JP6747780B2 - Method for producing 4-hydroxybenzoic acid long chain ester - Google Patents

Description

The present invention relates to a method for producing 4-hydroxybenzoic acid long chain ester.

4-Hydroxybenzoic acid long-chain ester has a structure having a hydroxyl group and a hydrophobic group, and its structural characteristics suggest its use as a plasticizer, a compatibilizer, a surfactant, and the like.

Generally, for esterification of a compound, a starting carboxylic acid and an alcohol are reacted in the presence of a protonic acid catalyst such as sulfuric acid to remove the catalyst and unreacted carboxylic acid from the resulting reaction solution, and crystallize as necessary. A method for producing by purification such as precipitation and distillation is known (Patent Document 1).

Regarding esterification of 4-hydroxybenzoic acid, it is known that 4-hydroxybenzoic acid short-chain ester can be relatively easily obtained by reaction with a short-chain alcohol having 1 to 6 carbon atoms.

However, when 4-hydroxybenzoic acid is reacted with a long-chain alcohol having 16 or more carbon atoms to obtain a 4-hydroxybenzoic acid long-chain ester, the reaction is similarly performed in the presence of a proton acid catalyst. However, the generation of by-products such as ethers obtained by dimerizing long-chain alcohols and by-products such as sulfates by the reaction of long-chain alcohols with a protonic acid catalyst was unavoidable.

These by-products have physical properties similar to the target 4-hydroxybenzoic acid long-chain ester, and therefore it is difficult to remove them by crystallization or distillation, and high-purity 4-hydroxybenzoic acid long-chain ester is obtained. There was a problem that could not be obtained.

JP, 2014-108928, A

An object of the present invention is to provide a method for producing a 4-hydroxybenzoic acid long chain ester in which the production of by-products is suppressed. Another object of the present invention is to provide a method for producing a high-purity long chain 4-hydroxybenzoic acid ester.

As a result of intensive studies on the method for producing 4-hydroxybenzoic acid long-chain ester, the present inventors have used a metal catalyst as a catalyst to convert 4-hydroxybenzoic acid short-chain ester and long-chain alcohol into a so-called transesterification reaction. It was found that by doing so, the production of by-products was suppressed, and high-purity 4-hydroxybenzoic acid long-chain ester was obtained, and the present invention was completed.

（式中、ｍは１〜１１の整数を示し、ｎは１５〜２３の整数を示す。） That is, the present invention comprises a step of reacting a 4-hydroxybenzoic acid short chain ester represented by the formula (1) with an aliphatic alcohol represented by the formula (2) in the presence of a metal catalyst, There is provided a method for producing a 4-hydroxybenzoic acid long chain ester represented by 3).

(In the formula, m represents an integer of 1 to 11, and n represents an integer of 15 to 23.)

ADVANTAGE OF THE INVENTION According to this invention, the production|generation of by-products, such as the ether body which dimerized the long-chain alcohol and the sulfuric acid ester which the catalyst reacted with the long-chain alcohol produced as a by-product in a normal esterification reaction, is suppressed, 4-Hydroxybenzoic acid long chain ester can be obtained.
Further, according to the present invention, a higher purity 4-hydroxybenzoic acid long chain ester can be obtained by a simple method without performing complicated purification.

In the present invention, the 4-hydroxybenzoic acid short-chain ester represented by the formula (1), which is a starting material, is a 4-hydroxybenzoic acid having 1 to 11 carbon atoms which may be linear or branched. It is an ester form with alcohol.

（ｍは１〜１１の整数を表す） Specific examples of the 4-hydroxybenzoic acid short chain ester represented by the formula (1) include methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate and isopropyl 4-hydroxybenzoate. Butyl 4-hydroxybenzoate, isobutyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, hexyl 4-hydroxybenzoate, heptyl 4-hydroxybenzoate, octyl 4-hydroxybenzoate, nonatyl 4-hydroxybenzoate, Decyl 4-hydroxybenzoate, undecyl 4-hydroxybenzoate, 2-ethylhexyl 4-hydroxybenzoate and the like can be mentioned.

