JPH03141242A - Production of carboxylic acid ester and formamide - Google Patents

Abstract

PURPOSE:To facilitate separation and recovery of a catalyst and enable reuse thereof by electrolyzing a reaction product solution in reacting a carboxamide with a formic acid ester, etc., in the presence of a metal alcoholate catalyst and producing a carboxylic acid ester and formamide. CONSTITUTION:A carboxamide is reacted with a formic acid ester in the presence of a metal alcoholate or the carboxamide is reacted with an alcohol and carbon monoxide to produce an industrially important carboxylic acid ester and formamide useful as solvents, various treating agents, electrolytes, antifreezing agents, etc. In the process, the reaction product solution is electrolyzed using an electrolytic cell preferably divided into the cathode compartment and the anode compartment with a cation exchange membrane at 0.005-10A/cm<2>, preferably 0.01-5A/cm<2> current density to readily separate and recover the catalyst, which is then reused for the reaction. Thereby, catalyst cost is remarkably reduced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the production of carboxylic acid amide and formic acid ester, or carboxylic acid amide and alcohol and carbon monoxide (hereinafter, these two cases are combined). The present invention relates to a method for efficiently producing carboxylic acid esters and formamide by reaction of esters, etc.).

Carboxylic acid esters are industrially important compounds,
Methods for producing carboxylic acid esters from carboxylic acid amide include production of methyl acetate from acetate amide, production of methyl methacrylate from methacrylic acid amide, production of methyl acrylate from acryl amide, or production of methyl acrylate from α-hydroxyisobutyric acid amide. production of methyl α-hydroxyisobutyrate, etc.

Formamide, on the other hand, is used as a solvent, various processing agents, electrolyte, and antifreeze agent, or as an intermediate raw material for organic synthesis of dyes, pigments, pharmaceuticals, etc., and is also used as a raw material for the production of hydrogen cyanide. It is an important basic chemical product.

(Prior art) As a method for producing a carboxylic acid ester from a carboxylic acid amide, a method in which a carboxylic acid amide and an alcohol are reacted in the presence of sulfuric acid is conventionally known, and as an industrial method for producing methyl methacrylate. Widely implemented.

However, in this method, a huge amount of acidic ammonium sulfate is generated as a by-product, and there are problems such as a large amount of processing cost is required and an expensive corrosion-resistant manufacturing equipment is required.

As a method to overcome these drawbacks, a method has been proposed in which a carboxylic acid ester is produced by catalytically reacting a carboxylic acid amide and an alcohol without using sulfuric acid. However, in addition to the low yield and selectivity of the desired carboxylic acid ester, there are problems such as the generation of a large amount of ammonia, which requires separation and recovery, and the formation of ammonium salts of carboxylic acid. , which is not industrially satisfactory.

On the other hand, as a method that does not generate ammonia,
No. 8-55444 and JP-A No. 60-78937, a catalyst in which a metal salt of an organic acid or an inorganic acid, or a metal carbonyl compound is combined with an organic compound containing nitrogen or phosphorus, is used to prepare a carboxylic acid amide and formic acid. A method of producing a carboxylic acid ester and formamide by reaction of esters has been proposed. However, these methods have problems such as the catalyst system being complex and expensive, and the cost of recovering the catalyst increasing.

Therefore, Japanese Patent Application No. 63-116970 proposes a method of producing a carboxylic acid ester and formamide by reacting a carboxylic acid amide and a formate in the presence of an alkali metal alcoholic catalyst. In this method, carboxylic acid esters and formamide can be obtained with high selectivity under mild conditions.

However, it is difficult to recover the catalyst because it is a homogeneous catalyst.
In addition, there were problems such as increased catalyst costs without recovery.

(Means for Solving the Problems) The present inventors have conducted intensive studies on improved methods for producing carboxylic acid esters and formamide from carboxylic acid amide, formic acid ester, etc., and have arrived at the present invention.

That is, in a method for producing a carboxylic acid ester and formamide by reacting a carboxylic acid amide with a formic acid ester, etc. in the presence of a metal alcoholade catalyst, a method for recovering the catalyst by electrolyzing the reaction solution was discovered, and the present invention was completed.

The present invention will be explained below.

