JPH10175918A - Production of tetrahydrobenzyl (meth)acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the water pollution, facilitate the purification and enable the obtaining of the subject compound useful as a resin modifier, a crosslinking agent, etc., with a small consumption of methacrylic acid by using a specific dehydrating solvent at the time of an esterifying reaction. SOLUTION: The esterifying reaction of (D) tetrahydrobenzyl alcohol with (E) (meth)acrylic acid is carried out in the presence of (A) a polymerization inhibitor and (B) a catalyst while dehydrating the reactional solution with (C) a 1-10C hydrocarbon as a dehydrating solvent according to azeotropic distillation, and a treatment of the resultant crude reactional solution for removing the component B is then conducted to reduce the concentration of the component B to <=10wt.%. The crude reactional solution is then purified by distillation. The purification by distillation is preferably conducted in the presence of a polymerization inhibitor such as quinones or hindered phenols and a polymerization inhibitor such as a phenothiazine compound or prescribed hydroxyamines by introducing a molecular oxygen-containing gas into the crude reactional solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing tetrahydrobenzyl (meth) acrylate, and more particularly to a method for improving the reaction efficiency and producing it under simple reaction conditions. And a method for producing the same.

[0002]

2. Description of the Related Art Since (meth) acrylic acid esters are easily polymerized by heat, radicals, ultraviolet rays or radiation, they are used as raw materials for paints, lenses or fibers.
Or, it is widely used as an adhesive or the like. These are generally obtained by direct esterification of the corresponding alcohol and (meth) acrylic acid, or by transesterification of the corresponding alcohol with readily available (meth) acrylates such as methyl (meth) acrylate. Manufactured.

On the other hand, tetrahydrobenzyl (meth) acrylate is a (meth) acrylate of tetrahydrobenzyl alcohol synthesized by the Diels-Alder reaction of butadiene and acrolein and the partial hydrogenation of formyl group, and the reactivity is intramolecular. It is a useful compound that can be used as a resin modifier, a cross-linking agent, a coating material, etc. because it has two different double bonds. For example, British Patent No. 2253208 discloses a method for directly esterifying tetrahydrobenzyl alcohol and methacrylic acid at 80 ° C. without a solvent in the presence of a sulfuric acid catalyst. According to this method, the target compound, tetrahydrobenzyl methacrylate, is obtained in a yield of 85% (based on alcohol).

[0004]

However, in the method of British Patent No. 2253208, methacrylic acid is used in a molar amount of 2 times the amount of tetrahydrobenzyl alcohol.
Further, when water generated by the reaction is removed, methacrylic acid as a raw material is distilled off together with water from the top of the distillation column. Therefore, the consumption of methacrylic acid is large, and the COD load of the wastewater is also increased. Further, the pressure at the time of purification is as high as 2 mmHg, which is not practical for industrial production.

On the other hand, US Pat. No. 3,536,687 discloses a method for producing tetrahydrobenzyl methacrylate by a transesterification method. However, this method also requires a pressure of 0.3 mmHg and a high vacuum at the time of purification, resulting in industrial production. Is difficult.

[0006]

Means for Solving the Problems The present inventors have solved the above problems by using a hydrocarbon having 10 or less carbon atoms as a dehydrating solvent in the esterification reaction in the production of tetrahydrobenzyl (meth) acrylate. The inventors have found that the present invention can be performed, and have completed the present invention.

