JPH0217149A - Production of high-purity acrylate or methacrylate - Google Patents

Abstract

PURPOSE:To obtain the title compound useful as a raw material for producing optical plastic resin readily, in high yield and in high purity by extracting a (meth)acrylate using a specific extracting solvent. CONSTITUTION:A (meth)acrylate shown by the formula (R is H or CH3; n is 0-3) is blended with a water-soluble extracting solvent with a glycol such as diethylene glycol, 1,3-butanediol or propylene glycol, allowed to stand, separated into a (meth)acrylate layer and a glycol layer, the glycol layer is removed, the glycol layer is removed, optionally the (meth)acrylate layer is extracted with water, a small amount of glycol dissolved in the (meth)acrylate layer is removed to give the aimed high-purity compound in high yield and in high purity. The glycol used as the extracting solvent is separated from an unreacted alcohol by distillation and purification, can be reused and reuse of glycol is preferable with respect to economic efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing highly pure acrylate or methacrylate.

[Conventional technology]

Various methods have been proposed for synthesizing acrylates or methacrylates. For example, ■ a method in which acrylic acid or methacrylic acid is reacted with a corresponding alcohol in the presence of an acid catalyst and the resulting water is removed from the system (dehydration reaction); ■ ethyl acrylate or methyl methacrylate and a corresponding alcohol A method of reacting with and removing the generated ethanol or methanol (ester exchange reaction)
etc. are representative.

The acrylate or methacrylate produced in the transesterification reaction (2) is an equilibrium reaction, so under normal synthesis conditions it is inevitable that 1% to 3% by weight of unreacted alcohol will remain. be.

Conventionally, a method of separating alcohol and acrylate or methacrylate by rectification has been adopted as a method for achieving high purity. However, even when attempting to rectify high-boiling point acrylates or methacrylates under reduced pressure, heat treatment at high temperatures is unavoidable, resulting in polymerization of the acrylates or methacrylates, making it extremely difficult to achieve high purity through rectification. It is. If a thin film distillation device is used as a measure to prevent polymerization, heat treatment at high temperatures can be avoided, and there is no risk of polymerization (although the boiling point of the unreacted raw material alcohol to be removed and the target product, acrylate or methacrylate) can be avoided. is close to each other, it is virtually impossible to remove only the unreacted raw material alcohol, and if the unreacted alcohol is still removed by distillation, a significant decrease in yield will result.

Conventionally, methods for obtaining high-purity acrylates or methacrylates with high boiling points and polyfunctional acrylates with virtually no boiling point involve reacting acrylic acid or methacrylic acid with the corresponding alcohol in the presence of an acid catalyst, In a method for producing acrylate or methacrylate in which produced water is removed from the system, there is a method in which acrylic acid or methacrylic acid is used in large excess, for example 2 to 3 times the mole, relative to the corresponding alcohol. When isolating methacrylate, excess acrylic acid or methacrylic acid is removed as an aqueous sodium salt solution and discarded, so it cannot be used industrially.

Moreover, as another method, a method using physical properties other than boiling point has also been proposed. For example, Tokuko Sho 61-4
No. 4538 proposes a purification method by recrystallization of diacrylate, which is solid at room temperature. However, this method cannot be applied to liquid acrylate or methacrylate as in the present invention.

[Problem to be solved by the invention]

General formula (I) [In the formula, R represents H or CH, and n is O or 3]
The acrylate or methacrylate polymer or copolymer represented by
No. 08 and JP-A-61-73705). Shigashi,
- In order to use acrylate or methacrylate of type (f) in optical plastics, it is necessary that the acrylate or methacrylate be of high purity.

That is, general formula (I) containing impurities such as raw material alcohol etc.
) When a polymer obtained by polymerizing or copolymerizing acrylate or methacrylate is used for optical plastics, raw material alcohol and the like remain in the resin, resulting in various problems. For example, when aluminum is deposited on a resin plate, the raw alcohol bleeds out onto the resin surface.
Problems such as a decrease in vapor deposition strength and a decrease in the heat resistance and mechanical strength of the resin also occur.

An object of the present invention is to provide a method for producing high-purity acrylate or methacrylate with a low content of unreacted alcohol that can be used for optical plastics.

