JPH0665149A - Production of usable compound from michael reactional adduct of acrylic acid ester - Google Patents

Abstract

PURPOSE:To efficiently obtain a compound while suppressing production of by-products, thickening of reactional liquid and gelation by thermally decomposing a Michael reactional adduct of an acrylic acid ester in the presence of an alkoxytitanate. CONSTITUTION:A Michael reactional adduct of an acrylic acid ester, especially an acryloxypropionic acid ester is hydrolyzed in the presence of an alkoxytitanate of the formula Ti(OR)n(OH)4-n [R is 1-8C alkyl, cycloalkyl, etc.: (n) is 1-4] at 50-200 deg.C to provide the objective usable compound consisting of an acrylic acid ester. A polymer inhibitor such as phenothiazine is preferably jointedly used in order to prevent polymerization of acrylic acid esters produced by decomposition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a useful compound from a Michael adduct of acrylic acid ester, and more specifically, acryloxypropion which is a by-product produced in the production process of acrylic acid ester. By reducing Michael adducts of acrylic acid esters such as acid esters and alkoxypropionic acid esters, and recovering useful compounds consisting of acrylic acid esters, the amount of industrial waste is reduced, and a high yield is achieved industrially. The present invention advantageously provides a method for producing an acrylic ester and the like, and can be used in the chemical industry for producing an acrylic ester.

[0002]

2. Description of the Related Art A method for producing a useful compound by decomposing a Michael adduct of an acrylic ester is a method of thermally decomposing in the presence of a Lewis acid or a Lewis base to recover a useful compound, and further, coexistence of water. And then disassemble,
There is a method of recovering useful compounds.

[0003]

The above-mentioned conventional method has the following problems. First, the method using a Lewis acid is that the alcohol produced by decomposition undergoes an intramolecular dehydration reaction or an intermolecular dehydration reaction, and byproducts such as alkenes and ethers are easily produced. Equipment must be provided to remove the.

Further, the method using a Lewis base is relatively excellent in decomposability of alkoxypropionate which is a Michael adduct of alcohol to acrylic ester, but Michael adduct of acrylic acid to acrylic ester. The acryloxypropionic acid ester is poor in decomposability, and further studies by the present inventor have the drawbacks that the reaction solution thickens and gels as the decomposition reaction progresses.

The object of the present invention is to overcome the disadvantages of such conventional methods. That is, the present invention can efficiently decompose a Michael adduct of an acrylic ester while suppressing the formation of by-products, thickening of the reaction solution, and gelation, and recovering a useful compound consisting of an acrylic ester. A method for producing a useful compound from a Michael adduct of an acrylate ester, which does not necessarily require equipment for removing by-products, and enables production of an acrylate ester industrially advantageous in high yield To provide.

[0006]

That is, the present invention is a useful compound characterized by recovering a useful compound consisting of an acrylic acid ester by thermally decomposing a Michael adduct of an acrylic acid ester in the presence of an alkoxy titanate. Is a method of manufacturing. Hereinafter, the present invention will be described in more detail.

As the Michael adduct of acrylic acid ester which is the object of the present invention, for example, acrylic acid is Michael compared to acrylic acid ester such as alkyl ester or cycloalkyl ester of acrylic acid having 1 to 8 carbon atoms. There are β-acryloxypropionic acid ester added, and β-alkoxypropionic acid ester to which an alcohol is Michael-added, and the like, and the present invention particularly decomposes the acryloxypropionic acid ester and is an excellent method for producing a useful compound. Is.

Specific examples of the acryloxypropionate include methyl acryloxypropionate, ethyl acryloxypropionate, propyl acryloxypropionate, butyl acryloxypropionate, cyclohexyl acryloxypropionate, and acryloxypropionate-2. -Ethylhexyl and the like, and specific examples of the alkoxypropionic acid ester include methyl methoxypropionate, ethyl ethoxycypropionate, propyl propoxypropionate, butyl butoxypropionate, cyclohexyloxypropionate cyclohexyl, 2-ethylhexyloxypropione. 2-ethylhexyl acid and the like can be mentioned. Many of these are by-produced during the production of acrylic acid ester by the reaction of acrylic acid and alcohol, but the present invention is not limited to the Michael adduct of acrylic acid ester itself separated from the esterification reaction product. That was treated as waste containing other products and raw materials by-produced in the acrylic ester production process, that is, alcohol, acrylic acid in addition to acryloxypropionic acid ester and alkoxypropionic acid ester. , Acrylic acid esters, polymers of acrylic acid esters or mixtures containing various other components. According to the present invention, the Michael adducts of these acrylic acid esters decompose acryloxypropionic acid ester into useful compounds mainly containing acrylic acid ester, and alkoxypropionic acid ester mainly decomposes into acrylic acid ester and alcohol. To be done.

