JP2002003426A - Method for producing 2,5-xylenol and 2,3,6-trimethylphenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing 2,5-xylenol and/or 2,3,6- trimethylphenol in a state in which methanol is not vapor phase from m-cresol and methanol. SOLUTION: This method for producing 2,5-xylenol and/or 2,3,6- trimethylphenol comprises reacting m-cresol with methanol in the presence of one or more catalysts selected from a group consisting of a hydroxide of an alkali metal, a hydroxide of an alkaline earth metal, a methlyte of an alkali metal and a methylate of an alkaline earth metal in a supercritical state of the methanol. Alternatively, the method comprises reacting m-cresol with methanol in the presence of one or more catalysts selected from a group consisting of a hydroxide of an alkali metal, a hydroxide of an alkaline earth metal, a methylate of an alkali metal and a methylate of an alkaline earth metal and further in the presence of carbon dioxide in a supercritical state of a mixture of the methanol with carbon dioxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing 2,5-xylenol and / or 2,3,6-trimethylphenol.

[0002]

2. Description of the Related Art 2,5-xylenol is in great demand as a basic raw material for dyes, agricultural chemicals and the like. Also, 2, 3, 6
Trimethylphenol is in great demand as a synthetic intermediate of trimethylhydroquinone, which is a raw material for vitamin E. Conventionally, as a method for producing 2,5-xylenol or 2,3,6-trimethylphenol by reacting m-cresol with methanol, a method for producing methanol in a gaseous phase is known. However, a production method in which methanol reacts in a gaseous state requires a reaction vessel having a large volume or a complicated apparatus for continuously performing a reaction, and a method for producing methanol in a non-gas state is required. Was sought. JP-A-6-116189 discloses that a catalyst in which iron oxide and vanadium oxide are supported on silica, and m-cresol and methanol are used to prepare 2,3,
A method for producing 6-trimethylphenol is shown. Japanese Patent Application Laid-Open No. 50-71636 discloses a method for producing 2,5-xylenol from m-cresol and methanol using a catalyst containing iron oxide and zinc oxide as main components. However, these are production methods in which methanol is reacted in a gaseous state.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an m-
From cresol and methanol, 2,5-xylenol and / or 2,3,6
-To provide a method for producing trimethylphenol.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have developed 2,5-xylenol and / or 2,5-xylenol.
Continued intensive research on the method for producing 3,6-trimethylphenol, and one or more of the group selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal methylates and alkaline earth metal methylates. The inventors have found that the above problem can be solved by reacting methanol in a supercritical state in the presence of a catalyst, and have completed the present invention.

That is, the present invention provides the following [1] or
Provide [2]. [1] Presence of one or more catalysts of m-cresol and methanol selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal methylates and alkaline earth metal methylates A method for producing 2,5-xylenol and / or 2,3,6-trimethylphenol, wherein methanol is reacted under supercritical conditions under the following conditions.
It is written.] [2] The presence of at least one catalyst selected from the group consisting of m-cresol and methanol, selected from alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal methylates and alkaline earth metal methylates Characterized by reacting the mixture of methanol and carbon dioxide in a supercritical state in the presence of carbon dioxide in the presence of carbon dioxide, under the condition that the mixture becomes a supercritical state. 2,5-xylenol and / or 2,3,6-trimethylphenol Method [Hereinafter, the production method (2) of the present invention]
It is written.]

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The present invention is characterized in that the reaction is carried out under the condition that methanol is in a supercritical state. Here, the supercritical state in the present invention means the following state. Substances have three distinctive states: gas, liquid, and solid. Further, when the temperature exceeds the critical temperature and critical pressure, there is a fluid phase that does not condense even when pressure is applied. This state is called a supercritical state. Fluids in the supercritical state exhibit properties that are different from the normal properties of liquids and gases. The density of a supercritical fluid is close to that of a liquid,
Viscosity is close to that of gas, and thermal conductivity and diffusion coefficient are "non-liquid solvents" that show intermediate properties between gas and liquid. Low viscosity, high diffusivity favor mass transfer, and high viscosity. High thermal mobility can be obtained due to conductivity.

The supercritical fluid exhibits higher reactivity than the liquid phase reaction using a usual solvent due to the above-mentioned properties. Since the density of the supercritical fluid is smaller than that of the gas, the target product can be manufactured in a small plant.

In the production method (1) or (2) of the present invention,
The molar ratio of methanol to m-cresol is generally from 1 to 1000, and preferably from 1 to 200. The upper limit of the reaction temperature is not limited, but is preferably 500 ° C. or lower so that m-cresol is not decomposed. Although the upper limit of the reaction pressure is not limited, it is preferable to be 25 MPa or less because the cost is required to increase the pressure resistance of the reactor.