(M represents an integer of 1 to 11)

Among these, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, isopropyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, and butyl 4-hydroxybenzoate in terms of availability and reactivity are excellent. Isobutyl 4-hydroxybenzoate is preferable, and methyl 4-hydroxybenzoate is more preferable because it is particularly excellent in reactivity.

The 4-hydroxybenzoic acid short chain ester used in the present invention may be a commercially available product, and 4-hydroxybenzoic acid and an aliphatic alcohol having 1 to 11 carbon atoms may be used as a proton acid catalyst. You may use what was obtained by the general esterification reaction which makes it react in presence.

（ｎは１５〜２３の整数を表す）
で表される炭素原子数１６〜２４の脂肪族アルコールである。その具体的としては、ヘキサデカノール、ヘプタデカノール、オクタデカノール、ノナデカノール、イコサノール、ヘンイコサノール、ドコサノール、トリコサノールおよびテトラコサノールからなる群から選択される１種以上が挙げられる。 The aliphatic alcohol used in the present invention has the formula (2):

(N represents an integer of 15 to 23)
Is an aliphatic alcohol having 16 to 24 carbon atoms. Specific examples thereof include one or more selected from the group consisting of hexadecanol, heptadecanol, octadecanol, nonadecanol, icosanol, henicosanol, docosanol, tricosanol and tetracosanol.

The aliphatic alcohol used in the present invention may be a commercially available one, or may be one produced by a method known to those skilled in the art.

The aliphatic alcohol used in the present invention is 0.1 to 3 mol, preferably 0.5 to 1.5 mol, more preferably 0.8 to 1 mol, per 1 mol of 4-hydroxybenzoic acid short chain ester. .2 mol, particularly preferably 0.9 to 0.98 mol.

When the amount of the aliphatic alcohol is less than 0.1 mol with respect to 1 mol of 4-hydroxybenzoic acid short-chain ester, a by-product reaction tends to occur, and 4-hydroxybenzoic acid short-chain ester becomes excessive. Waste of raw materials. When the amount of the aliphatic alcohol is more than 3 mol, an excessive amount of the aliphatic alcohol remains and the purity tends to be lowered.

In the present invention, in the reaction of 4-hydroxybenzoic acid short-chain ester with an aliphatic alcohol having 16 to 24 carbon atoms, a dimerized ether of a long-chain alcohol or a long-chain alcohol is prepared by allowing a metal catalyst to be present. It is possible to suppress the production of by-products such as sulfuric acid ester due to the reaction of the catalyst with the catalyst, and to obtain high-purity 4-hydroxybenzoic acid long-chain ester.

Examples of the metal catalyst used in the present invention include one or more selected from the group consisting of titanium-based catalysts, tin-based catalysts, antimony-based catalysts and zirconium-based catalysts, but they are excellent in availability and reactivity. Therefore, a titanium-based catalyst is preferably used.

Specific examples of titanium-based catalysts include tetramethoxy titanium, tetraethoxy titanium, tetra n-propoxy titanium, tetraisopropoxy titanium, tetra n-butoxy titanium, tetraisobutoxy titanium, tetra 2-ethylhexoxy titanium and tetraoctadecane. Soxy titanium is mentioned. Tetraisopropoxy titanium is preferable because of its excellent reactivity and availability.

Specific examples of the tin-based catalyst include monobutyltin oxide, dibutyltin oxide, dibutyltin laurate, dioctyltin laurate and dibutyldiisopropoxytin. Monobutyltin oxide and dibutyltin oxide are preferred because of their excellent reactivity and availability.

Specific examples of the antimony catalyst include antimony acetate, antimony trioxide, diantimony pentoxide, trimethoxyantimony, triethoxyantimony, tri-n-propoxyantimony and triphenylantimony. Antimony acetate is preferred because of its excellent reactivity and availability.

