JPS5942075B2 - Method for producing dimethyl brassylate - Google Patents

Description

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

More specifically, the present invention relates to a method for producing dimethyl brassylate by cross-Kolbe electrocondensation of monomethyl adipate and monomethyl azelaate. Dimethyl brassylate can be easily converted to brassylic acid by hydrolysis.

These are useful as raw materials for producing ethylene brasylate, which is extremely important as a musk fragrance, and have an extremely wide range of uses as raw materials for various polymers, plasticizers, and the like. Brassylic acid and its esters are produced by a method in which erucic acid contained in rapeseed oil is oxidized with ozone or permanganic acid.

However, this method has problems in that the yield of the oxidation reaction is low, various compounds are produced by the reaction, it is difficult to purify the desired product, and the purity is low. Furthermore, the following methods have been proposed for synthesizing brassylic acid.

A method of adding diethyl malonate to methyl undecylenate using ditertiary butyl peroxide and then hydrolyzing the product [Kirkiacharlan 9
Be dj Bull, Soc, Chim, Fr, (
5), 1797 (1971)]. A method in which ethyl 11-bromoundecanoate and ethyl cyanacetate are reacted by heating in dimethylformamide, and then the product is hydrolyzed and then decarboxylated [Dudinov, A, A, I2.

Akad. NaukSSSSRSer. Khiml974
99(6), 1421-1423] A method of heating 2-ethoxycarbonylcyclododecanone with sodium hydroxide in diethylene glycol and then making it acidic [Japanese Patent Publication No. 46-34406].

By reacting 2,2'-methylenebiscyclohexanone with peracid in the presence of an alkali carbonate salt in a halogenated organic solvent, 6
, 6'-methylenebis(6-hexanolide), and then heat-treated with pressurized hydrogen in the presence of a metal catalyst and an acid catalyst in an alcohol solvent (Japanese Patent Application Laid-open No. 55113741). However, these methods also require the availability of raw materials. This method is not always satisfactory as an industrial method because it is difficult and requires the use of expensive and highly dangerous peroxides in the reaction.

Furthermore, fermentation methods using yeast have also been proposed.
That is, this is a method of converting n-alkanes or monocarboxylic acids into dibasic acids using yeast. However, this fermentation method also has a low yield and is still not considered to be sufficient as an industrial method. On the other hand, brassylic acid diester has 13 carbon atoms.
Brassylic acid diester is generally considered to be obtained by cross-Kolbe electrolysis of adipic acid monoester and azelaic acid monoester, based on the general concept of crossed Kolbe electrolysis.

However, nothing is known about the specific conditions for producing brassylic acid diester by cross-Kolbe electrolysis of adipic acid monoester and azelaic acid monoester.

Note that studies have been made on methods for electrolytically condensing adipic acid monoester and azelaic acid monoester alone, and various findings have been obtained.

That is, regarding the method for producing dimethyl sebacate from monomethyl adipate, the present inventors previously described detailed industrial implementation techniques in JP-A-54-152672, JP-A-55-158285, and JP-A-55-158285. Showa 56-4478
It was disclosed in Publication No. 2, etc.

In addition, regarding the method for producing tabucic acid diester from azelaic acid monoester, Japanese Patent Publication No. 38-11116
No. Publication, Oil Chemistry, ↓? , 6-69 (1963), etc. For example, when producing dimethyl sebacate, conditions are set such that electrolysis is performed without a diaphragm, methanol is used as the electrolyte solvent, and the water concentration in the electrolyte is limited to a low range.

On the other hand, when producing tabsic acid diester, it is necessary to separate it 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. ing. Furthermore, another document [KO
vsman, E. P. ;Fraidlln, G.; N. ;
TarkhamOv,G. A. (USSR) Elect
rOsint. MOnOmerO. 49-73 (198
0)] states that in the case of electrolytic condensation of monomethyl azelaate, a polymeric film that is difficult to dissolve in water and methanol was formed on the anode, and that the film became thicker as the electrolysis progressed and was observed with the naked eye. There is. Judging from these findings, it seems that there are quite large differences in the conditions for industrially advantageous production of sebacic acid diester and tabucic acid diester, respectively. In view of the above circumstances, the present inventors have discovered that the current industrial production method for brassylic acid and its esters, a method of oxidizing erucic acid contained in rapeseed oil, and the various methods proposed to date have the potential to We have conducted extensive research in order to provide an industrially advantageous manufacturing method that can solve various problems all at once.

