JPH0812627A - Production of 2,4-dichloro-3-ethyl-6-nitrophenol - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as an intermediate for cyan color developing agents for color photographs. CONSTITUTION:This compound, 2,4-dichloro-3-ethyl-6-nitrophenol, is obtained by the following process: 4-chloro-3-ethylphenol is sulfonated with conc. sulfuric acid into 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid which is then chlorinated into 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid which is then nitrated with nitric acid. In this process, it is characteristic that an organic solvent is used as the sulfonating solvent and the amount of the conc. sulfonic acid to be used in this sulfonation is 1.5-3.5 molar times that of the 4-chloro-3- ethylphenol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing 2,4-dichloro-3-ethyl-6-nitrophenol which is useful as an intermediate for a cyan color former for color photography.

[0002]

2. Description of the Related Art A method for producing 2,4-dichloro-3-ethyl-6-nitrophenol is disclosed in JP-A-61-57.
No. 536, 5-chloro-3-ethylphenol was treated with (1) a sulfuric anhydride complex in a halogenated hydrocarbon solvent, or (2) sulfonated in a large excess of concentrated sulfuric acid to give 5-chloro. -4-Ethyl-2-hydroxybenzene sulfonic acid was chlorinated with chlorine gas or sulfuryl chloride to give 3,5-dichloro-4-ethyl-
A method for obtaining 2-hydroxybenzenesulfonic acid and then substituting the sulfo group with a nitro group with nitric acid to obtain 2,4-dichloro-3-ethyl-6-nitrophenol is described.

Further, in JP-A-3-223235, 4-chloro-3-ethylphenol is sulfonated with chlorosulfonic acid to give 5-chloro-4-ethyl-.
2-Hydroxybenzene sulfonic acid was chlorinated with hydrogen chloride in the presence of a hydrogen peroxide solution catalyst to give 3,5
-Dichloro-4-ethyl-2-hydroxybenzenesulfonic acid is obtained, and then a method for producing 2,4-dichloro-3-ethyl-6-nitrophenol by substituting a nitro group for a sulfone group with nitric acid is described. Has been done.

[0004]

The known method described above has various problems to be solved, for example, 4-
The method of sulfonation with a sulfuric anhydride complex using chloro-3-ethylphenol requires special consideration because it is a danger in handling sulfuric anhydride, and a raw material such as dioxane is required to form a complex. However, there is a problem that it is difficult to collect this. Further, in the method of sulfonation with a large excess of sulfuric acid using 4-chloro-3-ethylphenol, treatment of sulfuric acid becomes a problem.

For example, 2,4-dichloro-3-ethyl-
In the case where the production amount of 6-nitrophenol is 10 tons and the amount is 3 mol times in the present invention, the amount of industrial caustic soda (25%) used as the neutralizing agent is 30 tons, whereas the known formulation. When the amount of sulfuric acid used is 6 mol times, the amount of the neutralizing agent used must be 80 t. On the other hand, the method of sulfonation with chlorosulfonic acid using 4-chloro-3-ethylphenol requires special consideration because there is a risk of smoke emission when handling chlorosulfonic acid. There are problems such as.

The present inventors have earnestly studied to find an industrially advantageous production method of 2,4-dichloro-3-ethyl-6-nitrophenol, which is the final object, and as a result of the studies, the above-mentioned problems have been solved. The present inventors have found a small number of methods of the present invention and completed the present invention.

[0007]

That is, the present invention is
4-Chloro-3-ethylphenol was sulfonated with concentrated sulfuric acid to 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid which was then chlorinated to give 3,4.
5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid, then nitrated with nitric acid 2,4
In the method for producing -dichloro-4-ethyl-6-nitrophenol, the organic solvent is used as the sulfonation reaction solvent, and the amount of concentrated sulfuric acid used in the sulfonation reaction is 4-chloro-3-ethylphenol- That the amount of the organic solvent used for the sulfonation reaction is 1 to 10 times by weight that of 4-chloro-3-ethylphenol, The organic solvent separated after the sulfonation reaction is used as it is in the next sulfonation reaction, and the organic solvent is an organic solvent selected from halogenated hydrocarbons, aliphatic hydrocarbons and aromatic hydrocarbons. A method for producing 2,4-dichloro-3-ethyl-6-nitrophenol, which is characterized.

A preferred embodiment of the present invention is as follows. The method according to any one of the above 1 to 3, wherein the chlorination is performed in water or an acetic acid solvent. The method according to any one of the above 1 to 3, wherein the chlorination is performed in the presence of a catalyst. The method as described above, wherein the catalyst is iodine-ferric chloride or ferric chloride. The method according to any one of the above 1 to 3, wherein the chlorination is performed using chlorine gas. The method according to any one of the above 1 to 3, wherein the chlorination is performed using sulfuryl chloride in an acetic acid solvent.

