Method for producing (meth)acrylic ester having aromatic substituent

Abstract

To provide a method for producing a methacrylate having an aromatic substituent with low coloration and high purity.SOLUTION: The present invention provides a method for producing a methacrylate having an aromatic substituent, in which the reaction shown by the general formula (1) is performed in a secondary alcohol solvent (where n is 1-6, R is an aromatic substituent. X is a halogen group, M is a metal element, R' is hydrogen or a methyl group).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a (meth)acrylic acid ester having an aromatic substituent. [Background technology]

[0002] (Meth)acrylic acid esters having aromatic substituents have excellent optical properties such as refractive index and excellent dilutability, and are used as photo- and thermosetting resin compositions for optical applications and inkjet printers (Patent Documents 1, 2, etc.).

[0003] In optical applications such as light guide plates and light diffusion plates, coating applications, and dental applications, low coloration and high purity components are required for each component in order to reduce the impact on vision and deterioration of the properties of the resin composition. However, in conventional synthesis methods, coloration may occur or the purity of the obtained compound may not be sufficiently high. For this reason, purification is required, which increases costs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2015-083697 [Patent Document 2] Patent Publication No. 2017-128688 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, an object of the present invention is to provide a method for producing a low-colored, high-purity (meth)acrylic acid ester having an aromatic substituent. [Means for solving the problem]

[0006] The present invention relates to a reaction represented by the following general formula (1):

[0007] [ka] (In the formula, n is 1 to 6. R is an aromatic substituent. X is a halogen group. M is a metal element. R' is hydrogen or a methyl group. The above-mentioned step (a) is carried out in a secondary alcohol solvent.

[0008] R is preferably a phenyl group, a phenoxy group or a naphthyl group. Preferably, the secondary alcohol is 2-propanol and / or 2-butanol. Preferably, X is chlorine, bromine or iodine. Preferably, M is lithium, sodium, potassium or magnesium. Effect of the Invention

[0009] The method for producing a (meth)acrylic acid ester having an aromatic substituent of the present invention can provide a (meth)acrylic acid ester having an aromatic substituent that is low in color and has high purity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. The present invention relates to a method for producing a (meth)acrylic acid ester having an aromatic substituent. Aromatically substituted (meth)acrylic acid esters are used in optical applications such as light guide plates and light diffusion plates, as well as in paint applications and dental materials. In these fields, low coloration and high purity are required to minimize the effect on vision and deterioration of the properties of the resin composition.

[0011] The present inventors have investigated the reaction conditions in the production method and found that a (meth)acrylic acid ester having an aromatic substituent, which has low coloration and high purity, can be produced by carrying out the reaction in a specific solvent, thereby completing the present invention.

[0012] That is, in the present invention, the reaction represented by the above-mentioned general formula (1) is carried out in a secondary alcohol solvent. By selecting such a solvent, side reactions can be reduced, the target compound can be obtained with high purity, and coloring can be reduced. This can reduce the cost of purification after the reaction.

[0013] The present invention is characterized by the use of a secondary alcohol as a solvent. The secondary alcohol is not particularly limited, and 2-propanol and / or 2-butanol are particularly preferred. In addition, other solvents that can be mixed with these secondary alcohols may be included within the range that does not impair the effects of the present invention.

[0014] The solvents which have been conventionally used in such reactions have the following problems. Primary alcohols: The solvent itself reacts as a side reaction, increasing the amount of by-products. Amide solvents: Decompose to produce highly colorable amino compounds. Ether and ketone solvents: When heated, they produce peroxides, which lead to polymerization of (meth)acrylic esters, making them unsuitable for industrial manufacturing purposes. DMSO, etc.: High residual amounts in the final product. In the present invention, the use of a secondary alcohol as a solvent makes it possible to obtain the target compound with high purity and low coloration without causing these problems.

[0015] The reaction of the present invention represented by the general formula (1) will be described in detail below. [ka] (In the formula, n is 1 to 6. R is an aromatic substituent. X is a halogen group. M is a metal element. R' is hydrogen or a methyl group.

[0016] The above reaction is an ester group forming reaction between an alkyl halide and a metal salt of (meth)acrylic acid, and the reaction itself is a known reaction. In the present disclosure, the compound is characterized in that the R group has an aromatic substituent. Compounds having an aromatic substituent have a high refractive index, and are therefore often used in optical applications. In optical applications, it is required to reduce coloring as much as possible in order to minimize the impact of the material on vision. For this reason, it is particularly important to purify the compound to improve the problems of impurities and coloring. Therefore, it is a suitable target of the present invention, which provides a high-purity, low-coloring member.

[0017] The present inventors have investigated the reaction solvent and found that the use of an alcohol-based solvent has the advantage of less coloring, but the generation of by-products is a problem that needs to be improved. On the other hand, R a When using an alcohol solvent represented by the general formula OH, the by-products are: [ka] The occurrence of such side reactions is greatly affected by the reactivity of the alcohol used as a solvent. Therefore, it is presumed that the object of the present disclosure can be achieved by using a secondary alcohol that is less likely to cause such side reactions. In addition, when N,N-dimethylformamide (DMF) is used as a solvent, the production of the above impurities is suppressed, but another problem of coloration occurs. From the above viewpoints, the object of the present invention can be suitably achieved by using a secondary alcohol as a solvent in the reaction of the present invention.