That is, the present invention provides an esterification reaction between tetrahydrobenzyl alcohol and (meth) acrylic acid while dehydrating by azeotropic distillation using a hydrocarbon having 10 or less carbon atoms as a dehydrating solvent in the presence of a polymerization inhibitor and a catalyst. The present invention provides a process for producing tetrahydrobenzyl (meth) acrylate, characterized in that the crude reaction solution obtained is subjected to a catalyst removal treatment to reduce the catalyst concentration to 10% by weight or less, followed by purification and distillation. In addition, at the time of purification distillation, a molecular oxygen-containing gas is introduced into the reaction crude liquid, and at least one compound selected from the following group A and one or more compounds selected from the group B are added. It is intended to provide a method for producing the above-mentioned tetrahydrobenzyl (meth) acrylate, which is used as a polymerization inhibitor. Group A: quinones, hindered phenols, nitrosamines, phenylenediamines, Group B: phenothiazine compounds, general formula RR′NOH (R
And R ′ are each a hydrogen atom, an alkyl group or an aryl group, which may be the same or different, and hydroxyamines represented by the general formula Cu (S ₂ CNR ₂ ) ₂ (R
Is copper dithiocarbamate represented by an alkyl group or an aryl group), and iron dithiocarbamate represented by Fe (S ₂ CNR ₂ ) ₃ (R is an alkyl group or an aryl group). In addition, esterification is performed by using 0.9 to 1.1 mol of (meth) acrylic acid per 1 mol of tetrahydrobenzyl alcohol, and adding 0.1 mol of catalyst to tetrahydrobenzyl alcohol
The present invention provides a method for producing the above-mentioned tetrahydrobenzyl (meth) acrylate, wherein the conditions are 10 to 10 mol% and the reaction temperature is 40 to 90 ° C. Further, the present invention provides the method for producing tetrahydrobenzyl (meth) acrylate, wherein the dehydrating solvent is at least one selected from n-hexane, cyclohexane, toluene, and xylene. Further, the present invention provides a method for producing the above-mentioned tetrahydrobenzyl (meth) acrylate, wherein the catalyst is a compound having a sulfonic acid group. Further, the present invention provides the method for producing tetrahydrobenzyl (meth) acrylate, wherein the catalyst removal treatment is any one selected from washing with water, washing with alkaline water, and adsorption with a solid base. In addition, purification distillation is
It is intended to provide a method for producing said tetrahydrobenzyl (meth) acrylate, which is carried out at a pressure of 0 to 200 mmHg. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(Esterification reaction) In the present invention, tetrahydrobenzyl alcohol and (meth) acrylic acid are dehydrated by azeotropic distillation using a hydrocarbon having 10 or less carbon atoms as a dehydrating solvent in the presence of a polymerization inhibitor and a catalyst. Esterify.

The ratio of tetrahydrobenzyl alcohol to (meth) acrylic acid is from 0.9 to 0.9 mol of (meth) acrylic acid per mole of tetrahydrobenzyl alcohol.
It is preferable to use 1.1 mol, and more preferably, it is in the range of 0.9 to 1.0 mol. This is because the esterification reaction proceeds sufficiently within this range. It is more preferable that the ratio of the raw material alcohol is higher than that of (meth) acrylic acid, since (meth) acrylic acid, which is most easily polymerized, does not remain in the reaction solution at the end of the esterification reaction.

As the polymerization inhibitor that can be used in the esterification reaction, any one compound selected from the following groups A and B can be exemplified. Group A: quinones such as hydroquinone, hydroquinone monomethyl ether and benzoquinone; hindered phenols such as 3,5-ditert-butyl-4-hydroxytoluene; nitrosamines such as N-nitrosodiphenylamine; N, N'-diphenylphenylene Phenylenediamines such as diamines; Group B: phenothiazine and compounds having a phenothiazine skeleton, general formula RR′NOH (R and R ′ are each a hydrogen atom, an alkyl group or an aryl group, and may be the same or different) Hydroxyamines represented by
For example, (C ₂ H ₅ ) ₂ NOH, the general formula Fe (S ₂ CN)
R _{2) 3,} R in the general formula _{Cu (S 2 CNR 2) 2} ( both formulas, Cu [S ₂ CN (CH _{3) 2]} represented by an alkyl group or an aryl group.) _2, Cu [ S ₂ CN (C ₂
H _{5) 2] 2,} Cu _{[S 2 CN (C 3 H 7} ) 2 ] dithiocarbamates, such as _2, Fe [S ₂ CN (CH _{3) 2] 3,} etc. dithiocarbamic iron of. Among these compounds, hydroquinone, hydroquinone monomethyl ether, benzoquinone, 3,5-ditert-butyl-4-hydroxytoluene, N-nitrosodiphenylamine, N,
Any one selected from N′-diphenylphenylenediamine, phenothiazine, Cu
[S ₂ CN (CH ₃ ) ₂ ] ₂ , Cu [S ₂ CN (C ₂ H ₅ ) ₂ ]
₂ , Cu [S ₂ CN (C ₃ H ₇ ) ₂ ] ₂ , Fe [S ₂ CN (C
H ₃ ) ₂ ] ₃ . As the polymerization inhibitor, it is particularly preferable to use a combination of at least one compound selected from the group A, at least one compound selected from the group B, and a molecular oxygen-containing gas. The concentration of the polymerization inhibitor used is preferably in the range of 10 to 10000 ppm, particularly preferably 100 to 1000 ppm, based on the total weight of the starting materials tetrahydrobenzyl alcohol and (meth) acrylic acid. If the concentration is lower than 10 ppm, the effect of preventing polymerization may be insufficient. On the other hand, if the concentration is higher than 10000 ppm, the effect of preventing polymerization is sufficient, but it is uneconomical.
In the present invention, when a polymerization inhibitor is used, a method of charging a molecular oxygen-containing gas into a reaction solution can be used together. It is preferable to charge the molecular oxygen-containing gas at a concentration that does not form an explosive air-fuel mixture. As the molecular oxygen-containing gas to be introduced into the reaction crude liquid, a gas obtained by diluting an oxygen gas to an arbitrary concentration with an inert gas such as nitrogen, helium, argon, or carbon dioxide can be used. In general,
Air or a substance obtained by diluting air with nitrogen and adjusting the oxygen concentration can be used.