Concentrated sulfuric acid used in the present invention is usually one having a purity of 95 to 98%. The amount of concentrated sulfuric acid used is 1.5 with respect to 4-chloro-3-ethylphenol.
˜3.5 mol times, preferably 2.0 to 3.0 mol times. If it is less than 1.5 mol times, unreacted 4-chloro-3-
When the amount of ethylphenol increases and the amount is more than 3.5 mol times, it is difficult to treat excess sulfuric acid.

An organic solvent is used as a reaction solvent in the sulfonation of the present invention. In particular, the present inventors have found that by using the organic solvent described below as a sulfonation reaction solvent, the sulfonation yield can be significantly improved with a small amount of sulfuric acid. Examples of the organic solvent used as the sulfonation reaction solvent include halogenated hydrocarbons (eg, chloroform, chlorobenzene, 1,2-dichloroethane, etc.), aliphatic hydrocarbons (eg, normal hexane, cyclohexane, normal heptane, etc.),
Aromatic hydrocarbons (eg, toluene, xylene, t-butylbenzene, etc.) are used. The reaction temperature of the sulfonation with concentrated sulfuric acid of the present invention is preferably 20 to 90 ° C,
More preferably, it is carried out at 30 to 50 ° C. in terms of suppressing generation of by-products.

In the present invention, sulfuric acid which is usually required in a large excess amount (the above-mentioned JP-A-61-57536 also discloses that concentrated sulfuric acid in a 5 to 7-fold molar excess is used).
However, the reason why the sulfonation proceeds in such a small amount is not always clear, but it is considered that it is derived from the heterogeneous reaction system by using the organic solvent.

The 5-chloro-4-ethyl-2-hydroxybenzenesulfonic acid obtained by the method of the present invention is
It can then be chlorinated to lead to 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid.

For this chlorination, conventional means of passing chlorine gas through the reaction solution is applied. If the reaction temperature in this case is too high, by-products may occur, so it is advantageous to carry out the reaction at 40 ° C or lower, preferably 25 to 35 ° C in an aqueous system. Further, sulfuryl chloride can be used in this step in a non-aqueous system. In a non-aqueous system, no catalyst may be used,
It is preferable to use iodine / ferric chloride or ferric chloride as a catalyst, and 5-chloro-4-ethyl-2
-It is preferable to use a sulfonic acid solubilizing solvent such as acetic acid in order to dissolve hydroxybenzene sulfonic acid.

The chlorination reaction of the present invention is industrially excellent in that it can be carried out using water as a solvent.
This means that in the case of a method of sulfonation using concentrated sulfuric acid as a reaction solvent in an organic solvent, after sulfonation, water is added to the reaction solution to dissolve the sulfonic acid in the aqueous layer and then the oil layer is separated, The use of the aqueous layer in which the sulfonic acid is dissolved has the advantage that the chlorination can be carried out in an aqueous solvent without isolation of the sulfonic acid.

That is, the reaction product is 3,5-dichloro-4-
Obtained as an aqueous solution of ethyl-2-hydroxybenzenesulfonic acid. In addition, since the unreacted 4-chloro-3-ethylphenol remained in the oil layer separated here, by using this oil layer as the solvent for the next sulfonation reaction, 4-chloro-3-ethylphenol was used. It is possible to effectively use -3-ethylphenol.

The thus obtained 3,5-dichloro-4-
Ethyl-2-hydroxybenzenesulfonic acid can then be nitrated with nitric acid to produce the final target 2,4-dichloro-3-ethyl-6-nitrophenol. The nitration may be carried out by dropping a sulfonic acid solution into nitric acid or by dropping nitric acid into a sulfonic acid solution. The reaction temperature is 60 ° C or lower, preferably 40 ° C or lower. It is advantageous in suppressing generation.

The desired product, 2,4-dichloro-3-ethyl-6-nitrophenol, can be obtained by filtering the crystals after the reaction. If necessary, increase the pH with an alkali before filtration and filter with weak acidity, or extract with a less water-soluble solvent such as toluene, xylene, ethyl acetate and wash with water to remove water-soluble impurities. You can It is also possible to wash or recrystallize with methanol, 2-propanol or the like. Further, depending on the purpose, it is also possible to extract the crystal without filtering it with a solvent used in the next step and use it as a solution as it is.

