JPH01207253A - Production of 2,4-dichloro-3-methylphenol - Google Patents

Abstract

PURPOSE:To advantageously obtain the title compound useful as a raw material for agricultural chemicals or photographic agents, by subjecting 2,4-dichloro-3- methyl-6-tertiary butylphenol as a raw material with an alkylbenzene to rearrangement reaction in the presence of a specific catalyst. CONSTITUTION:2,4-Dichloro-3-methyl-6-tertiary butylphenol is used as a raw material and subjected to rearrangement reaction with an alkylbenzene in the presence of an aluminum halide or a complex of the alkylbenzene and the aluminum halide as a catalyst to give the aimed compound. The amount of the alkylbenzene used is preferably about 1-10mols based on 1mol of the raw material and the amount of the catalyst used is preferably 0.05-0.7mol based on 1mol of the raw material. The raw material is synthesized by chlorinating 3-methyl-6-tertiary butylphenol or 3-methyl-4,6-ditertiary butylphenol.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing 2,4-dichloro-3-methylphenol. More specifically, 3-methyl-6-tert-butylphenol or 3-methyl-
Using 4,6-ditertiarybutylphenol as a raw material,
Through 2.4-dichloro-3-methyl-6-tert-butylphenol, the desired 2,
The present invention relates to an improvement in a method for producing 4-dichloro-3-methylphenol.

2,4-dichloro-3- obtained by the method of the present invention
Methylphenol is useful as a raw material for agricultural chemicals, photographic agents, and the like.

<Prior art and its problems> Conventionally, 2,4-dichloro-3-methylphenol has been synthesized using 2.3
．． 6-) 2,4-dichloro-3-methylphenol has been obtained by the reaction of dichlorotoluene and methanol, but the yield is low and it is industrially disadvantageous as it requires the use of a large amount of caustic soda. .

Also, J, ^m, Chem, Sac 57.2176
(1935) sulfonated m-cresol, then chlorinated it with chlorine gas in a nitrobenzene solvent, and then hydrolyzed the sulfone group to form 2-chloro-3-
Methylphenol, 2. A method for obtaining 2,4-dichloro-3-methylphenol together with isomers such as 6-cyclo-3-methylphenol has been described, but the industrial implementation of this method requires the cumbersome processes of sulfonation and hydrolysis. In addition, the isomers must be separated, which is a difficult problem.

Furthermore, in Japanese Patent Publication No. 61-60056, 3-methyl-
Using 6-tert-butylphenol as a starting material, it is chlorinated to synthesize 2,4-dichloro-3-methyl-6-tert-butylphenol, and then detertiary-butylated to yield 2,4-dichloro-3-methylphenol. It has gained.

<Problem to be solved by the invention> However, the above-mentioned Japanese Patent Publication No. 61-60 by the present inventors
According to the results of follow-up tests and studies in Publication No. 056, the chlorination reaction is preferably carried out at as low a temperature as possible in order to suppress the by-product of trichloride. Since the melting point of the reaction mixture is as high as about 21° C., when carried out without a solvent, the cooling temperature on the jacket side is limited, making it difficult to remove the reaction heat, resulting in an extremely long reaction time, and causing problems in production efficiency, etc. Further, the use of organic solvents such as chloroform and carbon tetrachloride, which are normally used in chlorination reactions, is not preferable because it causes health and safety problems, environmental problems, and the like.

Furthermore, in the detertiary butylation reaction, the reaction temperature is 20
A high temperature of 0°C or higher is required, and therefore the equipment used must be large-scale.At the same time, there are restrictions in that high-quality materials must be used, and the detertiary butylation reaction 2,4-Dichloro-3-methylphenol undergoes a dechlorination reaction within the reaction system, resulting in monochloro-3-methylphenol such as 4-chloro-5-methylphenol.
3-Methylphenol is produced as a by-product. This not only reduces the content and yield of the target compound, 62.4-'; chloro-3-methylphenol, but also reduces the possibility that these monochloro compounds will be used in the next step in the synthesis of agricultural chemicals or photographic agents. , cannot be used as is.

On the other hand, even if attempts were made to separate these monochloro compounds, it was found that there were problems such as the fact that their boiling points were close to that of the target product, making it extremely difficult to separate them.

Further, since it is difficult to slowly control the detertiary butylation reaction, a large amount of isobutylene gas is generated in the detertiary butylation reaction. Therefore, it cannot be said to be satisfactory in industrial implementation, as it requires large-scale equipment for detoxification and the like.

