JPH0446161A - Purification of 2-aryl-2h-benzotriazoles - Google Patents

Abstract

PURPOSE:To purify 2-aryl-2H-benzotriazoles in high purity and yield at a low cost by treating the compounds with an alcoholic solvent and activated clay. CONSTITUTION:A compound of formula [R<1> is H, Cl, 1-4C alkyl, carboxyl, etc.; R<2> is R<1> or 2-9C carboalkoxy; R<3> is H, Cl, 1-12C alkyl, phenyl, etc.; R<4> is H, Cl, OH or 1-4C alkoxy; R<5> is H, 1-12C alkyl or phenyl-(1-4C)alkyl] is treated with an acid clay and an alcoholic solvent (preferably isopropanol) at 40-130 deg.C, preferably at the boiling point of the alcoholic solvent or thereabout. The amount of the solvent is preferably 1-50pts. (especially 2-10pts.) based on 1pt. of the compound of formula and that of the acid clay is preferably 0.1-30wt.% (especially 0.2-10wt.%) based on the compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for purifying 2-aryl-2H-hensitriazoles, and more particularly, to a method for purifying 2-aryl-2H-hensitriazoles with high purity, high yield, and low cost. The present invention relates to a purification method capable of purifying -2H hensitriazoles.

[Conventional technology]

2-Aryl-2H-benzotriazoles have various uses, but are particularly useful compounds as ultraviolet absorbers. Therefore, these compounds are used as ultraviolet absorbers in various fields.

In particular, when these compounds are used in photographic window light materials, highly pure products with little coloring are required.

Regarding purification methods of these compounds, please refer to 2-aryl-2
There are several descriptions in the known literature describing methods for producing H-hensitriazoles.

For example, JP-A-51-138676 discloses a method of dissolving a crude product in toluene and washing it with double sulfuric acid.
No. 1-138678 describes a method in which the crude product is dissolved in toluene and then treated with activated clay, and further described in U.S. Patent No. 4
, No. 041,044 discloses a method of treating a reaction product by adding isopropanol and salts.

However, these conventional purification methods have little purification effect,
This method has problems such as a low purification yield and a disadvantageous method in terms of cost.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for purifying 2-aryl-2H-benzotriazoles with high purity, high purification yield, and low cost. There is a particular thing.

[Structure of the invention]

As a result of intensive research, the present inventors have found that the above objects of the present invention are as follows:
The present inventors have discovered that this can be achieved by a purification method in which -aryl-2H-benzotriazoles are treated using an alcoholic solvent and activated clay, and have completed the present invention.

According to detailed study by the inventors, 2-end-rou2H
- Even if benzotriazoles are recrystallized using an alcoholic solvent, there is no purification effect at all, and
Even if recrystallization is performed in the same manner using a nonpolar solvent such as toluene, ligroin, n-hexano, etc., there is hardly any purification effect and the purification yield is significantly reduced. Furthermore, even when the activated clay was treated with the non-polar solvent at room temperature and under heating, no purification effect was observed at all.

Only when 2-aryl-2H-benzotriazoles are treated using an alcoholic solvent and acid clay, specifically, for example, 2-aryl-2H-benzotriazoles are treated using acidic clay in an alcoholic solvent. The impurities were adsorbed to the activated clay and purified 2-aryl-2H-benzotriazoles were obtained with high purity and high purification yield only when the treatment was carried out by the present inventor. This was completely unexpected for them.

The present invention will be explained in more detail below.

The 2-aryl-2H-benzotriazole in the present invention is represented by the following - Funakura (1).