[0018]

INDUSTRIAL APPLICABILITY According to the method of the present invention, 4-chloro-3-ethylphenol which does not require separation of isomers is used and 5-chloro-4-ethyl-phenol is industrially advantageous.
2-Hydroxybenzenesulfonic acid can be produced, and it can be further chlorinated by a known method to give 3,5-dichloro-4-ethyl-2-hydroxybenzenesulfonic acid, which is a known method. It is possible to produce the final target 2,4-dichloro-3-ethyl-6-nitrophenol in high purity and industrially advantageously by nitration with.

[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. In the following, “parts” means parts by weight unless otherwise specified.

Example 1 35 parts of 1,2-dichloroethane and 8 parts of 4-chloro-3-ethylphenol were placed in a four-necked flask, and
While maintaining at -45 ° C, 10 parts of 98% sulfuric acid was added dropwise over 10 to 20 minutes. Then, it stirred for 7 hours, maintaining at 40-45 degreeC. 15 parts of water was added and the oil layer was separated and removed. While keeping the water layer at 30 ° C., chlorine gas was passed through in an amount 1.1 times the theoretical value. 3 after blowing chlorine gas
After stirring for an hour, the mixture was allowed to stand, and then an aqueous solution of 10.3 parts of 61% nitric acid and 13.7 parts of water was added dropwise while stirring while maintaining the aqueous layer at 30 to 40 ° C. Then, the mixture was stirred at the same temperature for 1 hour. 2,4-Dichloro-3-ethyl-6 as the reaction proceeds
-Nitrophenol crystals have started to precipitate. The crystals were collected by filtration, washed with water and dried. Yield 9.6 parts (yield 75%)

Example 2 35 parts of 1,2-dichloroethane and 8 parts of 4-chloro-3-ethylphenol were placed in a four-necked flask to give 35
While maintaining the temperature at ˜45 ° C., 15 parts of 98% sulfuric acid was added dropwise over 10 to 20 minutes. Then, it stirred for 7 hours, maintaining at 40-45 degreeC. Next, 15 parts of acetic acid was added, and 7.4 parts of sulfuryl chloride was added dropwise at 30 ° C. or lower over 20 to 30 minutes. After completion of dropping, the reaction was carried out at the same temperature for 2 hours. Next, an aqueous solution of 61% nitric acid (10.3 parts) and water (13.7 parts) was added dropwise over 20 to 30 minutes while maintaining the temperature at 30 to 40 ° C, followed by stirring at the same temperature for 2 hours. Crystals of 2,4-dichloro-3-ethyl-6-nitrophenol are precipitated as the reaction proceeds. The crystals were collected by filtration, washed with water and dried. Yield 9.56 parts (81% yield)

Example 3 35 parts of 1,2-dichloroethane and 8 parts of 4-chloro-3-ethylphenol were placed in a four-necked flask, and
While maintaining at ~ 45 ° C, 10 parts of 7.5% 98% sulfuric acid is added.
After dropping over a period of time, the mixture was stirred at 40 to 45 ° C for 7 hours. Next, 25 parts of water was added and the mixture was stirred and then allowed to stand to separate an aqueous layer to obtain an oil layer-A. While keeping the separated aqueous layer at 30 ° C., chlorine gas was passed therethrough at 1.1 times the theoretical value, and then kept at the same temperature for 3 hours. Next, an aqueous solution of 10.3 parts of 61% nitric acid and 13.7 parts of water was added dropwise over 20 to 30 minutes while maintaining the reaction solution at 30 to 40 ° C., and then the temperature was maintained for 2 hours.
2,4-Dichloro-3ethyl-6 as the reaction proceeds
-Nitrophenol begins to precipitate. The crystals are collected by filtration, washed with water and dried. Yield 7.67 parts (yield 65%)

Example 4 Oil layer-A (about 15% of unreacted raw material was present in the reaction of sulfonation) obtained above in a four-necked flask and 4-chloro-
After adding 6.7 parts of 3-ethylphenol, 7.5 parts of 98% sulfuric acid was added dropwise over 10 to 20 minutes while maintaining the temperature at 35 to 45 ° C, followed by stirring at 40 to 45 ° C for 7 hours. next,
After adding 25 parts of water and stirring, the mixture was allowed to stand to separate an aqueous layer and an oil layer to obtain an oil layer-B (about 15% of unreacted raw material was present in the reaction of sulfonation). While keeping the separated aqueous layer at 30 ° C., chlorine gas was passed therethrough at 1.1 times the theoretical value, and then kept at the same temperature for 3 hours. Next, while maintaining the reaction solution at 30 to 40 ° C., an aqueous solution of 10.3 parts of 61% nitric acid and 13.7 parts of water was added to 20 to 20 ° C.
After dropping in 30 minutes, the mixture was stirred at the same temperature for 2 hours. As the reaction proceeds, 2,4-dichloro-3-ethyl-6-nitrophenol is precipitated. The crystals are collected by filtration, washed with water and dried. Yield 7.6 parts (yield 76%, yield based on 6.7 parts of 4-chloro-3-ethylphenol)

