JPH04305546A - Alkyl etherification of phenol compounds - Google Patents

Abstract

PURPOSE:To improve the selectivity and yield of the objective compound and further enable the continuation of the reaction by subjecting a phenol compound to the reaction under a specific condition when the compound is reacted with the lower alcohol in the presence of an acidic acid in a liquid phase to produce the alkyl-etherified product. CONSTITUTION:When a phenol compound such as catechol is etherified with a lower alcohol preferably in the presence of an acid catalyst in a liquid phase to produce a phenol-alkyl-etherified product useful as a raw material for drugs, agricultural chemicals, perfumes, etc., the reaction is performed, while the produced objective compound is distilled out together with the unreacted alcohol and the produced water and further preferably while the phenol compound and the acid catalyst are simultaneously added to the reaction system containing the phenol compound and the acid catalyst. The method permits to repeatedly use the catalyst and the unreacted raw material without requiring specific reaction device and isolation process and further to improve the selectivity of the objective compound. Especially, when an inorganic acid, an aliphatic sulfonic acid or heteropolyacid is employed as the catalyst, the conversion of the phenol compound is improved to provide the objective compound in an extremely high yield.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing alkyl ethers of phenols useful as raw materials for medicines, agricultural chemicals, and fragrances.

0002

[Prior Art] Conventionally, as an example of a gas phase reaction using an alcohol as an etherification agent in the alkyl etherification method of phenol, JP-A-53-65837 and JP-A-53-12790 disclose aluminum, A method using a catalyst consisting of boron and phosphorus is described in "Kagaku Gijutsu Kenkyusho Report, 1989, 285", which describes a method using a kaolin catalyst.

Furthermore, West German Published Patent Application No. 265582
No. 6 describes a method of etherification using alcohol in an autoclave using a cation exchange resin as a catalyst, and European Patent Publication No. 46719 describes a method of etherification using sodium acetate as a catalyst.

[0004] As a method under normal pressure, Japanese Patent Application Laid-open No. 61-1
No. 03848 describes a method for obtaining an ether using an arylsulfonic acid catalyst in the presence of a solvent capable of azeotroping with water, such as xylene.

[0005]

[Problem to be Solved by the Invention] However, even when using any of the above-mentioned methods proposed so far, satisfactory results have not been obtained in terms of yield, purity, product isolation, etc. do not have.

For example, in the gas phase method and the reaction in an autoclave, a large amount of by-products such as nuclear alkyl products are produced due to the reaction being carried out at high temperatures (200°C or higher). It was not possible to increase the proportion of phenols (hereinafter referred to as conversion rate), and it could not be said to be efficient.

[0007] In the method using arylsulfonic acid under normal pressure, a solvent such as xylene is used, so the pot yield is low and the conversion rate of the raw material is also low, making it uneconomical. As described above, in all conventional techniques, in order to increase the ratio of phenols converted to the target alkylphenol to the consumed phenols (hereinafter referred to as selectivity), the conversion rate of phenols has to be lowered. The yield was also not satisfactory.

The problem to be solved by the present invention is that, while the reaction method is simple, an extremely high selectivity can be obtained regardless of the conversion rate of phenol. It is an object of the present invention to provide a method for alkyl etherification of phenols, which can obtain alkyl etherified products in a high yield.

[0009]

[Means for Solving the Problems] As a result of intensive research aimed at solving the above problems, the present inventors have completed the present invention.

That is, the present invention relates to a method for alkyl etherification of phenols in which phenols are etherified using a lower alcohol in a liquid phase in the presence of an acid catalyst, and the alkyl etherified product is converted into unreacted alcohol and water produced. This invention relates to a method for alkyl etherification of phenols, which is characterized in that the reaction is carried out while distilling the phenols together.

The method for alkyl etherification of phenols according to the present invention will be explained in detail below. The alkyl etherification method of the present invention can take various forms, but for example, a lower alcohol as an etherification agent may be added to a mixed system of phenols and a catalyst, and then heated to a predetermined temperature and reacted. A preferred method is to heat a mixture of phenols and catalyst to a predetermined temperature and gradually add lower alcohol to the system. Furthermore, it is more preferable to gradually add a mixture of phenols and lower alcohols at an appropriate weight ratio to the mixture of phenols and catalyst.

