JPH11228473A - Production of aromatic nucleus hydrocarbyl substitution product of phenols - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aromatic nucleus hydrocarbyl substitution product of an aromatic compound from the aromatic compound having mutually independent at least one substituent group selected from hydroxyl group and a hydrocarbyl group and unsubstituted hydrogen atom on an aromatic ring and a lower alcohol according to a new unconventional method. SOLUTION: An aromatic compound is reacted with a lower alcohol under conditions for keeping the aromatic compound and/or the lower alcohol under supercritical states in a method for producing a hydrocarbyl substitution product of the aromatic compound from the aromatic compound having mutually independent at least one substituent group selected from hydroxyl group and a hydrocarbyl group and unsubstituted hydrogen atom on an aromatic ring and the lower alcohol by substituting the unsubstituted hydrogen atom on the aromatic ring of the aromatic compound with the hydrocarbyl group of the lower alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aromatic compound having at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other, and having an unsubstituted hydrogen atom ( Below, "phenols"
There is that. )). More specifically, the present invention comprises reacting an aromatic compound having at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other and having an unsubstituted hydrogen atom with a lower alcohol. And a hydrocarbyl substituent in which an unsubstituted hydrogen atom on the aromatic ring of the aromatic compound is substituted with a hydrocarbyl group of a lower alcohol (hereinafter, sometimes referred to as an "aromatic-nuclear hydrocarbyl-substituted phenol").
And a method for producing the same.

[0002]

2. Description of the Related Art Aromatic compounds having at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other and having an unsubstituted hydrogen atom are known as pharmaceuticals, agricultural chemicals and dyes. It is an indispensable organic compound widely used as a synthetic polymer and other synthetic raw materials or products. Among them, especially polyhydric phenols having an aromatic ring hydrocarbylated, for example, t-butylhydroquinone and its ether derivatives are added to foods and various materials as antioxidants and used widely.

Heretofore, such aromatic-hydrocarbyl-substituted phenols have been produced by various methods. In the production of t-butyl hydroquinone and its ether derivative, for example, a method is disclosed in which hydroquinone is reacted with isobutylene or t-butyl alcohol in a gaseous phase or a liquid phase in the presence of various catalysts as disclosed in Japanese Patent Application Laid-Open No. H8 (1996).
-176044. On the other hand, in the production of methylhydroquinone, a method of reacting phenol with a ketone peroxide in the presence of various catalysts (Japanese Patent Application Laid-Open No. 52-78843), or a method in which o-cresol is converted to an inorganic acid such as alcohols or phenols A method of reacting with hydrogen peroxide in the presence of an ester or a salt thereof (JP-A-3-34947), a method of reacting o-cresol with hydrogen peroxide in the presence of a bisulfite adduct of aldehyde or ketone (Japanese Patent Application Laid-Open No. 3-34948) is known.

[0004]

The above-mentioned known method is as follows.
Usually, a catalyst is required, and a step of removing the catalyst is required, so that there is a problem that the step is complicated. Further, the method using peroxide generally requires unstable control of reaction conditions and complicated equipment in order to carry out the reaction selectively and safely, since peroxide is generally unstable.

On the other hand, as an organic reaction using a lower alcohol in a supercritical state, for example, an esterification reaction of an organic carboxylic acid is known (German Patent No. 118684).
No. 5 specification). However, there is no known method for producing an aromatic nucleus hydrocarbyl-substituted phenol using a lower alcohol in a supercritical state.

An object of the present invention is to provide a method for producing an aromatic nucleus hydrocarbyl-substituted phenol from a phenol and a lower alcohol by an unprecedented new method.