On the other hand, 0RGANIC PREPARATIONS A
ND PROCED[lR[:5IN7.6 (3)
107-115 (1974), a method of transalkylation using benzene as an acceptor is reported.

According to this document, 2,4-dichloro-3-methyl-6
-2.4-dichloro-2.4-dichloro- 3-methylphenol is obtained. According to this document, not only is the yield low, but also a large amount of benzene must be used, and post-reaction post-treatment is extremely difficult due to the use of a large amount of aluminum chloride. There are various problems in manufacturing.

In view of the above circumstances, the present inventors have determined that 2,4-dichlor-3
Using methyl-6-tert-butylphenol or its precursor 3-methyl-6-tert-butylphenol or 3-methyl-4,6-diter-butylphenol as a starting material, the desired 2,4- The present invention has been completed as a result of extensive research and study into a method for selectively producing dichloro-3-methylphenol.

Specific Means for Solving the Problems> The present invention provides 2,4- 2, 4 characterized in that the rearrangement reaction between dichloro-3-methyl-6-tert-butylphenol and alkylbenzene is carried out in the presence of an aluminum halide or a complex of alkylbenzene and aluminum halide as a catalyst.
- A method for producing dichloro-3-methylphenol.

The method of the present invention will be explained in detail below.

In the method of the invention, the synthesis of 2,4-dichloro-3-methyl-6-tert-butylphenol can be carried out, for example, by chlorinating 3-methyl-6-tert-butylphenol or alternatively by chlorinating 3-methyl-4-tert-butylphenol. , 6-ditertyabutylphenol with chlorine, preferably in the presence of a catalyst.

As a result of extensive studies, the present inventors have found that in this chlorination reaction, when alkylbenzene is allowed to coexist in the reaction system, the reaction system becomes in a favorable state and is excellent as an industrial production method.

The amount of alkylbenzene used to coexist in the chlorination reaction is 0.01 to 5 times by weight, preferably 0.01 to 5 times the weight of 3-methyl-6-tert-butylphenol or 3-methyl-4,6-di-tert-butylphenol as the raw material. .05～
It is 1 times by weight, more preferably 0.05 to 0.5 times by weight.

As the alkylbenzene used here, the exemplified compounds mentioned below are used, and among them, alkylbenzenes such as toluene, xylene, ethylbenzene, isopropylbenzene, or isopropyltoluenes are preferably used.

Conditions for chlorination reaction> 3-methyl-6-tert-butylphenol or 3-
In the chlorination of methyl-4,6-ditertiarybutylphenol, 2.4- Dichlor-3-
Methyl-6-tert-butylphenol can be produced in high yield.

When using 3-methyl-4,6-ditertiarybutylphenol as a raw material, the desired 2,4-dichloro-3-methyl-6- Tertiary butylphenol can be produced. Here, as the iron-based catalyst, iron, iron chloride, iron sulfate, or the like is used.

In addition, the amount of the chlorinating agent used is around the theoretical amount, specifically 0.98 to 1.5 times the theoretical amount, preferably 1.0 to 1.
．． 05 molar times.

<Treatment after chlorination reaction> After the chlorination reaction is completed, the chlorine is removed using the usual post-chlorination treatment method, i.e., by passing nitrogen gas through it to remove chlorine,
Or after washing with an aqueous solution such as sodium sulfite,
In the case of using a catalyst, it is possible to proceed to the next step after removing the catalyst by filtration or the like, or without filtration.

An excellent feature of the method of the present invention as an industrial production method is that the alkylbenzene used in the chlorination reaction is separated from the chlorination product 2,4-dichloro-3-methyl-6-tert-butylphenol. However, it can be conveniently used in the following rearrangement reaction.

Other important features of the process of the invention are, for example, the 2,4-dichloro-3-methyl-6-
A means for removing tert-butyl from tert-butylphenol is to carry out a rearrangement reaction using a transalkylation reaction with an alkylbenzene. - Another important feature of the process of the invention is the use of aluminum halide or a complex of aluminum halide and alkylbenzene as catalyst. Specifically, a liquid complex consisting of alkylbenzene, hydrogen halide, and aluminum is preferably used as this complex.

In the present invention, when using the complex, the amount of alkylbenzene, which is one of the reaction components, and the catalyst used is extremely streamlined in industrial scale implementation.
More favorable results are brought about, such as providing a method for producing 4-dichloro-3-methylphenol.