In the present invention, the alkyl etherified product, the lower alcohol, and the water produced can be distilled out by setting the reaction temperature at a level higher than the boiling point of the lower alcohol and lower than the boiling point of the phenol. In addition, the reaction temperature is 100 to 200℃ while satisfying this temperature range.
By setting it within this range, unreacted alcohol, produced water, and produced ether can be easily distilled off, which is preferable.

[0013] The addition rate when adding and reacting a lower alcohol or a mixture of phenols and lower alcohols is not particularly limited, but in order to obtain an appropriate reaction rate, it is necessary to On the other hand, 0.1~
A rate of 10.0 mol/hr is preferred. Furthermore, when adding a mixed solution of phenols and alcohol, the mixing ratio of phenols and alcohol is not particularly limited;
In order to obtain an appropriate reaction rate, the ratio of phenol to alcohol is preferably in the range of 1:1 to 5 by weight.

[0014] The amount of the catalyst added is in the range of 1 to 20 weight per 100 weight of the raw material phenol. If the amount of catalyst is less than this, a sufficient reaction rate cannot be obtained, and if it is more than this, by-products will be produced, which is not preferable.

[0015] By using this addition method and appropriate reaction temperature, unreacted alcohol is distilled out at the same time as the produced water and the ether form of the target product, making it easy to reuse it. In addition, since the raw material phenol remains in the reaction system, separation and purification of the target ether form from the raw material phenol becomes easy. Furthermore, when a mixed solution of phenols and alcohol is added, the reaction can be made continuous, improving production efficiency. After the reaction is completed, by separating the distillate by an operation such as distillation, unreacted alcohol can be easily recovered and the ether form of the target product can be obtained.

[0016] The unreacted phenols and catalyst remaining in the reactor after the completion of the reaction can be used repeatedly. Examples of the phenols used in the present invention include catechol derivatives, hydroquinone derivatives, and phenol derivatives. For example, the catechol derivative has the general formula [1]

[0017]

[C4]

(In the formula, R is a hydrogen atom or a carbon atom having 1
~4 alkyl group. ) is preferable, and more specifically, catechol and the 3- or 4-position are preferable.
Substituted methylcatechol, ethylcatechol,
n-propylcatechol, i-propylcatechol, n
-butylcatechol, i-butylcatechol, sec-
Examples include butylcatechol.

As the hydroquinone derivative, the general formula [2
]

[0020]

[C5]

(In the formula, R is a hydrogen atom or a carbon atom having 1
~4 alkyl group. ) are preferred, and more specifically, hydroquinone and methylhydroquinone substituted at the 2-position, ethylhydroquinone,
Examples include n-propylhydroquinone, i-propylhydroquinone, n-butylhydroquinone, sec-butylhydroquinone, and the like.

In addition, as a phenol derivative, the general formula [
3]

[0023]

[C6]

(In the formula, R is a hydrogen atom or a carbon number of 1
~4 alkyl group. ) are preferred, more specifically 2-methylphenol, 3-methylphenol, 4-methylphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2-ethylphenol,
-methoxyphenol, 3-methoxyphenol, 4-
Examples include methoxyphenol, 2-ethoxyphenol, 3-ethoxyphenol, 4-ethoxyphenol and the like.

However, the phenols used in the present invention are not limited to these examples. Examples of the lower alcohol used in the present invention include compounds such as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, and sec-butyl alcohol.

[0026] The catalyst used for alkyl etherification of phenols in the present invention is not particularly limited;
Compounds selected from heteropolyacids are preferred, particularly sulfuric acid as the inorganic acid, methanesulfonic acid as the aliphatic sulfonic acid, and silicotungstic acid with silicon as the central atom, silicomolybdic acid or phosphorus with the central atom as the heteropolyacid. Preferred are phosphotungstic acid, phosphomolybdic acid, etc., which are atoms.

[0027] By using these catalysts, the conversion rate of the raw material by the alkyl etherification method of the present invention can be improved, and in combination with the high selectivity by the alkyl etherification method of the present invention, an extremely high yield can be obtained. .

Further, the above catalyst can be used not only in the alkyl etherification method of the present invention but also in conventional alkyl etherification methods to improve the yield.

[0029]

EXAMPLES The present invention will be specifically explained below using examples. In addition, in the following examples, the yield and selectivity are based on phenols and are expressed in "mol%".
It is expressed as

Examples 1 to 4 A 200 ml four-necked flask was equipped with a stirrer, a thermometer, and a condenser (with a water removal device).
0g (1.0 mol) and 5.0g of the compound shown in Table 1 as a catalyst were added.

