JPH05208938A - Method for purifying 2-nitro-4,6-dichloro-5-methylphenol - Google Patents

Abstract

PURPOSE:To obtain the subject high-purity compound in high yield by carrying out recrystallization from a hydrous lower alcohol having a specific moisture content. CONSTITUTION:Crude 2-nitro-4,6-dichloro-5-methylphenol is recrystallized from a solvent of hydrous lower alcohols having 2-50%, preferably 5-40% moisture content. The solvent is used in an amount of 1-5 times, preferably 2-4 times based on the nitrophenol in the crude product. A crude product prepared by carrying out methods for converting sulfone group in 2,4-dichloro-3-methyl-6- sulfophenol into nitro group with nitric acid, etc., chlorinating 3-methyl-6- nitrophenol, hydrolyzing 1,3,4-trichloro-2-methyl-4-nitrobenzene with an alkali, etc., is used as the crude nitrophenol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for purifying 2-nitro-4,6-dichloro-5-methylphenol.
Characterized by recrystallizing crude 2-nitro-4,6-dichloro-5-methylphenol from hydrous lower alcohols
The present invention relates to a method for purifying 2-nitro-4,6-dichloro-5-methylphenol.

[0002]

[Prior Art and Problems to be Solved by the Invention] 2-Nitro
-4,6-Dichloro-5-alkylphenol is known as an important intermediate for photographic couplers, and its synthetic method is also based on the sulfone group of 2,4-dichloro-3-alkyl-6-sulfophenol such as nitric acid. To convert it to a nitro group (for example, JP-A-47-34326), a method of chlorinating 3-alkyl-6-nitrophenol, an alkali of 2,3,6-tochloro-4-nitroalkylbenzene. Method of hydrolysis using (for example,
JP-A-61-60634), 4,6-dichloro-
Method for nitrating 5-alkylphenols (eg,
Various methods such as JP-A-63-303958) are known.

However, the crude nitrophenols thus obtained contain various impurities and it is necessary to improve the purity. The present inventors have conducted extensive studies on the purification method for producing high-purity nitrophenols, and as a result, the recrystallization method is effective,
It was found that if a water-containing lower alcohol having a specific water content is used as the solvent, not only the target product can be obtained in high purity but also the yield can be maintained at a high level, and further investigations will be conducted. Completed the invention.

[0004]

Means for Solving the Problems That is,
Water content of nitro-4,6-dichloro-5-methylphenol 2
Industrially superior 2-nitro-4,6-dichloro-5 characterized by being recrystallized from -50% hydrous lower alcohols
-Provides a method for purifying methylphenol.

The crude nitrophenol used in the present invention is, for example, a method of converting the sulfone group of 2,4-dichloro-3-methyl-6-sulfophenol into a nitro group using nitric acid or the like, 3-methyl- Method for chlorinating 6-nitrophenol, method for hydrolyzing 1,3,4-trichloro-2-methyl-4-nitrobenzene with alkali, method for nitrating 4,6-dichloro-5-methylphenol And the crude product obtained by the above method. 4,
The crude product obtained by the method of nitrating 6-dichloro-5-methylphenol is preferably used. In these methods, it is inevitable that impurities are mixed in, and various kinds of impurities such as those caused by side reactions and those caused by impurities in the raw materials used are mixed in.

According to the present invention, crude nitrophenol containing such impurities is recrystallized from a specific solvent containing hydrous lower alcohols having a water content of 2 to 50%.
Examples of the lower alcohols include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and tert-butanol.

Recrystallization is carried out by heating the crude nitrophenol until it dissolves in the solvent and then cooling. The water content is usually prepared by diluting the solvent with a predetermined amount of water before recrystallization, but it can also be prepared by adding water after the crude nitrophenol is dissolved, or by adding water after cooling. It can also be prepared. When the crude nitrophenol contains water, the amount of water is also taken into consideration for the preparation.

The water content of the solvent is important and is adjusted so as to be in the range of 2 to 50%. When it is less than 2%, the purity is good, but the yield is remarkably lowered. On the contrary, when it exceeds 50%, the yield is good but the purity is remarkably lowered.
It is preferably 5 to 40%. The amount of the solvent used is usually 1 to 5 times by weight, preferably 2 to 4 times by weight that of the nitrophenol in the crude product.

The cooling temperature is usually from room temperature to about -20 ° C, and seed crystals can be added if necessary. The precipitated crystals are separated from the solvent by means such as filtration, washed and dried if necessary.

[0010]

According to the present invention, not only high purity 2-nitro-4,6-dichloro-5-methylphenol of 99% or more can be obtained, but also the yield can be maintained at a high level.

[0011]

EXAMPLES Next, the present invention will be explained in detail based on examples, but the present invention is not limited to these.

Reference Example 1 6-t-Butyl-3-methylphenol (500 g, purity 99%) and toluene (102 g) were placed in a flask, and 199 g of chlorine gas was added for 3 hours while stirring and maintaining the liquid temperature at 25 ° C. Then, nitrogen gas was blown in to remove residual chlorine gas to obtain 805 g of a toluene solution of 6-t-butyl-2,4-dichloro-3-methylphenol (content: 85.4%).