The carboxylic acid amide used in the method of the present invention is an aliphatic or aromatic carboxylic acid amide, an α-hydroxycarboxylic acid amide, or an α-aminocarboxylic acid amide,
Examples of carboxylic acid amides that are synthesized by the hydration reaction of nitrile or the reaction between amines and carbon monoxide include acetamide, lactic acid amide, acryl amide, methacrylic amide, benzamide, and α-hydroxyisobutyric acid. There are amides, alanine amides, etc.

The alcohol or formic acid ester used in the method of the present invention is an aliphatic alcohol having 1 to 10 carbon atoms, or an ester of the alcohol and formic acid.

Further, examples of aliphatic alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, and the like. Examples of formic acid esters include methyl formate, ethyl formate, propyl formate, isopropyl formate, n-butyl formate, S-butyl formate, and n-pentyl formate.

The metal alcoholades used in the present invention are alkali metals such as lithium, sodium, and potassium, or magnesium,
It is synthesized from one or more alkaline earth metals such as calcium and barium and an aliphatic alcohol. Typical examples include sodium methylate, sodium ethylate, sodium butylade, and potassium methylate. Examples include methylate, lithium methylate, magnesium methylate, calcium methylate, barium methylate, and the like.

Further, these metal alcoholades can be synthesized by electrolyzing inexpensive metal hydroxides or metal salts using an electrolytic bath in the presence of alcohol. At this time, the metal salts include organic acid salts such as formates and acetates,
Inorganic acid salts such as hydrochloride and nitrate are used.

The electrode used in the present invention includes, for example, a Ti plate coated with Pt-1r, Rub, PdO, and PdO as an anode.
The material is suitably selected from commonly used materials such as T-plated materials, and iron, stainless steel, and Ni-plated materials for cathodes.

The electrolytic cell used in the present invention is preferably a two-chamber type electrolytic cell in which an anode chamber and a cathode chamber are separated by a diaphragm.

Examples of the diaphragm of the electrolytic cell include a filter diaphragm made of asbestos or ceramics, a dense diaphragm made of β-alumina, or an ion exchange membrane. Although any diaphragm may be used to prevent diffusion and mixing of the products in the bipolar chambers, it is particularly preferable to use a cation exchange membrane in terms of electrolysis efficiency.

The method of the present invention will be explained in more detail below.

When using a formic acid ester as a raw material, it is desirable to use an appropriate solvent since carboxylic acid amides are generally solid at room temperature.

As the solvent, a polar solvent such as alcohol is preferred, and it is particularly preferred to select an alcohol that constitutes a formic acid ester.

Further, when alcohol and carbon monoxide are used as raw materials instead of formic acid ester, it is preferable to use an excess of alcohol to also serve as a solvent for the carboxylic acid amide.

In the case of the reaction between carboxylic acid amide and formic acid ester in the present invention, the amount of formic acid ester used per mole of carboxylic acid amide is 0.5 to 20 moles, preferably 1 mole.
．． It is in the range of 5 to 8 moles.

If the amount is less than this, the conversion rate of carboxylic acid amide is low;
Moreover, if the amount is more than this, the amount of unreacted formic acid ester recovered increases, which is disadvantageous in practice.

In addition, in the case of the reaction of carboxylic acid amide, alcohol, and carbon monoxide in the present invention, the amount of alcohol used per 1 mole of carboxylic acid amide is in the range of 1 to 30 moles, preferably in the range of 2 to 20 moles. be. In amounts less than this,
The carboxylic acid amide will not dissolve, and if the amount exceeds this amount, the amount of alcohol recovered from the reaction solution will increase, which is not practical.

Further, in the present invention, a carboxylic acid amide can be reacted with a formic acid ester, an alcohol, and a carbon oxide. In this case, the amounts of formic acid ester and alcohol used per mole of carboxylic acid amide are each 0.
．． The range is 5 to 15 mol, and 0.5 to 30 mol, preferably 1 to 8 mol, and 2 to 15 mol.

In the reaction of carboxylic acid amide and formic acid ester of the present invention, the amount of metal alcoholade per mole of carboxylic acid amide is from o.ooi to 0.3 mole, preferably from 0.00 mole to 0.3 mole.
003 to 0.1 mole.