The above mixture was heated to 150° C., and a mixed solution of methanol and catechol (4/1 weight ratio) was added into the reaction system at a rate of 40 g/hr for 6 hours. This reaction solution was analyzed by gas chromatography to determine the yield of guaiacol (catechol monomethyl ether).

The results are shown in Table 1. Example 5 An experiment was conducted in the same manner as in Example 1, except that only methanol was added to the reaction system at a rate of 32 g/hr. Results first
Shown in the table.

[0033]

[Table 1]

Examples 6 to 10 Experiments were carried out in the same manner as in Example 1, except that the compounds shown in Table 2 were used as the lower alcohols. The results are shown in Table 2.

[0035]

[Table 2]

Examples 11 to 15 Experiments were carried out in the same manner as in Example 1, except that the compounds shown in Table 3 were used as catechols. However, the amount of catechols used in the reaction vessel was 1.0 mol. 3rd result
Shown in the table.

[0037]

[Table 3]

Examples 16-20 Experiments were carried out in the same manner as in Example 1, except that the compounds shown in Table 4 were used as hydroquinones. However, the amount of catechols used in the reaction vessel was 1.0 mol. The results are shown in Table 4.

[0039]

[Table 4]

Examples 21 to 24 Experiments were carried out in the same manner as in Example 1, except that the compounds shown in Table 5 were used as phenols. The results are shown in Table 5.

[0041]

[Table 5]

Comparative Example 1 5 g of sulfuric acid and 30 g of xylene were added to 110 g of catechol. Bring the temperature to 130℃ and add 32g of methanol.
The reaction was continued for 3 hours while water was removed from the system by azeotropy with xylene. As a result of gas chromatographic analysis of the reaction product, 40.1 g of guaiacol and 59.2 g of unreacted catechol were obtained. Yield 32.3%, selectivity 69.1
%Met.

[0043]

[Effects of the Invention] According to the present invention, by reacting the ether form of the product and unreacted alcohol while distilling it from the reaction system, isolation operations can be carried out without the need for a special reaction device. In addition to being able to use the catalyst and unreacted raw materials repeatedly, the selectivity to alkyl ether compounds can be improved. Furthermore, if an inorganic acid, aliphatic sulfonic acid or heteropolyacid is used as a catalyst, the conversion rate of phenols can be improved and alkyl etherified phenols can be obtained at extremely high yields.

[0044] Furthermore, the alkyl etherified product of phenol produced by the present invention is useful as a raw material for medicines, agricultural chemicals, and fragrances.

Claims (9)

[Claims] [Claim 1] In the alkyl etherification method of phenols in which phenols are etherified using a lower alcohol in the liquid phase in the presence of an acid catalyst, the alkyl etherified product produced is distilled together with unreacted alcohol and produced water. A method for alkyl etherification of phenols, which is characterized in that the reaction is carried out while reacting. 2. The method for alkyl etherification of phenol according to claim 1, wherein the reaction is carried out while simultaneously adding phenols and a lower alcohol to a system containing phenols and an acid catalyst. 3. The method for alkyl etherification of phenols according to claim 1 or 2, wherein a compound selected from the group consisting of inorganic acids, aliphatic sulfonic acids and heteropolyacids is used as the acid catalyst. 4. The method for alkyl etherification of phenols according to claim 3, wherein the acid catalyst is sulfuric acid. 5. The method for alkyl etherification of phenols according to claim 3, wherein the acid catalyst is methanesulfonic acid. 6. The method for alkyl etherification of phenols according to claim 3, wherein the acid catalyst is a heteropolytungstic acid or a heteropolymolybdic acid having a central atom of phosphorus or silicon. [Claim 7] The phenol has the general formula (1) [Chemical formula 1]
The method for alkyl etherification of phenols according to claim 1, 2 or 3, wherein the catechol derivative is a catechol derivative represented by the formula (wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms). [Claim 8] The phenol has the general formula (2) [Claim 2]
The method for alkyl etherification of phenols according to claim 1, 2 or 3, which is a hydroquinone derivative represented by the formula (wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms). [Claim 9] The phenol has the general formula (3) [Claim 3]
4. The alkyl ether of phenols according to claim 1, 2 or 3, which is a phenol derivative represented by the formula (wherein R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkyl ether group) cation law.