JP2943523B2 - Method for producing useful compound from 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 producing a useful compound from a Michael adduct of an acrylate, and more specifically, to acryloxypropion by-produced in a process for producing an acrylate. By decomposing Michael adducts of acrylates such as acid esters and alkoxypropionates, and recovering useful compounds consisting of acrylates, the amount of industrial waste can be reduced, and industrial yields can be reduced with high yield. The present invention advantageously provides a method for producing an acrylate ester or the like, and can be used in the chemical industry for producing an acrylate ester.

[0002]

2. Description of the Related Art As a method for producing a useful compound by decomposing a Michael adduct of an acrylic acid ester, a method of recovering a useful compound by heat decomposition in the presence of a Lewis acid or a Lewis base, and further, coexistence of water After disassembly,
There are methods for recovering useful compounds.

[0003]

However, the above-mentioned conventional method has the following problems. First, in the method using a Lewis acid, alcohol generated by decomposition causes an intramolecular dehydration reaction or an intermolecular dehydration reaction, and a by-product such as an alkene or an ether is easily generated. Equipment must be provided to remove the

In the method using a Lewis base, the decomposability of an alkoxypropionate, which is a Michael addition product of an alcohol to an acrylate ester, is relatively excellent, but a Michael addition product of acrylic acid to an acrylate ester. The acryloxypropionate ester is poor in decomposability, and the present inventors have the disadvantage that the reaction solution thickens and gels as the decomposition reaction progresses.

It is an object of the present invention to overcome such disadvantages of the prior art. That is, the present invention can efficiently decompose the Michael adduct of the acrylate ester while suppressing the formation of by-products, the increase in the viscosity of the reaction solution, and the gelation, thereby recovering a useful compound composed of the acrylate ester. Method for producing useful compound from Michael adduct of acrylate, which does not necessarily require equipment for removing by-products and enables production of industrially advantageous acrylate in high yield Is to provide.

[0006]

That is, the present invention provides a useful compound characterized in that a Michael adduct of an acrylate ester is thermally decomposed in the presence of an alkoxy titanate to recover a useful compound composed of an acrylate ester. It is a method of manufacturing. Hereinafter, the present invention will be described in more detail.

The Michael adduct of acrylic acid ester, which is the object of the present invention, is, for example, acrylic acid is replaced by acrylic acid such as alkyl ester having 1 to 8 carbon atoms or cycloalkyl ester. There are β-acryloxypropionate esters added, and β-alkoxypropionate esters to which alcohols have been added, and the present invention is an excellent method for decomposing acryloxypropionate esters to produce useful compounds. It 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 alkoxypropionate include methyl methoxypropionate, ethyl ethoxypropionate, propyl propoxypropionate, butyl butoxypropionate, cyclohexyl cyclohexyloxypropionate, and 2-ethylhexyloxypropionate. Acid-2-ethylhexyl and the like. These are by-produced in the production of acrylates by the reaction of acrylic acid and alcohol, but the present invention is not limited to Michael adducts of acrylates separated from esterification reaction products. In addition, those containing other products and raw materials by-produced in the acrylic acid ester production process and treated as waste, that is, alcohol, acrylic acid other than acryloxypropionate and alkoxypropionate , An acrylate ester, a polymer of an acrylate ester or a mixture containing various other components. According to the present invention, the Michael adduct of these acrylates decomposes acryloxypropionate into useful compounds mainly composed of acrylate, and alkoxypropionate decomposes mainly into acrylate and alcohol. Is 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) (where R represents an alkyl or cycloalkyl group having 1 to 8 carbon atoms, and n is an integer of 1 to 4) As the alkoxy titanate, when it is desired to recover the same acrylate ester as the acrylate ester constituting the Michael adduct, an alkoxy titanate having the same alkoxy group as the alkoxy group of the Michael adduct of the acrylate ester to be decomposed is used. When the acrylate constituting the Michael adduct and the acrylate to be recovered may be different, a different acrylate from the alkoxy group of the Michael adduct of the acrylate can be used. As the alkoxy titanate, it is possible to use tetraalkoxy titanate,
It is preferable because it has excellent solubility in the reaction system and generates little by-products. The preferred use amount of the alkoxy titanate catalyst is 5 to 30 mol% based on 1 mol of the Michael adduct of an acrylate ester. When the amount of the alkoxy titanate used is less than 5 mol%, the decomposition does not proceed sufficiently, while when 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 type of the Michael adduct of the acrylic acid ester to be decomposed and the reaction pressure, but is usually preferably from 50 to 200 ° C., and is considered from the viewpoint of equipment and operability when industrialized. The decomposition temperature is more preferably 90 to 150C.

