JPH0558962A - Purification of 2,4-dichloro-3-ethyl-6-nitrophenol - Google Patents

Abstract

PURPOSE:To easily produce 2,4-dichloro-3-ethyl-6-nitrophenol in high purity and yield. CONSTITUTION:Crude 2,4-dichloro-3-ethyl-6-nitrophenol is purified by dissolving the crude compound in at least one kind of organic solvent selected from lower alcohol, lower carboxylic acid and lower ketone, precipitating the crystal of the compound and adding water to the system to effect further precipitation of the crystal.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for purifying 2,4-dichloro-3-ethyl-6-nitrophenol. Specifically, crude 2,4-dichloro-3-ethyl-6-nitrophenol is dissolved in at least one organic solvent selected from lower alcohols, lower carboxylic acids and lower ketones, and then crystals are once precipitated. 2,4-dichloro, which is characterized in that crystals are further precipitated by adding water.
The present invention relates to a method for purifying -3-ethyl-6-nitrophenol.

[0002]

2. Description of the Related Art 2,4-Dichloro-3-alkyl-6-nitrophenol is known as an important intermediate for photographic couplers and the like, and its synthetic method is 2,4. -A method of converting a sulfone group of dichloro-3-alkyl-6-sulfophenol into a nitro group using nitric acid or the like (for example, JP-A-47-34326), chlorination of 3-alkyl-6-nitrophenol. Method, a method of hydrolyzing 2,3,6-trichloro-4-nitroalkylbenzene with an alkali (for example, JP-A-61-60634), and nitration of 4,6-dichloro-5-alkylphenol. Various methods such as the method (for example, JP-A-63-303958) are known.

However, the crude nitrophenol thus obtained contains various impurities and it is necessary to improve its purity. As a result of intensive studies on the purification method for producing high-purity nitrophenol, the present inventors have found that the recrystallization method is effective, and lower alcohols, lower carboxylic acids, lower ketones, and other organic solvents. It was found that a high-purity target substance can be easily obtained in a high yield by using a specific method in which crystals are once precipitated, and then water is added, and further various studies are conducted. To complete the present invention.

[0004]

Means for Solving the Problems That is,
4-Dichloro-3-ethyl-6-nitrophenol is dissolved in at least one organic solvent selected from lower alcohols, lower carboxylic acids and lower ketones, and then crystals are once precipitated, and then water is added. 2,4-dichloro-3-ethyl, which is characterized by further precipitating crystals.
-6-Provides an industrially excellent purification method for nitrophenol.

The crude nitrophenol used in the present invention includes, for example, a method of converting a sulfone group of 2,4-dichloro-3-ethyl-6-sulfophenol into a nitro group using nitric acid or the like, 3-ethyl- Method for chlorinating 6-nitrophenol, method for hydrolyzing 1,3,4-trichloro-2-ethyl-4-nitrobenzene with alkali, method for nitrating 4,6-dichloro-5-ethylphenol And the crude product obtained by the above method. 4,
The crude product obtained by the method of nitrating 6-dichloro-5-ethylphenol 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.

In the present invention, crude nitrophenol containing such impurities is dissolved in an organic solvent such as lower alcohols, lower carboxylic acids and lower ketones, and then crystals are once precipitated and then water is added. The lower alcohols, for example, to further precipitate crystals, include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol. Examples of the lower carboxylic acids include acetic acid and propionic acid, and examples of the lower ketones include acetone and methyl ethyl ketone. The amount used is usually 1 to 10 times by weight, preferably 1 to 6 times by weight that of nitrophenol.

The recrystallization is carried out by heating the crude nitrophenol until it is dissolved in the solvent, then once precipitating the crystals, and then adding water to further precipitate the crystals. The temperature at which crystals are once precipitated is usually from room temperature to 10 ° C, and seed crystals can be added if necessary. The amount of water added is usually 0.1 to 5 times the weight of the solvent, preferably
0.1 to 2 times by weight, more preferably 0.1 to 0.5 times by weight when methanol is used, 0.1 to 0.7 times by weight when ethanol, acetic acid, etc. are used, and 0.4 to 0.1 times by weight when isopropanol is used. 1.5 times by weight, and 0.7 to 1.5 times by weight when acetone is used. When the crude nitrophenol contains water, the amount of this water is also added.

It is important to add water after the crystals are once precipitated. For example, when water is added before the precipitation of the crystals is started, or as the solvent, water to be added to the organic solvent is previously prepared. When a dissolved product is used, layer separation occurs and oil precipitates, and even when cooled, the oil droplets solidify in a dispersed form, so the purity of nitrophenol is hardly improved.

After adding water, the precipitation of crystals is usually completed at a temperature of room temperature to -20 ° C. The precipitated crystals are separated from the solvent by means such as filtration, washed as necessary,
To be dried.