Comparative Example 1 8 parts of 4-chloro-3-ethylphenol was placed in a four-necked flask and heated to 60 ° C., and 10 parts of 98% sulfuric acid was added to 80 to 80 parts.
It was added dropwise at 90 ° C. After the dropping was completed, the mixture was stirred at the same temperature for 2 hours, and then 20 parts of acetic acid was added when the temperature had dropped.
The mixture was stirred for 30 minutes and cooled to 45 to 50 ° C. Next, 8.1 parts of sulfuryl chloride was added dropwise at 40 to 45 ° C. over 5 hours, followed by stirring at the same temperature for 30 minutes. 80-90 again gradually
After the temperature was raised to 0 ° C. and the reaction was kept warm for 2 hours, 20 parts of acetic acid was added and the temperature was lowered to 30 ° C. when the temperature was slightly lowered by cooling. To this reaction solution, 10.3 parts of 61% nitric acid was added dropwise at 15 ° C or lower. After stirring for 4 hours at the same temperature, 2,4-dichloro-3-ethyl-6-nitrophenol begins to precipitate.
The crystals are collected by filtration, washed with water and dried. Yield 5.4 parts (Yield 46%)

Comparative Example 2 The procedure of Comparative Example 1 was carried out using 7.5 parts of sulfuric acid. Yield 3.78 parts (yield 32%)

Comparative Example 3 The procedure of Comparative Example 1 was carried out using 15 parts of sulfuric acid. Yield 6.25 parts (yield 53%)

Comparative Example 4 8 parts of 4-chloro-3-ethylphenol was placed in a four-necked flask and 30 parts of 98% sulfuric acid was slowly added while cooling. After stirring at 80 to 90 ° C. for 2 hours after completion of dropping, 6
Cooled to 0 ° C. 25 parts of water was added at the same temperature. Next, while maintaining the temperature at 30 ° C., chlorine gas was passed in an amount 1.1 times the theoretical value, followed by stirring for 3 hours. Next, the reaction solution is heated at 30 to 40 ° C.
The aqueous solution of 61% nitric acid (10.3 parts) and water (13.7 parts) was added dropwise over 20 to 30 minutes, and then the mixture was stirred at the same temperature for 2 hours. As the reaction proceeds, crystals of 2,4-dichloro-3-ethyl-6-nitrophenol start to precipitate. The crystals were collected by filtration, washed with water and dried. Yield 8.26 parts (79% yield)

Comparative Example 5 The procedure of Comparative Example 4 was carried out using 40 parts of sulfuric acid. Yield 8.5 parts (yield 72%)

Comparative Example 6 The procedure of Comparative Example 4 was carried out using 50 parts of sulfuric acid. Yield 8.14 parts (yield 69%)

Comparative Examples 7 to 8 The same procedure as in Example 1 was carried out using 30, 40 and 50 parts of sulfuric acid. Table 1 shows the respective yields obtained when the amount of sulfuric acid was changed.

[0031]

[Table 1]

As described above, when a halogenated hydrocarbon solvent such as 1,2-dichloroethane is used, the yield is greatly improved as compared with the case where the sulfonation reaction is carried out using sulfuric acid alone.

Example 5 35 parts of monochlorobenzene and 8 parts of 4-chloro-3-ethylphenol were placed in a four-neck flask and placed in a range of 35-4.
While maintaining the temperature at 5 ° C, 15 parts of 98% sulfuric acid was added dropwise over 10 to 20 minutes. Then, while maintaining at 40-45 ℃, 7
Stirred for hours. 15 parts of water was added and the oil layer was separated and removed. While keeping the water layer at 30 ° C., chlorine gas was passed through in an amount 1.1 times the theoretical value. When the blowing of the chlorine gas was completed, the mixture was stirred for 3 hours and allowed to stand, and then an aqueous solution of 10.3 parts of 61% nitric acid and 13.7 parts of water was added dropwise while stirring while maintaining the aqueous layer at 30 to 40 ° C. Then, the mixture was stirred at the same temperature for 1 hour. Crystals of 2,4-dichloro-3-ethyl-6-nitrophenol began to precipitate as the reaction proceeded. The crystals were collected by filtration, washed with water and dried. Yield 9.80 parts (83% yield)

Example 6 The procedure of Example 5 was repeated using 35 parts of normal hexane instead of monochlorobenzene. Yield 9.80 parts (83% yield)

Example 7 The procedure of Example 5 was repeated using 35 parts of toluene instead of monochlorobenzene. Yield 9.09 parts (yield 77%) As described above, it is understood that the effects of the present invention can be obtained even when an aliphatic hydrocarbon or an aromatic hydrocarbon is used as the organic solvent.