Specific examples of the zirconium-based catalyst include tetramethoxyzirconium, tetraethoxyzirconium, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetraisobutoxyzirconium, tetra-2-ethylhexoxyzirconium and tetraoctadecane. Examples include soxyzirconium and zirconium acetate oxide. Tetra n-butoxy zirconium is preferred because of its excellent reactivity and availability.

These catalysts may be used alone or in combination of two or more.
The amount of the metal catalyst used in the present invention is 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, and more preferably 1 to 5 parts by weight with respect to 100 parts by weight of 4-hydroxybenzoic acid short chain ester. Good parts by weight.

When the amount of the metal catalyst is less than 0.1 part by weight with respect to 100 parts by weight of 4-hydroxybenzoic acid short chain ester, the reaction tends not to proceed sufficiently. If the amount of the metal catalyst exceeds 10 parts by weight, by-products such as dimerized ethers of aliphatic alcohol tend to be produced, and it is economically disadvantageous.

The reaction of the 4-hydroxybenzoic acid short chain ester with the aliphatic alcohol having 16 to 24 carbon atoms is preferably carried out at a temperature of 120 to 200°C, more preferably 150 to 180°C. preferable. When the reaction temperature is lower than 120° C., the reaction tends not to proceed sufficiently, and when the reaction temperature is higher than 200° C., a by-product tends to be generated and energy is lost.

The reaction time is not particularly limited because it varies depending on conditions such as reaction temperature, but is appropriately selected from 1 to 20 hours, preferably 3 to 15 hours, and more preferably 5 to 10 hours.

In the present invention, the reaction of the 4-hydroxybenzoic acid short chain ester with the aliphatic alcohol having 16 to 24 carbon atoms is preferably carried out under a nitrogen stream, under bubbling, or under reduced pressure. By reacting under such conditions, it is possible to avoid reaction inhibition and catalyst deactivation by oxygen and water, easily remove short-chain alcohol by-produced from the reaction, and allow the reaction to proceed smoothly. Become.

（式中、ｎは１５〜２３の整数を示す）
で表される４−ヒドロキシ安息香酸長鎖エステルが得られる。 The reaction solution obtained by the transesterification reaction is separated and recovered by a known method such as liquid separation, recrystallization, or a preparative operation to obtain the compound represented by the formula (3):

(In the formula, n represents an integer of 15 to 23)
A 4-hydroxybenzoic acid long chain ester represented by the following formula is obtained.

Specifically, 4-hydroxybenzoic acid long chain ester represented by the formula (3) includes hexadecyl 4-hydroxybenzoate, heptadecyl 4-hydroxybenzoate, octadecyl 4-hydroxybenzoate, and 4-hydroxybenzoic acid. Nonadecyl, icosyl 4-hydroxybenzoate, henicosyl 4-hydroxybenzoate, docosyl 4-hydroxybenzoate, tricosyl 4-hydroxybenzoate and tetracosyl 4-hydroxybenzoate.

In this way, a high-purity 4-hydroxybenzoic acid long-chain ester in which the production of by-products is suppressed can be obtained. In order to further purify the product, the obtained 4-hydroxybenzoic acid long-chain ester is purified. Can be subjected to operation. The purification method is not particularly limited, for example, after melting the obtained 4-hydroxybenzoic acid long-chain ester, or after diluting with a non-water-soluble solvent, extraction with water or alkaline water, and the obtained Examples include a method of solidifying the product and suspension washing with water or alkaline water. These purification methods can be performed alone or in combination.

In the present invention, it is preferable to remove the metal catalyst remaining in the reaction solution obtained by the transesterification reaction of the 4-hydroxybenzoic acid short chain ester and the aliphatic alcohol and then purify. In this case, catalyst removal and purification are not particularly limited, but an acid aqueous solution was added to the reaction solution obtained by the reaction of 4-hydroxybenzoic acid short chain ester and an aliphatic alcohol to separate an organic layer and an aqueous layer. After that, it can be performed by a step of extracting the organic layer and a step of adding an organic solvent to the extracted organic layer and performing crystallization.