[Means to solve the problem]

The present invention provides -Form (1) [In the formula, R represents H or CH2, and n is O or 3]
The present invention relates to a method for producing a highly pure acrylate or methacrylate, which is characterized by extracting the acrylate or methacrylate shown by using water-soluble glycols as an extraction solvent.

That is, in the present invention, after mixing the acrylate or methacrylate of the above-mentioned format (1) and a water-soluble glycol, the mixture is allowed to stand to separate into an acrylate or methacrylate layer and a glycol layer, and then the glycol layer is separated. and, if necessary, extracting the acrylate or methacrylate layer with water to remove a small amount of glycol dissolved in the acrylate or methacrylate layer, thereby obtaining a high-yield, high-purity acrylate or methacrylate. It is.

The water-soluble glycols used in the present invention are not particularly limited as long as they can be mixed with water at room temperature in any proportion;
For example, examples of the aliphatic alcohol having 2 to 9 carbon atoms include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1.3-propanediol, and 1.3-butanediol. diethylene glycol, 1
3-Butanediol and propylene glycol are preferred. These glycols can be used alone or in combination of two or more. The method and device for extracting and purifying the acrylate or methacrylate using these glycols as extraction solvents are not particularly limited, and conventionally known methods and devices can be used as they are.

For example, 100 parts by weight of acrylate or methacrylate of the above-mentioned form (1) and 30 to 100 parts by weight of glycol are charged into a mixing tank, stirred, and then allowed to stand to separate into the acrylate or methacrylate layer and the glycol layer. can be purified by extracting it from the mixing tank. Note that this extraction operation may cause a trace amount of glycol to be dissolved or dispersed and mixed into the acrylate or methacrylate layer. At this time, it is preferable to remove the acrylate or methacrylate layer by washing with water.

Incidentally, the glycol used as the extraction solvent can be separated from unreacted alcohol by distillation purification or the like and reused. Reusing glycol is preferable from an economical point of view.

Further, the extraction operation using glycol is not limited to one time, but may be performed two to three times depending on the target purity. In addition, combining with other purification methods such as distillation purification using a thin film distillation device after extraction purification can be used to reduce the color of the acrylate or methacrylate, etc.
This is preferred because it achieves higher purity.

General formula (1) to which the present invention is applied [In the formula, R represents H or CH3, and n is 0 or 3]
The acrylate or methacrylate represented by -Form (II) (in the formula, n is O or 3) is produced by a known method using an alcohol represented by the formula (II) (wherein n is O or 3) and acrylic acid or methacrylic acid as raw materials, or -Form (II) It can also be produced by a known method using the alcohol represented by II) and ethyl acrylate or methyl methacrylate as raw materials. The method for producing the acrylate or methacrylate of type (1) to which the present invention can be applied is not particularly limited;
If the acrylate or methacrylate containing an alcohol represented by the - format [■] is included as an impurity, the method for synthesizing the acrylate or methacrylate is studied, and the alcohol is 3% by weight.

Further, the acrylate or methacrylate of general formula (1) to which the present invention can be applied does not need to be isolated. That is, the acrylate or methacrylate synthesized from the alcohol represented by the -format (n) and acrylic acid or methacrylic acid is first treated with a reaction solvent such as toluene,
obtained as a reaction solution containing a catalyst such as p-toluenesulfonic acid and excess acrylic acid or methacrylic acid,
Next, alkaline water purification or the like is performed to obtain a cleaning liquid which is a mixture of the acrylate or methacrylate and the reaction solvent. Furthermore, the acrylate or methacrylate of form (1) can be obtained as a concentrated liquid by distilling off the solvent and a distilled product by distilling this, but the present invention can be applied to any of these stages. . However, it is not preferable to carry out the production method of the present invention at a stage where the catalyst and acrylic acid or methacrylic acid are mixed into the glycol and recovery of the glycol is difficult.

It is possible to achieve higher purity by carrying out (Example) The present invention will be specifically explained based on Examples below.
The present invention is not limited to this.

