JPH09169705A - Production of 2,4-dichloro-3-ethyl-6-nitrophenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply obtain the subject compound useful as the intermediate of a cyanide coupler for color photography in high purity. SOLUTION: This method for producing the 2,4-dichloro-3-ethyl-6-nitrophenol of formula I comprises sulfonating 4-chloro-3-ethylphenol of formula II with fuming sulfate (28-65% concentration) in an organic solvent (e.g. methylene chloride) preferably at 10-50 deg.C chlorinating the produced 5-chloro-4-ethyl-2- hydroxybenzene-sulfonic acid with chlorine gas in an aqueous solvent, converting the produced 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid into a sulfonic acid, depositing the sulfonic acid, and further nitrating the sulfonic acid with nitric acid or a nitrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing 2,4-dichloro-3-ethyl-6-nitrophenol useful as an intermediate for color photographic cyan color formers.

[0002]

2. Description of the Prior Art 2,4-Dichloro-3-ethyl-
A method for producing 6-nitrophenol is disclosed in JP-A-63 / 1988.
-44552 and JP-A-64-47741, 3,
A method of nitrating 5-dichloro-4-ethylnitrobenzene to obtain 3,5-dichloro-4-ethyl-1,2-dinitrobenzene, which is obtained by hydrolyzing the 2-position nitro group with an alkali metal hydroxide. Is listed. Further, in JP-A-61-60634, para ethyl nitrobenzene is chlorinated with chlorine to prepare 2,3,5-trichloro-
A method for obtaining 4-ethylnitrobenzene and hydrolyzing it to obtain 2,4-dichloro-3-ethyl-6-nitrophenol is described. Japanese Patent Laid-Open No. 60-20544
No. 7 describes a method in which 5-ethyl-2-nitrophenol is obtained by chlorinating with sulfuryl chloride in the presence of a catalyst. Japanese Patent Application Laid-Open No. 1-228943 discloses that paraethylbenzenesulfonic acid is chlorinated to give 2,
After obtaining 3,5-trichloro-4-ethylbenzenesulfonic acid, desulfonation, nitration to give 2,3,5-trichloro-4-ethylnitrobenzene, and hydrolysis of chlorine to give 2,4-dichloro-3 A method for obtaining -ethyl-6-nitrophenol is described. JP-A-61-5
No. 7536, 4-chloro-3-ethylphenol or metaethylphenol was sulfonated with a anhydrous sulfuric acid complex in a halogenated hydrocarbon solvent or sulfonated in excess concentrated sulfuric acid to give 5-chloro-4-ethylphenol. 2-Hydroxybenzenesulfonic acid or 4-ethyl-2-hydroxybenzenesulfonic acid is chlorinated with chlorine gas or sulfuryl chloride to give 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid. And then replacing the sulfone group with a nitro group with nitric acid to produce 2,4-dichloro-3-ethyl-6-nitrophenol. Further, in JP-A-3-223235 and JP-A-4-29966, 4-chloro-3-ethylphenol is sulfonated with chlorosulfonic acid in a halogenated hydrocarbon solvent to give 5-chloro-4-ethyl. Ethyl-2-hydroxybenzene sulfonic acid was chlorinated with hydrogen peroxide and hydrochloric acid to give 3,5-dichloro-
4-ethyl-2-hydroxybenzenesulfonic acid is obtained,
Then, replace the sulfo group with a nitro group with nitric acid.
A method for making 4-dichloro-3-ethyl-6-nitrophenol is described.

