JPS6045628B2 - Production method of malonic acid dialkyl ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing malonic acid dialkyl esters.

A method for producing malonic acid dialkyl esters by reacting halogenoacetic esters with carbon monoxide and alcohol in the presence of a cobalt carbonyl catalyst and a basic substance is already known (JP-A-50-111015).

This method is more reactive than the conventional industrial production method in which sodium monochloroacetate and sodium cyanide are reacted to obtain sodium cyanoacetate, which is then reacted with alcohol under acidic conditions to produce malonic acid dialkyl ester. It has advantages such as a small number of steps and no need to use sodium cyanide, a toxic substance, and is attracting a lot of attention as a technology that can be industrialized. However, in the above method, if a basic substance that does not dissolve in the reaction solution is used, a satisfactory space-time yield cannot always be obtained.

The present inventors have determined the space-time yield of a method for producing malonic acid dialkyl ester by reacting mono-genoacetate alkyl ester with carbon monoxide and lower aliphatic alcohol in the presence of a cobalt carbonyl catalyst and a basic substance. As a result of studies for improvement, it was discovered that by coexisting an appropriate amount of water in the reaction system, the reaction rate could be increased while maintaining the yield of malonic acid dialkyl ester, and the present invention was achieved. .

The present invention will be explained in detail below.

The monohalogenoacetic acid alkyl ester used as a raw material in the method of the present invention is not particularly limited, but lower alkyl esters such as methyl, ethyl, n-propyl, isopropyl, butyl are preferable, and a chlorine atom is particularly preferable as the halogen substituent. It is.

Examples of lower aliphatic alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and butyl alcohol.

Although pure carbon monoxide is usually used as carbon monoxide, diluted carbon monoxide such as water gas, which is a mixed gas with hydrogen, can also be used.

As the cobalt carbonyl catalyst, dicobalt octacarbonyl, cobalt hydrotetracarbonyl, their sodium salts, etc. can be used, but dicobalt octacarbonyl is usually preferably used.

The amount of cobalt carbonyl catalyst to be used is selected within the range of 0.001 to 0.2 mol, preferably 0.005 to 0.1 mol per mol of monohalogenoacetic acid alkyl ester. Examples of basic substances include carbonates, bicarbonates, phosphates, borates, and oxides of alkali metals and alkaline earth metals, and carbonates of alkali metals such as sodium carbonate and potassium carbonate are preferably used. be done.

These basic substances are used in an amount greater than the stoichiometric amount required to react with the hydrogen halide produced by the reaction to produce an alkali metal or alkaline earth metal halide. In the method for producing malonic acid dialkyl ester according to the method of the present invention, water is supplied to the reaction system.

The amount of water is 50 mol% or less, usually 0.1 to 5 mol%, based on the monohalogenoacetic acid alkyl ester supplied to the reaction system.
0 mol%, preferably 1 to 20 mol%. The reaction rate can be improved by supplying water to the reaction system, but excessive supply may cause side reactions or adversely affect the catalyst, reducing the yield of malonic acid dialkyl ester. This is not desirable because it causes In carrying out the method of the present invention, a solvent is not particularly required, but if desired, ethers such as tetrahydrofuran and dioxane, saturated aliphatic hydrocarbons such as hexane and octane, and aromatic hydrocarbons such as benzene, toluene and xylene may be used. An inert organic solvent can also be used for the reaction.

In the method of the present invention, the reaction temperature is selected within the range of 10 to 200°C, preferably 20 to 150°C, more preferably 30 to 80°C, and the partial pressure of carbon monoxide is 1 to 150 atm.
Preferably, the pressure is selected within the range of 4 to pressurized pressure. From the reaction product solution containing malonic acid dialkyl ester and cobalt carbonyl catalyst obtained by the method of the present invention, for example, an inorganic acid is added to decompose the cobalt carbonyl catalyst to recover cobalt, and then the cobalt is recovered under normal pressure or reduced pressure. The malonic acid dialkyl ester can be easily separated by a treatment such as distillation.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Monoku Town isopropyl acetate 100rrL, m0ee1
Isopropyl alcohol 750rrLm0ee1 Sodium carbonate with particle size 100-150 mesh 657n,m
0ee1 dicobalt octacarbonyl 2.27TLm0
ee and water 12.57nm0'e with an internal volume of 200cc
into an autoclave at a temperature of 55℃ and a pressure of 6kg/
7. Under CItG conditions, while flowing 6Ne carbon monoxide per hour. A reaction between C@ was carried out.

After the reaction was completed, the product was analyzed by gas chromatography, and the conversion rate of isopropyl monochloroacetate was 97.
1%, and the selectivity of diisopropyl malonate is 96.
It was 5%. Moreover, monoisopropyl malonate is 0.
It was produced as a by-product at a yield of 7%. The half-life of isopropyl monochloroacetate calculated from the cumulative amount of carbon dioxide produced by the reaction was 18 times. Comparative Example 1 8. Same as Example 1 except that water was not used. When the time reaction was carried out, the conversion rate of isopropyl monochloroacetate and the selectivity of diisopropyl malonate were 91.6% and 99.5%, respectively, and the yield of monoisopropyl malonate was 0.5%. .

Furthermore, the half-life of isopropyl monochloroacetate was 24 particles. Example 2 A reaction was carried out for 6.5 hours in the same manner as in Example 1, except that the amount of water used was changed to 25 w1, m0ee, and fine sodium carbonate with a particle size of 350 mesh or less was used as the sodium carbonate.

As a result, the half-life of isopropyl monochloroacetate was 7 times. Comparative Example 2 The same reaction as in Example 2 was carried out in 9. except that water was not used. The half-life of isopropyl monochloroacetate was 16 times.

Example 3 Isopropyl monochloroacetate 20TrLm0e
e1 isopropyl alcohol 400TrI, m0ee1
Fine sodium borate (N
a2B4O7) 11.25m, m0ee1 dicobalt octacarbonyl 0.4mm0'e and water 2.5mm0
FE was charged into an autoclave with an internal volume of 100cc, and carbon monoxide was further charged to 15k9/DG and heated at 55℃ for 6 hours.
．． He performed inter-scream reactions.

Analysis of the reaction products revealed that the conversion rate of isopropyl monochloroacetate was 49.4% and the selectivity of diisopropyl malonate was 90.5%. Comparative Example 3 An experiment was conducted under the same conditions as Example 3 except that water was not used. The conversion rate of isopropyl monochloroacetate was 32.4%, and the selectivity of diisopropyl malonate was 86%. It was .1%.

Example 4 Methyl monochloroacetate 100m. m0ee1 methanol 750m, m0ee1 fine sodium carbonate with a particle size of 350 mesh or less 65771. m0ee1 dicobalt octacarbonyl 22rr1, m0ee1 water 12
．． 57TL. 8. under the same conditions as Example 1 using m0'e and 25 ml of toluene. A time reaction was performed.

Claims (1)

[Claims] 1. In a method for producing dialkyl malonic acid ester by reacting monohalogenoacetic acid alkyl ester with carbon monoxide and lower aliphatic alcohol in the presence of a cobalt carbonyl catalyst and a basic substance, 50 mol%
A method for producing malonic acid dialkyl ester, characterized by supplying the following water to the reaction system.