In the present invention, the useful compound recovered after the decomposition of the Michael adduct of the acrylate ester is
In addition to the acrylic ester, it is composed of alcohol and / or acrylic acid, and a mixture composed of these is separated into respective components to produce a product, or these mixtures are directly supplied to an acrylic ester manufacturing process,
The acrylic acid and the alcohol can be reacted to form an acrylic ester of the product. These are formed by decomposition of Michael adduct of acrylic acid ester, and in some cases, are included in the decomposed raw material.

As a method for recovering a useful compound comprising an acrylate ester, a useful compound produced by decomposition is used.
A method of continuously distilling out of the system by distillation is preferable because the decomposition reaction proceeds more advantageously and a mixture composed of an acrylate ester can be efficiently recovered. Therefore, as a decomposition method, it is preferable to decompose by heating under reduced pressure,
The pressure at that time depends on the type of the Michael adduct of the acrylic ester to be decomposed, but the decomposition temperature is preferably 50 to 200 ° C., more preferably 9 to 200 ° C.
It is preferable to adjust the pressure so as to be 0 to 150 ° C.

In the present invention, it is preferable to use a polymerization inhibitor in combination in order to prevent the polymerization of acrylates formed by decomposition. Polymerization inhibitors widely used in the field can be used. Specific examples include hydroquinone, methoxyhydroquinone, phenothiazine, hydroxylamine, and the like. Further, when the decomposition reaction is performed in the presence of molecular oxygen, the effect of inhibiting polymerization can be enhanced.

The present invention can be carried out in a batch system or a continuous system. In the batch method, both a tank reactor and a tower reactor can be used. Furthermore, it is an effective method to use a distillation column having a stage in the reactor or a device in which the reactor and the distillation column are combined to suppress the distillation of Michael adduct of acrylic acid ester. In the continuous method, it is desirable that the decomposition rate of the Michael adduct of the acrylate and the supply rate be balanced.

[0015]

The reason why the present invention is superior in decomposing Michael adducts of acrylic acid esters, in particular, acryloxypropionate esters and recovering useful compounds is unknown, but the alkoxy titanate used in the present invention is unknown. Is known to be a catalyst effective as a transesterification catalyst, and is considered to have a remarkable effect on the decomposition of Michael adducts of acrylates, especially acryloxypropionates.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples in order to more specifically explain the present invention. The definitions of the decomposition rate, low boiling rate, and recovery rate used in the present specification are as follows.

Decomposition rate (%) = [(moles of distilled active ingredient−moles of acrylic acid ester in charged liquid) / (moles of Michael adduct of acrylic acid ester in charged liquid)] × 100 Low boiling rate (%) = (mol number of distilled low boiling component / mol number of Michael adduct of acrylic acid ester in charge) × 1
00 Recovery (%) = (weight of distilled active ingredient / weight of charged liquid) × 100 active ingredient = alcohol, acrylic acid and acrylate Low boiling 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 tower filled with 10 cm glass Raschig rings and a condenser. 19.2 g (0.0565 mol) of tetrabutoxytitanate and 0.1 g of phenothiazine were added, and the pressure was reduced to 60 mmHg, and heating was started while stirring. At a reaction temperature of around 95 ° C., a distillate containing butyl acrylate as a main component began to distill,
Distillation was stabilized at a reaction temperature of 120, and further heated to 130 ° C. The reaction solution did not thicken or gel during the reaction. The test was terminated because distillation stopped 3 hours after the start of distillation. The distillate amounted to 54.3 g, and the liquid was analyzed by gas chromatography. As a result, the composition was found to be 0.423 mol for butyl acrylate and 0.00005 mol for the low boiling point. The calculation of the decomposition rate, low boiling rate and recovery rate was as follows. Decomposition rate = 84.4%, low boiling rate = 0.01%, recovery rate = 5
4.2%