Examples of usable catalysts include inorganic acids such as phosphoric acid and sulfuric acid, and organic acids such as toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid and strongly acidic ion exchange resins. Among these, sulfonic acids such as toluenesulfonic acid, methanesulfonic acid, and trifluoromethanesulfonic acid are particularly preferable. The amount of the catalyst used is preferably in the range of 0.1 to 10 mol%, more preferably 1 to 5 mol%, based on tetrahydrobenzyl alcohol. If the amount is less than 0.1 mol%, the reaction rate is decreased, and the productivity is undesirably decreased. On the other hand, if it exceeds 10 mol%, the amount of by-products generated due to corrosion of the reactor, oxidation of raw materials and products, etc. will increase.
Further, when the catalyst is removed by washing with water, there arise problems such as an increase in the amount of water required for removing the catalyst and an increase in the amount of wastewater.

In the present invention, a hydrocarbon having 10 or less carbon atoms is used as a dehydrating solvent for azeotropic distillation. Specific examples of the hydrocarbon having 10 or less carbon atoms include saturated hydrocarbons such as n-pentane, n-hexane, n-heptane, cyclohexane and methylcyclohexane, unsaturated hydrocarbons such as cyclohexene, benzene, toluene and xylene. And aromatic monocyclic hydrocarbons such as ethylbenzene, mesitylene and the like. Among these, the price and (meth) in the wastewater of the reaction crude liquid
It is preferable to use n-hexane, cyclohexane, toluene, and xylene from the viewpoint of acrylic acid concentration and the like.

The method of charging the raw materials includes a method in which tetrahydrobenzyl alcohol and (meth) acrylic acid, a catalyst, a dehydrating solvent and a polymerization inhibitor are charged into a reactor at one time, and a method in which polymerization is most easily performed during the esterification reaction (meth). A method in which acrylic acid is later charged into the reactor can be used.
According to the method of charging (meth) acrylic acid later, the (meth) acrylic acid concentration in the reaction solution can be reduced,
Further, polymerization of tetrahydrobenzyl (meth) acrylate can be suppressed, which is more preferable.

The temperature of the esterification reaction is 40 to 90 ° C.,
In particular, it is preferable to carry out the reaction at 60 to 90 ° C. The reason is that if the temperature is lower than 40 ° C., the reaction rate is reduced and the productivity is not good. If the temperature is higher than 90 ° C., the polymerization of the raw materials and products is liable to proceed, which may cause adverse effects.

As the distillation apparatus used for the azeotropic distillation of the present invention, a general apparatus for azeotropic distillation can be used, and preferably, a distillation column having a decanter at the top or a modular column This is a distillation column equipped with a reflux tank filled with a dehydrating agent such as a sieve at the top. The reason is that water generated by the reaction can be effectively removed. In the production method of the present invention, the distillate obtained from the top of the distillation column is led to a decanter, separated into an aqueous layer and an organic solvent layer, and only the organic solvent layer is refluxed. Thereby, water can be removed from the reaction system.

