JPH0768168B2 - Decomposition method of Michael adduct of acrylic acid ester - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing Michael adducts of acrylic acid esters, and more particularly, the present invention decomposes Michael adducts of acrylic acid esters by-produced in the acrylic ester production process. , Which contributes to a method for producing an acrylate ester industrially with a high yield by reducing the amount of industrial waste by recovering a useful compound. Is used in.

[0002]

2. Description of the Related Art As a method for decomposing Michael adducts of acrylic acid esters, a decomposition method of heating in the presence of a Lewis acid or a Lewis base and a decomposition method in the presence of water are generally adopted. ing.

[0003]

The above-mentioned conventional method has the following problems. First, the method using Lewis acid is that the alcohol produced by decomposition causes an intramolecular dehydration reaction or an intermolecular dehydration reaction and easily produces by-products such as alkenes and ethers. Must be equipped with facilities to do so. The method using a Lewis base is
Although the degradability of Michael adduct of alcohol to acrylic ester is excellent, it has a drawback that the decomposition is extremely poor in the presence of the Michael adduct of acrylic acid to acrylic ester.

An object of the present invention is to eliminate the drawbacks of such conventional methods. That is, the present invention suppresses the formation of by-products during the decomposition thereof even when a Michael adduct of acrylic acid to an acrylic ester is present,
It is an object of the present invention to provide a method for decomposing a Michael adduct of an acrylate ester, which does not require equipment for removing a by-product and enables an industrially advantageous method for producing an acrylate ester with a high yield.

[0005]

Means for Solving the Problems The present inventors suppress the formation of alkenes and ethers when decomposing Michael adducts of acrylic acid esters, and further, not only Michael adducts of alcohols to acrylic acid esters. In addition, the present invention has been completed as a result of repeated studies of a method of efficiently decomposing even in a system in which a Michael adduct of acrylic acid to an acrylic ester is present.

That is, according to the present invention, while the produced acrylic acid ester, acrylic acid and alcohol are distilled out of the system by distillation with water, the presence of water in excess of the number of moles corresponding to the decomposition amount using Lewis acid as a catalyst. A method for decomposing a Michael adduct of an acrylic acid ester, which is characterized by thermally decomposing below, and an acrylic acid ester, an acrylic acid, and an acrylic acid produced when thermally decomposing a Michael adduct of an acrylic acid ester with a Lewis acid as a catalyst. The present invention relates to a method for decomposing a Michael adduct of an acrylate ester, which comprises distilling alcohol together with water out of the reaction system and supplying water in excess of the distillate amount into the reaction system.

The present invention will be described in more detail below. The Michael adduct of acrylic acid ester which is the object of the present invention is, for example, Michael adduct of acrylic acid with acrylic acid ester such as alkyl ester or cycloalkyl ester having 2 to 8 carbon atoms, specifically β- Examples thereof include acryloxypropionic acid ester and the like, and Michael adduct of alcohol, specifically β-alkoxypropionic acid ester. Further, these are mostly by-produced when the acrylic ester is produced by the reaction of acrylic acid and alcohol, but in the present invention, the by-product Michael adduct itself, and further the above-mentioned acrylic acid are used. Those that have been treated as waste containing other by-products and raw materials by-produced in the ester production process, that is, Michael adducts of acrylic acid esters, as well as acrylic acid esters of raw materials, polymers of acrylic acid esters, etc. It is also applicable to a mixture containing various components of.

In the present invention, the Michael adduct of acrylic acid ester needs to be thermally decomposed in the presence of water in a molar amount exceeding the amount of decomposition.

The amount of water used in the present invention is an amount exceeding the number of moles corresponding to the decomposition amount of the Michael adduct of acrylic acid ester, and together with the acrylic acid ester, acrylic acid and alcohol produced by the decomposition reaction. It is the amount of water that can satisfy the amount of water distilled out of the system by distillation. Therefore, the specific amount of water varies depending on the kind of the Michael adduct of the acrylic acid ester to be decomposed, but in terms of weight ratio, it is preferably 0.2 to 2 times that of the Michael adduct of the acrylic acid ester to be decomposed. Yes, and more preferably 0.3 to 1 times.