In the production method (1) of the present invention, it is necessary to carry out the reaction under the condition that methanol becomes a supercritical state. Methanol has a critical temperature of 240 ° C and a critical pressure of 8
Since the pressure is MPa, the reaction is performed under the conditions of 240 ° C. or more and 8 MPa or more.

Next, the production method (2) of the present invention will be described. In the production method (2) of the present invention, it is necessary to carry out the reaction in the presence of carbon dioxide under conditions where the mixture of methanol and carbon dioxide is brought into a supercritical state.

The mixing ratio of methanol and carbon dioxide is not particularly limited, but the mixing ratio of methanol and carbon dioxide is preferably from 10:90 to 90:10 in consideration of the solubility of m-cresol used in the reaction in methanol.

The molar ratio of methanol to carbon dioxide is 75:
In the case of a mixture of 25, the literature (Journal of Chemical Thermodynamics [J. Chem. Therm]
Odynamics), Vol. 23, p. 970 (199)
1 year)], the critical temperature of the mixture is 204
° C, critical pressure is 12.75 MPa. When 2,5-xylenol and 2,3,6-trimethylphenol are produced under a temperature and pressure condition at which a mixture of methanol and carbon dioxide becomes a supercritical state, the temperature and pressure at which the exemplified mixture becomes a supercritical state Conditions, temperature 204 ° C
Above, it is necessary to carry out at a pressure of 12.75 MPa or more, and it is preferable to carry out at a temperature of 240 ° C. or more and a pressure of 12.75 MPa or more.

In the production method (1) or (2) of the present invention,
The reaction time is appropriately determined depending on various conditions such as temperature and pressure, but is preferably in the range of 1 minute to 24 hours.

In the present invention, a catalyst is used for the purpose of accelerating the reaction. As the catalyst, at least one selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal methylate and an alkaline earth metal methylate is used. That is, these catalysts may be used alone, or a plurality of catalysts may be used in combination. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Examples of the alkaline earth metal hydroxide include magnesium hydroxide and hydroxide. Calcium, strontium hydroxide, barium hydroxide and the like. Examples of the alkali metal methylate include lithium methylate, sodium methylate, potassium methylate and the like, and examples of the alkaline earth metal methylate include magnesium methylate and calcium methylate.

Both the reactions of the production methods (1) and (2) of the present invention can be carried out in multiple stages. That is, 2,5-xylenol is produced from m-cresol in the first reaction, and 2,3,6-trimethylphenol is produced in the second reaction. The catalysts used in the first and second stage reactions may be the same catalyst or different catalysts.

In the present invention, the amount of the catalyst to be added is not limited and is determined by the reaction mode and reaction conditions. In particular, when the reaction is performed in a batch-type reaction apparatus, the amount of the catalyst added is 0.01 to 20% by mass based on m-cresol used in the reaction.
And more preferably in the range of 0.05 to 2% by mass.

In each of the processes (1) and (2) of the present invention, a plurality of compounds may be produced in addition to 2,5-xylenol and 2,3,6-trimethylphenol. Separation of these compounds is not particularly limited, and general methods such as liquid chromatography, distillation, and extraction can be applied depending on the nature of the product.

The processes (1) and (2) of the present invention can be carried out in various reaction modes such as a batch system and a flow system, but are preferably carried out in a batch system.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The reactants and products in the examples were identified using a gas chromatography mass spectrometer HP-6890 (GC; manufactured by Yokogawa Electric) -HP5973 (MS; manufactured by Yokogawa Electric), and FID (hydrogen flame ionization detector) was used. Quantitative analysis was performed using the attached gas chromatography device GC-353B (manufactured by GL Sciences). The conversion and selectivity in the examples were calculated by the following methods.
The conversion was determined by measuring the standard substance of m-cresol to determine the relationship between the area of the gas chromatograph and the amount of the sample. (Conversion) = ｛1− (m− remaining unreacted in the reaction solution)
Cresol amount) / (m-cresol amount used in reaction)｝
It was calculated using the formula of × 100 (mol%). The selectivity is assumed to be equal to the area of the gas chromatograph per mole of each reaction product, and (selectivity) = ｛(the area of the gas chromatograph of the reaction product to be calculated) / (total excluding m-cresol) The sum was calculated using the following equation: Sum of areas of gas chromatographs of reaction products) グ ラ フ × 100 (mol%).