As a result, based on the electrolytic method previously proposed by the present inventors for producing dimethyl sebacate from monomethyl adipate, we used monomethyl adipate in an equimolar or more ratio to monomethyl azelate to cross-collate. By electrolyzing, it has become possible to perform cross-Kolbe electrolysis while maintaining high current efficiency and low electrolysis voltage, and it has become possible to produce dimethyl brassylate very advantageously industrially. That is, in the present invention, a mixed acid of monomethyl adipate and monomethyl azelaate is prepared in a methanol solution containing an alkali metal salt thereof, and the ratio of monomethyl adipate to monomethyl azelaate is equal to or more than that of monomethyl azelaate. It is characterized by intercondensation.

The commercial processing method of the present invention is based on the electrolytic method for milling trimethyl sebacate from monomethyl adipate as described above.

Of course, it is also possible to use the electrolytic method for milling dimethyl thapsate from monomethyl azelaate as described in Japanese Patent Publication No. 3811116 and the like. However, the former performs electrolysis without a diaphragm, while the latter uses a cation exchange membrane to separate the anode and cathode compartments, and when comparing the two, industrially, electrolysis is performed without a diaphragm. It is clear that doing so would be advantageous if there were no particular problems. As is clear from Table 1, the ratio of monomethyl adipate to monomethyl azelate during electrolysis of the present invention does not have much effect on the selectivity, but it has a very large effect on the electrolytic sliding voltage and current efficiency.

Reference Examples 1 and 2 show examples in which monomethyl adipate and monomethyl azelaate are used alone, but when monomethyl azelate is used alone, the average electrolytic sliding voltage is more than 1.5 times higher, and the current efficiency is also 150. /o It's getting worse. As the ratio of monomethyl adipate to monomethyl azelaate increases, the improvement is improved, and when the ratio of monomethyl adipate to monomethyl azelaate is equal to or more than the same molar ratio, the improvement is considerably improved. In particular, when monomethyl adipate is used in moles at least twice as much as monomethyl azelaate, especially at least five times as much, the situation is improved to almost the same as in the case of electrolysis using monomethyl adipate alone. As is clear from the above results, by electrolytically condensing monomethyl adipate in an equimolar or more, preferably twice or more, or even five times mole or more ratio relative to monomethyl azelaate, this cross-corbelization can be achieved. The electrolytic condensation reaction can be carried out in substantially the same manner as the electrolytic condensation reaction of monomethyl adipate alone.

In the present invention, in addition to the target dimethyl brassylate, dimethyl sebacate and dimethyl thapsinate can be simultaneously obtained by electrolytic condensation.

Moreover, the amount of each product produced can be adjusted by changing the molar ratio of the starting materials, heptadmethyl adipate and monomethyl azelate, during the reaction. The solution in which electrolytic condensation is carried out in the present invention is a methanol solution containing the raw materials monomethyl adipate, monomethyl azelate, and their neutralized salts, and the products dimethyl sebacate, dimethyl brassylate, and dimethyl tapsinate. , and other species may also be included.

Further, the electrolytic condensation may be carried out batchwise until the raw materials monomethyl adipate and monomethyl azelaate are substantially eliminated, or it may be carried out continuously while maintaining the raw material carboxylic acid at a constant concentration. It's okay. Alternatively, the reaction may be carried out continuously by maintaining the raw material carboxylic acid at a constant concentration for a certain period of time, and then carried out batchwise until the raw material carboxylic acid is substantially exhausted. However, in consideration of the separation and purification of the product in the post-process, if the raw material carboxylic acid remains, the separation operation between the raw material carboxylic acid and the product becomes complicated. Therefore, electrolytic condensation can be carried out batchwise from the beginning, or it can be carried out continuously by maintaining the raw material carboxylic acid at a constant concentration for a certain period of time, and then carried out batchwise, so that at the end of electrolytic condensation, the raw material carboxylic acid is substantially reduced. It is preferable to carry out the process to the extent that it is completely eliminated. Considering the purity of the product, etc., it is preferable to continue electrolytic condensation until the concentration of monomethyl adipate and monomethyl azelaate in the electrolytic solution becomes 1% by weight or less. Regarding the water concentration in the methanol solution during electrolytic condensation of the present invention, as shown in Examples and Comparative Examples, if the water concentration during electrolytic condensation is extremely reduced, the current efficiency becomes extremely poor. If the concentration exceeds 3.5% by weight, the material yield and current efficiency will also deteriorate. Therefore, in order to keep the material yield and current efficiency high, the water concentration should be 0.15 to 3.
5% by weight range: It is necessary to maintain this range. The mixed acid of monomethyl adipate and monomethyl azelaate 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. Further, the degree of neutralization (defined as the molar proportion of the mixed acid to be neutralized with a base) during charging of the mixed acid of monomethyl adipate and monomethyl azelaate is preferably 2 to 50 mol%. Neutralization degree is 2
If the concentration is less than 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: A cathode plate and an anode plate are placed parallel to each other, and a polypropylene plate is placed between the two electrodes to define the electrode spacing. This polypropylene plate has an opening in the center so that the electrolyte can flow therethrough. The electrolytic conduction area 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 m71L. 0.5m
m. If it is less than 3 mm, the pressure loss within the electrolytic cell will increase, and if it is wider than 3 mm, the voltage will increase.