The water supplied to the reaction system may be cold water or hot water, and for the purpose of reducing the amount of waste water discharged from the process,
It is also possible and preferable to condense the vapor distilled by distillation and reuse the liquid on the water layer side of the condensed liquid separated into two phases as water. Water may be added to the reaction system in such a manner that the entire amount of water is present at the start of the decomposition reaction or intermittently during the reaction, but the method of continuously adding water to be supplied lowers the reaction temperature sharply. This is a preferred method for the present invention, because the decomposition reaction can be carried out stably without being carried out.

Specific examples of the Lewis acid used as the catalyst in the present invention include inorganic acids and organic acids such as sulfuric acid, iron chloride and p-toluenesulfonic acid. The preferable amount of the catalyst used is 2 to 20% by weight based on the Michael adduct of acrylic acid ester.

The thermal decomposition in the present invention is usually carried out at a temperature in the range of 50 to 150 ° C., though it varies depending on the kind of Michael adduct of acrylic acid ester to be decomposed and the reaction pressure. A preferable condition is a temperature of 110 to 130 ° C. under normal pressure in view of equipment and operability in industrialization.

In the decomposition method of the present invention, in order to prevent polymerization of acrylic acid ester and acrylic acid produced,
A polymerization inhibitor is preferably used in combination, and as the polymerization inhibitor used in combination, a polymerization inhibitor generally widely used in the acrylic ester production process can be used.
Specific examples include hydroquinone, methoxyhydroquinone, phenothiazine, and hydroxylamine. Further, the effect of the polymerization inhibitor can be enhanced by carrying out the decomposition reaction in the presence of molecular oxygen.

The present invention can be carried out batchwise or continuously. In the batch method, both a tank reactor and a tower reactor can be used. Furthermore, it is an effective method to install a distillation column having stages in the reactor or an apparatus combining the reactor and the distillation column to suppress the distillation of the Michael adduct of acrylic ester. In the continuous method, it is desirable that the decomposition rate of the Michael adduct of acrylic ester and the feed rate of the Michael adduct of acrylic ester are balanced.

[0015]

In the present invention, since the decomposition is carried out under the harsh conditions of heating in the presence of a Lewis acid, it is highly likely that an alkene or an ether will be formed. Decomposition products should be removed from the system. Even if an alkene or an ether is produced due to the presence of a large amount of water and a Lewis acid, a water addition reaction or a hydrolysis reaction occurs again to return to an alcohol. It is thought that the remarkable effect that the generation of alkenes and ethers is extremely small is exerted by the two actions.

[0016]

EXAMPLES In order to describe the present invention more specifically, examples and comparative examples will be described in detail below. The definitions of the decomposition rate and the low boiling rate used in the present specification are as follows. Active ingredient = Alcohol, acrylic acid, acrylic ester Low boiling point ingredient = Alkene, ether

Example 1 183.1 g of β-butoxypropionic acid butyl ester, 16.3 g of sulfuric acid and 0.2 g of phenothiazine were placed in a 500 ml flask equipped with a continuous titrator, thermometer, stirrer, empty column and condenser. (1000ppm vs. total amount),
Heating was started with stirring under atmospheric pressure. Reaction temperature is 1
Room temperature distilled water 155.0 so that it can be maintained at 20 ± 5 ℃
g was continuously fed over 5 hours for decomposition. The distillate was separated into an upper layer and a lower layer at room temperature and weighed to find that the upper layer was 60.9 g and the lower layer was 125.7 g. Each was analyzed by gas chromatography, and the decomposition rate and low boiling point were calculated as follows. Decomposition rate = 30.6%, low boiling rate = 0.10%