[0003]

All of the above-mentioned known methods have various problems to be solved in order to carry out them industrially. For example, the method using 3,5-dichloro-4-ethylnitrobenzene as a starting material is a known method in the production of para-ethylnitrobenzene as a starting material. And a para-form mixture, which requires purification. This purification method can only be carried out in low yields. In addition, dichlorination also results in the formation of isomers, which requires a complicated method for purification. On the other hand, the method of trichlorolating para-ethylnitrobenzene has the same drawbacks as the above-mentioned method. Furthermore, the method using 5-ethyl-2-nitrophenol as a starting material is not practical because it is difficult to produce this starting material. That is, since nitration of metaethylphenol forms a mixture of isomers, a step of removing by-products is essential. Furthermore, in the method using paraethylbenzenesulfonic acid as a starting material, it is necessary to separate the ortho and meta forms when obtaining paraethylbenzenesulfonic acid as a starting material. Further, chlorination is carried out in an excess amount of sulfuric acid, but in the case of industrial production, the productivity is low and the treatment of waste sulfuric acid becomes a problem. Further, the method using metaethylphenol as a starting material is not an industrially advantageous method because the isomers are formed during the sulfonation, resulting in a low yield. Furthermore, the method of sulfonation with a sulfuric anhydride complex using 4-chloro-3-ethylphenol requires a complex auxiliary material such as dioxane, which requires a large amount of equipment and labor for recovery of the auxiliary material. Is required. In addition, there is a problem that the recovery rate is low. Since the method of sulfonating 4-chloro-3-ethylphenol with concentrated sulfuric acid requires the use of excessive concentrated sulfuric acid, the productivity is low, and the treatment of excess concentrated sulfuric acid may cause environmental problems. Intrinsic in nature. or,
The method in which 4-chloro-3-ethylphenol is used as a raw material and is sulfonated with chlorosulfonic acid requires an absorption facility for hydrogen chloride gas generated by the reaction, and also in the production of 4-chloro-3-ethylphenol as a raw material. According to the known method, since methacrylic acid is chlorinated to produce it, the reaction product becomes a mixture of isomers having close boiling points, and complicated operations such as precision separation operation are required to obtain the desired product. become. This is because no purification operation was included in each step of producing 2,4-dichloro-3-ethyl-6-nitrophenol.
This is because a high-purity raw material 4-chloro-3-ethylphenol is required to produce -dichloro-3-ethyl-6-nitrophenol. In view of the above problems of the prior art, the present inventors have found that 2,4-dichloro-3-ethyl-
The present invention has been completed as a result of extensive studies to find out an industrially advantageous production method of 6-nitrophenol, and the object of the present invention is to provide a novel 2,4-dichloro-3-ethyl-6- The present invention provides a method for producing nitrophenol and an intermediate for the compound.

[0004]

Means for Solving the Problems 2,4-Dichloro-3-ethyl- of the present invention made to solve the above problems
The outline of the method for producing 6-nitrophenol is as follows. 4-Chloro-3-ethylphenol is sulfonated with fuming sulfuric acid in an organic solvent to give 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid. Is chlorinated to give 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid, which is then converted into a sulfonate and crystallized, and the sulfonate is nitrated with nitric acid or nitrate. Method for producing 2,4-dichloro-3-ethyl-6-nitrophenol; fuming sulfuric acid used for sulfonation is 28% to 65%
The above-mentioned production method in which chlorination is carried out in a water solvent and chlorine gas is used as a chlorinating agent to be used; 3,5-dichloro-4-produced after chlorination Ethyl-
The above-mentioned production method in which 2-hydroxybenzenesulfonic acid is crystallized by forming an alkali metal salt of the sulfonic acid with an alkali metal salt or an ammonium salt of the sulfonic acid. Is. In addition, the gist of the method for producing the intermediate is that of 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid, which comprises sulfonation of 4-chloro-3-ethylphenol with fuming sulfuric acid in an organic solvent. Manufacturing method: 4-chloro-3-ethylphenol is sulfonated with fuming sulfuric acid in an organic solvent to give 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid, which is then chlorinated. , 5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid production method;

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION 2,4-Dichloro-3- of the present invention
The method for producing ethyl-6-nitrophenol is represented by the following reaction process formula, and the target compound (5) is obtained from the compound (1) as a raw material through the compounds (2), (3) and (4). The method for producing the above intermediate and the method for obtaining compound (2) from compound (1) and compound (3) via compound (1) to compound (2), respectively.
Is a way to get