[0018] The secondary alcohol is not particularly limited, but is preferably inexpensive and has a low boiling point. This is because the secondary alcohol used as a solvent needs to be removed after the reaction. From this viewpoint, 2-propanol and / or 2-butanol are particularly preferred. In addition, other solvents may be used in the reaction as long as they do not adversely affect the effects of the present invention. There are no particular limitations on the other solvents, and they may be mixed with the above-mentioned secondary alcohol in any ratio and do not significantly affect the reactivity.

[0019] In the above reaction, n is 1 to 6.

[0020] The above R is an aromatic substituent. In terms of the reaction mechanism of the present invention, the aromatic substituent is not particularly limited, but it is one having an aromatic hydrocarbon group, and further, the aromatic group and (CH2) n The aromatic ring may have an atom of oxygen, nitrogen, sulfur, or the like between the group. The aromatic ring may have a substituent such as an alkyl group having 1 to 3 carbon atoms, an ester group, an alkoxy group, a hydroxyl group, an amino group, or an amide group. R may be an aromatic hydrocarbon group having an aromatic substituent such as a phenyl group or a phenoxy group. Furthermore, the aromatic ring may have a structure having a fluorene ring or an anthracene ring.

[0021] Specific examples of the phenyl group, phenoxy group, naphthyl group, etc., which are available as industrial raw materials in the expected fields, may be mentioned. In the case of the naphthyl group, the substitution position may be either the 1-position or the 2-position.

[0022] The above X is a halogen group. The halogen group is not particularly limited, but is particularly preferably any one of Cl, Br, and I. The above M is not particularly limited, and examples thereof include Li, Na, K, and Mg. R' may be either hydrogen or a methyl group.

[0023] When carrying out the above reaction, it is preferable to use both components in approximately equivalent amounts, more specifically, it is preferable to mix them in a ratio of halide / (meth)acrylic acid metal salt = 1.0 / 1.0 to 1.0 / 1.5 (molar ratio). The above ratio is more preferably 1.0 / 1.0 to 1.0 / 1.3, and even more preferably 1.0 / 1.0 to 1.0 / 1.1.

[0024] When carrying out the above reaction, a phase transfer catalyst may be used to facilitate the reaction. Examples of phase transfer catalysts include quaternary ammonium salts and crown ethers. More specifically, quaternary ammonium salts such as tetramethylammonium chloride, triethylmethylammonium chloride, ethyltrimethylammonium chloride, methyltributylammonium chloride, methyltrioctylammonium chloride, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, benzyltributylammonium chloride, trimethylstearylammonium chloride, hydroxyethyltrimethylammonium chloride, triethylmethylammonium bromide, tetraethylammonium bromide, ethyltrimethylammonium bromide, and tetrabutylammonium bromide are preferred because of the ease of industrial raw material availability. These phase transfer catalysts may be used alone or in combination of two or more. They may also be used in aqueous solution.

[0025] When the phase transfer catalyst is used, the amount of the catalyst used is preferably within the range of 0.1 to 10.0% by weight based on the total weight of the reaction raw materials. By setting the amount within this range, the reaction can proceed easily, and the catalyst can be easily removed in the subsequent purification step.

[0026] When carrying out the above reaction, a conventional polymerization inhibitor can be used to prevent polymerization of the (meth)acrylic acid derivative due to heating during the reaction. Representative examples include, but are not limited to, polymerization inhibitors such as quinones, alkylphenols, and amines.

[0027] In the reaction mixture, the total amount of the raw material compounds added to the secondary alcohol solution is preferably within the range of 20 to 80% by weight. By keeping the amount within this range, the reaction can be carried out efficiently and the effects of the present invention can be obtained.

[0028] The reaction conditions in the production method of the present invention are not particularly limited, and the reaction can be carried out, for example, at 60° C. or higher, with the upper limit being under reflux. The lower limit of the reaction temperature is more preferably 70° C., and even more preferably 80° C.

[0029] The reaction product obtained by the method of the present invention preferably contains the target (meth)acrylic acid ester having an aromatic substituent in a proportion of 20% by weight or more, which is preferable in that the subsequent purification step can be easily carried out.

[0030] The reaction product obtained by the method of the present invention preferably has a Hazen color unit number (APHA) as specified in JIS K 0071-1:2017 of 30 or less. According to the method of the present invention, such a compound with little coloring can be obtained.

[0031] The reaction product obtained by the method of the present invention can then be filtered or diluted with a non-polar solvent, which are known techniques depending on the selected production method, and then the removed salts can be removed by oil-water separation using neutral water, acidic water, or alkaline water, and the solvent can be distilled off, to obtain the desired compound with high purity.

[0032] The (meth)acrylic acid ester having an aromatic substituent obtained by the production method of the present invention can be suitably used in applications such as optical components such as lenses and displays, inkjet paints, and dental materials, combining the optical properties derived from the chemical structure with the low color number and high purity of the present invention. EXAMPLES

[0033] The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited to the following examples. In the text, parts are by weight.