(Catalyst Removal Treatment) Next, in the present invention, the catalyst contained in the reaction crude liquid is removed. Examples of the method for removing the catalyst include methods such as water washing (water extraction), alkaline water washing, and adsorption with a solid base. Also, neutralization with a base,
Since the acid used as a catalyst is converted into another compound, this corresponds to catalyst removal in the present invention. Among these methods, it is preferable to remove the catalyst by washing with water from the point that the catalyst can be reused or to remove the catalyst by washing with alkaline water from the viewpoint of high catalyst removal efficiency. For removing the catalyst, the concentration of the catalyst in the crude reaction solution is preferably adjusted to 10% by weight or less, more preferably 1% by weight or less. If it exceeds 10% by weight, polymerization of the product at the bottom of the column during refining becomes severe,
This is because the yield decreases.

(Purification) In the present invention, the reaction crude liquid subjected to the catalyst removal treatment is purified and distilled. During the distillation, a new polymerization inhibitor can be added in order to obtain tetrahydrobenzyl (meth) acrylate in a higher yield. As the polymerization inhibitor to be added, any of the compounds of the above-mentioned groups A and B can be used. Among them, phenothiazine, Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ , Cu [S ₂
CN (C ₂ H ₅ ) ₂ ] ₂ , Cu [S ₂ CN (C ₃ H ₇ ) ₂ ] ₂ ,
It is preferably Fe [S ₂ CN (CH ₃ ) ₂ ] ₃ . The concentration of the polymerization inhibitor is preferably from 10 to 10000 ppm, particularly preferably from 100 to 1000 ppm. If it is less than 10 ppm, the effect of preventing polymerization is reduced, and the yield is reduced. On the other hand, if it exceeds 10,000 ppm, the effect of preventing polymerization is sufficient, but the production cost of the product increases and it is not economical. Further, since the polymerization inhibitor is a high-boiling fraction compound, if present in a large amount, the bottom temperature during purification is increased, and the polymerization at the bottom during purification may proceed, which may lead to a decrease in yield. Absent. It is more preferable to use a molecular oxygen-containing gas in combination with the use of the polymerization inhibitor. It is preferable to charge the molecular oxygen-containing gas at a concentration that does not form an explosive air-fuel mixture.
As the molecular oxygen-containing gas charged in the reaction crude liquid, a gas obtained by diluting oxygen gas to an arbitrary concentration with an inert gas such as nitrogen, helium, argon, or carbon dioxide can be used. Generally, air or air diluted with nitrogen to adjust the oxygen concentration can be used. In the present invention, by adding a polymerization inhibitor during purification,
The polymerization of tetrahydrobenzyl (meth) acrylate is suppressed, and the pressure of the purification distillation can be increased as compared with the case where no polymerization inhibitor is used. The polymerization inhibitor used in the purification and the polymerization inhibitor used in the esterification reaction may be the same or different.

The pressure of the purification distillation is 10 to 200 mmH
g, particularly preferably 10 to 100 mmHg. The reason is that in this range, industrial implementation is easy, and the temperature at the bottom of the column where polymerization does not proceed during purification can be adjusted.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. “%” Indicates “% by weight” unless otherwise indicated.