[0006]

Embedded image

In the above method of the present invention, first, 4
-Chloro-3-ethylphenol (1) in an organic solvent,
Sulfonation with fuming sulfuric acid gives 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid (2).
The purity of fuming sulfuric acid used in this reaction is not particularly limited, and may be 28 to 65% in purity and usually easily available. The amount of fuming sulfuric acid used is 4-chloro-3 as the raw material.
-Ethylphenol (1) is used in an amount of 0.3 to 0.8 mol times, preferably 0.4 to 0.6 mol times.
If it is less than 0.3 mol times, the amount of unreacted raw material compound (1) will increase, and if it exceeds 0.8 mol times, the amount of tar-like substances as reaction by-products will increase. The financial burden increases significantly. It is preferable to use a highly pure compound (1) as a raw material,
In the present invention, since it is purified in the reaction step, a chloroethylphenol isomer mixture obtained by chlorinating metaethylphenol by a known method can also be used as a raw material. Examples of the organic solvent used in this sulfonation reaction include halogenated hydrocarbons (for example, methylene chloride, chloroform, carbon tetrachloride, dichloroethylene,
Dichloroethane, tetrachloroethylene, tetrachloroethane, bromochloromethane, dibromoethane, etc.), nitro compounds (eg, nitromethane, nitrobenzene, etc.), aromatic halogenated carbons (eg, chlorobenzene, dichlorobenzene, trichlorobenzene, etc.), etc. These solvents may be used as a mixture of two or more kinds. The amount of the solvent used is the compound (1)
However, it is preferably about 1 to 10 times by weight. The reaction temperature of the sulfonation reaction is 0 to 100 ° C, preferably 10 to 5
It is advantageous to carry out in the range of 0 ° C. According to the above-mentioned sulfonation, only fuming sulfuric acid is used as the sulfonating agent, the operation is simple, and since the sulfonating agent is not used in a large excess, the post-treatment is easy. The compound (2) thus obtained is used in the next reaction with or without isolation.

5 obtained by the above sulfonation method
-Chloro-4-ethyl-2-hydroxybenzenesulfonic acid (2) is subsequently chlorinated to give 3,5-dichloro-4.
Lead to ethyl-2-hydroxybenzenesulfonic acid (3). This chlorination step can be carried out by various conventional chlorination methods, but preferably, since the compound (2) is water-soluble, chlorination is carried out by passing chlorine gas into the water solvent of the compound (2), This is carried out by the method for obtaining the compound (3). This method is economically advantageous because it does not use an organic solvent. If necessary, a catalyst may be used, and examples of the catalyst include hydrochloric acid and sulfuric acid. The amount of chlorine gas introduced is 0.5 to 1.5 mol times, preferably 0.9 to 1.3, of the compound (2).
A molar range is preferable. If it is less than 0.5 mol times, the amount of unreacted compound (2) will increase, and if it exceeds 1.5 mol times, the amount of tar-like substances as reaction by-products will increase, and it is economical to remove these undesirable substances. Burden increases significantly. The amount of water used as a solvent is based on the compound (2),
It is used in an amount of 1 to 5 times by weight, preferably 2 to 4 times by weight. The reaction temperature in the chlorination reaction step is 0 to 70.
C., preferably in the range of 30-40.degree. C., is advantageous. The compound (3) thus obtained is used in the next reaction with or without isolation.

