JPH0257532B2 - - Google Patents

Description

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

Malonic acid diester is an important raw material in the fine chemical field such as medicines and agricultural chemicals, but conventionally, malonic acid diester is produced by reacting monochloroacetic acid with sodium cyanide to form cyanoacetic acid. This method had the drawbacks that sodium cyanide was a toxic substance and the manufacturing process was long.
Further, Japanese Patent Publication No. 10967/1983 describes a method for producing malonic acid diester by reacting monochloroacetic ester with carbon monoxide, alcohol, and a basic substance using a salt of cobalt hydrocarbonyl as a catalyst.

However, this method has serious problems such as (1) impractical because the catalyst is produced from dicobalt octacarbonyl and sodium amalgam, and (2) problems with catalyst activity and low yield. There was a problem.

The present inventors previously proposed a method for producing a solution of cobalt tetracarbonyl anion in alcohol or acetone by reacting a cobalt salt with carbon monoxide and hydrogen in alcohol or acetone. If used as a catalyst, conditions (temperature, pressure) can be significantly relaxed, and by applying this solution to the above reaction, malonic acid diester can be obtained in high yield, and the catalyst has an extremely high activity. This is an industrially advantageous method.

However, in order to implement this method on an industrial scale, it is necessary to (1) treat the by-product malonic acid monoester, (2) quantitatively recover cobalt as a catalyst,
(3) It was necessary to establish an efficient method for obtaining malonic acid monoester, which is a by-product in distillation residues.

The present applicant has already solved these problems and proposed a specific method in Japanese Patent Application No. 54-150358 (Japanese Unexamined Patent Publication No. 56-73044), and the present invention further relates to an improved method thereof.

The specific content of JP-A-56-73044 is that monochloroacetic ester, carbon monoxide, a basic substance, and alcohol are reacted in the presence of a catalyst consisting of an alcohol or acetone solution of cobalt tetracarbonyl anion to form a reaction solution containing malonic acid diester. After decomposing the catalyst contained in this reaction solution, the alcohol is removed and the reaction solution is concentrated.Water is then added to this reaction solution to separate it into an organic layer and an aqueous layer, and the organic layer is distilled. At the same time, malonic acid monoester in the residual solution of the pot is diesterized to obtain malonic acid diester in the same manner as above, while cobalt sulfate in the aqueous layer is recovered as an insoluble salt. At the same time, by reacting this with carbon monoxide and hydrogen in an alcohol or acetone solvent in the presence or absence of a seed catalyst to obtain a solution of cobalt tetracarbonyl anion in alcohol or acetone, malonic acid diester can be obtained in good yield. , is characterized by producing malonic acid diester by a series of methods that repeatedly use a cobalt compound as a catalyst.

In the above method, when sodium carbonate is generally used as the basic substance, the pH of the reaction system is maintained in the range of 4 to 8, and the amount of by-products produced is small, so that sodium carbonate is conveniently used. Sodium carbonate reacts with hydrogen chloride liberated during the reaction to form common salt, which becomes a slurry in the reaction system.

In JP-A No. 56-73044, this salt is present as a slurry in the concentrated liquid obtained through the catalytic decomposition process and alcohol removal, and by adding water in an amount equal to or more than the saturated solubility of the salt to this slurry Cobalt sulfate and common salt are extracted into the aqueous phase and removed from the organic layer, so that the aqueous layer is separated from the organic layer with the common salt completely dissolved.

On the other hand, malonic acid diesters and malonic acid monoesters dissolve in the water layer in an amount corresponding to their solubility in the water layer, but depending on the type of malonic acid diester and malonic acid monoester, a non-negligible amount of water is dissolved in the water layer. Since the liquid is transferred to the liquid phase, not only does the yield decrease, but also a burden is placed on waste liquid treatment and the like.

Particularly, dimethyl malonate and its monoester have a high solubility in water, so some countermeasure is required, and as a countermeasure, the combined use of an extractant is disclosed in JP-A-56-73044. When using such an extractant, the costs associated with collecting the extractant, equipment, and in some cases, installing a separate extraction tower are required, but the cost is reduced by improving the yield of dimethyl malonate and its monoester. In addition, even if an extractant is used, dimethyl malonate and its monoester cannot be completely extracted from the aqueous layer, and there are certain limits.