The alkoxy titanate used as a catalyst in the present invention is an alkoxy titanate or alkoxy hydroxy titanate compound represented by the following general formula (1). Ti (OR) _n (OH) _4-n (1) (wherein R represents an alkyl or cycloalkyl group having 1 to 8 carbon atoms, etc., and n is an integer of 1 to 4) As the alkoxy titanate, when it is desired to recover the same acrylic acid ester as the acrylic acid ester constituting the Michael adduct, an alkoxy titanate having the same alkoxy group as the alkoxy group of the Michael adduct of the acrylic acid ester to be decomposed is used, When the acrylic acid ester constituting the Michael adduct and the recovered acrylic acid ester may be different from each other, a different alkoxy group from the Michael adduct of the acrylic acid ester to be decomposed can be used. As the alkoxy titanate, it is possible to use tetraalkoxy titanate,
It is preferable because it is excellent in solubility in the reaction system and little by-products are produced. The preferable amount of the alkoxy titanate catalyst used is 5 to 30 mol% relative to 1 mol of the Michael adduct of acrylic acid ester. If the amount of the alkoxy titanate used is less than 5 mol%, the decomposition does not proceed sufficiently, while if it exceeds 30 mol%, the amount of by-products may increase during the decomposition.

The decomposition temperature in the present invention varies depending on the kind of the Michael adduct of acrylic acid ester to be decomposed and the reaction pressure, but it is usually preferably 50 to 200 ° C., considering the equipment and operability in industrialization. The decomposition temperature is more preferably 90 to 150 ° C.

In the present invention, the useful compound recovered after the decomposition of the Michael adduct of acrylic acid ester is
In addition to acrylic ester, it is composed of alcohol and / or acrylic acid, and a mixture of these is separated into each component to obtain a product, or these mixtures are directly supplied to the production process of acrylic ester,
Acrylic acid and alcohol can be reacted to form the acrylic ester of the product. These are produced by the decomposition of the Michael adduct of acrylic acid ester, and in some cases, they are contained in the raw material that decomposes.

As a method for recovering a useful compound composed of an acrylic ester, a useful compound produced by decomposition is
The method of continuously distilling out of the system by distillation is preferable because the decomposition reaction can be more favorably promoted and the mixture of acrylic ester can be efficiently recovered. Therefore, as the decomposition method, it is preferable to thermally decompose under reduced pressure,
The pressure at that time varies depending on the kind of the Michael adduct of acrylic acid ester to be decomposed, but the decomposition temperature is preferably 50 to 200 ° C., more preferably 9
It is preferable to adjust the pressure so as to be 0 to 150 ° C.

In the present invention, in order to prevent the polymerization of acrylic acid esters produced by decomposition, it is preferable to use a polymerization inhibitor in combination, and the polymerization inhibitor used in combination is generally used in the acrylic acid ester production process. The polymerization inhibitor widely used in can be used. Specific examples include hydroquinone, methoxyhydroquinone, phenothiazine, and hydroxylamine. Further, the effect of inhibiting polymerization can be enhanced by conducting 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. Further, it is an effective method to suppress the distillation of the Michael adduct of acrylic acid ester by using a distillation column having a reactor with a stage or an apparatus combining the reactor and the distillation column. In the continuous method, it is desirable that the decomposition rate and the feed rate of the Michael adduct of acrylic acid ester are balanced.

[0015]

The details of the reason why the present invention is excellent for recovering useful compounds by decomposing Michael adducts of acrylic acid esters, particularly acryloxypropionic acid esters, are unknown, but the alkoxy titanates used in the present invention are unknown. Is known to be an effective catalyst as a transesterification catalyst. Therefore, it is considered that a remarkable effect is exerted on the decomposition of Michael adduct of acrylic acid ester, particularly acryloxypropionic acid ester.

[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, low boiling point rate, and recovery rate used in the present specification are as follows.

Decomposition rate (%) = [(number of moles of active ingredient distilled out-number of moles of acrylate ester in feed solution) / (number of moles of Michael adduct of acrylate ester in feed solution)] × 100 Low boiling rate (%) = (number of moles of low boiling point component distilled out / number of moles of Michael adduct of acrylic acid ester in charging liquid) × 1
00 yield (%) = (weight of distilled active ingredient / weight of feed liquid) × 100 active ingredient = alcohol, acrylic acid and acrylate ester Low boiling point component = alkene and ether

<Example 1> 100.2 g (0.501 mol) of butyl acryloxypropionate was placed in a 500 ml flask equipped with a thermometer, a stirrer, a packed column filled with a glass Raschig ring of 10 cm and a condenser. 19.2 g (0.0565 mol) of tetrabutoxy titanate and 0.1 g of phenothiazine were added, and the pressure was reduced to 60 mmHg and heating was started with stirring. When the reaction temperature was around 95 ° C, a distillate containing butyl acrylate as a main component began to distill,
When the reaction temperature was 120, the distillation was stable, and the mixture was heated to 130 ° C. During the reaction, the reaction solution did not thicken or gel. Since the distillation stopped 3 hours after the start of distillation, the test was terminated. The distillate amounted to 54.3 g. As a result of analyzing the liquid by gas chromatography, the composition was 0.423 mol of butyl acrylate and 0.00005 mol of low boiling point. The decomposition rate, low boiling rate and recovery rate were calculated as follows. Decomposition rate = 84.4%, low boiling rate = 0.01%, recovery rate = 5
4.2%