The 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid (3) obtained by the above-mentioned method is reacted with a substance capable of forming a salt to give 3,5-dichloro-4-ethyl. 2-Hydroxybenzene sulfonate (4) is crystallized and separated. This salt formation reaction may be carried out by neutralization reaction with a basic substance (eg sodium hydroxide), but is preferably carried out by metathesis with an alkali metal salt or ammonium salt. Specific examples of the alkali metal salt or ammonium salt used here include sodium chloride, potassium chloride, potassium sulfate, ammonium chloride, ammonium sulfate and the like. The amount of these salts used is 1 to 3 times, preferably 1.5 to 2.5 times the amount of the compound (3). It does not matter if these ranges are exceeded or insufficient,
When the amount is less than the above range, the yield of the compound (4) decreases, and when the amount exceeds the above range, the amount of by-products mixed in increases, and there is no economic benefit. The temperature at which these salts are introduced into the system is 20 to 100 ° C, preferably 80 to 95 ° C. The separation temperature of the further precipitated compound (4) is usually 0.
It is carried out in the range of -50 ° C, preferably 10-30 ° C. By washing the separated compound (4) with water or a lower alcohol, a high-purity product used as a raw material for the next step can be easily obtained. In the method of the present invention, since the highly purified compound (4) purified at this stage is obtained, the purity of the target compound (2,4-dichloro-3-ethyl-6-nitrophenol) obtained in the next step is obtained. Can be increased.

The thus obtained 3,5-dichloro-4-
Ethyl-2-hydroxybenzenesulfonate (4)
Is a sulfonate group (-SO
₃ ^-) can be obtained nitro-substituted (the final object by nitration) 2,4-dichloro-3-ethyl-6-nitrophenol (5). The nitro group substitution is
Dilute nitric acid or nitrate is added dropwise to an aqueous suspension of compound (4), or compound (4) is added to dilute nitric acid solution or nitrate solution.
The sulfonate group can be easily replaced with the nitro group by adding The reaction temperature in the nitro group substitution step is 80 ° C or lower, preferably 40 ° C or lower.
The compound (5), which is the final target product, is obtained by filtering the precipitated crystals after the reaction. If a high-purity product is required in advance, impurities can be removed by adding methanol or isopropanol before filtration. The compound (5) thus obtained is reduced to give 2-amino-4,6-dichloro-5-ethylphenol, which is useful as an intermediate for a color photographic cyan color former.

[0011]

According to the method of the present invention, a chloroethylphenol isomer mixture obtained by chlorinating metaethylphenol by a known method can be used as a raw material, which is economical. Further, since sulfonation is performed using fuming sulfuric acid, the reaction is simple and the post-treatment is easy, which is industrially advantageous. Further, from the raw material to the target product can be carried out in a continuous process, and water can be used as a solvent except for the sulfonation process, so that the production cost can be remarkably reduced. Further, since the compound (4) which is an intermediate is obtained as a crystallized product with high purity, there is an advantage that the target product (5) with high purity can be obtained.

[0012]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 70 g (0.3772 mol) of chloroethylphenol isomer mixture (4-chloro-3-ethylphenol purity 84.4%) and 250 g of bromchloromethane were placed in a 1-liter glass 4-necked flask, Dissolve. While keeping the temperature in the range of 30-35 ° C, 28% fuming sulfuric acid 6
After 6.5 g was added dropwise and kept at the same temperature for 4 hours while stirring, water 189 was added, and 30.9 g (0.3551 mol) of chlorine gas was introduced at 35 to 40 ° C. while stirring without separation. (Chlorination yield 94.1%). Then, the reaction was aged at the same temperature for 2 hours while stirring, and then allowed to stand, the lower oil layer was discharged, and then the aqueous layer was mixed with sodium chloride 5
1.9 g was added and the mixture was kept warm at 85 to 90 ° C for 1 hour. After maintaining the temperature, it was cooled to 15 ° C., and the precipitated crystals were separated by filtration. The crystalline product was washed with water and 3,5-dichloro-4-ethyl-2
-Hydroxybenzenesulfonic acid sodium salt 127.
9 g (purity 77.3%, 0.3375 mol) was obtained (yield 89.4%). Next, 283.5 g of 15% nitric acid aqueous solution
While maintaining the temperature at 35-40 ° C, 3,5-dichloro-
127.9 g of 4-ethyl-2-hydroxybenzenesulfonic acid sodium salt was gradually added, and the mixture was kept warm with stirring at the same temperature for 3 hours. After keeping the temperature still and removing it by removing the upper water layer, 45
While maintaining the temperature at -50 ° C, the solution was washed and separated with 50 ml of warm water and the same operation was repeated 3 times to wash the oil layer. Then, the mixture was cooled to 10 ° C., and the precipitated crystals were separated, washed with cold water and dried under reduced pressure to give 7,4-dichloro-3-ethyl-6-nitrophenol (75.7 g, purity 98.5%, 0.3157). Mole,
Nitration yield 93.5%) was obtained (melting point 46.5-4)
7.5 ° C., yield 83.7%).