[0007]

Means for Solving the Problems In view of the above circumstances, the present inventors have at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other, and Intensive research on a method for producing a hydrocarbyl-substituted aromatic compound from an aromatic compound having a non-hydrogen atom and a lower alcohol, and found that the above known method can be solved by using a supercritical state. Thus, the present invention has been completed.
That is, the present invention provides an aromatic compound having, on an aromatic ring, at least one substituent selected from a hydroxyl group and a hydrocarboxy group independently of each other, and having an unsubstituted hydrogen atom, and a lower alcohol. A method for producing a hydrocarbyl-substituted aromatic compound by substituting an unsubstituted hydrogen atom on the aromatic ring of an aromatic compound with a hydrocarbyl group of a lower alcohol, wherein the aromatic compound and / or lower alcohol is supercritical The present invention relates to a method for producing a hydrocarbyl-substituted aromatic compound [hereinafter referred to as the production method (1) of the present invention] to be reacted under the condition of becoming a state.

Further, the present invention provides an aromatic compound having at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other and having an unsubstituted hydrogen atom, A method for producing a hydrocarbyl-substituted aromatic compound from an alcohol by substituting an unsubstituted hydrogen atom on the aromatic ring of the aromatic compound with a hydrocarbyl group of a lower alcohol in the presence of an inert medium. The present invention relates to a method for producing a hydrocarbyl-substituted aromatic compound (hereinafter referred to as the production method (2) of the present invention) in which at least one of an aromatic compound, a lower alcohol and an inert medium is reacted under supercritical conditions. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, an aromatic compound having at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring independently of each other and having an unsubstituted hydrogen atom is used as one of the starting materials.

As the aromatic ring, a benzene ring, a condensed benzene ring such as a naphthalene ring, an anthracene ring, a pyrene ring, a pyridine ring, a furan ring, a pyrrole ring,
Examples of heteroaromatic rings such as a benzofuran ring, an indole ring, a carbazole ring, a quinoline ring, a benzimidazole ring, and a quinoxaline ring include a benzene ring, a naphthalene ring,
An anthracene ring is preferred, and a benzene ring is more preferred.

Examples of the hydrocarboxy group include an alkoxy group, an aryloxy group, an aralkyloxy group, an alkenyloxy group and an alkynyloxy group.

The alkoxy group includes methoxy, ethoxy, propyloxy, isopropyloxy, n-
Butoxy group, isobutoxy group, t-butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, desyloxy group, and the like, and a methoxy group, an ethoxy group, a propoxy group, an isopropyloxy group, an n-butoxy group, Isobutoxy and t-butoxy are preferred, and methoxy and ethoxy are more preferred.

The aryloxy group includes, for example, a phenoxy group. Examples of the aralkyloxy group include a benzyloxy group and a p-methylbenzyloxy group, and a benzyloxy group is preferable. Examples of the alkenyloxy group include an allyloxy group. Examples of the alkynyl group include an ethynyloxy group.

The phenol may have another hydrocarbyl group on the aromatic ring as long as it has an unsubstituted hydrogen atom on the aromatic ring.

The hydrocarbyl group includes an alkyl group,
Examples include an aryl group, an aralkyl group, an alkenyl group, and an alkynyl group.

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group and a decyl group. Illustrative are methyl, ethyl, propyl, isopropyl, n-
Butyl, isobutyl and t-butyl are preferred. As the aralkyl group, a benzyl group, an α-phenethyl group,
Examples thereof include a β-phenethyl group, and a benzyl group is preferable. Examples of the aryl group include a phenyl group and a naphthyl group, and a phenyl group is preferable. Examples of the alkenyl group include an allyl group. Examples of the alkynyl group include an ethynyl group.

As the phenols, those having two or more hydroxyl groups or hydrocarboxy groups independently of each other are preferred. Such compounds include, for example, hydroquinone and p-hydrocarboxyphenol.
Specific examples of p-hydrocarboxyphenol include:
p-methoxyphenol, p-ethoxyphenol and the like.

The lower alcohol, which is another starting material used in the present invention, may be monovalent or divalent or higher. The monohydric lower alcohol of the present invention has the general formula

Embedded image R—OH (1) (R represents a hydrocarbyl group having 1 to 10 carbon atoms.)
Is a lower alcohol represented by In the present invention,
Replacing an unsubstituted hydrogen atom on the aromatic ring of the phenol with a hydrocarbyl group (R) of a lower alcohol,
An aromatic nucleus hydrocarbyl substituent of the desired phenol is formed.

