JPS5950755B2 - Production method of dimethyl thapsinate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel industrial method for producing dimethyl thapsinate.

More specifically, the present invention relates to a method for producing dimethyl thapsinate by cross-Kolbe electrolytic condensation of monomethyl adipate and monomethyl dodecanedioate. Dimethyl thapsinate has an extremely wide range of uses as a raw material for perfumes, various polymers, plasticizers, etc.

In particular, it is extremely useful as a raw material for macrocyclic musk fragrances. The following methods have been proposed as methods for producing thapsic acid and its esters.

Various methods have been proposed, such as a method for producing it using Fenton's reagent using cyclohexanone and olefin as raw materials, and a fermentation method for converting n-alkane or monocarboxylic acid into dibasic acid using yeast. However, all of these methods have problems such as extremely long reaction steps, use of special reagents, and low yields, and are still not sufficient as industrial production methods. Furthermore, a method for producing thapsic acid diester from azelaic acid monoester by Kolbe electrolytic reaction is disclosed in Japanese Patent Publication No. 11116/1983, Yukagaku, 12, 669 (1963), and the like. However, this method requires separation into an anode chamber and a cathode chamber using a cation exchange membrane, and the water concentration in the anolyte is also set at a value of 30 to 40% by weight. This method for producing thapsic acid diester uses a cation exchange membrane, which causes problems such as a complicated apparatus and extremely low current efficiency, and it cannot be said to be an adequate method for industrial production. Regarding the method of electrolytically condensing adipic acid monoester, research has been actively conducted and various findings have been obtained. That is, the present inventors previously published a detailed industrial implementation technique in Japanese Unexamined Patent Publication No. 55
It is disclosed in Japanese Patent Application Laid-open No. 56-44782, etc. However, when this technology is simply applied to produce dimethyl thapsinate from monomethyl adipate and monomethyl dodecanoate, a sudden voltage rise occurs in the latter half of electrolysis, making electrolysis impossible and leaving unreacted monomethyl adipate and monomethyl dodecanoate. remains in large quantities. In the post-process purification of dimethyl thapsinate in which monomethyl adipate and monomethyl dodecanoate are present, the equipment for separating monomethyl adipate and monomethyl dodecanoate becomes complicated, and the loss of monomethyl adipate and monomethyl dodecanoate;
There is also a problem that the product purity of dimethyl thapsinate is reduced. The inventors of the present invention have conducted intensive research to provide an industrially advantageous manufacturing method that can solve all the problems of the various methods proposed to date, and as a result, they have developed the present invention. When producing dimethyl sebacate from monomethyl adipate proposed by the inventors. Applying the electrolysis method described above, the monomethyl adipate in the charging solution is made 0.5 to 2.0 times the mole of monomethyl dodecanoate, electrolyzed for a certain period of time, and then monomethyl adipate is added and electrolysis is continued to continue the electrolysis. We have discovered that it is possible to prevent sudden voltage increases that would otherwise be impossible.

This discovery was made based on the knowledge described above, and it is possible to produce tapsin industrially advantageously by suppressing the rapid voltage rise and carrying out electrolysis until monomethyl adipate and monomethyl dodecanoate are substantially eliminated. The object of the present invention is to provide a method for producing dimethyl acid.

The method for producing dimethyl thapsinate of the present invention which achieves the above object is to add a mixture of monomethyl dodecanoate and monomethyl adipate in an amount of 0.5 to 2.0 times the mole of monomethyl dodecanoate to their alkali metal salts. The method is characterized in that electrolytic condensation is carried out in batches for a certain period of time in a methanol solution containing methane, and then monomethyl adipate is further added and electrolyzed.

The details of the method for cross-Kolbe electrolytic condensation of dimethyl thapsinate from monomethyl adipate and monomethyl dodecanoate according to the present invention are as follows.