The current density is preferably 5 to 40 A/Dm2, and 5 A/Dm
If it is less than 2, the current efficiency will be low. The temperature of the electrolyte is 45~
65°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 removing methanol from the electrolytic solution, it is directly separated into two layers into an oil-water layer, or water is added to separate the two layers, and high-purity dimethyl sebacate, dimethyl brassylate, and dimethyl thapsinate are obtained by distillation from the oil layer. Obtainable. As detailed above, the method of the present invention has the following advantages over conventional methods and various other proposed methods.

First, raw materials are extremely easy to obtain and are inexpensive. Furthermore, no special chemicals or chemicals that pose safety issues are used. Second, the desired product can be obtained with extremely high yield and high current efficiency. That is, it is extremely easy to purify the target product from the reaction product, and it is possible to obtain a product of high purity. Thirdly, in addition to the target product dimethyl brassylate, dimethyl sebacate and dimethyl thapsinate can be obtained simultaneously. These substances are also of great industrial importance. That is, dimethyl sebacate is widely used as a raw material for plasticizers, lubricating oils, nylon 6/10, plastic light stabilizers, adhesives, and the like. Dimethyl thapsinate is also useful as a raw material for macrocyclic musk fragrances. Examples 1 to 4, Comparative Example 1,
2. Reference Examples 1 and 2 Put monomethyl adipate and/or monomethyl azelaate in the amount shown in Table 1 into an electrolyte tank, and then add potassium hydroxide so that the degree of neutralization of the carboxylic acid is 8%. Next, methanol was added, and finally water was added so that the water concentration in the charging liquid was 3.0% by weight.

This prepared solution was circulated to the electrolytic cell. Both poles of the electrolytic cell are 1.
0? XlOO (has a current carrying area of 1-J mo V1, the cathode is a titanium plate with a thickness of 2 mm, and the anode is a titanium plate with a thickness of 2 mm.
A plate plated with micron platinum is used, and the current carrying area between the two electrodes is 1.0 CrIL x 100? A 1 mm thick polyethylene plate with openings was placed so that the electrodes were held at a distance of 1 mm.

The electrolytic cell used had a liquid supply port and a liquid outlet. The liquid was flowed between the two electrodes at a flow rate of 2 m/Sec, and the current density was set to 20
Electrolysis was carried out using A/DTrI while maintaining the temperature of the solution at 50 to 52°C. Electrolysis was carried out while sampling the electrolytic solution and measuring the remaining amount of monomethyl adipate by gas chromatography analysis, and the end of electrolysis was determined when the concentration became 0.1% by weight or less. After the electrolysis was completed, each component in the electrolyte was measured by gas chromatography analysis. The results are shown in Table 1. Note that the selectivity and current efficiency were calculated assuming that monomethyl adipate and monomethyl azelaate were neutralized with potassium hydroxide at the charged molar ratio of each carboxylic acid.

In addition, the current efficiency is 1 for each product from 2 Faradays of electricity.
It was calculated assuming that moles are produced. The calculation formulas for selectivity and current efficiency are as follows. Selectivity of dimethyl sebacate based on monomethyl adipate (based on monomethyl adipate)
Selectivity of dimethyl brassylate (based on monomethyl azelate) (number of moles of monomethyl azelaate consumed) Dimethyl brassylate based on monomethyl azelaate The same procedure was carried out in the following Examples and Comparative Examples.

Example 5 Using the same electrolyzer as in Example 1, monomethyl adipate 23511 monomethyl azelate 5 was added to the electrolyte tank.
Prepare by adding 9g of methanol and 5799% of methanol, then adding potassium hydroxide so that the degree of neutralization of the carboxylic acid is 10%, and finally adding water so that the water concentration in the liquid is 2.0% by weight. did.