The step of adding an aqueous acid solution to the reaction solution to separate it into an organic layer and an aqueous layer, and then extracting the organic layer (hereinafter referred to as extraction step) is specifically performed by adding the aqueous acid solution to the reaction solution and then stirring. The catalyst is deactivated by heating below to melt the organic matter in the reaction solution and continuing stirring. After that, the reaction system is allowed to stand and separated into an organic layer and an aqueous layer, and the organic layer is recovered.

The solvent used for the aqueous acid solution in the extraction step is preferably a mixture of water and a lower alcohol. Examples of the lower alcohol include one or more selected from the group consisting of methanol, ethanol, 1-propanol and 2-propanol, and among these, methanol is preferably used because of its excellent yield and economy.

The weight ratio of water and lower alcohol (water/lower alcohol) is not particularly limited because it varies depending on the type of alcohol used, but it is preferably 5/5 to 2/8, preferably 4/6 to 2/8. ..

If the weight ratio of water to lower alcohol exceeds 5/5, the reaction solution and aqueous acid solution may be emulsified, and the catalyst may not be sufficiently removed. If the weight ratio of water to lower alcohol is below 2/8, the reaction Since the entire system becomes a uniform solution, the catalyst also tends to be insufficiently removed.

The acid used in the aqueous acid solution is one that inactivates the catalyst, and specifically, one or more selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, carboxylic acid and sulfonic acid can be mentioned. To be Among these, phosphoric acid is preferable in that the color tone of the obtained 4-hydroxybenzoic acid long chain ester is improved.

The amount of the solvent and the acid used in the aqueous acid solution is 0.1 to 10% by weight, preferably 0.5 to 8% by weight, and more preferably 1 to 5% by weight, based on the solvent.

When the amount of the acid is less than 0.1% by weight based on the solvent, the catalyst tends to be insufficiently removed, and when it exceeds 10% by weight, the acid tends to remain as an impurity.

The amount of the aqueous acid solution is 3 times by weight or more, preferably 5 times by weight or more with respect to the raw material 4-hydroxybenzoic acid short chain ester. When the amount of the aqueous acid solution is less than 3 times the weight, the liquid separation property between the organic layer and the aqueous layer is deteriorated, and the catalyst tends to be insufficiently removed.

In the extraction step, in order to melt the organic matter in the reaction system, it is heated to 50° C. or higher, preferably 60° C. or higher, and stirring is continued at that temperature to deactivate the catalyst, and then the organic layer and the aqueous layer are added. The reaction system is allowed to stand until and are sufficiently separated, and the separated organic layer is recovered.

The organic layer recovered in the extraction step is then subjected to a step of adding an organic solvent to the extracted organic layer for crystallization (hereinafter referred to as a crystallization step). In the crystallization step, an organic solvent is added to the organic layer, heated and dissolved, and then cooled to crystallize the target substance. Highly pure 4-hydroxybenzoic acid long-chain ester can be obtained by subjecting the precipitated crystals to solid-liquid separation by filtration or the like, washing and drying.

Examples of the organic solvent used in the crystallization step include alcohols such as methanol, ethanol, 1-propanol, 2-propanol and ethylene glycol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, methyl acetate, ethyl acetate and acetic acid. Esters such as propyl and butyl acetate, amide compounds such as N,N'-dimethylformamide, N-methylpyrrolidone and pyridine, hydrocarbon compounds such as pentane, hexane, heptane, benzene, toluene, xylene and cyclohexane, chloroform , Organic halogens such as dichloromethane, diisopropyl ether, tetrahydrofuran, ethers such as 1,4-dioxane. Among these, methanol, ethanol, 1-propanol, 2-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, in terms of excellent industrial productivity such as availability and drying efficiency. Hexane, heptane, toluene and xylene are preferable, and methanol is particularly preferable in terms of excellent yield.