Example 2 59 g of an aqueous 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid solution obtained in the same manner as in Example 1.
7.6 g of ammonium chloride was added to (purity 26.3%, 0.0582 mol), and the mixture was heated and stirred at 85 to 90 ° C for 1 hour, cooled to 30 ° C, and the precipitated crystals were filtered. Then, it was washed with 80% isopropanol to obtain 18.6 g (0.0558 mol) of 3,5-dichloro-4-ethyl-hydroxybenzenesulfonic acid ammonium salt (yield 95.8%). Thereafter, the same operation as in Example 1 was repeated to give 2,4
-Dichloro-3-ethyl-6-nitrophenol 10.
3 g (purity 99.0%, 0.0535 mol) was obtained (yield 91.9%).

Example 3 2,4-Dichloro-3 was prepared in the same manner as in Example 1 except that orthodichlorobenzene was used as the solvent for the sulfonation step.
-Ethyl-6-nitrophenol was obtained (yield 84.7).
%, Purity 98.7%).

Example 4 3,5-Dichloro-obtained in the same manner as in Example 1
To a suspension of 20 g of 4-ethyl-2-hydroxybenzenesulfonic acid sodium salt (purity 71.3%, 0.0487 mol) and 40 g of water, 40 g of 7.1% 61% nitric acid aqueous solution was added.
The solution was added dropwise while maintaining it at 45 ° C. After dropping, at the same temperature
After stirring for a while while maintaining the temperature, the mixture was cooled to 10 ° C, and the precipitated crystals were filtered, washed with water and dried to give 11.4-g of 2,4-dichloro-3-ethyl-6-nitrophenol (purity 99%).
Was obtained (yield 96.4%).

Example 5 The procedure of Example 2 was repeated except that potassium chloride was used instead of ammonium chloride and methanol was used instead of isopropanol, and 12.8 g of 2,4-dichloro-3-ethyl-6-nitrophenol was used. (Purity of 98.5%) was obtained (potassium chloride yield 96.6%, nitration yield 95%).

Claims (6)

[Claims] 1. 4-Chloro-3-ethylphenol is sulfonated in an organic solvent with fuming sulfuric acid to give 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid, which is then chlorinated to give 3,4. 5-dichloro-4-
2. Ethyl-2-hydroxybenzene sulfonic acid is converted to a sulfonate and crystallized, and the sulfonate is nitrated with nitric acid or a nitrate salt.
A method for producing 4-dichloro-3-ethyl-6-nitrophenol. 2. The method according to claim 1, wherein the fuming sulfuric acid used for the sulfonation has a concentration of 28% to 65%. 3. The method according to claim 1, wherein chlorination is carried out in a water solvent and chlorine gas is used as the chlorinating agent used. 4. After chlorination, the produced 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid is converted to an alkali metal salt of the sulfonic acid by using an alkali metal salt, or an ammonium salt is used. The method according to claim 1, wherein the sulfonic acid is used as an ammonium salt to crystallize. 5. A method for producing 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid, which comprises sulfonation of 4-chloro-3-ethylphenol with fuming sulfuric acid in an organic solvent. 6. 4-Chloro-3-ethylphenol is sulfonated with fuming sulfuric acid in an organic solvent to give 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid, which is then chlorinated. Characteristic 3,5
-Method for producing dichloro-4-ethyl-2-hydroxybenzenesulfonic acid.