The present invention relates to improvements in this point,
Its features are as follows: By reducing the amount of water used to extract common salt and cobalt salt as much as possible and separating the aqueous layer containing the salt slurry from the organic layer, the malonic acid diester and monoester aqueous layer is extracted. It is characterized by reducing losses to an extent that does not become an economic burden.

That is, the present invention provides (1) monochloroacetic ester,
A carbonylation step in which carbon monoxide, soda carbonate, and alcohol are reacted in the presence of a catalyst consisting of a solution containing cobalt tetracarbonyl anion and alcohol or acetone as main components to obtain a reaction solution containing malonic acid diester, (2 ) a catalyst decomposition step in which the catalyst in the product solution is treated with sulfuric acid and oxygen; (3) a concentration step in which excess alcohol in the catalyst decomposition product solution is removed by distillation; (4) the product obtained in the concentration step. Weight ratio of 0.1 to concentrate
(5) Adding ~0.5 of water to separate the aqueous layer containing the salt slurry and the organic layer containing malonic acid diester as the main component, and extracting cobalt sulfate to the aqueous layer, (5) a step of distilling the organic layer and obtaining malonic acid diester as a distillate;
(6) The malonic acid monoester in the distillation pot residue is diesterized to malonic acid diester in the presence of an acid catalyst and alcohol, and this is distilled to obtain the malonic acid diester; (7)
After diluting the aqueous layer containing the salt slurry and cobalt sulfate separated in step (4) with water to dissolve the salt, the cobalt sulfate in the separated aqueous layer is carbonated or hydroxylated to become water-insoluble. and (8) reacting the recovered cobalt compound with carbon monoxide and hydrogen in the presence of an alcohol or acetone solution of cobalt tetracarbonyl anion, using alcohol or acetone as a solvent, to obtain cobalt tetracarbonyl anion. It is characterized by comprising a catalyst production process of producing an alcohol or acetone solution.

The raw materials used in the carbonylation step of the present invention are monochloroacetic ester, alcohol, carbon monoxide, and soda carbonate, and these will be explained in order below.

First, specific examples of monochloroacetic ester include lower alkyl esters such as methyl, ethyl, n-propyl, iso-propyl, and butyl, but are not particularly limited.

Next, the alcohol is not particularly limited, and methyl, ethyl, n-propyl, isopropyl, and butyl alcohol are preferred. In addition, the molar ratio of alcohol and monochloroacetic ester is 1
~10 times the molar amount, preferably 2 to 5 times the molar amount.

Carbon monoxide does not need to be particularly pure;
Even if hydrogen and an inert gas are used together, the yield will not decrease.

Moreover, there is no problem even if it contains a small amount of water. The amount of soda carbonate to be used is preferably a stoichiometric amount or more, particularly preferably 1.0 to 1.5 equivalents, relative to the by-product hydrogen halide.

Furthermore, in addition to alcohol, inert solvents such as aliphatic saturated hydrocarbons, aromatic hydrocarbons, pyridine, picoline, and alcohol esters of organic acids may be coexisting.

As a catalyst, an alcohol or acetone solution of cobalt tetracarbonyl anion is used.
The molar ratio of catalyst and monochloroacetic ester is 1:
The ratio is 1 to 1:400, preferably 1:4 to 1:100.

As for the reaction conditions of the carbonylation step, the reaction temperature is 30 to 100°C, preferably 40 to 70°C.
The reaction pressure is 2 to 50 kg/ ^cm2 , preferably 5 to 30 kg/cm2.
Kg/ ^cm2 .

In the method of the present invention, there is no restriction on the charging method, and all the raw materials may be charged at once, or other raw materials may be charged in advance, and the monochloroacetic ester may be added in portions. Furthermore, other raw materials may be charged and an alcohol or acetone solution of cobalt tetracarbonyl anion may be added in portions. No matter which method is used, there is little change in yield.

After the carbonylation reaction, in the catalytic decomposition step, concentrated sulfuric acid and oxygen are added after the reaction to decompose the cobalt tetracarbonyl anion. When decomposing the catalyst,
Decomposition is incomplete with concentrated sulfuric acid or oxygen alone;
The rate of decomposition is extremely slow, and only by using both in combination can they be decomposed quickly and safely. In addition, performing the catalyst decomposition process after the next concentration process may cause the dangerous catalyst that generates carbon monoxide to be dispersed throughout the equipment and cause unexpected operational accidents. Furthermore, there is a problem because it is assumed that the recovery rate will decrease, and it is necessary to decompose it before the concentration step.