The amount of the organic solvent used in the crystallization step is not particularly limited because it varies depending on the type of solvent used, but is 1 to 20 times by weight, preferably 3 to 10 times by weight of 4-hydroxybenzoic acid short chain ester as a raw material. The weight is more preferably 5 to 7 times.

When the amount of the organic solvent is less than 1 time by weight, poor stirring tends to occur during crystallization, and when it exceeds 20 times by weight, the yield tends to decrease and it is economically disadvantageous.

The crystallization step is performed by adding an organic solvent, heating it to completely dissolve the organic matter in the organic layer, and then slowly cooling the solution while continuing stirring to cause crystallization.

If a supersaturation phenomenon occurs during crystallization, a seed crystal may be appropriately added to promote crystallization.

The crystals precipitated in the crystallization step are subjected to solid-liquid separation by a conventional means such as filtration to recover the desired product, 4-hydroxybenzoic acid long chain ester. Upon solid-liquid separation, it is preferable to pour an organic solvent as appropriate to wash the crystals. As the organic solvent used in the solid-liquid separation, the same organic solvent used in the crystallization step is used.

The crystals recovered by solid-liquid separation are dried under reduced pressure in a crystalline state at a temperature of 50° C. or lower, or heated to 50° C. or higher to melt the crystals, and then the solvent is distilled off. A high-purity 4-hydroxybenzoic acid long-chain ester can be obtained.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[Conversion rate and residual rate]
The conversion was defined as the molar ratio of the produced amount of each component to the charged amount of aliphatic alcohol. Further, the molar ratio of the residual amount to the charged amount of each starting material was defined as the residual ratio.
The amount of each component produced and the amount of each starting material remaining were determined by quantitative analysis by high performance liquid chromatography (HLPC) and gas chromatography (GC) under the following conditions.

[High Performance Liquid Chromatography (HLPC)]
Device: Waters Alliance 2487/2996
Column model number: L-Column
Flow rate: 1.0 mL/min Solvent ratio: H ₂ O (pH 2.3)/CH ₃ OH=58/42 (30 minutes)→5 minutes→10/90 (55 minutes), gradient analysis Wavelength: 229 nm/254 nm
Column temperature: 40°C

[Gas chromatography (GC)]
Equipment: Shimadzu Corporation GC-2014/GC-14A
Column model number: G-100
Injection volume: 1.0 μL
Oven temperature: 310°C
Carrier gas: Helium Detector: FID

Example 1
To a 1 L four-necked flask equipped with a stirrer, a temperature sensor, and a Dean-Stark apparatus, 179 g of hexadecanol (CeOH) was added, and the mixture was heated to 70° C. under a nitrogen stream and melted. Next, 125 g of methyl 4-hydroxybenzoate (MOB) and 3.76 g of tetraisopropoxy titanium (TIPT) as a catalyst were added, the temperature was raised to 160° C. over 1 hour, and the reaction was carried out at the same temperature for 6 hours.

When the reaction solution was quantitatively analyzed by high performance liquid chromatography (HPLC) and gas chromatography (GC), the conversion rate from the charged MeOH was found to be hexadecyl 4-hydroxybenzoate (CEBP) 96.2 mol% (91 0.5% by weight), and MOB 8.2 mol% (3.5% by weight) and CeOH 2.6 mol% (1.6% by weight) remained. In addition, formation of dicetyl ether (Ce ₂ O) which is an ether body and hexadecyl p-toluenesulfonate (PTS-Ce) which is a sulfuric acid ester was not confirmed.