[0010]

INDUSTRIAL APPLICABILITY According to the present invention, highly pure 2,4-dichloro
Since 3-ethyl-6-nitrophenol can be easily obtained in high yield, it is advantageous as a method for purifying 2,4-dichloro-3-ethyl-6-nitrophenol on an industrial scale.

[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 1465 g of 6-t-butyl-3-ethylphenol (purity 99%) and 290 g of toluene were placed in a flask and, under stirring, while maintaining the liquid temperature at 25 ° C., 1157 g of chlorine gas was taken for 3 hours. After blowing, nitrogen gas was blown in to remove residual chlorine gas to obtain a toluene solution of 6-t-butyl-2,4-dichloro-3-ethylphenol.

Then, 1157 g of toluene and 429 g of aluminum chloride were added thereto, and the mixture was kept at 45 ° C. under stirring for 4 hours for transalkylation, and then poured into 1287 g of water to decompose aluminum chloride. The organic layer was separated, washed with 644 g of water, and then 2888 g of 13% caustic soda solution was added.
The mixture was stirred at 30 ° C for 1 hour. Then, the aqueous layer was separated, to which 2673 g of toluene and 2300 g of 40% sulfuric acid aqueous solution were added, and the mixture was stirred at 30 ° C for 0.
After stirring for 5 hours, the organic layer was separated and washed with 2084 g of 30% sodium sulfate aqueous solution to give 2,4-dichloro-3-
4828 g of a toluene solution of ethylphenol was obtained.

Then, with stirring, 2531 g of toluene was added thereto, 782 g of 69% nitric acid was added dropwise over 3 hours while maintaining the temperature at 50 ° C., and the mixture was stirred at the same temperature for 1 hour. The organic layer was separated, washed with water, and concentrated under reduced pressure to obtain 2000 g of 2,4-
Dichloro-3-ethyl-6-nitrophenol was obtained. The purity was 90% as determined by liquid chromatography.

Example 1 250 g of isopropyl alcohol was mixed with the crude 2, obtained in Reference Example 1,
After adding 100 g of 4-dichloro-3-ethyl-6-nitrophenol and heating to 50 ° C under stirring to dissolve it, this was heated to 15 ° C.
It was confirmed that crystals were deposited after cooling to room temperature. Then water 25
After 0 g was added dropwise over 1 hour, the temperature was further cooled to 10 ° C.
The crystals formed are filtered, washed with 90 g of 40% isopropyl alcohol aqueous solution at 10 ℃, and dried to give 2,4-
84.4 g of dichloro-3-ethyl-6-nitrophenol was obtained. Purity determined by liquid chromatography 9
9.5%, and the purification yield was 93.3%.

Example 2 The same procedure as in Example 1 was carried out except that the amount of water to be dropped was 107 g, whereby pure 2,4-dichloro-3-ethyl-6-nitrophenol 82.2 was obtained. got g. The purity was 99.6% and the purification yield was 91%.

Example 3 The same procedure as in Example 1 was carried out except that the amount of water added was 375 g, to obtain pure 2,4-dichloro-3-ethyl-6-nitrophenol 87.2. got g. The purity was 99.2% and the purification yield was 96.1%.

Comparative Example 1 100 g of the crude 2,4-dichloro-3-ethyl-6-nitrophenol obtained in Reference Example 1 was added to a solution of 250 g of isopropyl alcohol and 250 g of water, and the temperature was raised to 50 ° C. with stirring. And dissolved. When this was cooled, layer separation occurred at about 25 ° C. and oil was precipitated, and when it was further cooled, the oil droplets solidified. 10 ° C
The mixture was cooled to 40 ° C., the crystals were filtered, washed with 90 g of 40% isopropyl alcohol aqueous solution at 10 ° C., and dried to obtain 91.6 g of 2,4-dichloro-3-ethyl-6-nitrophenol.
The purity was 93.3% and the purification yield was 95%.

Comparative Example 2 The crude 2, obtained in Reference Example 1, was added to 250 g of isopropyl alcohol.
After adding 100 g of 4-dichloro-3-ethyl-6-nitrophenol and heating to 50 ° C under stirring to dissolve it, this was heated to 10 ° C.
Cooled down. The crystals that have formed are filtered, washed with 90 g of isopropyl alcohol at 10 ° C, and then dried to dryness.
30 g of 2,4-dichloro-3-ethyl-6-nitrophenol was obtained. The purity was 99.8% and the purification yield was 33.3%.

Example 4 The crude 2,4-dichloro-3 obtained in Reference Example 1 was added to 375 g of methanol.
Add 100 g of -Ethyl-6-nitrophenol and stir 50 while stirring.
After the temperature was raised to ℃ and melted, this was cooled to 15 ℃ and it was confirmed that crystals were precipitated. Next, 125 g of water was added dropwise over 1 hour, and then further cooled to 10 ° C. The crystals formed were filtered and washed with 90 g of 50% methanol aqueous solution at 10 ° C.
By drying, 85 g of purified 2,4-dichloro-3-ethyl-6-nitrophenol was obtained. The purity was 99.5% and the purification yield was 94%.