The concentrated sulfuric acid used is generally an aqueous solution, but the malonic acid diester produced at a low concentration changes to malonic acid monoester, and the water content of dehydration increases when alcohol is recycled. Therefore, highly concentrated sulfuric acid, preferably
70wt% or more sulfuric acid aqueous solution, more preferably,
Commercially available concentrated sulfuric acid (98wt%) is good.

The amount of sulfuric acid used may be equal to or more than the mole of cobalt tetracarbonyl anion used, but is preferably 1.5 to 5 times the mole.

The oxygen may be pure oxygen, but air is preferably used. Oxygen is preferably bubbled into the reaction solution, and the amount used is equal to or more than the same mole relative to the cobalt tetracarbonyl anion.

Catalyst decomposition temperature is 0~80℃, preferably 10~70℃
It is ℃.

In the concentration step, excess alcohol is distilled off to obtain a concentrated liquid.

In the extraction step, water is added to the concentrated solution to extract malonic acid diester and malonic acid monoester in the organic layer, and cobalt sulfate and by-product common salt in the aqueous layer.

The amount of water to be added is equal to or less than the amount equivalent to the saturation solubility of the by-produced common salt, in other words, slurry may be present in the separated water layer, and it is preferably as small as possible. However, if the amount of water added is too small, the transfer of the salt slurry to the aqueous phase will be insufficient, and not only will the salt be present in the organic layer, but also the extraction of the cobalt compounds into the aqueous phase will be incomplete. Generally, the amount of water added to the above concentrate obtained by the present invention is preferably in the range of 0.1 to 0.5 in terms of weight ratio, and within this range, the aqueous layer containing the salt slurry and the organic layer are completely free of salt. The cobalt compound clearly separated in the state transferred to the aqueous layer is also extracted into the aqueous layer as desired.

If the amount of water added is enough to completely dissolve the salt or is added, phenomena such as the interface between the aqueous layer and the organic layer becoming unclear or an intermediate phase often occurring occur. Thus, when the aqueous layer is reduced and the salt slurry is present in the aqueous layer, the above-mentioned disadvantageous phenomenon in separation between layers is not observed.

When salt is completely dissolved, the amount of malonic acid diester and its monoester dissolved in the separated aqueous layer is easily influenced by the solubility of the salt, and as the salt concentration decreases, the amount of malonic acid diester and its monoester dissolved The amount of ester dissolved in the aqueous layer tends to increase, and it is necessary to strictly control the amount of water added. However, according to the method of the present invention, the aqueous layer is constantly maintained at the saturated solubility of common salt. , the above considerations are not required.

It was also revealed that the salt slurry in the aqueous layer was milk-like with extremely good fluidity and sedimentation, and that the separation operation was easier than expected.

The above method not only significantly reduces the loss of malonic acid diester and its monoester, but also reduces the burden on wastewater treatment equipment, eliminates the need for economic burdens such as extraction operations, etc., and reduces process and pollution problems. Measures and economic improvements were achieved.

In the distillation step, the organic layer is distilled to obtain malonic acid diester. Malonic acid monoester is also obtained as can residue.

Distillation is usually carried out under reduced pressure and can be carried out either continuously or batchwise.

Specifically, for example, first, the organic layer is distilled under reduced pressure to separate substances with a high boiling point from the malonic acid diester, and then the resulting distillate is distilled under reduced pressure, and the low-boiling components are separated by distillation. Obtain malonic acid diesters. At this time, depending on the case, an organic layer or
When high-boiling substances are separated, the resulting distillate is brought into contact with an alkaline aqueous solution (aqueous solution of soda carbonate, caustic soda, etc.) to remove residual acidic substances.

In the diesterification step, malonic acid monoester is diesterized using an alcohol and an acid catalyst. At this time, it is preferable to use an azeotropic agent.

The amount of alcohol used is 1 to 10 times the mole of malonic acid monoester, preferably 1.5 to 5 times
It is twice the mole.

As the acid catalyst, commonly used esterification catalysts may be used, such as sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid.
The amount used is 0.001 per malonic acid monoester.
~0.5 times the mole, preferably 0.01 to 0.2 times the mole.

Various substances can be used as the entrainer, but cyclohexane, benzene and the like are preferred.

The amount of the entrainer to be used is 0.1 to 10 times the amount of malonic acid monoester, preferably 0.5 to 5 times the amount of malonic acid monoester.

Reaction temperature is 50-200℃, preferably 70-150℃
It is.