Example 2 In the same apparatus as in Example 1, 142.0 g of β-butoxypropionic acid butyl ester, 35.6 g of β-acryloxypropionic acid butyl ester, 3.1 g of acrylic acid butyl ester and sulfuric acid were added. 15.2 g and phenothiazine at 0.
2 g (1000 ppm vs. total amount) was added and heating was started under atmospheric pressure with stirring. Decomposition was carried out by continuously supplying 140.0 g of room temperature distilled water over 6 hours so that the reaction temperature could be maintained at 120 ± 5 ° C. The distillate was separated into an upper layer and a lower layer at room temperature, and the weight was measured. As a result, the upper layer was 66.5.
g and the lower layer became 117.4 g. Each was analyzed by gas chromatography, and the decomposition rate and low boiling point were calculated as follows. Decomposition rate = 34.7%, low boiling rate = 0.11%

Comparative Example 1 182.0 g of β-butoxypropionic acid butyl ester, 15.6 g of sulfuric acid and 0.2 g of phenothiazine (1000 ppm relative to the total amount) were added to the same apparatus as in Example 1, and 6
Heating was started with stirring at 0 mmHg. Reaction temperature is 12
The distillation was stopped 5 hours after the distillation was started at 0 to 130 ° C., so the experiment was terminated. The distillate amounted to 41.7 g. Analysis by gas chromatography and calculation of the decomposition rate and low boiling rate gave the following. Decomposition rate = 22.7%, Low boiling rate = 0.18%

Comparative Example 2 In the same apparatus as in Example 1, 141.6 g of β-butoxypropionic acid butyl ester, 35.5 g of β-acryloxypropionic acid butyl ester, 3.1 g of acrylic acid butyl ester and hydroxylated. Add 6.8 g of sodium and 0.2 g of phenothiazine (1000 ppm to total amount), 50
Heating was started with stirring at mmHg. Reaction temperature is 120
Since the distillation stopped 4 hours after starting distillation at ~ 130 ° C,
The experiment was completed. The distillate amounted to 7.9 g. Analysis by gas chromatography and calculation of the decomposition rate and low boiling rate gave the following. Decomposition rate = 4.5%, Low boiling rate = 0.00%

Comparative Example 3 In the same equipment as in Example 1, 141.6 g of β-butoxypropionic acid butyl ester, 36.1 g of β-acryloxypropionic acid butyl ester, 3.1 g of acrylic acid butyl ester and sulfuric acid were added. 15.4 g and phenothiazine at 0.
2 g (1000 ppm relative to the total amount) was added, and heating was started while stirring at 50 mmHg. Reaction temperature is 120-130 ℃
Since the distillation stopped 3 hours after the start of distillation, the experiment was terminated. The distillate amounted to 42.4 g. Analysis by gas chromatography and calculation of the decomposition rate and low boiling rate gave the following. Decomposition rate = 23.0%, Low boiling rate = 0.15%

[0022]

EFFECTS OF THE INVENTION By decomposing and recovering the Michael adduct of acrylic acid ester, which is a by-product of the acrylic acid ester production process, the amount of industrial waste is reduced, and it is industrially advantageous in high yield. The present invention has an excellent effect of enabling the production of various acrylic acid esters.

Claims (2)

[Claims] 1. The produced acrylic acid ester, acrylic acid and alcohol are distilled out of the system by distillation with water and heated in the presence of water in excess of the number of moles corresponding to the decomposition amount using Lewis acid as a catalyst. A method for decomposing a Michael adduct of an acrylic ester, which comprises decomposing. 2. When thermally decomposing a Michael adduct of an acrylate ester with a Lewis acid as a catalyst, the produced acrylate ester, acrylic acid and alcohol are distilled out of the reaction system together with water and the amount of the distillate or more The method for decomposing Michael adducts of acrylic acid ester, characterized in that the water of the above is supplied into the reaction system.