Example 5 The procedure of Example 4 was repeated except that the amount of water to be dropped was 66 g, whereby pure 2,4-dichloro-3-ethyl-6-nitrophenol 81.7 was obtained. got g. The purity was 99.6% and the purification yield was 90.4%.

Example 6 The same procedure as in Example 4 was carried out except that the amount of water added was 160 g, whereby pure 2,4-dichloro-3-ethyl-6-nitrophenol 86.3 was obtained. got g. The purity was 99% and the purification yield was 94.9%.

Comparative Example 3 Crude 2,4-dichloro-3-ethyl-6-nitrophenol 10 obtained in Reference Example 1 was added to a solution of 375 g of methanol and 125 g of water.
0 g was added and the temperature was raised to 50 ° C. with stirring to dissolve. When this was cooled, layer separation occurred at about 25 ° C. and oil was precipitated, and when it was further cooled, the oil droplets solidified. After cooling to 10 ° C, the crystals were filtered, washed with 90g of 75% methanol water at 10 ° C, and dried to obtain 92.4g of 2,4-dichloro-3-ethyl-6-nitrophenol. The purity was 92.9% and the purification yield was 95.4%.

Comparative Example 4 The crude 2,4-dichloro-3 obtained in Reference Example 1 was added to 375 g of methanol.
Add 100 g of -Ethyl-6-nitrophenol and stir 50 while stirring.
After the temperature was raised to 0 ° C to dissolve it, it was cooled to 10 ° C.
The formed crystals are filtered, washed with 90 g of methanol at 10 ℃, and dried to give pure 2,4-dichloro-3-ethyl-6-.
60 g of nitrophenol was obtained. The purity was 99.7% and the purification yield was 66.5%.

Example 7 To 350 g of acetic acid, 100 g of the crude 2,4-dichloro-3-ethyl-6-nitrophenol obtained in Reference Example 1 was added, and the mixture was heated to 50 ° C. with stirring and dissolved. Was cooled to 15 ° C, and it was confirmed that crystals were precipitated. Then, 150 g of water was added dropwise over 1 hour and then cooled to 10 ° C. The formed crystals are filtered, washed with 90g of 50% acetic acid aqueous solution at 10 ℃, and then dried to give pure 2,4-dichloro-3-ethyl-6-nitrophenol.
85.1 g was obtained. Purity is 99.4%, purification yield is 94%
Met.

Comparative Example 5 100 g of the crude 2,4-dichloro-3-ethyl-6-nitrophenol obtained in Reference Example 1 was added to 350 g of acetic acid, and the mixture was heated to 50 ° C. with stirring to dissolve it. Cooled to ° C. The crystals formed were filtered, washed with 90 g of acetic acid at 10 ° C and dried to give pure 2,4-dichloro-3-ethyl-6-nitrophenol 3
Obtained 6.1 g. Purity is 99.6%, purification yield is 40%
Met.

Example 8 The crude 2,4-dichloro-3-obtained in Reference Example 1 was added to 200 g of acetone.
Add 100g of ethyl-6-nitrophenol and stir at 40 ℃.
After the temperature was raised to dissolve and the mixture was cooled to 10 ° C., it was confirmed that crystals were precipitated. Then, 300 g of water was added dropwise over 1 hour. The produced crystals were filtered, washed with 90 g of 40% acetone aqueous solution at 10 ° C., and dried to obtain 81.3 g of pure 2,4-dichloro-3-ethyl-6-nitrophenol. The purity was 99.6% and the purification yield was 90%.

Comparative Example 6 100 g of crude 2,4-dichloro-3-ethyl-6-nitrophenol obtained in Reference Example 1 was added to a solution of 200 g of acetone and 300 g of water.
Was added, and the temperature was raised to 40 ° C. with stirring to dissolve. When this was cooled, layer separation occurred at about 25 ° C. and oil was precipitated, and when it was further cooled, the oil droplets solidified. After cooling to 10 ° C, the crystals were filtered, washed with 90g of 40% acetone water at 10 ° C, and dried to obtain 93.8g of 2,4-dichloro-3-ethyl-6-nitrophenol. The purity was 92.5% and the purification yield was 96.4%.

Claims (1)

[Claims] 1. After dissolving crude 2,4-dichloro-3-ethyl-6-nitrophenol in at least one organic solvent selected from lower alcohols, lower carboxylic acids and lower ketones, the crystals are once formed. A method for purifying 2,4-dichloro-3-ethyl-6-nitrophenol, which comprises precipitating and then further crystallizing by adding water.