Example 1 0.035 g of m-cresol and 1.358 of methanol
g and 0.33 mg of lithium hydroxide in an autoclave (S
US316, internal volume 4.5ml), 3 by sand bath
The temperature was raised to 70 ° C. to start the reaction. After 15 minutes, the autoclave was rapidly cooled, and after returning to room temperature (about 25 ° C.), the reaction solution was taken out. As determined by the above method, the conversion of m-cresol was 64 mol%, the selectivity of 2,5-xylenol was 51 mol%, and the selectivity of 2,3,6-trimethylphenol was 11 mol%. Was. Besides these products, the selectivity for 2,3-xylenol is 17 mol%,
The selectivity of 3,4-xylenol is 5 mol%, the selectivity of m-methylanisole is 1 mol%, the total selectivity of trimethylphenol other than 2,3,6-trimethylphenol is 4 mol%, 2,3 , 4,6-tetramethylphenol selectivity was 1 mol%. The reaction solution was separated into components using liquid chromatography, and 2,5
-Xylenol and 2,3,6-trimethylphenol were fractionated. The fraction was analyzed using a gas chromatography mass spectrometer, and it was confirmed that 2,5-xylenol and 2,3,6-trimethylphenol could be separated from the product. Since the autoclave was not provided with a pressure gauge, the following experiment was performed to estimate the pressure during the reaction. That is, a pressure gauge was attached to the same autoclave, equal amounts of m-cresol and methanol were charged, the temperature was raised to 370 ° C. in a sand bath, and the pressure was measured. Estimated pressure during reaction is 10MP
a.

Example 2 0.034 g of m-cresol and 1.379 of methanol
g and 0.51 mg of lithium hydroxide in an autoclave (S
US316, internal volume 4.5ml), 3 by sand bath
The temperature was raised to 70 ° C. to start the reaction. After 30 minutes, the autoclave was rapidly cooled, and after returning to room temperature, the reaction solution was taken out.
As determined by the above method, the conversion of m-cresol was 95 mol%, the selectivity of 2,5-xylenol was 30 mol%, and the selectivity of 2,3,6-trimethylphenol was 38 mol%. Was. In addition to these products,
Selectivity of 3-xylenol is 5 mol%, selectivity of 3,4-xylenol is 2 mol%, selectivity of m-methylanisole is 1 mol%, selection of trimethylphenol other than 2,3,6-trimethylphenol Total of 9 mol%,
The selectivity of 2,3,4,6-tetramethylphenol is 8
Mole%. Since the autoclave was not provided with a pressure gauge, the following experiment was performed to estimate the pressure during the reaction. That is, a pressure gauge was attached to the same autoclave, equal amounts of m-cresol and methanol were charged, the temperature was raised to 370 ° C. in a sand bath, and the pressure was measured. The estimated value of the pressure during the reaction was 10 MPa.

Example 3 0.055 g of m-cresol and 2.275 of methanol
g and sodium hydroxide 0.2 mg in an autoclave (S
US316, internal volume 4.5ml), 3 by sand bath
The temperature was raised to 50 ° C. to start the reaction. After 2 hours, the autoclave was rapidly cooled, and after returning to room temperature, the reaction solution was taken out.
As determined by the above method, the conversion of m-cresol was 82 mol%, the selectivity of 2,5-xylenol was 25 mol%, and the selectivity of 2,3,6-trimethylphenol was 8 mol%. Was. In addition to these products,
-Selectivity of xylenol is 7 mol%, selectivity of 3,4-xylenol is 10 mol%, selectivity of m-methylanisole is 5 mol%, selectivity of trimethylphenol other than 2,3,6-trimethylphenol Was 14 mol%, and the selectivity for 2,3,4,6-tetramethylphenol was 3 mol%. Since the autoclave is not equipped with a pressure gauge, to estimate the pressure during the reaction,
The following experiment was performed. That is, a pressure gauge was attached to the same autoclave, equal amounts of m-cresol and methanol were charged, the temperature was raised to 370 ° C. in a sand bath, and the pressure was measured. The estimated value of the pressure during the reaction was 20 MPa.

[0023]

According to the method of the present invention, m-cresol and methanol are used in a state where methanol is not in a gaseous phase.
Since 5-xylenol and / or 2,3,6-trimethylphenol can be produced, 2,5-xylenol and / or 2,3,6
-Trimethylphenol can be produced.

Claims (2)

[Claims] 1. A catalyst comprising m-cresol and methanol selected from the group consisting of hydroxides of alkali metals, hydroxides of alkaline earth metals, methylates of alkali metals and methylates of alkaline earth metals. Characterized in that methanol is reacted under supercritical conditions in the presence of 2,5-xylenol and / or 2,3,6
-A process for producing trimethylphenol. 2. A catalyst comprising at least one of m-cresol and methanol selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal methylates and alkaline earth metal methylates. Characterized in that the reaction is carried out in the presence of a mixture of methanol and carbon dioxide in a supercritical state in the presence of carbon dioxide, wherein 2,5-xylenol and / or 2,3,6-
A method for producing trimethylphenol.