In addition, the metal alcoholade used in the present invention is prepared by electrolyzing in alcohol using an inexpensive metal hydroxide or salt from the beginning, and from the next time, the reaction solution of carboxylic acid amide and formate ester is electrolyzed. It is economically advantageous to recycle the metal alcoholade recovered.

A specific embodiment of the first metal alcoholade preparation according to the present invention is that a solution of a metal hydroxide or salt is first charged into the anode chamber of an electrolytic cell, and the solvent at this time is one that dissolves the metal hydroxide or salt. good. The concentration of the metal hydroxide or salt varies depending on the metal hydroxide or salt and the type of solvent, but as long as it has sufficient electrical conductivity to dissolve the metal hydroxide or salt and electrolyze it. After filling the cathode chamber and the anode chamber with a suitable alcohol solvent, etc., electrolysis occurs by applying a DC voltage between the two electrodes, and metal alcoholade can be generated in the cathode chamber. can.

In the present invention, the reaction temperature and reaction time for the reaction between carboxylic acid amide and formate ester can be selected from a wide range depending on the type of raw materials, the amount of catalyst charged, and the target reaction rate. , the reaction temperature is 0-2
00 DEG C. The range of 20 to 150 DEG C. is particularly preferred; temperatures below this range do not provide a practical reaction rate, and temperatures higher than this are disadvantageous as they tend to cause decomposition of formamide and deactivation of the catalyst. The reaction time is 0.1 to 20 hr, especially 0
, a range of 2 to 10 hours is preferred.

The reaction may be carried out under a vapor pressure indicated by the reaction temperature, but in order to suppress the decomposition of the formate ester, the reaction may also be carried out under a -carbon oxide pressure. Specifically, the reaction pressure is from normal pressure to 300 atm, and economically from normal pressure to lo
A range of oatm is preferred.

In addition, the reaction pressure during the reaction of carboxylic acid amide, alcohol and -carbon oxide is 10 as the partial pressure of -carbon oxide.
-500 atm, preferably 30-200 atm.

Although the method of the present invention can be carried out either batchwise or continuously, industrially preferred is a continuous mode.

Recovery of the metal alcoholade catalyst in the present invention is carried out by electrolyzing a reaction solution of carboxylic acid amide, formate, etc. in an electrolytic cell partitioned into an anode chamber and a cathode chamber by a diaphragm.

That is, when the reaction solution is placed in the anode chamber of the electrolytic cell and the alcohol is placed in the cathode chamber, and a DC voltage is applied between the two electrodes, electrolysis occurs, and the generated alkali metal or alkaline earth metal cations pass through the diaphragm from the anode chamber. By moving the catalyst directly to the cathode chamber, the catalyst is removed from the anode chamber and the metal alcoholade can be regenerated into the cathode chamber.

The current density in the method of the present invention is O, OO5-10
A/cm", preferably 0.01-5 A/c
The electrolysis temperature can be low or high, but it is economical to perform it at room temperature.

The catalyst recovered by the method of the present invention or the catalyst electrolytically synthesized may be taken out from the electrolytic cell and used for the reaction of carboxylic acid amide and formate, etc. in another reactor, or it may be directly reacted in the electrolytic cell. You can also do it. That is, for the latter method, the reaction solution or a solution of metal hydroxide or salt is charged into the anode chamber of the electrolytic cell, and the raw material solution for the reaction of carboxylic acid amide and formate ester is charged into the cathode chamber, and a direct current is applied between the two electrodes. When a voltage is applied, electrolysis occurs, and the catalyst can be recovered or produced in the cathode chamber, and at the same time, a reaction between carboxylic acid amide and formate can be carried out, which is one of the major features of the method of the present invention.

〔Example〕

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

Note that the present invention is not limited to these examples.

Point-based cation exchange membrane (manufactured by DuPont, trade name Nafyon 32)
4) Effective membrane area divided into anode chamber and cathode chamber by 6
．． A two-chamber electrolytic cell with an electrode distance of 811111 was used.