Malonic acid diester can be recovered almost quantitatively by diesterification using the above method and distillation.

On the other hand, the aqueous layer containing the salt slurry obtained in the extraction step and in which cobalt sulfate has been dissolved is added to the mother liquor from which salt has been removed by filtration, or to a solution in which water is added to the slurry liquid to dissolve salt. By adding a metal carbonate or hydroxide, cobalt sulfate is converted into water-insoluble cobalt carbonate or cobalt hydroxide.

The alkali metal carbonates used include sodium carbonate, potassium carbonate, and hydroxides.
Sodium hydroxide and potassium hydroxide are preferred.

Regarding the concentration used, it may be used as a solid, or an aqueous solution may be used.

The amount to be used is, in the case of carbonation, the pH is 7 or more, preferably 9 or more, and in the case of hydroxylation, the PH is 9 or more,
By adding preferably up to 12 or more,
It is possible to make a cobalt salt with very good sedimentation properties, making subsequent filtration operations easier.

A slurry containing carbonated or hydroxylated cobalt salt is washed with water and filtered to obtain a cake containing 50 wt% or more of water. This method includes centrifugal filtration,
Methods such as filter press and centrifugal sedimentation can be employed.

The resulting water-containing cobalt salt cake can be dehydrated by various conventionally known methods. Examples include spray drying, azeotropic dehydration, blow drying, and vacuum drying, but industrially, drying with a spray dryer is particularly suitable, and the cobalt salt obtained in this case is in the form of a fine powder suitable for producing cobalt carbonyl. becomes a powder. Also,
Azeotropic dehydration is also preferably used industrially.

Although complete dehydration can be achieved by the above method, it is sufficient to reduce the water content in the cobalt salt to 10 wt% or less. The cobalt carbonate or cobalt hydroxide thus recovered is used as a catalyst for producing malonic acid diester. Next, a method for producing this catalyst will be explained. First, the recovered cobalt carbonate or cobalt hydroxide is reacted with carbon monoxide and hydrogen in an alcohol or acetone solution to obtain an alcohol or acetone solution of cobalt tetracarbonyl anion. In this case, if an alcohol or acetone solution of cobalt tetracarbonyl anion is used as a seed catalyst, the reaction conditions can be significantly relaxed.

The amount of alcohol or acetone used is greater than the amount required to dissolve the cobalt tetracarbonyl anion produced. For example, the solubility of cobalt tetracarbonyl anion is 20wt/in methanol.
v%, in isopropyl alcohol, 5wt/v
%, and in acetone it is about 15wt/v%.

The amount of cobalt tetracarbonyl anion used as a seed catalyst is 0.005 or more in atomic ratio to cobalt carbonate or cobalt hydroxide.
If the atomic ratio is 0.005 or more, the pressure is 150Kg/ ^cm2 or less,
If the atomic ratio is 0.01 or more, the reaction will proceed at a pressure of 50 kg/cm ² or less, and if the atomic ratio is 0.02 or more, the reaction will proceed at a pressure of 30 kg/cm ² or less.

The molar ratio of carbon monoxide and hydrogen is 1:1 to 1:
A range of 0.1 is sufficient, and the reaction pressure is 150Kg/cm ²
Hereinafter, it is preferably 5 to 100 Kg/cm ² for operational reasons.
The reaction temperature is 50-150°C.

It is preferred that the solution of cobalt tetracarbonyl anion produced by the above method is used as a catalyst for carbonylation, and a portion is used as a subsequent seed catalyst.

The present invention is particularly effective for dimethyl malonate, which has a high solubility in water, but can also be applied to other esters.

Examples will be described in more detail below.

Example 1300g of methyl alcohol, 550g of sodium carbonate
g, 350 c.c. of an acetone solution of cobalt tetracarbonyl anion (containing 43 g of C(CO) ₄ ), 6
After replacing the inside of the reactor with carbon monoxide, the amount of carbon monoxide was adjusted to 5 kg/cm ² and the temperature to 60° C., and 1085 g of monochloroacetic ester was added in portions over 4 hours. After addition, the mixture was aged for 2 hours. During this time, carbon monoxide was continuously passed through at a rate of 60/hr.

After the reaction, after returning to normal pressure, add 53g of concentrated sulfuric acid (97wt%) while bubbling air at a rate of 50/hr.
product) was added dropwise over 45 minutes.