The charging molar ratio of monomethyl adipate to monomethyl azelaate was 5:1. Next, increase the current density to 11A/
The conditions were the same as in Example 1 except for changing to Dm2,
Electrolytic condensation was carried out while continuously supplying a mixed solution of monomethyl adipate 929 and monomethyl azelate 229 (mole ratio of monomethyl adipate/monomethyl azelate 5/1) to the electrolyte tank for 5.0 hours. Ta.
Electrolytic condensation was continued for an additional 2.0 hours. The voltage is 6.8-6.
It was 6. The amount of liquid after electrolysis is 9009, and the concentration of each component in the liquid is 17.0% by weight of dimethyl sebacate.
The dimethyl brassylate was 6.5% by weight, the dimethyl thapsinate was 0.8% by weight, and the remaining monomethyl azelaate was 0.6% by weight. The selectivity and current efficiency of each electrolytic condensation product were as follows. Example 6 Using the same electrolyzer as in Example 1, monomethyl adipate 1739 and monomethyl azelaate 1 were added to the electrolyte tank.
079 and methanol 6629 were added, then potassium hydroxide was added so that the degree of neutralization of the carboxylic acid was 8.0%, and finally the water concentration in the liquid was adjusted to 1.2% by weight.

The molar ratio of monomethyl adipate to monomethyl azelaate charged is 2:1. Next, under the same conditions as in Example 1, the concentration of monomethyl adipate and monomethyl azelaate in the electrolytic solution was 2.48% by weight or less.
Time electrolytic condensation was carried out. The voltage was 12.7 to 9.5V, and the average voltage was 11.1V. The amount of liquid after electrolytic condensation was 8859, and the concentrations of each component in the liquid were 7.2% by weight for dimethyl sebacate, 7.5% by weight for dimethyl brassylate, and 2% for tapsin/dimethyl acid.
．． 3% by weight, and the selectivity and current efficiency of each electrolytic condensation product were as follows. Example 7 Using the same electrolyzer as in Example 1, the electrolyte tank contained 358 f11 monomethyl adipate, 44 g monomethyl azelate, 9.9 g sodium hydroxide, and 548 g methanol.
9 and finally added water so that the water concentration in the liquid was 2.5% by weight.

The molar ratio of monomethyl adipate to monomethyl azelate was 10:1, and the degree of neutralization was 10%.

Next, electrolysis was carried out under the same conditions as in Example 1 except that the current density was changed to 10 A/Dm2. Electrolysis was carried out for 7.70 hours until the concentrations of both monomethyl adipate and monomethyl azelaate in the electrolytic solution became 0.1% by weight or less. The voltage varied from 7.7V to 5.8V. The amount of liquid after electrolytic condensation was 8839, and the concentrations of each component in the liquid were 19.4% by weight for dimethyl sebacate, 4.3% by weight for dimethyl brassylate, and 0.0% for dimethyl thapsinate.
It was 2% by weight. The selectivity and current efficiency of each electrolytic condensation product were as follows. Comparative Example 3 Water concentration in the preparation liquid was 4.

Electrolytic condensation was carried out in the same manner as in Example 7 except that the amount was changed to 5% by weight. The electrolysis time was 9.04 hours and the voltage varied from 7.5 to 5.6.

The amount of liquid after electrolytic condensation was 8789, and the concentrations of each component in the liquid were 17.4% by weight for dimethyl sebacate, 3.8% by weight for dimethyl brassylate, and 0.2% by weight for dimethyl thapsinate. It was in weight%. The selectivity and current efficiency of each electrolytic condensation product were as follows. Competitive? 14 In Example 7, the alkali to neutralize the mixed acid ranges from 9.99% sodium hydroxide to 13.4% sodium methylate.
Electrolytic condensation was carried out in exactly the same manner as in Example 7, except that the concentration of water in the charging liquid was changed to 0.10% by weight.

Claims (1)

[Scope of Claims] 1. A mixed acid of monomethyl adipate and monomethyl azelaate is electrolyzed in a methanol solution containing their alkali metal salts in an equimolar or more ratio of monomethyl adipate to monomethyl azelaate. A method for producing dimethyl brassylate, which is characterized by condensation. 2. The method for producing dimethyl brassylate according to claim 1, wherein the amount of monomethyl adipate used is at least twice the molar amount of monomethyl azelaate. 3. The method for producing dimethyl brassylate according to claim 2, wherein the amount of monomethyl adipate used is at least 5 times the molar amount of monomethyl azelaate. 4 The water concentration in the methanol solution during electrolytic condensation was set to 0.1
The method for producing dimethyl brassylate according to claim 1, wherein the content is maintained at 5 to 3.5% by weight. 5 The mixed acid of monomethyl adipate and monomethyl azelate used during electrolytic condensation is adjusted to 10 to 50% by weight, and the mixed acid is selected from potassium or sodium hydroxide, carbonate, bicarbonate, methylate, and ethylate. neutralization of 2 to 50 mol% using at least one type of base
The flow rate of the electrolyte in the decomposition tank is reduced to 1.
~4m/sec, electrode spacing set to 0.5~3mm,
Current density: 5 to 40 A/dm^2, electrolyte temperature: 45
The method for producing dimethyl brassylate according to claim 1, characterized in that the temperature is in the range of -65°C.