[0034] [Examples and Comparative Examples] In order to compare the coloring in each of the examples and comparative examples, the Hazen color unit number (APHA) as specified in JIS K 0071-1:2017 was confirmed by visual color comparison and quantified. The purity and by-product content in each of the examples and comparative examples were quantified by the area percentage method using gas chromatography according to JIS K 0114:2012 using a Shimadzu GC-2014 equipped with a dimethylpolysiloxane column. In addition, the main product and by-product compounds were identified by mass spectrometry using a JEOL JMS-Q1050GC under the same gas chromatography conditions as above, and the molecular weights of any compounds were confirmed.

[0035] Example 1. Method for producing 4-phenoxybutyl acrylate (2-propanol solvent) 32.0g (173.4mmol) of 4-phenoxybutyl chloride, 21.6g (196.4mmol) of potassium acrylate, 3.2g (27.7mmol) of tetramethylammonium chloride, and 15.0mg of BHT were dissolved in 24g of 2-propanol and reacted at 90℃ for 8 hours. After the reaction was completed, the mixture was diluted with 40g of cyclohexane. 40g of clean water was added and stirred, then the mixture was allowed to stand, and the oil-water separation was performed, and the aqueous phase was discarded to remove the salt produced. This was repeated three times, after which the organic phase was collected and the solvent was distilled off under reduced pressure, and the desired product was obtained. (Yield 36.4g, 95.5%) The product had an APHA of 20, a purity of 97.6% (m / z=220), and the total amount of by-products derived from 2-propanol was 0.76% (m / z=208, m / z=280).

[0036] Example 2. Method for producing 2-phenylethyl acrylate The synthesis was carried out in the same manner as in Example 1, except that the raw material in Example 1 was changed to 32.0 g (173.0 mmol) of 2-phenylethyl bromide. The target product was obtained in an amount of 28.9 g and a yield of 95.0%, with APHA=40 and a purity of 98.2% (m / z=176), and the total amount of by-products derived from 2-propanol was 0.36% (m / z=164, m / z=236).

[0037] Example 3. Method for producing 4-phenoxybutyl acrylate (2-butanol solvent) The synthesis was carried out in the same manner as in Example 1, except that the solvent in Example 1 was changed to 2-butanol. The target product was obtained in an amount of 36.0 g and a yield of 94.5%, with APHA=20 and a purity of 98.4% (m / z=220), and the total amount of by-products derived from 2-butanol was 0.52% (m / z=222, m / z=294).

[0038] Example 4. Method for producing 1-naphthalenemethyl acrylate The synthesis was carried out in the same manner as in Example 1, except that the raw material in Example 1 was changed to 32.0 g (181.3 mmol) of 1-naphthalenemethyl chloride. The target product was obtained in an amount of 37.0 g and a yield of 96.2%, with APHA=40 and a purity of 97.7% (m / z=212), and the total amount of by-products derived from 2-propanol was 1.56% (m / z=200, m / z=272).

[0039] Comparative Example 1. Method for producing 4-phenoxybutyl acrylate (solvent: ethanol) The synthesis was carried out in the same manner as in Example 1, except that the solvent in Example 1 was changed to ethanol. The target product was obtained in an amount of 38.0 g and a yield of 99.8%, with APHA=40 and a purity of 87.7% (m / z=220), and the total amount of by-products derived from ethanol was 10.75% (m / z=194, m / z=266).

[0040] Comparative Example 2. Method for producing 4-phenoxybutyl acrylate (DMF) The synthesis was carried out in the same manner as in Example 1, except that the solvent in Example 1 was changed to DMF. The target product was obtained in an amount of 36.0 g and a yield of 94.5%, with APHA=200 and a purity of 99.0% (m / z=220), and the total amount of by-products derived from DMF was below the detection limit. In other words, although the target product was obtained with high purity, it was significantly colored, and purification would be required for practical use. [Industrial Applicability]

[0041] The (meth)acrylic acid ester having an aromatic substituent obtained by the method for producing a (meth)acrylic acid ester of the present invention can be suitably used in the optical field, optical members, inkjet paints, dental materials, and the like.

Claims

1. The reaction represented by the following general formula 【Chemistry 1】 (In the formula, n is 1 to 6. R is an aromatic substituent. X is a halogen group. M is a metal element. R' is hydrogen or a methyl group.

1. A method for producing a (meth)acrylic acid ester having an aromatic substituent, comprising the steps of:

2. 2. The method for producing a (meth)acrylic acid ester according to claim 1, wherein R is a phenyl group, a phenoxy group or a naphthyl group.

3. 3. The method for producing a (meth)acrylic acid ester according to claim 1 or 2, wherein the secondary alcohol is 2-propanol and / or 2-butanol.

4. The method for producing a (meth)acrylic acid ester according to any one of claims 1 to 3, wherein X is chlorine, bromine or iodine.

5. The method for producing a (meth)acrylic acid ester according to any one of claims 1 to 4, wherein M is lithium, sodium, potassium or magnesium.

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