Comparative Example 1 1 with thermometer, air inlet tube, stirring device and water separator
8-tricyclo[5゜2, 1.0
"°h] Decyl alcohol [hereinafter abbreviated as TCD-OH] 152 kg (1 kilomol), acrylic acid 86.4 kg
(1.2 kmol), 200 kg of toluene, 7 kg of p-1-luenesulfonic acid as a catalyst, and 44 g of methoquinone as a polymerization inhibitor, and air was introduced (4ryf/
h) Toluene was refluxed at a constant volume of L, and the reaction was carried out while water was distilled off. After reacting until almost no water is distilled out, the cooled reaction solution is added to a 10% caustic soda aqueous solution 12
After washing with 3 kg, toluene was distilled off under reduced pressure and 8-tricyclo(5,2,1,0
"°6] Decyl acrylate [hereinafter abbreviated as TCD-AA" was obtained in magazine 3205. When this TCD-AA was analyzed by gas chromatography under the following conditions, it was found that TCD-0H
It contained 2.2% by weight.

Analysis conditions Column 5E-5210% 2m Column temperature 160'C Inlet temperature 200'C Detector FID 20kg of this crude TCD-AA was heated using a thin film evaporator (Japan Vacuum)
CEH-300B) at a vacuum degree of 1.0 torr and an evaporation surface heating medium temperature of 105°C. At this time, first, 30% of the feed liquid was vaporized and 6 kg of low-boiling fraction was removed, and then the remaining liquid was fed again and distilled to produce 13.3 kg of distilled product.
(yield 66.5%). This distilled product has a hue (APH)
A) Gas chromatography analysis at 10 or less revealed that TCD-OH was contained in an amount of 1.1% by weight.

Comparative Example 2 Methacrylic acid 103. was used instead of acrylic acid in Comparative Example 1.
Crude 8-tricyclo(5,2,1,0""6]decyl methacrylate [5,2,1,0""6]decyl methacrylate having a hue (APHA) of 120 was treated in the same manner as in Comparative Example 1, except that 2 kg (1,2 kmol) was used.
Hereinafter, abbreviated as TCD-MA] 209 kg was obtained. This T
When CD-MA was analyzed by gas chromatography,
It contained 2.5% by weight of TCD-OH. In addition, the crude TCD-MA was purified by distillation in the same manner as in Comparative Example 1, and purified TC with a distillation yield of 65% and a TCD-OH content of 1.0% by weight was obtained.
D-MA was obtained.

Comparative Example 3 Norborneol [
Hereinafter, the same treatment as in Comparative Example 1 was performed except that NB-OH and abbreviation 1112 kg (1 kmol) were used.
I got g. Gas chromatography analysis of this crude NB-MA revealed that it contained 2.3% by weight of NB-OH. In addition, the crude NB-MA was purified by distillation in the same manner as in Comparative Example 1, and the distillation yield was 60% and the NB-OH content was 1.3% by weight.
Purified NB-MA was obtained.

Example 1 After stirring and mixing 100 parts by weight of the crude TCD-AA obtained in Comparative Example 1 and 50 parts by weight of diethylene glycol, the mixture was allowed to stand and separated into two layers, and the diethylene glycol in the lower layer was separated.

Furthermore, the same treatment was performed using 50 parts by weight of diethylene glycol. Since the TCD-AA layer contained a small amount of diethylene glycol, it was washed with 30 parts by weight of water.
96 parts by weight of purified TCD-AA was obtained. This purified TCD
-TCD-OH in AA was 0.38% by weight.

In addition, this cleaned product (purified TCD-AA) was distilled using the thin film evaporator used in Comparative Example 1 without removing the low-boiling fraction,
Distillation yield 95%, hue (APHA) below 1O, TCD-
High purity TCD-AA with an OH content of 0.40% by weight was obtained.

Examples 2 and 3 The treatment was carried out in the same manner as in Example 1 except that crude TCD-MA or crude NB-MA obtained in Comparative Example 2 or 3 was used instead of crude NB-AA in Example 1, and further distillation was performed. I did it. The results are shown in Table 1.

Examples 4 to 8 Crude TCD-MA was used instead of crude NB-AA in Example 1, and engineered glycol, propylene glycol, dipropylene glycol, and diethylene glycol were used instead of diethylene glycol.
The same treatment as in Example 1 was performed except that 1,3-butanediol or triethylene glycol was used, and further distillation was performed. The result [effect of the invention]

Claims (1)

[Claims] 1. Acrylate or acrylate represented by general formula [ I ] ▲ Numerical formula, chemical formula, table, etc. A method for producing highly pure acrylate or methacrylate, which comprises extracting methacrylate using water-soluble glycols as an extraction solvent. 2. As a glycol, diethylene glycol 1,3-
The method for producing highly pure acrylate or methacrylate according to claim 1, which uses butanediol and/or propylene glycol.