The ratio of monomethyl adipate and monomethyl dodecanoate at the time of charging in the present invention has a large effect on the electrolytic voltage. If monomethyl adipate is less than 0.5 times the mole of monomethyl dodecanoate, a voltage rise will occur after the start of electrolysis, making electrolysis impossible. When monomethyl adipate is 0.5 times mole or more relative to monomethyl dodecanoate, electrolysis can be carried out without voltage increase. Further, as the proportion of monomethyl adipate increases, the electrolytic voltage decreases, which is preferable. However, as the proportion of monomethyl adipate increases, the amount of by-product dimethyl sebacate produced increases, and the amount of dimethyl thapsinate produced decreases. From the above, it is necessary that monomethyl adipate be present in an amount of 0.5 to 2 moles relative to monomethyl dodecanoate. The present invention applies the above-mentioned electrolysis method for producing dimethyl sebacate from monomethyl adipate, in which unreacted monomethyl adipate and In order to prevent monomethyl dodecanoate from remaining, it is necessary to add monomethyl adipate to the electrolytic solution after electrolysis for a certain period of time and conduct electrolysis until monomethyl adipate and monomethyl dodecanoate are substantially eliminated.

That is, monomethyl adipate is added to the electrolytic solution before the voltage rises and electrolysis is performed subsequently, but monomethyl adipate can also be added after the voltage rises and electrolysis is performed again. It is preferable to add monomethyl adipate when the concentration of monomethyl dodecanoate is about 2% by weight or more at the time when the voltage increases. It is more preferable to use less than % by weight. The amount of monomethyl adipate added in the present invention is such that the amount of monomethyl adipate and its alkali metal salt after addition is 3 to 8 times the mole of unreacted monomethyl dodecanoate and its alkali metal salt. is preferable, and 5 to 7 times the molar amount is more preferable.

Below 3 times the mole, a rapid voltage increase occurs again and unreacted monomethyl dodecanoate and monomethyl adipate remain.

When the molar ratio is 8 times or more, the amount of dimethyl sebacate produced other than the main product increases.

The solution in which electrolytic condensation is carried out in the present invention is the raw material monomethyl adipate and dodecani! Although the methanol solution contains acid monomethyl and its neutralized salt, it may also contain the products dimethyl thapsate, dimethyl sebacate, dimethyl docosaniate, and other by-products.

If the water concentration in the methanol solution is extremely reduced during electrolytic condensation, the current efficiency will become extremely poor, and if the water concentration exceeds 3.5% by weight, the selectivity and current efficiency will decrease. Deteriorate. Therefore, in order to maintain high selectivity and current efficiency, it is necessary to maintain the water concentration in the range of 0.15 to 3.5% by weight. The electrolytic condensation of the present invention is
The charged raw materials, monomethyl adipate and monomethyl dodecanoate, were heated until the voltage rose in the second half.
Alternatively, it may be carried out batchwise until the voltage rises, or it may be carried out continuously by maintaining monomethyl adipate and monotumethyl dodecanoate at a constant concentration for a certain period of time, and then at the time when the voltage rises in the latter half, or It may be performed batchwise until the voltage rises.

Considering the separation and purification of the product in the subsequent process, the concentration of monomethyl adipate and monomethyl dodecanoate is 0.5% by weight during electrolytic condensation after addition of monomethyl adipate.
It is preferable to continue until below. The mixed acid of monomethyl adipate and monomethyl dodecanoate used in the electrolytic condensation of the present invention is used in an amount of 10 to 50% by weight.

At a concentration higher than 50% by weight, the voltage becomes high, and at a concentration lower than 10% by weight, the volumetric efficiency deteriorates, and the current efficiency also deteriorates.

In the present invention, hydroxides, carbonates, bicarbonates, methylates, ethylates or amines of lithium, potassium, sodium are used as neutralizing bases in order to increase the conductivity of the solution during electrolytic condensation. However, amines are oxidized at the anode and accelerate the consumption of the anode, and the use of lithium compounds deteriorates current efficiency. Therefore, it is desirable to use sodium and potassium hydroxides, carbonates, bicarbonates, and methylates. Also, the degree of neutralization (defined as the molar ratio of the mixed acid to be neutralized with a base) during the preparation of the mixed acid of monomethyl adipate and monomethyl diate.

) is preferably 2 to 50 mol%. If the degree of neutralization is less than 2 mol%, the voltage will be high, and if the concentration is higher than 50 mol%, the current efficiency will be low. The electrolytic cell used in the present invention may be one commonly used in organic electrolytic reactions, as long as it is capable of passing an electrolytic solution between the two electrodes at a high flow rate.