(Example 1) (Esterification reaction) Into a 2-liter round bottom flask equipped with a 5-stage Older Shaw tower (inner diameter 4 cm, made of glass) equipped with a decanter at the top, 449 g (4 Mol) and 346 g of n-hexane,
27.5 g (0.2%) of 70% methanesulfonic acid as a catalyst
Mol), 1.15 g of hydroquinone monomethyl ether as a polymerization inhibitor, 3,5-ditert-butyl-4-
1.15 g of hydroxytoluene was charged. 0.1 liter / air of air was introduced into the reaction solution through a capillary tube.
h was bubbled. The flask was heated in an oil bath, and the reaction solution was boiled to total reflux. At this time, n-hexane refluxed, and the overhead temperature was about 64 ° C. Then, 327.7 g (3.8 mol) of methacrylic acid was dropped into the reaction solution over 5 hours. The decanter attached to the top of the tower was charged with 85 g of n-hexane in advance before heating,
Only the upper layer was refluxed, and after the completion of the dropwise addition, the reflux was further continued for 3 hours. The bottom temperature was 75 ° C. immediately after the start of the dropping of methacrylic acid, but gradually increased and finally rose to 86 ° C. After completion of the heating, the reaction crude liquid was analyzed by gas chromatography, and it was found that tetrahydrobenzyl methacrylate was 680.
g (3.77 mol). The lower layer weight of the decanter was 70.3 g, and 0.1 mol / liter Bu.
₄ N ⁺ OH ^- was analyzed by potentiometric titration using,
The content of methacrylic acid is 0.07% (0.049 g)
Met. (Removal of catalyst) 1100 g of the resulting crude reaction solution was charged into a 2-liter separable flask and heated to 40 ° C.
Then, 110 g of water was added thereto, and the mixture was stirred for 10 minutes and left standing for 1 hour. After standing, the upper layer and the lower layer are separated (upper layer: organic layer 1083).
g, lower layer: aqueous layer 127 g). As a result of analysis by potentiometric titration, the methanesulfonic acid concentration in the upper layer was 0.03%
(0.32 g). 9 of the catalyst charged during the reaction
It was confirmed that 8.3% was removed. (Purification) A 2-liter round bottom flask equipped with a 5-stage Older Shaw tower (inner diameter 4 cm, made of glass) was charged with 1083 g of the reaction crude solution subjected to the catalyst removal treatment, and Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ was charged in an amount of 0.35 g and purified under reduced pressure. During the purification distillation, air was bubbled into the reaction solution through a capillary tube at a rate of 0.1 L / h. Top pressure 300mmHg, reflux ratio 1
Then, n-hexane was recovered until the bottom temperature reached 100 ° C., and then n-hexane was recovered until the bottom temperature reached 100 ° C. at a tower top pressure of 100 mmHg and a reflux ratio of 1. Thereafter, the top pressure is 30 mmHg (bottom pressure is 40 mmHg),
At a reflux ratio of 5, unreacted tetrahydrobenzyl alcohol and a small amount of tetrahydrobenzyl methacrylate (4% of the charged tetrahydrobenzyl methacrylate) were recovered as initial distillation. After the first distillation recovery, the reflux temperature was 0.5 and the bottom temperature was 15
Distillation was performed until the temperature reached 0 ° C., and 547.8 g of tetrahydrobenzyl methacrylate (GC purity: 99.3%) (purification yield: 8)
0%). Since the tetrahydrobenzyl methacrylate recovered together with the raw material as the initial distillation can be recycled as the raw material, the actual purification yield is 84%.

(Embodiment 2) The esterification reaction, catalyst removal treatment and purification were carried out under the same conditions as in Embodiment 1, and the polymerization inhibitor used in the purification was Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ to phenothiazine 0.1. The pressure was changed to 7 g, and purification was performed at a top pressure of 30 mmHg and a bottom pressure of 40 mmHg. As a result, tetrahydrobenzyl methacrylate (GC purity 99.3%) 48
9.6 g (purification yield 71.5%) were obtained. The tetrahydrobenzyl methacrylate recovered together with the raw materials as the first distillation was 3.7 parts of the charged tetrahydrobenzyl methacrylate.
%, The actual purification yield was 75.1%.

Example 3 A reaction and catalyst removal treatment were carried out under the same conditions as in Example 1 without using a polymerization inhibitor used for purification, and the pressure at the top of the column after the first distillation recovery was set at 20 mmHg (at the bottom pressure). 27 mmHg) for purification. As a result, tetrahydrobenzyl methacrylate (GC purity 9
9.3%) 498.5 g (purification yield 72.8%) was obtained. Since the tetrahydrobenzyl methacrylate recovered together with the raw materials as the initial distillation was 2.6% of the charged tetrahydrobenzyl methacrylate, the actual purification yield was 75.4%.

(Example 4) Under the reaction conditions of Example 1, methacrylic acid was replaced with 273.8 g (3.8) of acrylic acid.
Mol). After the heating, the reaction crude liquid was analyzed by gas chromatography, and it was found that 628 g (3.78 mol) of tetrahydrobenzyl acrylate was produced. Further, 70 g of the lower layer of the decanter was distilled off, and as a result of analysis by potentiometric titration, the acrylic acid content was 0.95% (0.67 g). The catalyst was removed by washing with water under the same conditions as in Example 1. As a result of analysis by potentiometric titration, the methanesulfonic acid concentration in the upper layer was
It was 0.015% (0.19 g). It was confirmed that 99.0% of the catalyst charged during the reaction was removed. Next, purification was performed under the same conditions as in Example 3, and distillation was performed until the bottom temperature reached 140 ° C., to obtain 476.1 g (purification yield: 75.2%) of tetrahydrobenzyl acrylate (GC purity: 99.2%). . The amount of tetrahydrobenzyl acrylate recovered together with the raw materials as the initial fraction was 10% of the charged tetrahydrobenzyl acrylate. Since the tetrahydrobenzyl acrylate recovered together with the raw material as the first fraction can be recycled as the raw material, the actual purification yield of tetrahydrobenzyl acrylate is 85.2%.
Met.