Specific examples of the alkylbenzene used in the present invention include toluene, 0-lm- or p-cresol, ethylbenzene, diethylbenzene isomer, triethylbenzene isomer, ethyltoluene isomer, diethyltoluene isomer, xylene isomer, trimethyl Benzene isomer, tetramethylbenzene isomer, ethylxylene isomer, isopropylbenzene, diisopropylbenzene isomer, triisopropylbenzene isomer, isopropyltoluene isomer, diisopropyltoluene isomer, isopropylxylene isomer, isopropylethylbenzene isomer, Secondary butylbenzene, di-sec-butylbenzene isomer, secondary-butyltoluene isomer, di-sec-butyltoluene isomer, secondary-butylxylene isomer, secondary-butyl ethylbenzene isomer, hexylbenzene, Mention may be made of cyclohexylbenzene, and mixtures thereof. Although benzene is not a raw material component of the complex, it can be mixed into the alkylbenzene mixture.

Among these alkylbenzenes, toluene, ethylbenzene, xylenes (o-1m-mody(p-
Preferred examples include 1 silane), isopropylbenzene, and isopropyltoluene.

Here, the amount of alkylbenzene used is 2.4-
1 to 10 molar amount, preferably 1.5 to 5.0 molar amount based on dichloro-3-methyl-6-tert-butylphenol.
The amount is 0 mol, more preferably 1.5 to 30 mol.

Note that the amount of alkylbenzene used here takes into consideration the alkylbenzene coexisting during the chlorination reaction and the alkylbenzene used as a liquid complex as a catalyst in the transalkylation reaction.

The method of the present invention requires the use of an aluminum halide catalyst as a catalyst. As the catalyst,
Examples include powder catalysts and liquid complex catalysts that are complexes of alkylbenzene and aluminum halide.

Specific examples of the powder catalyst include anhydrous aluminum chloride and anhydrous aluminum bromide. These catalysts are used in bulk or granular form, or in finely ground form.

On the other hand, a liquid complex catalyst is a more preferred catalyst in the method of the present invention, and specifically, for example, in the presence of aluminum and alkylbenzene, gaseous hydrogen halide is passed between aluminum halide and hydrogen halide and alkylbenzene. This liquid complex can be used.

This liquid complex is preferably produced by the method described in Japanese Patent Publication No. 54-1298, for example.

The hydrogen halide used in the synthesis of this liquid complex is a conventional hydrogen halide, for example, one dried to a moisture content of 0.1% or less.

As the alkylbenzene used for producing this liquid complex, the alkylbenzenes described above can be used.

The amount of catalyst used is 2,4-dichloro-3-methyl-
Usually about 0.0 for 6-tert-butylphenol
The amount is 1 to 1.0 molar times, preferably 0.05 to 0.7 molar times, and more preferably 0.1 to 0.5 molar times.

In particular, when using the above-mentioned liquid complex, the purpose can be achieved efficiently with a relatively small amount of catalyst compared to when using a powder catalyst.

In the method of the present invention, by using a liquid complex, as mentioned above, not only the amount of catalyst used can be reduced, but also a liquid reaction can be carried out in industrial implementation, the handling of the reactants is extremely preferable, and the reaction It is truly surprising that it contributes so effectively in terms of yield.

<Conditions for rearrangement reaction> The temperature for rearrangement reaction in the present invention is 30 to 150°C, preferably 30 to 100°C, more preferably 30 to 70°C.

The reaction temperature can be determined in combination with the amount of aluminum halide or the complex used to provide an industrially advantageous reaction time.

A reaction time of 0.5 to 10 hours is usually sufficient.

It goes without saying that the reaction mode of the present invention can be carried out in either a batchwise or continuous manner under normal pressure, increased pressure or reduced pressure.

Treatment after the rearrangement reaction> The reaction mass after the rearrangement reaction is poured into water to dissolve the aluminum halide in the water layer, and the oil layer is taken out by liquid separation.

The obtained oil layer can be directly distilled to separate 2,4-dichloro-3-methylphenol, but depending on the alkylbenzene used in the rearrangement reaction, the desired 2,4-dichloro-3-methylphenol can be separated.
It becomes difficult to separate it from dichloro-3-methylphenol.

In this case, a preferable separation method is to add an alkaline aqueous solution to the oil layer obtained by liquid separation to lower the pH of the system to 1.
1 to 12 are dissolved in the aqueous layer as an alkali salt of 2,4-dichloro-3-methylphenol, and the aqueous layer is taken out by liquid separation.

At this time, raw materials and undesirable impurities are dissolved and separated in the oil layer, which is extremely convenient.

In particular, 2,4-dichloro-3-methyl-6-tert-butylphenol, which is a raw material for the rearrangement reaction, is dissolved in the oil layer within this pH range.