Then, 208 g of toluene and 156 g of aluminum chloride were added thereto, and the mixture was heated at 45 ° C. for 4 hours under stirring to carry out a transalkylation reaction. The aluminum was decomposed. Then, the organic layer was separated, washed with 150 g of water, and
560 g of 20% aqueous sodium hydroxide solution was added, and the mixture was stirred at 30 ° C. for 1 hour. The aqueous layer was separated, toluene 1235 g and 20% sulfuric acid aqueous solution 830 g were added thereto, and the mixture was stirred at 30 ° C. for 0.5 hours. Then, the organic layer was separated and washed with 870 g of 30% sodium sulfate water to obtain 1746 g of a toluene solution of 2,4-dichloro-3-methylphenol (content: 29.1%).

Then, after adding 540 g of toluene to this,
While maintaining the temperature at 50 ° C., 305 g of 68% nitric acid aqueous solution was added dropwise over 3 hours with stirring, and the temperature was kept at the same temperature for 1 hour. Then
The organic layer was separated, washed with water, and concentrated under reduced pressure to give 2,4-dichloro-3-methyl-6-nitrophenol 694.
3g was obtained. When analyzed by gas chromatography,
Nitride of toluene was not observed. Purity is 90
%Met.

Example 1 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was mixed with 5% hydrous isopropyl alcohol.
After adding 350g and heating up to 70 ℃, cool to 10 ℃,
The produced crystals were filtered, washed with 90 g of 50% hydrous isopropyl alcohol at 10 ° C., and dried to obtain 83.4 g of pure 2-nitro-4,6-dichloro-5-methylphenol.
The purity determined by gas chromatography was 99.9%, and the purification yield was 92.6%.

Example 2 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was added with 15% hydrated isopropyl alcohol.
After adding 350g and heating up to 70 ℃, cool to 10 ℃,
The produced crystals were filtered, washed with 90 g of 50% hydrous isopropyl alcohol at 10 ° C., and dried to obtain 85.5 g of purified 2-nitro-4,6-dichloro-5-methylphenol.
When the purity was determined by gas chromatography, it was 99.9%, and the purification yield was 94.9%.

Example 3 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was mixed with 50% hydrous isopropyl alcohol.
After adding 400g and heating up to 70 ℃, cool to 10 ℃,
The resulting crystals were filtered, washed with 90 g of 50% hydrous isopropyl alcohol at 10 ° C., and dried to obtain 86.6 g of pure 2-nitro-4,6-dichloro-5-methylphenol.
When the purity was determined by gas chromatography, it was 99.9%, and the purification yield was 96.2%.

Comparative Example 1 To 100 g of the crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1, 350 g of 0.1% hydrous isopropyl alcohol was added, and the temperature was raised to 70 ° C. After cooling to ℃, the resulting crystals are filtered, washed with 90 g of 50% hydrous isopropyl alcohol at 10 ℃, and dried to give the desired product.
71.6 g of nitro-4,6-dichloro-5-methylphenol was obtained. The purity was determined by gas chromatography to be 99.9.
%, And the purification yield was 79.5%.

Comparative Example 2 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was mixed with 70% hydrous isopropyl alcohol.
After adding 480g and heating up to 70 ℃, cool to 10 ℃,
The resulting crystals were filtered, washed with 90 g of 50% hydrous isopropyl alcohol at 10 ° C. and dried to obtain 88.1 g of purified 2-nitro-4,6-dichloro-5-methylphenol.
When the purity was determined by gas chromatography, it was 98.0%, and the purification yield was 97.9%.

Example 4 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol
15% hydrous isopropyl alcohol (purity 70%) 275
After adding g, the mixture was heated to 70 ° C, cooled to 10 ° C, and the formed crystals were filtered, washed with 50 g of 15% hydrous isopropyl alcohol at 10 ° C, and dried to give pure 2-nitro-
66.4 g of 4,6-dichloro-5-methylphenol was obtained. When the purity was determined by gas chromatography, it was 98.8%, and the purification yield was 94.7%.

Example 5 To 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was added 350 g of 5% hydrous methanol and the temperature was raised to 60 ° C., followed by 10 ° C. The resulting crystals were filtered, washed with 90 g of 50% water-containing methanol at 10 ° C., and dried to obtain 82.7 g of purified 2-nitro-4,6-dichloro-5-methylphenol. The purity was determined by gas chromatography to be 99.9%, and the purification yield was 91.8%.
Met.

Example 6 To 100 g of crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1 was added 350 g of methanol containing 30% water and the temperature was raised to 60 ° C. The resulting crystals were filtered, washed with 90 g of 50% water-containing methanol at 10 ° C. and dried to obtain 85.8 g of pure 2-nitro-4,6-dichloro-5-methylphenol. The purity was determined by gas chromatography to be 99.7%, and the purification yield was 95.1%.
Met.

Comparative Example 3 To 100 g of the crude 2-nitro-4,6-dichloro-5-methylphenol obtained in Reference Example 1, 350 g of 0.1% hydrous methanol was added and the temperature was raised to 60 ° C., then 10 ° C. The resulting crystals are filtered, washed with 90 g of 50% hydrous methanol at 10 ° C.,
By drying, 75.0 g of purified 2-nitro-4,6-dichloro-5-methylphenol was obtained. The purity was determined by gas chromatography to be 99.9%, and the purification yield was 83.2%.
%Met.

Front Page Continuation (72) Inventor Shizuo 2200 Tsurusaki, Oita City, Oita Prefecture Sumitomo Chemical Co., Ltd.

Claims (1)

[Claims] 1. 2-Nitro-4,6-dichloro, characterized in that crude 2-nitro-4,6-dichloro-5-methylphenol is recrystallized from hydrous lower alcohols having a water content of 2 to 50%.
-5-Methylphenol purification method