Examples of R include an alkyl group, an aralkyl group, an alkenyl group and an alkynyl group.

The lower alcohols in which R is an alkyl group include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t
-Butanol, pentanol, hexanol, cyclohexanol, heptanol and the like. Among them, those having 1 to 5 carbon atoms are preferable, and specifically, methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, t-butanol, and pentanol are preferable, and methanol and ethanol are more preferable. And more preferably methanol.

Examples of the lower alcohol in which R is an aralkyl group include benzyl alcohol, α-phenethyl alcohol and β-phenethyl alcohol, with benzyl alcohol being preferred.

Examples of the lower alcohol in which R is an alkenyl group include allyl alcohol, 1-methylallyl alcohol, 2-methylallyl alcohol, 3-buten-1-ol, 3-buten-2-ol and the like. Illustrated, allyl alcohol is preferred.

The lower alcohol in which R is an alkynyl group includes 2-propyn-1-ol and 2-butyn-1-ol.
Examples thereof include allyl, 3-butyn-1-ol, and 3-butyn-2-ol.

The dihydric lower alcohols include, for example, ethylene glycol, propylene glycol,
1,3-propanediol and the like.

The molar ratio of the lower alcohol to the phenol is appropriately determined depending on the compound used, but is generally from 2 to 500, and preferably from 2 to 100.

This reaction can be carried out in the presence of an inert medium. The inert medium is a substance that does not react with phenols and lower alcohols under the conditions for reacting phenols with lower alcohols. Examples of the inert medium include, for example, carbon dioxide, argon, methane and the like, and carbon dioxide is preferred.

The mixing ratio of the lower alcohol and the inert medium is not particularly limited, but is determined in consideration of the solubility of the phenol used in the reaction in the lower alcohol. For example,
When the lower alcohol is a mixture of methanol and carbon dioxide, the mixing ratio of methanol and carbon dioxide is preferably from 10:90 to 90:10.

The present invention is characterized in that the reaction is carried out under the condition of becoming a supercritical state. Here, the supercritical state referred to in the present invention means the following state. A substance has three distinct states of gas, liquid, and solid, and further, has a fluid phase that does not condense even when pressure is applied when the critical temperature is exceeded and the critical pressure is exceeded. This state is called a supercritical state. Fluids in such a state exhibit properties different from the normal properties of liquids and gases. A supercritical fluid has a density close to that of a liquid, a viscosity close to that of a gas, and a thermal conductivity and a diffusion coefficient that are intermediate properties between a gas and a liquid. Therefore, mass transfer is advantageous, and high heat transfer can be obtained due to high heat transfer.

Next, the reaction of the present invention will be described specifically. Although the upper limit of the reaction temperature is not limited, it is preferably 380 ° C. or lower so that phenols are not decomposed. Although the upper limit of the reaction pressure is not limited, it is preferable that the reaction pressure is 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 the phenols and / or lower alcohols become supercritical. "Conditions under which phenols and / or lower alcohols become supercritical"
The condition includes the following conditions (a) to (c). (A) Temperature and pressure conditions under which a mixture of a phenol and a lower alcohol becomes a supercritical state. (B) Temperature and pressure conditions at which the lower alcohol becomes supercritical. (C) Temperature and pressure conditions under which phenols become supercritical. Of the above, the reaction is preferably performed under the condition (a) or (b), and more preferably the reaction is performed under the condition (a).

The case where methanol is used as the lower alcohol and hydroquinone is used as the phenol will be specifically described. Methanol enters a supercritical state when the pressure exceeds 8.0 MPa and the temperature exceeds 240 ° C. On the other hand, hydroquinone enters a supercritical state when the pressure exceeds 7.45 MPa and the temperature exceeds 549 ° C. In this case, in order to produce an aromatic nucleus hydrocarbyl-substituted hydroquinone, it is necessary to carry out the reaction at a pressure higher than 8.0 MPa and a temperature higher than 240 ° C., when the pressure exceeds 15 MPa and the temperature is higher than 15 MPa. It is preferable to carry out the reaction in a range exceeding 250 ° C.