For example, an electrolytic cell has a cathode plate and an anode plate facing each other in parallel,
A polypropylene plate defining the electrode spacing is placed between the two electrodes. This polypropylene plate has an opening in the center so that the electrolyte can flow therethrough. The current-carrying area of the electrode is determined by the size of this opening, and the electrode spacing is determined by the thickness of this plate.

The electrolytic solution enters through a supply port provided in the electrolytic cell, undergoes a reaction while passing between the two electrodes, exits through an outlet port, and is circulated to the electrolyte tank. As the electrode material used in the electrolytic condensation of the present invention, platinum, rhodium, ruthenium, iridium, etc. are used alone or in an alloy for the anode, and are usually used as a plating, and the plating substrate is made of titanium, rhodium, iridium, etc.
Tantalum etc. are used.

The cathode preferably has a low hydrogen overvoltage, but is not particularly limited, and platinum, iron, stainless steel, titanium, etc. can be used. The flow rate of the electrolytic solution in the electrolytic cell is preferably 1 to 4 m/sec.

If the flow rate is less than 1 m/sec, the current efficiency will be low, and if the flow rate is faster than 4 m/sec, the pressure loss within the electrolytic cell will increase.

The spacing between the electrodes is preferably 0.5 to 3 mm. If it is less than 0.5 mm, the pressure loss inside the electrolytic cell will be large, and if it is wider than 3 mm, the voltage will be high.

The current density is preferably 5 to 40 A/Dm2, and 5/Dm・
If it is less than that, the current efficiency will be low. The temperature of the electrolyte is 45-6
5°C is preferred. If the temperature is lower than 45° C., the current efficiency will be low and the voltage will be high, and in some cases, products will precipitate.
Temperatures higher than 65°C are limited by the boiling point of the electrolyte.

After the electrolytic condensation is completed, the product can be purified and separated from the electrolytic solution by a conventional method. That is, after methanol is removed from the electrolyte, it is directly separated into two oil-water layers, or water is added and two layers are separated, and the oil layer is distilled to produce highly purified dimethyl thapsinate, dimethyl sebacate, and dimethyl docosaniate. can be obtained. As detailed above, the method of the present invention has the following advantages over conventional methods and various other proposed methods.

First, by applying the technology of the production method for dimethyl sebacate proposed by the present inventors, after electrolyzing for a certain period of time, adding monomethyl adipate and continuing electrolysis, monomethyl dodecanoate and monomethyl adipate can be substantially converted. It can be easily produced in the same way as the method for producing dimethyl sebacate. Second, by electrolytic condensation, in addition to the target dimethyl thapsinate, dimethyl sebacate and dimethyl docosaniate can be obtained at the same time. These are useful substances that have an extremely wide range of uses as raw materials for perfumes, various polymers, plasticizers, etc. as well as desired products. Thirdly, no special chemicals or chemicals that pose safety issues are used. Fourthly, a desired product can be obtained with high current efficiency and high selectivity. Example 1 In an electrolytic solution tank, the concentrations of monomethyl adipate, monomethyl dodecanoate, their respective potassium salts, and water were 9.84% by weight, 15.0% by weight, and 1.35% by weight, respectively.
, 1.93% by weight, 3.0% by weight, and the amount of liquid to be charged is 1k.
methanol, potassium hydroxide, water, monomethyl adipate, and monomethyl dodecanoate were added in this order to prepare a solution.

This adjusted solution was circulated to the electrolytic cell. Both poles of the electrolytic cell are 1.
It has a current-carrying area of 0cm x 100cm, and the cathode is 2m thick.
m titanium plate, the anode is a 2 mm thick titanium plate plated with 4 micron platinum, and the current carrying area between the two electrodes is 1 mm.
．． A polyethylene Z plate having a thickness of 1 mm and having an opening was placed so as to be maintained at 0 cm x 100 cm, and the electrode spacing was defined as 1 mm.