Comparative Example 1
To a 1 L four-necked flask equipped with a stirrer, a temperature sensor and a Dean-Stark apparatus, 258 g of MeOH was added, and the temperature was raised to 70° C. under a nitrogen stream to melt. Next, 150 g of 4-hydroxybenzoic acid (POB), 5.0 g of p-toluenesulfonic acid monohydrate and 2.4 g of hypophosphorous acid are added, the temperature is raised to 130° C. over 1 hour, and the temperature is adjusted to 8 at the same temperature. Reacted for hours. When the reaction solution was quantitatively analyzed by HPLC and GC, the conversion rate from the charged MeOH was 92.9 mol% (86.1% by weight) of CEPB, and 8.7 mol% (2.8% by weight) of POB and 3.4 mol% (1.4 wt%) of MeOH remained. The conversion rate of Ce ₂ O, which is an ether, was 2.5 mol% (1.8 wt %), and the conversion rate of PTS-Ce, which was a sulfuric ester, was 0.81 mol% (1.0 wt %), Generation of by-products was confirmed.

Example 2
The reaction was performed in the same manner as in Example 1 except that 263 g of tetracosanol (TcOH) was added as a raw material instead of MeOH. The conversion rate from the charged TcOH was tetracosyl 4-hydroxybenzoate (TCPB) 94.8 mol% (89.1% by weight), MOB 9.5 mol% (3.9% by weight) and TcOH 3.8 mol% (2%). 0.5% by weight) remained. In addition, formation of ditetracosyl ether (Tc ₂ O) which is an ether body and tetracosyl p-toluenesulfonate (PTS-Tc) which is a sulfate ester was not confirmed.

Comparative example 2
The reaction was performed in the same manner as in Comparative Example 1 except that 347 g of tetracosanol (TcOH) was added as a raw material instead of MeOH. The conversion from the charged TcOH was 92.3 mol% TCPB (88.6 wt%), and 9.0 mol% POB (3.2 wt%) and 3.7 mol% TcOH (2.5 wt%) remained. The conversion rate of Tc ₂ O, which is an ether, was 2.7 mol% (1.8 wt %), and the conversion rate of PTS-Tc, which was a sulfuric ester, was 0.90 mol% (1.0 wt %). Generation of by-products was confirmed.

Example 3
The reaction was performed in the same manner as in Example 1 except that butyl 4-hydroxybenzoate (NBE) was added as a raw material instead of MOB. The CEPB conversion rate from the charged MeOH was 70.3 mol%, and NBE43.8 mol% and MeOH29.7 mol% remained. Further, formation of dicetyl ether (Ce ₂ O) which is an ether form and hexadecyl p-toluenesulfonate which is a sulfuric ester was not confirmed.

Examples 4-6
The reaction was carried out in the same manner as in Example 1 except that the equivalent amount of MeOH shown in Table 1 was used, the reaction temperature was 180° C., and the reaction time was 4 hours. The results are shown in Table 1.

MOB: Methyl 4-hydroxybenzoate CeOH: Hexadecanol CEBP: Hexadecyl 4-hydroxybenzoate Ce ₂ O: Dicetyl ether PTS-Ce: Hexadecyl p-toluenesulfonate CeOH equivalent: Remaining molar ratio of the amount of CeOH charged to the raw material MOB Ratio: mol% of each remaining starting material with respect to the charged amount of each starting material
Conversion rate: mol% of each component produced relative to the charged amount of MeOH
N. D. : Below detection limit

Examples 7-10
The reaction was performed in the same manner as in Example 1 except that the conditions shown in Table 2 were used for the MeOH equivalent, the catalyst, the catalyst amount, the reaction temperature, and the reaction time. The results are shown in Table 2 together with Example 1.

TIPT: tetraisopropoxy titanium PTS.H ₂ O: p-toluenesulfonic acid monohydrate MBTO: monobutyltin oxide DBTO: dibutyltin oxide Sb(OAc) ₃ : antimony acetate Zr(OBu) ₄ : tetrabutoxyzirconium

Examples 11-13
The reaction was performed in the same manner as in Example 1 except that the amount of catalyst was set to the amount shown in Table 3. The results are shown in Table 3.

Examples 14-16
The reaction was performed in the same manner as in Example 1 except that the reaction temperature was set to the temperature shown in Table 4. The results are shown in Table 4.