After 1 hour, a portion of the reaction solution was sampled and IR
Analysis by the iodine decomposition method revealed that the catalyst had completely decomposed, and 1211 g of dimethyl malonate and 51 g of monomethyl malonate were produced in the reaction solution.

Next, methyl alcohol and acetone were distilled off, and 2016 g of a concentrated slurry liquid was obtained, which contained 1205 g of dimethyl malonate and 50 g of monomethyl malonate. Next, 410 g of water was added to separate the organic layer and the aqueous layer containing the salt slurry.
The organic layer contained 1185 g of dimethyl malonate and 45 g of monomethyl malonate, and when both were combined, the recovery rate from the concentrate was 98.0%.

The organic layer was obtained by rectifying dimethyl malonate and its monoester containing small amounts of methanol, water and methyl monochloroacetate under reduced pressure (30 mmHg).
1090 g of purified dimethyl malonate was obtained.

When 100 g of methanol and 1.5 g of concentrated sulfuric acid were added to a liquid containing 66 g of dimethyl malonate recovered from the can in the above distillation and 45 g of its monoester to esterify the monoester, 113 g of dimethyl malonate and 3.2 g of dimethyl malonate were obtained. A liquid containing monoester was obtained.

When this reaction solution was purified, 106 g of dimethyl malonate was obtained.

Meanwhile, in the water layer containing the salt slurry, 140g
After adding water to make a homogeneous aqueous solution, a 30 wt% aqueous solution of NaOH was added until the pH reached 13 or higher, and centrifugation was performed to obtain a slurry of cobalt hydroxide with a water content of 65 wt%.

Add 150g of cyclohexane to this cake,
Azeotropic dehydration was performed at a temperature of 100°C. After dehydration, cyclohexane was distilled off to almost completely remove water. 350 c.c. of acetone was added to the obtained cobalt hydroxide to form a slurry, and the slurry was charged into the reactor No. 1.

This container contains 120 c.c. of an acetone solution of cobalt tetracarbonyl anion as a seed catalyst.
(CO) ₄ (containing 14g) remained from the previous production.

Carbon monoxide and hydrogen (CO/H ₂ =
After replacing with 4/1), same mixed gas 9Kg/cm ² temperature 70
The reaction was carried out at ℃ for 4 hours.

After the reaction, the reaction solution was taken out and found to be a completely homogeneous solution containing 56.6 g of Co(CO) ₄ .

Comparative example Carbonylation was carried out under the same charging reaction conditions as in the example, and catalyst decomposition and methyl alcohol,
When acetone was distilled off using the same method,
2019 g of concentrate was obtained, which contained 1210 g of dimethyl malonate and 46 g of monomethyl malonate. Next, add 1800g of water to completely dissolve the salt.
Separated into organic and aqueous layers.

The organic layer contains 1126 g of dimethyl malonate and 28 g of monomethyl malonate, and when both are combined, the recovery rate from the concentrated solution is 91.7%, which is 6.3% from the example.
% was low.

Claims (1)

[Claims] 1 (1) Monochloroacetic ester, carbon monoxide,
a carbonylation step in which sodium carbonate and alcohol are reacted in the presence of a catalyst consisting of a solution containing cobalt tetracarbonyl anion and alcohol or acetone as main components to obtain a reaction solution containing malonic acid diester; (2) in the produced solution; a catalyst decomposition step in which the catalyst is treated with sulfuric acid and oxygen, (3) a concentration step in which excess alcohol in the catalyst decomposition product liquid is removed by distillation, (4) a concentrated liquid obtained in the above concentration step, a step of adding water in a weight ratio of 0.1 to 0.5, separating an aqueous layer containing a salt slurry and an organic layer containing malonic acid diester as a main component, and extracting cobalt sulfate into the aqueous layer; (5) the above step; (6) Diesterifying malonic acid monoester in the residual liquid of the distillation pot in the presence of an acid catalyst and alcohol to obtain malonic acid. (7) On the other hand, the aqueous layer containing the salt slurry and cobalt sulfate separated in step (4) is diluted with water to dissolve the salt. After that, the cobalt sulfate in the aqueous layer is carbonated or hydroxylated to recover it as a water-insoluble cobalt compound, and (8) the recovered cobalt compound is treated with alcohol in the presence of an alcohol or acetone solution of cobalt tetracarbonyl anion. Or, a method for producing malonic acid diester, which comprises a catalyst production step of producing a solution of cobalt tetracarbonyl anion in alcohol or acetone by reacting with carbon monoxide and hydrogen using acetone as a solvent.