The electrolytic cell used had a liquid supply port and a liquid outlet. The liquid was flowed between the electrodes at a flow rate of 2 m/Sec, and the current density was set to II.
Electrolysis was carried out at A/Dm· while maintaining the temperature of the liquid at 48 to 52°C. Further, at the same time as the start of electrolysis, monomethyl adipate and monomethyl dodecanoate were continuously added to the electrolyte tank ↓ at 23.0 g/Hr and 36.8 g/Hr, respectively, for 5 hours. After the addition was completed, the electrolytic solution was sampled and the residual concentration of monomethyl adipate and monomethyl dodecanoate was measured by gas chromatography analysis, and electrolysis was performed while the concentration reached 0.52% by weight and 2.6% by weight. Then, 150 g of monomethyl adipate was added, and electrolysis was performed while sampling the electrolytic solution and measuring the remaining concentration of monomethyl adipate and monomethyl dodecanoate. When the concentration reached 0.03% by weight, Electrolysis has finished. The energization time from start to end of electrolysis is 11.9
It was hot for 6 hours. The electrolysis voltage varied from 12.8V to 8.9V. Moreover, when monomethyl adipate was added, the voltage increased from 9.5V to 10.0V. The amount of liquid at the end was 1227 g. After the electrolysis was completed, each component of the electrolytic solution was measured by gas chromatography analysis, and the respective concentrations of dimethyl thapsinate, dimethyl docosaniate, and dimethyl sebacate were 14.6% by weight, 7.59% by weight, and 11% by weight.
．． It was 7% by weight. The selectivity and current efficiency of each electrolytic condensation product were as follows. Note that the selectivity and current efficiency were calculated using the following formulas. Selectivity of dimethyl sebacate based on monomethyl adipate Selectivity of dimethyl thapsinate based on monomethyl adipate (based on monomethyl dodecanoate) (Number of moles of monomethyl dodecanoate consumed) Selection of dimethyl docosaniate based on monomethyl dodecanoate However, the composition ratio of the hydrium salt of monomethyl adipate and the potassium salt of monomethyl dodecanoate at the end of electrolysis was the molar ratio of monomethyl adipate and monomethyl dodecanoate after addition of monomethyl adipate.

Further, the current efficiency was determined on the assumption that 1 mole of each product was produced from the amount of electricity of 2 Farads. The same procedure was carried out in the following examples.

Example 2 Electrolysis was started using the same preparations, the same electrolyzer, and the same electrolytic conditions as in Example 1.

At the same time as starting electrolysis, add 23.0g/Hr each of monomethyl adipate and monomethyl dodecanoate to the electrolyte tank.
, 36.8 g/Hr, and was continuously added for 7 hours. After the addition, electrolysis was carried out while analyzing the concentrations of monomethyl diate and monomethyl adipate in the same manner as in Example 1.
When the respective concentrations reached 2.4% by weight and 0.48% by weight, 209 g of monomethyl adipate was added at once and electrolysis was continued until the concentrations of monomethyl dodecanoate and monomethyl adipate reached 0.04% by weight. Electrolysis was terminated at that point. The current application time was 15.08 hours.
The electrolysis voltage varied from 12.7V to 9.0V. or,
From 9.3V to 11 when monomethyl adipate was added
．． It rose to 0V. The amount of liquid at the end of electrolysis was 1348 g. After the electrolysis was completed, each component of the electrolyte was measured by gastromatograph analysis, and the concentrations of dimethyl thapsinate, dimethyl docosaniate, and dimethyl sebacate were 16.2% by weight, 8.44% by weight, and 14.0% by weight, respectively. It was %. The selectivity and current efficiency of each electrolytic condensation product were as follows. Example 3 In the same electrolytic apparatus as in Example 1, monomethyl adipate, monomethyl dodecanoate and their respective potassium salts, and water at a concentration of 14.8% by weight, were added.
15.0% by weight, 0.96% by weight, 0.91% by weight, 1
．． The preparation was carried out in the same manner as in Example 1 so that the amount of the charged liquid was 1 kg at 0% by weight, and electrolysis was started under the same electrolytic conditions as in Example 1.

