was 4j715 gr, and the flow-through exchange capacity was 0.33g.
meq/ml-resin.

The purity of sebacic acid dimethyl ester in this effluent is 9
It was 9.9φ or more.

Further, the amount of liquid flowing out to the flow-through point of the potassium salt of monomethyl adipic acid was 870 gr, and the flow-through exchange capacity was 0.73 meq/ml-resin.

(2) In the regeneration process, the amount of adipic acid monomethyl ester recovered in the effluent was 5 gr, and the recovery rate was 88%.

In addition, the amount of potassium salt of adipic acid monomethyl ester recovered in the effluent was 18.9 gr, and the recovery rate was 9.
It was 2 charges.

(3) Also in the re-adsorption process, 1000 g of the electrolyte from which methanol had been removed was passed through the anion tower.

The amount of liquid flowing out to the flow-through point of adipic acid monomethyl ester was 675 gr, and the flow-through exchange capacity was 0.31
meq/Ttl-resin.

The purity of sebacic acid dimethyl ester in this effluent is 9
It was 9.9% or more.

Further, the amount of liquid flowing out to the flow-through point of the potassium salt of adipic acid monomethyl ester was 850 gr, and the flow-through exchange capacity/d O, 71 meq/rul-resin.

Example 3 The tertiary amine type weakly basic anion exchange resin of Example 1 was changed from Diaion WA-30 to Amberlite IRA-9.
4 (manufactured by Rohm & Barth, trade name) and the temperature in each step of adsorption, regeneration, and re-adsorption was changed from 55° C. to room temperature, and the same operation as in Example 1 was performed.

The results are shown below. (1) In the adsorption process, adipic acid monomethyl ester and its potassium salt reached the flow-through point at the same time, and the amount flowing out up to the flow-through point was 167 gr.

The flow exchange capacity of adipic acid monomethyl ester is 0.5
0 meq/ml-resin and the flow-through exchange capacity of the potassium salt of adipic acid monomethyl ester is 0.21 m
eq/ml-resin.

Also, what is the purity of sebacic acid dimethyl ester in the effluent? t
It was 99.9% or more.

(2) In the regeneration process, the amount of adipic acid monomethyl ester recovered in the effluent was 17.3 gr, and the recovery rate was 72 g.

In addition, the amount of potassium salt of adipic acid monomethyl ester recovered in the effluent was 10.2 gr, and the recovery rate was 9.
It was 0φ.

(3) In the re-adsorption process, adipic acid monomethyl ester and its potassium salt reached the flow-through point at the same time, and the amount that flowed out up to the flow-through point was 160 gr.

The flow exchange capacity of adipic acid monomethyl ester is 0.4
6 meq/ml-resin and the through-flow exchange capacity of the potassium salt of adipic acid monomethyl ester is 0.20 m
eq/ml-resin.

In addition, the purity of sebacic acid dimethyl ester in the effluent was 9.
It was 9.9% or more.

[Brief explanation of the drawing]

The drawing is an example of a flow sheet for implementing the present invention, and in the drawing, 1 is an electrolyte tank, 2 is an electrolytic tank, 3 is a distillation column, and 4 is an anion column.

Claims (1)

[Scope of Claims] 1 Adipic acid monomethyl ester is electrolytically condensed to obtain an electrolytic solution containing sebacate dimethyl ester, and when separating sebacate dimethyl ester from this electrolytic solution, methanol is removed from the electrolytic solution, and then methanol is removed from the electrolytic solution. The residual liquid is passed through an anion column filled with anion exchange resin, and adipic acid monomethyl ester and adipic acid monomethyl ester alkali metal salt are adsorbed and separated by the resin, and then adipic acid monomethyl ester and adipine adsorbed on the resin are separated. A method for producing dimethyl sebacate, which comprises recovering the alkali metal salt of acid monomethyl ester by passing methanol through an anion column to regenerate the resin. 2. The method for producing dimethyl sebacate according to claim 1, wherein the anion exchange resin is a weak or medium basic anion exchange resin. 3. The method for producing dimethyl sebacate according to claim 2, wherein the weak or medium basic anion exchange resin is a tertiary amine type anion exchange resin. 4 Anion exchange resin Claim 1: The anion exchange resin is a weak or medium basic anion exchange resin, and the concentration of methanol in the adsorption stock solution passed to the anion column is 5 weight φ or less.
A method for producing sebacic acid dimethyl ester as described in . 5. The method for producing dimethyl sebacate according to claim 1, wherein the methanol used to regenerate the resin is methanol removed from the electrolyte. 6. The method for producing dimethyl sebacate according to claim 1, wherein the regeneration of the resin with methanol is carried out at a temperature of room temperature to 60°C. 7. The method for producing dimethyl sebacate according to claim 1, wherein the regeneration solution remaining in the anion column is replaced with an electrolytic solution from which methanol, monomethyl adipic acid, and its alkali metal salt have been removed.