Example 2 20.2 g (0.10) of butyl acryloxypropionate was placed in the same apparatus as in Example 1.
1 mol), and 137.7 g of butyl butoxypropionate.
(0.681 mol), 13.6 g of butyl acrylate
(0.106 mol), tetrabutoxy titanate 3
1.4 g (0.0924 mol) and 0.1 g of phenothiazine were added, the pressure was reduced to 60 mmHg and heating was started with stirring. When the reaction temperature is around 95 ° C, distillate begins to distill, and when the reaction temperature is 110, the distillate stabilizes, and further at 130 ° C.
Heated up. During the reaction, the reaction solution did not thicken or gel. The test was terminated because the distillation of the distillate stopped 2 hours after the start of the distillation. The distillate amounted to 41.7 g, and the result of gas chromatographic analysis of the liquid showed that the composition was 0.250 mol of butyl acrylate, 0.129 mol of butanol, 0.00008 mol of acrylic acid, and low boiling point. It was a trace amount. The decomposition rate, low boiling rate and recovery rate were calculated as follows. Decomposition rate = 35.0%, low boiling rate = 0.00%, recovery rate = 2
4.2%

Comparative Example 1 101.4 g (0.5%) of butyl acryloxypropionate was added to the same apparatus as in Example 1.
07 mol) and 3.8 g of sodium hydroxide, which corresponds to 1.7 times the molar amount of tetrabutoxy titanate of Example 1 in terms of the number of moles.
(0.095 mol) and 0.1 g of phenothiazine were added, and the pressure was reduced to 60 mmHg and heating was started with stirring. The reaction temperature was 120 to 130 ° C., and the mixture was heated for 3 hours, but the distillate did not distill and the reaction solution gelled, so the test was terminated.

Comparative Example 2 32.8 g (0.16 g) of butyl acryloxypropionate was placed in the same apparatus as in Example 1.
4 mol), and 143.3 g of butyl butoxypropionate
(0.709 mol), 4.0 g of butyl acrylate
(0.031 mol), sodium hydroxide 6.8 g
(0.17 mol) and phenothiazine (0.2 g) were added, the pressure was reduced to 60 mmHg, and heating was started with stirring. When the reaction temperature was around 95 ° C, distillate began to distill, and
Heated to 0-130 ° C. The reaction solution gelled while heating was continued. Since the distillation stopped 3.5 hours after the start of distillation, the test was terminated. The distillate amounted to 11.0 g. As a result of gas chromatographic analysis of the liquid, the composition was found to be 0.040 mol of butyl acrylate, 0.080 mol of butanol, trace amounts of acrylic acid, and trace amounts of low-boiling components. Met. The decomposition rate, low boiling rate and recovery rate were calculated as follows. It was not possible to perform sufficient decomposition. Decomposition rate = 10.2%, low boiling rate = 0.00%, recovery rate =
6.1%

Comparative Example 3 36.1 g (0.18) of butyl acryloxypropionate was added to the same apparatus as in Example 1.
1 mol) and 141.6 g of butyl butoxypropionate
(0.701 mol), 3.1 g of butyl acrylate
(0.024 mol), 15.4 g (0.157 mol) of sulfuric acid and 0.2 g of phenothiazine were added, the pressure was reduced to 50 mmHg, and heating was started while stirring. Reaction temperature is 95 ℃
Distillate began to distill around, the reaction temperature was 120, the distillate became stable, and the mixture was further heated to 130 ° C. As the heating was continued, the reaction solution thickened. The test was terminated because the distillation of the distillate stopped 3 hours after the start of the distillation. The distillate is 4
As a result of gas chromatographic analysis of the liquid, the composition was found to be 0.306 mol of butyl acrylate,
Butanol 0.005 mol, acrylic acid 0.036
The amount of 1 mol and the low boiling point were 0.0019 mol. Decomposition rate,
The low boiling rate and recovery rate were calculated as follows. Although the decomposition was sufficient, a low boiling point component was found to be generated, and the low boiling point component was mixed into the acrylic ester, so a facility for removing it was required. Decomposition rate = 36.6%, low boiling rate = 0.22%, recovery rate = 2
3.2%

[0023]

INDUSTRIAL APPLICABILITY The present invention efficiently decomposes the Michael adduct of acrylic acid ester, which is a by-product of the acrylic acid ester production process, by suppressing the thickening, gelation and generation of by-products of the reaction solution. By recovering the useful compound,
This has the excellent effect of reducing the amount of industrial waste and enabling industrially advantageous production of acrylic ester with high yield.

Claims (1)

[Claims] 1. A method for producing a useful compound, which comprises thermally decomposing a Michael adduct of an acrylate ester in the presence of an alkoxy titanate, and recovering a useful compound comprising the acrylate ester.