Therefore, in controlling the end point of the rearrangement reaction, it is possible to stop the reaction at a point where the selectivity for the target product, 2,4-dichloro-3-methylphenol, is high even if some raw materials remain.

The aqueous layer taken out is then adjusted to pH 2 to 4 to produce 2,4-dichloro-3-methylphenol;
It can be precipitated and removed by filtration. or,
At this time, by adjusting the pH to 2 to 4 in the coexistence of an organic solvent, it can be dissolved in the organic layer and taken out in a form dissolved in the oil layer by liquid separation.

Thereafter, the organic solvent was distilled off using a conventional method, and the desired 2.4-
Dichloro-3-methylphenol can be obtained, but if the organic solvent used at this time is the same as the solvent used in the next step, the separated solution can be used as a membrane layer. can.

<Effects of the Invention> According to the present invention, 2,4-dichloro-3-methyl-6-
Tert-butylphenol or its precursor 3
- Methyl-6-tert-butylphenol or 3-methyl-4,6-di-tert-butylphenol [1] is used to industrially produce the desired 2,4-dichloro-3-methylphenol in high yield and purity. can be advantageously manufactured.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

In addition, parts and % in the examples are parts by weight or % by weight, respectively.
means.

Example 1 3-methyl-6-tert-butylphenol 100
(purity 99.5%) and 10 parts of toluene were placed in a flask, and 85% of chlorine gas was added while maintaining the temperature at 20-25°C.
5 parts were injected over 6 hours.

After the reaction was completed, nitrogen gas was blown into the system to remove dissolved hydrochloric acid gas and the like.

Next, add 29.2 parts of toluene and heat to 40-50℃.
The temperature rose to . A liquid complex consisting of aluminum chloride, hydrogen chloride, and toluene (composition: 26% aluminum chloride, 3% hydrogen chloride, 71% toluene>90.2IS was added dropwise over 1 hour, and then stirred at the same temperature for 3 hours. The mixture was poured into 150 parts of water.The mixture was stirred and allowed to stand at a temperature of 60 to 70°C, and the water layer was removed by liquid separation.
8% sodium hydroxide was added dropwise.

Finally, the pH was adjusted to 11.5. 30-40
After stirring at a temperature of °C for 1 hour, the mixture was allowed to stand, and the aqueous layer was taken out.

Toluene was added to this aqueous layer, and 50% sulfuric acid was added dropwise while stirring. The final pH was adjusted to 3.5.

After stirring for 1 hour at a temperature of 30 to 40°C, the mixture was allowed to stand still and the toluene layer was taken out by liquid separation. 235.0 parts of toluene layer containing 42.5% of 2.4-dichloro-3-methylphenol was obtained. The total amount of low impurities contained in this toluene layer is 2 for 2.4-dichloro-3-methylphenol.
% or less, and the yield was as high as 92.5% based on the raw material 3-methyl-6-tert-butylphenol.

Example 2 In Example 1, 3-methyl-6-tert-butylphenol 1001 (purity 99.5%) was replaced with 3-methyl-6-tert-butylphenol 1001 (purity 99.5%).
Methyl-4,6-ditertiary-butylphenol 11
High purity 2,4-dichloro-3-methylphenol was obtained by carrying out the chlorination and rearrangement reaction treatment in the same manner as in Example 1, except that 0 part (purity 95%) was used and 0.7 part of iron powder was further added. I got it.

Example 3 100 parts of 2.4-dichloro-3-methyl-6-tert-butylphenol (purity 95%) was charged into a flask, and a liquid complex consisting of aluminum chloride, hydrogen chloride, and toluene (composition: 26% aluminum chloride) was prepared. , hydrogen chloride 3
%, toluene 71%) and 11.5 parts of toluene were added, and the temperature was raised to 50 to 60°C.

After being kept at the same temperature for 6 hours, it was cooled and poured into 100 parts of water. Stir and leave at 60 to 70°C, remove the aqueous layer by liquid separation, and distill the resulting oil layer to obtain 25 to
69.3 parts of the target 2°4-dichloro-3-methylphenol (purity 98%) as a fraction of 118 to 120°C
) was obtained. The yield was 94.3%.

Example 4 2.4-dichloro-3-methyl-6-tert-butylphenol (1 oom <95% purity) and xylene 13
0 part was placed in a flask, 27 parts of aluminum chloride was added under stirring, and the temperature was raised to 60-65°C. After being kept at the same temperature for 6 hours, it was cooled and poured into 100 parts of water. 60-70
Stir and leave to stand at ℃, remove water layer by liquid separation, and distill the obtained oil layer to 1 ill ~ 25 torr.
67.6 parts (purity 96%) of the target 2,4-dichloro-3-methylphenol was obtained as a 120°C fraction. The yield was 90.1%.