The temperature is preferably 380 ° C. or less. If the temperature is higher than this, the phenols are decomposed and the yield decreases. The pressure is preferably 25 MPa or less. If the pressure is higher than this, it is not preferable because the cost is increased in order to increase the pressure resistance of the reactor.

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 an inert medium under a condition in which at least one of a phenol, a lower alcohol and an inert medium becomes a supercritical state. "Conditions under which at least one of phenols, lower alcohols or an inert medium becomes a supercritical state" includes the following conditions (d) to (j). (D) Temperature and pressure conditions under which the mixture of phenols, lower alcohols, and inert media becomes supercritical. (E) Temperature and pressure conditions under which the lower alcohol and / or the inert medium become supercritical. (F) Temperature and pressure conditions under which the phenols and / or the inert medium become supercritical. (G) Temperature and pressure conditions under which phenols and / or lower alcohols become supercritical. (H) Temperature and pressure conditions at which the lower alcohol becomes a supercritical state. (I) Temperature and pressure conditions under which the inert medium becomes supercritical. (J) Temperature and pressure conditions under which the phenols become supercritical. The terms "and / or" in (d)-(e) are used in the same meaning as in the above-mentioned "conditions under which phenols and / or lower alcohols become supercritical". Of the above, the reaction is preferably performed under the condition (d) or (e), and more preferably the reaction is performed under the condition (d).

The case where methanol is used as the lower alcohol, carbon dioxide is used as the inert medium, and hydroquinone is used as the phenol will be specifically described. Carbon dioxide enters a supercritical state when the pressure exceeds 7.4 MPa and the temperature exceeds 31 ° C. In this case, the production of an aromatic nucleus hydrocarbyl-substituted hydroquinone requires that the reaction be carried out under conditions that exceed the critical temperature of carbon dioxide and exceed the critical pressure. It is preferable to carry out the reaction within the range of temperature and pressure at which the state is reached. For example, in the case of a mixture of methanol and carbon dioxide at a molar ratio of 75:25, the literature (AD Leu,
SYK Chung and DB Robinson, J. Che
m. Thermodynamics, 1991, 23, 979)
According to the critical temperature of the mixture is 204 ° C. and the critical pressure is 12.75 MPa. When the aromatic hydrocarbon hydrocarbyl-substituted hydroquinone is produced at a temperature and pressure at which the mixture of the lower alcohol and the inert medium becomes a supercritical state, the conditions under which the exemplified mixture is brought into the supercritical state, that is, the pressure is 12. Exceeds 75 MPa and temperature is 204
It is preferable to carry out the reaction at a temperature exceeding 15 ° C.
More preferably, the reaction is carried out under a condition exceeding a and at a temperature exceeding 250 ° C.

In the present invention, a catalyst can be used, if necessary, for the purpose of further promoting the reaction. However, when a catalyst is used, the steps are complicated because a step for removing the catalyst is required. There is a problem that. Here, any catalyst may be used as long as it generally promotes hydrocarbylation.Examples include acid catalysts such as phosphoric acid, sulfuric acid, and sulfonic acid, ion exchange resins having a strongly acidic substituent introduced into the resin, and alumina. And solid catalysts such as magnesium oxide.

The reaction can be carried out in various reaction modes. For example, it may be performed in a batch system or a distribution system.

[0037]

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 amounts of the reactants and products in the examples were determined by the area percentage method based on the total ion amount of each substance detected using a gas chromatography mass spectrometer (manufactured by Shimadzu Corporation).