In the anode chamber, a Pt-plated Ti plate was used as an anode, and 12 g of a 1% by weight methanol solution of sodium hydroxide (3 mmol of sodium hydroxide) was placed in the anode chamber. In the cathode chamber, a Ni plate was used as a cathode, and α-hydroxyisobutyric acid amide 10 .3g (0,1
mol), 12 g (0.2 mol) of methyl formate, and 9.6 g (0.3 mol) of methanol were added. 0 between anode and cathode.
A direct current of 3 A was applied for 1 hour. The voltage at this time was about 30V.

After electrolysis, the sodium in the anode chamber was 0.08 mmol, the sodium in the cathode chamber was 2.7 mmol, and the sodium transfer rate was 97%.

The obtained cathode chamber solution was transferred to a stainless steel autoclave with an internal volume of 70 ml, and reacted at 60° C. for 2 hours. After cooling the autoclave to 10"C, the product was taken out and analyzed by gas chromatography. As a result, the reaction rate of α-hydroxyisobutyric acid amide was 63%, and the selectivity to methyl α-hydroxyisobutyrate was The selectivity to formamide was 98% and 99%.

Using the same electrolytic cell as in Example 1, the reaction solution obtained in Example 1 (2.6 mmol of sodium) was placed in the anode chamber, and α-hydroxyisomer as in Example 1 was placed in the cathode chamber. Butyric acid amide 10.3g (0.1 mol), methyl formate 12g (0.2
mol), and a direct current of 0.3 A was applied between the anode and cathode for 1 hour. The voltage at this time was about 30V. After electrolysis,
The sodium content in the cathode compartment was 0.07 mmol, the sodium content in the cathode compartment was 2.3 mmol, and the sodium transfer rate was 97%.

The obtained cathode chamber solution was transferred to an autoclave, reacted and analyzed in the same manner as in Example 1, and the reaction rate of α-hydroxyisobutyric acid amide was 62%, and the selectivity to methyl α-hydroxyisobutyrate was 98%. %, and the selectivity to formamide was 98%.

Using the same electrolytic cell as in Example 1, 23 g of a 10% by weight methanol solution of sodium hydroxide (57.5 mmol of sodium hydroxide) was placed in the anode chamber, and 20 g of methanol was placed in the cathode chamber.
g (0,625 mol) was added.

A direct current of IA was applied between the anode and the cathode for 1 hour.

The voltage at this time was about 10V. The sodium content in the cathode chamber after electrolysis was 52.7 mmol, and the sodium transfer rate was 92%.

10 g of the obtained cathode chamber liquid was transferred to a 500IIll equipped with an electromagnetic stirrer, a carbon oxide inlet pipe, a pressure gauge, and an exhaust pipe.
51.5 g (0.5 mol) of α-hydroxyisobutyric acid amide,
After adding 150 g (4.7 mol) of methanol, the mixture was pressurized to 40 atm with carbon oxide and heated with stirring.

When the temperature inside the autoclave reached 80° C., the reaction was continued for 3 hours while introducing carbon monoxide gas to maintain the reaction pressure at 40 atm.

Thereafter, the autoclave was cooled to 10° C., and the internal pressure was gradually lowered to normal pressure, after which the product was taken out and analyzed.

As a result, the reaction rate of α-hydroxyisobutyric acid amide was 8
6%, the selectivity to methyl α-hydroxyisobutyrate was 97%, and the selectivity to formamide was 95%.

(Effects of the Invention) According to the method of the present invention, in the method of producing a carboxylic acid ester and formamide by reacting a carboxylic acid amide with a formic acid ester, etc. in the presence of a metal alcoholic catalyst, the catalyst is removed by electrolysis of the reaction product liquid. It can be easily separated and recovered and reused for reactions. This makes it possible to significantly reduce catalyst costs, which has great industrial significance.

Claims (2)

[Claims] (1) In the method of producing a carboxylic acid ester and formamide by reacting a carboxylic acid amide and a formate ester, or a carboxylic acid amide, an alcohol, and carbon monoxide in the presence of a metal alcoholade catalyst, the reaction solution is electrolyzed. A method for producing a carboxylic acid ester and formamide, which comprises recovering the catalyst. (2) The method according to claim (1), which uses an electrolytic cell divided into an anode chamber and a cathode chamber by a cation exchange membrane.