Examples 17-19
The reaction was carried out in the same manner as in Example 1 except that the reaction time was set as shown in Table 5. The results are shown in Table 5.

Example 20
A 1 L 4-bottomed flask equipped with a stirrer, a temperature sensor, and a cooling pipe and having a discharge port with a cock at the bottom was charged with a mixed solution of 372 g of water, 875 g of methanol and 15 g of an 85% by weight phosphoric acid aqueous solution. .. Then, 273 g of the reaction solution obtained in Example 1 was cooled to 110° C. and then added to the mixed solution. After the temperature of the solution was raised to 60° C. and melted, the solution was stirred at the same temperature for 1 hour, stopped stirring, and allowed to stand at the same temperature for 1 hour to separate into an organic layer and an aqueous layer. Was recovered from the bottom outlet.

688 g of methanol was added to the recovered organic layer, the temperature was raised to 60° C. again to dissolve it, and the mixture was cooled to 15° C. for crystallization. The solid substance obtained by crystallization was taken out by filtration, washed with 230 g of methanol, and then dried under the conditions of 45° C. and 10 mmHg to obtain 236 g of crystals.

The obtained crystal was subjected to quantitative analysis by HPLC and GC, and was found to have a purity of 99.4% by weight, 0.2% by weight of CeOH, 0.8% by weight of CE(PB) _{2 and} 1.2 ppm of titanium content. Met. In addition, dicetyl ether (Ce ₂ O), which is an ether, and hexadecyl p-toluenesulfonate, which is a sulfate, were not detected.

Comparative Example 3
To a 2 L bottomed 4-necked flask equipped with a stirrer, a temperature sensor and a cooling pipe and having a discharge port with a cock at the bottom, a mixed solution of 450 g of water, 1050 g of methanol and 4.5 g of 48% by weight sodium hydroxide was placed. I prepared. Then, 386 g of the reaction solution obtained in Comparative Example 1 was cooled to 110° C. and then added to the mixed solution. The solution was heated to 60° C. and melted, then stirred at the same temperature for 1 hour, stopped stirring, and allowed to stand at the same temperature for 1 hour to separate into an organic layer and an aqueous layer.

The lower organic layer was collected from the bottom outlet, 825 g of methanol was added to the collected organic layer, the temperature was raised to 60° C. again to dissolve, and the mixture was cooled to 15° C. for crystallization. The solid substance obtained by crystallization was taken out by filtration, washed with 300 g of methanol, and dried under the conditions of 45° C. and 10 mmHg to obtain 352 g of crystals.

When the obtained crystals were subjected to quantitative analysis by HPLC and GC, the purity was 94.3% by weight, POB was 0.04% by weight, CeOH was 0.5% by weight, and CE(PB) _{2 was} 0.61% by weight. Ce ₂ O, which is an ether, remained at 2.0% by weight.

Example 21
Crystals of 349 g were obtained in the same manner as in Example 20, except that 395 g of the reaction liquid obtained in Example 2 was used. Quantitative analysis of the obtained crystals by HPLC and GC revealed that the purity was 98.0% by weight, TcOH was 0.2% by weight, TC(PB) _{2 was} 1.5% by weight, and the titanium content was 1.8 ppm. , Ether Tc ₂ O and sulfate ester PTS-Tc were not detected.

Comparative Example 4
480 g of crystals were obtained in the same manner as in Comparative Example 3 except that 520 g of the reaction liquid obtained in Comparative Example 2 was used. When the obtained crystals were subjected to quantitative analysis by HPLC and GC, the purity was 94.0% by weight, POB was 0.03% by weight, TcOH was 0.6% by weight, and TC(PB) _{2 was} 0.58% by weight. 2.4 wt% of Tc ₂ O, which is an ether body, remained.