(Example 5) Esterification reaction and catalyst removal treatment were carried out under the same conditions as in Example 4, and 0.35 g of Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ was added as a polymerization inhibitor during purification.
The purification was carried out by changing the pressure at the top of the column after purification from the initial distillation to 30 mmHg (40 mmHg at the bottom). Other purification conditions were the same as those in Example 4. As a result, tetrahydrobenzyl acrylate (GC purity 9
(9.2%) 507.7 g (purification yield 80.2%) was obtained. Since the tetrahydrobenzyl acrylate recovered together with the raw materials as the initial distillation was 4.9% of the charged tetrahydrobenzyl acrylate, the actual purification yield of tetrahydrobenzyl acrylate was 85.1%.

Example 6 An esterification reaction and catalyst removal treatment were carried out under the same conditions as in Example 5, and 0.7 g of phenothiazine was used from Cu [S ₂ CN (CH ₃ ) ₂ ] _{2 for} the polymerization inhibitor used in the purification. And the top pressure was 30 mmHg and the bottom pressure was 4
Purification was performed at 0 mmHg. As a result, tetrahydrobenzyl acrylate (GC purity 99.2%) 4
63.4 g (purification yield: 73.2%) was obtained. The tetrahydrobenzyl acrylate recovered together with the raw materials as the first distillation was 5.4 of the charged tetrahydrobenzyl acrylate.
%, The actual purification yield of tetrahydrobenzyl acrylate was 78.6%.

Example 7 An esterification reaction and a catalyst removal treatment were carried out under the same conditions as in Example 5, and Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ was not added as a polymerization inhibitor at the time of purification. Purification was performed at a pressure of 30 mmHg. As a result, tetrahydrobenzyl acrylate (GC purity 99.2%) was used as the main fraction.
431.1 g (purification yield: 68.1%) was obtained. The tetrahydrobenzyl acrylate recovered together with the raw materials as the initial distillation was 5.1 parts of the charged tetrahydrobenzyl acrylate.
%, The actual purification yield of tetrahydrobenzyl acrylate was 73.2%.

Comparative Example 1 An esterification reaction was carried out under the same conditions as in Example 3, and purification was carried out under the same conditions as in Example 3 without removing the catalyst by washing with water. As a result, 395. tetrahydrobenzyl methacrylate (GC purity 99.3%).
8 g (purification yield 57.8%) was obtained. Tetrahydrobenzyl methacrylate recovered together with the raw materials as the first distillation,
Since it was 3.2% of the charged tetrahydrobenzyl methacrylate, the actual purification yield was 61.0%.

(Comparative Example 2) A reaction was carried out under the same conditions as in Example 4, and purification was carried out under the same conditions as in Example 4 without removing the catalyst by washing with water. As a result, 342.5 g (purification yield: 54.1%) of tetrahydrobenzyl acrylate (GC purity: 99.2%) was obtained. Since the tetrahydrobenzyl acrylate recovered together with the raw materials as the initial fraction was 4.9% of the tetrahydrobenzyl acrylate charged, the purified yield of tetrahydrobenzyl acrylate was actually 5%.
It was 9.0%.

Example 8 The esterification reaction and the catalyst removal treatment were carried out under the conditions of Example 3, and the purification was carried out at a top pressure of 20 mmHg without using a polymerization inhibitor used in the purification.
As a result, 498.5 g (purification yield: 58.9%) of tetrahydrobenzyl methacrylate (GC purity: 99.3%) was obtained. The tetrahydrobenzyl methacrylate recovered together with the raw materials as the first fraction was 4.9% of the charged tetrahydrobenzyl methacrylate, and the actual purification yield was 63.8%.