Example 2 In the same apparatus as in Example 1, 20.2 g (0.10 g) of butyl acryloxypropionate was added.
1 mol), 137.7 g of butyl butoxypropionate
(0.681 mol), 13.6 g of butyl acrylate
(0.106 mol), tetrabutoxytitanate in 3
1.4 g (0.0924 mol) and 0.1 g of phenothiazine were added, and the pressure was reduced to 60 mmHg, and heating was started with stirring. The distillate started to be distilled at a reaction temperature of around 95 ° C, and the distillate was stable at a reaction temperature of 110.
Until heated. The reaction solution did not thicken or gel during the reaction. Since the distillation of distillate stopped 2 hours after the start of distillation, the test was terminated. The distillate amounted to 41.7 g, and the liquid was analyzed by gas chromatography. As a result, the composition was as follows: butyl acrylate: 0.250 mol, butanol: 0.129 mol, acrylic acid: 0.00008 mol, and low boiling point: Trace amount. The calculation of the decomposition rate, low boiling rate and recovery rate was 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 placed in the same apparatus as in Example 1.
07 mol), and 3.8 g of sodium hydroxide equivalent to 1.7 times the tetrabutoxytitanate of Example 1 in 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. However, no distillate was distilled out and the reaction solution was gelled, so the test was terminated.

Comparative Example 2 In a device similar to that in Example 1, 32.8 g (0.16 g) of butyl acryloxypropionate was added.
4 mol), 143.3 g of butyl butoxypropionate
(0.709 mol), 4.0 g of butyl acrylate
(0.031 mol), 6.8 g of sodium hydroxide
(0.17 mol) and 0.2 g of phenothiazine were added, and the pressure was reduced to 60 mmHg, and heating was started with stirring. The distillate started to distill at a reaction temperature of around 95 ° C.
Heated to 0-130 ° C. The reaction solution gelled while heating was continued. The test was stopped because distillation stopped 3.5 hours after the start of distillation. The distillate weighed 11.0 g, and the liquid was analyzed by gas chromatography. As a result, the composition was found to be 0.040 mol for butyl acrylate, 0.080 mol for butanol, trace amounts of acrylic acid, and trace amounts of low boiling components. Met. The calculation of the decomposition rate, low boiling rate and recovery rate was as follows. Sufficient decomposition could not be performed. Decomposition rate = 10.2%, low boiling rate = 0.00%, recovery rate =
6.1%

Comparative Example 3 In the same apparatus as in Example 1, 36.1 g (0.18 g) of butyl acryloxypropionate was added.
1 mol), 141.6 g of butyl butoxypropionate
(0.701 mol), 3.1 g of butyl acrylate
(0.024 mol), sulfuric acid (15.4 g, 0.157 mol) and phenothiazine (0.2 g) were added, and the pressure was reduced to 50 mmHg, and heating was started with stirring. Reaction temperature is 95 ° C
A distillate started to be distilled out in the vicinity, the distillation was stabilized at a reaction temperature of 120, and the mixture was further heated to 130 ° C. As the heating was continued, the reaction solution thickened. The test was stopped because the distillation of distillate stopped 3 hours after the start of distillation. The distillate is 4
As a result of analyzing the liquid by gas chromatography, the composition was found to be 0.306 mol of butyl acrylate,
Butanol 0.005 mol, acrylic acid 0.036
1 mol, low boiling point was 0.0019 mol. Decomposition rate,
Calculations of low boiling and recovery yielded: Decomposition was sufficient, but low-boiling components were generated, and low-boiling components were mixed into the acrylate ester, so that a removal facility was required. Decomposition rate = 36.6%, low boiling rate = 0.22%, recovery rate = 2
3.2%

[0023]

According to the present invention, the Michael adduct of an acrylate ester, which is a by-product of the acrylate ester production process, is efficiently decomposed by suppressing the increase in the viscosity of the reaction solution, gelation, and the generation of by-products. And by recovering useful compounds,
An excellent effect of reducing the amount of industrial waste and enabling production of an industrially advantageous acrylate in high yield is achieved.

Claims (1)

(57) [Claims] 1. A method for producing a useful compound, which comprises decomposing a Michael adduct of an acrylate ester in the presence of an alkoxy titanate to recover a useful compound comprising an acrylate ester.