Example 8 2,4-Dichloro-3-ethyl-6 synthesized in Example 5
-Dissolve 100 parts of nitrophenol in 200 parts of ethyl acetate, reduce with hydrogen gas using 0.2 part of 5% palladium carbon catalyst, and add 46 parts of 35% hydrochloric acid to add 6 parts.
Recovered as -amino-2,4-dichloro-3-ethylphenol hydrochloride.

Further, 150 parts of thionyl chloride was added to 300 parts of α- (2,4-di-t-pentylphenoxy) -butanoic acid for chlorination, and then excess thionyl chloride was recovered under reduced pressure to obtain chloride. Thionyl content is 2% or less, α-
(2,4-di-t-pentylphenoxy) -butanoic acid chloride was obtained.

After dissolving 100 parts of 6-amino-2,4-dichloro-3-ethylphenol hydrochloride and 120 parts of N, N-dimethylaniline in 400 parts of ethyl acetate, α-
Acylation was carried out by adding 153 parts of (2,4-di-t-pentylphenoxy) -butanoic acid chloride to give 2,4-dichloro-3-ethyl-6- {α- (2,4-di-t- Pentylphenoxy) -butanoic acid amide} phenol 16
8 parts (yield 80%) were obtained.

Example 9 2,4-Dichloro-3-ethyl-6 synthesized in Example 5
After dissolving 100 parts of nitrophenol in 400 parts of ethyl acetate and reducing with hydrogen gas using 0.2 part of 5% palladium carbon catalyst, α- (synthesized in Example 8 in a reducing reaction solution under a nitrogen atmosphere was used. 2,4-di-t-pentylphenoxy) -butanoic acid chloride (157 parts) and N, N-dimethylaniline (72 parts) were added for acylation to obtain 2,4
-Dichloro-3-ethyl-6- {α- (2,4-di-t
182 parts (yield 85%) of -pentylphenoxy) -butanoic acid amide} phenol were obtained.

[0040]

[Table 2]

2,4-Dichloro-3-ethyl-6-obtained by the present invention by the above Examples 8 and 9.
Couplers made from nitrophenol, ie 2,4
-Dichloro-3-ethyl-6- {α- (2,4-di-t
It has been found that -pentylphenoxy) -butanoic acid amide} phenol has sufficient quality as a photographic material.

In particular, Example 9 is advantageous in terms of yield and process shortening, and has a quality of Example 8.
It has the same quality as (the conventional method for producing couplers), and it is understood that it is advantageous in terms of production cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C07C 303/08 309/42 7419-4H // C07B 61/00 300

Claims (4)

[Claims] 1. 4-Chloro-3-ethylphenol is sulfonated with concentrated sulfuric acid to give 5-chloro-4-ethyl-2.
2,4-dichloro-4-ethyl-6, which is converted to hydroxybenzene sulfonic acid, which is then chlorinated to 3,5-dichloro-4-ethyl-2-hydroxybenzene sulfonic acid and then nitrated with nitric acid. In the method for producing nitrophenol, an organic solvent is used as the sulfonation reaction solvent, and the amount of concentrated sulfuric acid used in the sulfonation reaction is 4-chloro-3-ethylphenol.
2,4-dichloro-3-ethyl-6-nitropheno-, characterized in that the molar ratio is 1.5 to 3.5
Manufacturing method. 2. The amount of the organic solvent used in the sulfonation reaction is 1 to 1 with respect to 4-chloro-3-ethylphenol.
The amount of 2,4-dichloro-3 according to claim 1, which is 0 times by weight.
-Method for producing ethyl-6-nitrophenol. 3. The 2,4-dichloro-3-ethyl-6-nitropheno according to claim 1 or 2, wherein the organic solvent separated after the sulfonation reaction is used as it is in the next sulfonation reaction. -A method for manufacturing a le. 4. The 2,4-dichloro according to claim 1, 2 or 3, wherein the organic solvent is an organic solvent selected from halogenated hydrocarbons, aliphatic hydrocarbons and aromatic hydrocarbons. A method for producing 3-ethyl-6-nitrophenol.