Reference Examples 1 to 9 Under the same conditions as in Example 4,
The esterification reaction, the catalyst removal treatment, and the recovery of n-hexane (100 mmHg) were performed. The polymerization inhibitor was added to the remaining crude reaction solution according to Table 1, and air was bubbled at a rate of 0.1 liter / h. Heated at 140 ° C. under normal pressure. After heating, the crude tetrahydrobenzyl acrylate was absorbed into a glass fiber filter paper, and dried under reduced pressure at 5 mmHg and 120 ° C. for 1 hour to measure the concentration of the polymer of tetrahydrobenzyl acrylate. The reaction crude liquids in which n-hexane was used in Reference Examples 1 to 9 were all the same samples. According to high performance liquid chromatography analysis, the polymerization inhibitor used in the reaction was 1% of hydroquinone monomethyl ether. It is confirmed that most of the polymerization inhibitor used in the reaction remains only by disappearing.

[0031]

[Table 1]

[0032]

According to the present invention, the reaction efficiency is improved by using a dehydration solvent during the esterification reaction,
A method for producing tetrahydrobenzyl (meth) acrylate which can be produced under simple reaction conditions is provided. By using a polymerization inhibitor during purification, tetrahydrobenzyl (meth) acrylate can be produced under industrially feasible conditions.

Claims (8)

[Claims] 1. The method according to claim 1, wherein said compound has 1 carbon atom in the presence of a polymerization inhibitor and a catalyst.
An esterification reaction is performed between tetrahydrobenzyl alcohol and (meth) acrylic acid while dehydrating by azeotropic distillation using a hydrocarbon of 0 or less as a dehydrating solvent, and the resulting crude reaction liquid is subjected to a catalyst removal treatment to reduce the catalyst concentration to 10% by weight. A method for producing tetrahydrobenzyl (meth) acrylate, which is followed by purification and distillation. 2. During the purification distillation, a molecular oxygen-containing gas is introduced into the reaction crude liquid, and at least one compound selected from the following group A and one or more compounds selected from the group B: The method for producing tetrahydrobenzyl (meth) acrylate according to claim 1, wherein the compound of the formula (1) is used as a polymerization inhibitor. Group A: quinones, hindered phenols, nitrosamines, phenylenediamines, Group B: phenothiazine compounds, general formula RR′NOH (R
And R ′ are each a hydrogen atom, an alkyl group or an aryl group, which may be the same or different, and hydroxyamines represented by the general formula Cu (S ₂ CNR ₂ ) ₂ (R
Is copper dithiocarbamate represented by an alkyl group or an aryl group), iron dithiocarbamate represented by Fe (S ₂ CNR ₂ ) ₃ (R is an alkyl group or an aryl group) 3. In the purification distillation, a molecular oxygen-containing gas is introduced into the reaction crude liquid, and at least one compound selected from the following group A and at least one compound selected from the group B The method for producing tetrahydrobenzyl (meth) acrylate according to claim 1, wherein the compound of the formula (1) is used as a polymerization inhibitor. Group A: hydroquinone, hydroquinone monomethyl ether, benzoquinone, 3,5-ditert-butyl-4
-Hydroxytoluene, N-nitrosodiphenylamine, N, N'-diphenylphenylenediamine, Group B: phenothiazine, Cu [S ₂ CN (CH ₃ ) ₂ ] ₂ ,
Cu [S ₂ CN (C ₂ H ₅ ) ₂ ] ₂ , Cu [S ₂ CN (C
₃ H _{7) 2] 2,} Fe [S ₂ CN (CH _{3) 2] 3,} (C ₂ H _5)
2 NOH 4. The esterification is carried out in such a manner that (meth) acrylic acid 0.9 to 1.
The tetrahydro (meth) acrylate according to any one of claims 1 to 3, wherein the catalyst is 0.1 mol to 10 mol% with respect to tetrahydrobenzyl alcohol, and the reaction temperature is 40 to 90 ° C. Method for producing benzyl. 5. The method according to claim 1, wherein the dehydrating solvent is at least one selected from n-hexane, cyclohexane, toluene and xylene.
The method for producing tetrahydrobenzyl (meth) acrylate according to the above item. 6. The method for producing tetrahydrobenzyl (meth) acrylate according to claim 1, wherein the catalyst is a compound having a sulfonic acid group. 7. The catalyst removing treatment includes washing with water, washing with alkaline water,
The method for producing tetrahydrobenzyl (meth) acrylate according to any one of claims 1 to 6, wherein the method is any one selected from adsorption by a solid base. 8. The method for producing tetrahydrobenzyl (meth) acrylate according to claim 1, wherein the purification distillation is performed at a pressure of 10 to 200 mmHg.