Example 1 0.103 g of hydroquinone and 5.119 g of methanol were charged into an autoclave (manufactured by SUS316, internal volume: 20 ml, pressure system included), and the air in the autoclave was replaced with argon gas. The temperature was raised to 350 ° C. to start the reaction. The pressure during the reaction was 12 MPa. After 2 hours, the reaction vessel was rapidly cooled, and after returning to room temperature, the reaction solution was taken out of the reaction vessel. As determined by the above method, the conversion of hydroquinone was 35 mol% and 2
The selectivity for -methylhydroquinone was 43 mol%.

Example 2 0.115 g of hydroquinone and 5.869 g of ethanol were charged into an autoclave (manufactured by SUS316, internal volume: 20 ml, pressure system included), and the air in the autoclave was replaced with argon gas. The temperature was raised to 350 ° C. to start the reaction. The pressure during the reaction was 13 MPa. After 2 hours, the reaction vessel was rapidly cooled, and after returning to room temperature, the reaction solution was taken out of the reaction vessel. As determined by the above method, the conversion of hydroquinone was 20 mol%,
The selectivity for -ethylhydroquinone was 98 mol%.

Example 3 0.115 g of p-methoxyphenol and methanol5.
364 g of autoclave (made of sus316, internal volume 20 ml,
After the air in the autoclave was replaced with argon gas, 35 g of the fluidized bed was heated in a sand bath.
The temperature was raised to 0 ° C. to start the reaction. Reaction pressure is 16M
Pa. After 2 hours, the reaction vessel was rapidly cooled, and after returning to room temperature, the reaction solution was taken out of the reaction vessel. As determined by the above method, the conversion of p-methoxyphenol was 14 mol%, and the selectivity for the aromatic nucleus methyl-substituted p-methoxyphenol was 21 mol%.

[0041]

According to the method of the present invention, an aromatic nucleus hydrocarbyl-substituted phenol can be produced from a phenol and a lower alcohol by a new method which has not been used before.

Continued on the front page (72) Inventor Akihiko Okada 6 Kitahara, Tsukuba, Ibaraki Pref. Within Sumitomo Chemical Co., Ltd. (72) Inventor Takeshi 1-1-1 Higashi, Tsukuba, Ibaraki Pref.

Claims (8)

[Claims] (1) at least one substituent selected from a hydroxyl group and a hydrocarboxy group on an aromatic ring, independently of each other;
An aromatic compound having an unsubstituted hydrogen atom and a lower alcohol, wherein the unsubstituted hydrogen atom on the aromatic ring of the aromatic compound is substituted with a hydrocarbyl group of the lower alcohol to form the aromatic compound. A method for producing a hydrocarbyl-substituted compound, which comprises reacting the aromatic compound and / or lower alcohol under a supercritical condition. 2. A method according to claim 1, wherein a substituent selected from a hydroxyl group and a hydrocarboxyl group is independently present on the aromatic ring.
An aromatic compound having an unsubstituted hydrogen atom and a lower alcohol, wherein the unsubstituted hydrogen atom on the aromatic ring of the aromatic compound is substituted with a hydrocarbyl group of the lower alcohol to form the aromatic compound. A method for producing a hydrocarbyl-substituted compound in the presence of an inert medium, wherein the aromatic compound, lower alcohol or inert medium is reacted under supercritical conditions. A method for producing a hydrocarbyl-substituted compound of a group III compound. 3. The method according to claim 2, wherein the reaction is carried out under a condition in which the lower alcohol and / or the inert medium become supercritical. 4. The method according to claim 2, wherein the inert medium is carbon dioxide. 5. The method according to claim 1, wherein an aromatic compound having two or more hydroxyl groups or hydrocarboxy groups on the aromatic ring independently of each other is used. 6. The production method according to claim 5, wherein the aromatic compound having two or more hydroxyl groups or hydrocarboxy groups independently on the aromatic ring is hydroquinone. 7. An aromatic compound having two or more hydroxyl groups or hydrocarboxy groups on an aromatic ring independently of each other is p
The production method according to claim 5, which is -hydrocarboxyphenol. 8. The method according to claim 1, wherein the lower alcohol is methanol or ethanol.