Example 5 100 parts of 2.4-dichloro-3-methyl-6-tert-butylphenol (purity 95%) and 113 parts of toluene
1 part was placed in a flask, 32 parts of aluminum chloride was added under stirring, and the temperature was raised to 50 to 55°C. After being kept at the same temperature for 5 hours, it was cooled and poured into 100 parts of water. 60~70℃
The mixture was stirred and allowed to stand, and the aqueous layer was removed by liquid separation, and 28% hydroxylated IJum was added dropwise to the resulting oil layer. Finally, the pH was adjusted to 11.5. The amount of 28% sodium hydroxide aqueous solution required at this time was 56 parts. 30-4
After stirring at a temperature of 0° C. for 1 hour, the mixture was allowed to stand and the aqueous layer was taken out.

70 parts of toluene was added to this aqueous layer, and 50% sulfuric acid was added dropwise while stirring. The final pH was adjusted to 3.5.

After stirring for 1 hour at a temperature of 30 to 40°C, the mixture was allowed to stand still and the toluene layer was taken out by liquid separation. The amount obtained was 151 parts, and the target content of 2,4-dichloro-3-methylphenol was 44
%Met. The total amount of low impurities is 2゜4-dichloro-
The purity was 2% or less based on 3-methylphenol, which was extremely high purity.

Example 6 100 parts of 2.4-dichloro-3-methyl-6-tert-butylphenol (purity 95%) and 88 parts of m-cresol were charged into a flask, and 43.5 parts of aluminum bromide was charged.
of the mixture was added under stirring, and the temperature was raised to 40-45°C.

After being kept at the same temperature for 9 hours, it was cooled and poured into 100 parts of water. Stir and leave to stand at 60 to 70°C, remove water layer by liquid separation, and remove target compound m2.4- in 185 parts of the resulting oil layer.
Dichloro-3-methylphenol content was 37.4%.

The total amount of impurities such as 4-chloro-3-methylphenol is 2% based on 2.4-dichloro-3-methylphenol.
The purity was as follows.

Comparative Example 2. After adding 0.6 parts of metallic aluminum to 100 parts of 4-dichloro-3-methyl-6-tert-butylphenol (purity 95%), the temperature was raised to 220° C. with stirring.

The mixture was kept at the same temperature for about 2 hours until no inbutylene gas was generated. When we analyzed the composition of the reaction solution, we found that the second objective was
．． The 4-dichloro-3-methylphenol content was 80%. In this reaction product, the total amount of impurities such as monochloro-3-methylphenol, which is a dechlorination product, is 10%.
This was extremely unsatisfactory because it could not be sufficiently separated even by rectification in the next step.

Claims (9)

[Claims] (1) Rearrangement reaction between 2,4-dichloro-3-methyl-6-tert-butylphenol and alkylbenzene,
A method for producing 2,4-dichloro-3-methylphenol, which is carried out in the presence of an aluminum halide or a complex of alkylbenzene and aluminum halide as a catalyst. (2) Claim 1, characterized in that the catalyst for the rearrangement reaction is a complex of alkylbenzene and aluminum halide.
The method described in. (3) The method according to claim 1 or 2, wherein the alkylbenzene is toluene, ethylbenzene, xylene, isopropylbenzene, or isopropyltoluenes. (4) Claim 1, wherein the amount of alkylbenzene used is about 1 to 10 times the mole of 2,4-dichloro-3-methyl-6-tert-butylphenol.
The method according to any one of items 3 to 3. (5) Claim 1, wherein the amount of aluminum halide used is about 0.01 to 1.0 times the mole of 2,4-dichloro-3-methyl-6-tert-butylphenol. 4. The method according to any one of items 4 to 4. (6) 2,4-dichloro-3-methyl-6-tert-butylphenol is obtained by chlorinating 3-methyl-6-tert-butylphenol or 3-methyl-4,6-di-tert-butylphenol. The method according to any one of claims 1 to 5, wherein: (7) The method according to claim 6, characterized in that alkylbenzene is allowed to coexist in the reaction system during the chlorination. (8) The amount of alkylbenzene used is 3-methyl-6-
Tert-butylphenol or 3-methyl-4,6-
Approximately 0.01 to 5 for ditertiarybutylphenol
8. A method according to claim 7, characterized in that the weight is doubled. (9) The method according to claim 7 or 8, wherein the alkylbenzene is toluene, ethylbenzene, xylene, isopropylbenzene or isopropyltoluenes.