（式中、ｍは１〜１１の整数を示し、ｎは１５〜２３の整数を示す。）
〔２〕式（３）で表される４−ヒドロキシ安息香酸長鎖エステルが、４−ヒドロキシ安息香酸ヘキサデシルである、〔１〕に記載の製造方法。
〔３〕式（１）で表される４−ヒドロキシ安息香酸短鎖エステルが、４−ヒドロキシ安息香酸メチルである、〔１〕または〔２〕に記載の製造方法。
〔４〕４−ヒドロキシ安息香酸短鎖エステル１モルに対し、脂肪族アルコール０．１〜３モルを反応させる、〔１〕〜〔３〕のいずれかに記載の製造方法。
〔５〕４−ヒドロキシ安息香酸短鎖エステル１００重量部に対し、金属触媒０．１〜１０重量部を存在させる、〔１〕〜〔４〕のいずれかに記載の製造方法。
〔６〕４−ヒドロキシ安息香酸短鎖エステルと脂肪族アルコールとを、１２０〜２００℃の温度で反応させる、〔１〕〜〔５〕のいずれかに記載の製造方法。
As described above, according to the present invention, a high-purity ether compound obtained by dimerizing a long-chain alcohol, which is a starting material, or a by-product such as a sulfate ester by a reaction between a long-chain alcohol and a proton acid catalyst is produced. It can be seen that a long chain ester of 4-hydroxybenzoic acid is obtained. Further, it is understood that by further removing the metal catalyst in the reaction solution and performing the purification operation, a higher purity 4-hydroxybenzoic acid short chain ester can be obtained.
Preferred embodiments of the present invention include:
[1] Formula (3) including a step of reacting a 4-hydroxybenzoic acid short chain ester represented by Formula (1) with an aliphatic alcohol represented by Formula (2) in the presence of a metal catalyst. A method for producing a 4-hydroxybenzoic acid long chain ester represented by:

(In the formula, m represents an integer of 1 to 11, and n represents an integer of 15 to 23.)
[2] The production method according to [1], wherein the 4-hydroxybenzoic acid long-chain ester represented by the formula (3) is hexadecyl 4-hydroxybenzoate.
[3] The production method according to [1] or [2], wherein the 4-hydroxybenzoic acid short chain ester represented by the formula (1) is methyl 4-hydroxybenzoate.
[4] The production method according to any one of [1] to [3], wherein 0.1 to 3 mol of an aliphatic alcohol is reacted with 1 mol of 4-hydroxybenzoic acid short chain ester.
[5] The production method according to any one of [1] to [4], wherein 0.1 to 10 parts by weight of the metal catalyst is present with respect to 100 parts by weight of 4-hydroxybenzoic acid short chain ester.
[6] The production method according to any one of [1] to [5], wherein the 4-hydroxybenzoic acid short chain ester and the aliphatic alcohol are reacted at a temperature of 120 to 200°C.

Claims (5)

4-hydroxybenzoic acid short-chain comprising a step of reacting 4-hydroxybenzoic acid short-chain ester represented by formula (1) with an aliphatic alcohol represented by formula (2) in the presence of a metal catalyst. 0.1 to 10 parts by weight of one or more metal catalysts selected from the group consisting of titanium-based catalysts, tin-based catalysts, antimony-based catalysts and zirconium-based catalysts is present with respect to 100 parts by weight of the ester, formula (3) A method for producing a 4-hydroxybenzoic acid long chain ester represented by:

(In the formula, m represents an integer of 1 to 11, and n represents an integer of 15 to 23.) The production method according to claim 1, wherein the 4-hydroxybenzoic acid long-chain ester represented by the formula (3) is hexadecyl 4-hydroxybenzoate. The production method according to claim 1 or 2, wherein the 4-hydroxybenzoic acid short-chain ester represented by the formula (1) is methyl 4-hydroxybenzoate. The production method according to claim 1, wherein 0.1 mol to 3 mol of an aliphatic alcohol is reacted with 1 mol of 4-hydroxybenzoic acid short chain ester. The production method according to claim 1, wherein the 4-hydroxybenzoic acid short chain ester and the aliphatic alcohol are reacted at a temperature of 120 to 200° C. 5.