At the same time as electrolysis started, 28.1g/Hr each of monomethyl adipate and monomethyl dodecanoate were added to the electrolyte tank.
, was added continuously for 5 hours at 30.0 g/Hr. After the addition, the electrolytic solution was sampled and electrolysis was performed while measuring the residual concentration of monomethyl adipate and monomethyl dodecanoate by gas chromatography analysis, and the concentration was 1.1% by weight.
, 3.5% by weight, monomethyl adipate 1
34.0 g was added at once, and electrolysis was performed while sampling the electrolytic solution and measuring the residual concentration of monomethyl adipate and monomethyl dodecanoate until the concentration was 0.
The process was finished when the concentration reached 0.3% by weight. The current application time from the start to the end of electrolysis was 12.61 hours. The electrolysis voltage varied from 13.5V to 9.0V. Moreover, when monomethyl adipate was added, the voltage rose from 9.7V to 10.3V. The amount of liquid at the end was 1190 g. After the electrolysis was completed, each component of the electrolyte was analyzed, and the concentrations of dimethyl thapsinate, dimethyl docosaniate, and dimethyl sebacate were 15.7% by weight, 5.75% by weight, and 5.75% by weight, respectively.
It was 14.6% by weight. The selectivity and current efficiency of each electrolytic condensation product were as follows. Example 4 In the same electrolytic apparatus as in Example 1, monomethyl adipate, monomethyl dodecanoate and their respective potassium salts, and water concentrations of 13.8% by weight, 30.0% by weight, and 1% by weight, respectively, were added.
．． 89% by weight, 3.85% by weight, and 3.3% by weight, and prepared in the same manner as in Example 1 so that the liquid amount was 1 kg. Electrolysis was started under the same electrolytic conditions as in Example 1, and the voltage was Electrolysis was continued until the voltage rose, and once the voltage rose, electrolysis was stopped.

The current application time was 6.71 hours. At this point, the concentrations of monomethyl adipate and monomethyl dodecanoate were 0.
They were 41% by weight and 2.2% by weight. 103 g of monomethyl adipate was added to this electrolytic solution and electrolysis was started again. The voltage suddenly increased 2.28 hours after restarting electrolysis. At this point, electrolysis was terminated. The amount of electrolyte is 93
In 7.7 g, the concentrations of monomethyl adipate and monomethyl dodecanoate were 0.02% by weight and 0.29% by weight, respectively. Further, the respective concentrations of dimethyl thapsinate, dimethyl sebacate, and dimethyl docosaniate were 15.
They were 0% by weight, 8.41% by weight, and 11.6% by weight.
The selectivity and current efficiency of each electrolytic condensate were as follows.
Comparative Example 1 In the same electrolytic apparatus as in Example 1, monomethyl adipate, monomethyl dodecanoate and their respective hydrium salts, and water concentrations of 5.9% by weight, 30.0% by weight, and 0.8% by weight, respectively.
As in Example 1, the amount of liquid was charged to be 1 kg, and electrolysis was started under the same electrolytic conditions as in Example 1.

Claims (1)

[Claims] 1. A mixture of monomethyl dodecanedioate and monomethyl adipate in an amount of 0.5 to 2.0 times the mole of monomethyl dodecanedioate is batchwise prepared for a certain period of time in a methanol solution containing an alkali metal salt thereof. 1. A method for producing dimethyl thapsinate, which comprises electrolytically condensing it, and then further adding monomethyl adipate and electrolyzing it. 2. The method according to claim 1, wherein monomethyl adipate is added at the time of electrolytic condensation until the concentration of monomethyl dodecanedioate in the electrolytic solution reaches about 2% by weight or more. 3. The method of claim 2, wherein monomethyl adipate is added at the time of electrolytic condensation until the concentration of monomethyl dodecanedioate is in the range of about 2 to 4% by weight. 4 The amount of monomethyl adipate to be added after electrolytic condensation for a certain period of time is 3 to 8 times the amount of monomethyl adipate and its alkali metal salt relative to the unreacted monomethyl dodecanedioate and its alkali metal salt in the electrolytic solution. The method according to claim 1 or 2. 5 The amount of monomethyl adipate to be added after electrolytic condensation for a certain period of time is 5 to 7 times the amount of monomethyl adipate and its alkali metal salt relative to the unreacted monomethyl dodecanedioate and its alkali metal salt in the electrolytic solution. The method according to claim 4. 6 The water concentration in the methanol solution during electrolytic condensation was set to 0.1
The method according to claim 1, characterized in that the amount is maintained at 5 to 3.5% by weight.