- In stock (r) In the general formula (1), R' represents a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a carboxyl group, or a sulfonic acid group. represent. R
2 is a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a low m alkoxy group having 1 to 4 carbon atoms, and 2 to 9 carbon atoms;
represents a carbalkoxy group, carboxyl group, or sulfonic acid group. R3 is hydrogen or chlorine atom, carbon number 1
-12 alkyl group, alkoxy group having 1 to 4 carbon atoms, phenyl group, phenyl group substituted with an alkyl group having 1 to 8 carbon atoms, phenoxy group, or phenylalkyl group having 1 to 4 carbon atoms in the alkyl part represents. R4 represents a hydrogen or chlorine atom, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms.

R5 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a phenylalkyl group having 1 to 4 carbon atoms in the alkyl portion.

Next, specific examples of the compounds represented by -Funazo[N are shown below, but the 2-aryl-2H-benzotriazoles that can be purified by the present invention are not limited to the exemplified compounds below.

H CH.

The alcoholic solvent used in the present invention includes:
Methanol, ethanol, n-propanol, isopropanol, isobutanol, 2-methoxyethanol and the like are preferred, with isopropanol being particularly preferred. Moreover, you may use these alcoholic solvents in combination.

The amount used is preferably 1 to 50 times, more preferably 2 to 10 times, the amount of the 2-aryl-2H-benzotriazole.

As the acid clay used in the present invention, the trade name Galleon Earth NS and Galleon Earth NV manufactured by Mizusawa Chemical Co., Ltd.
, Galleon Earth ■2 etc. are preferred, particularly preferably,
This is Galleon Earth NS.

The amount of acid clay used is preferably 0.1 to 30% by weight, more preferably 0.2 to IO, based on the 2-aryl-2H-benzotriazole.
Weight%. The preferred temperature is 40-130°C,
It is preferable to purify at or near the boiling point of the alcoholic solvent used.

〔Example〕

Next, in order to concretely demonstrate the method of the present invention, examples will be described below along with comparative examples. However, of course,
The present invention is not limited to the following examples.

Comparative Example 1 (Purification of Exemplified Compound 1 by Comparative Method) Exemplified Compound 1 was produced as follows according to the synthesis method described in JP-A-51-138678 to obtain a crude product.

That is, a solution obtained by dissolving 20 g of 2-nitro-2'-hydroxy-5' methylazohenzene in a mixture of 55 g of toluene, 25 g of methanol, and 5 g of diethylamine was added to an autoclave No. 11, and then 5% palladium charcoal was added. After adding 1.5 g of hydrogenation catalyst, replacing with hydrogen, and reacting at a hydrogen pressure of 1 atm for 20 minutes at a temperature not exceeding 35°C,
The temperature was raised to 50°C and the reaction was continued for 40 minutes. Next, after replacing hydrogen with nitrogen gas, the palladium hydrocarbon addition catalyst was filtered, washed with toluene, and the filtrate and washings were combined and concentrated to dryness under reduced pressure to give 13.3 g of a tan crude product. I got it.

8 g of the yellow-brown crude product obtained above was dissolved in 1 g of toluene, extracted with 0.8 g of a 70% sulfuric acid aqueous solution, and then 0.8 g of activated clay (Galleon Earth N S ) was added to the toluene layer. After stirring at 25°C for 1 hour, the galleon earth was filtered and the filtrate was condensed.

After distilling off 6 g of toluene, 6.5 g of isopropanol was added dropwise and dissolved therein, then cooled to 0 to 5°C, and the crystals were filtered. After washing this with 4g of cold isopropanol,
Dry under reduced pressure. Yield was 7g. The purification yield is 87
．． It was 5%.

The melting point of the obtained purified product was 128-130°C.

Comparative Example-2 (Purification of Exemplified Compound 1 by the Comparative Method) 8 g of the same crude product as in Comparative Example-1 was added to 40 g of toluene.
After dissolving in d, 0.8 g of Galleon Earth NS was added, and after stirring under reflux for 1 hour, the Galleon Earth NS was filtered, the filtrate was concentrated under reduced pressure, and the residual isopropanol 40- was added.
Dissolved at 0°C. Thereafter, the mixture was cooled to 0 to 5°C, and the precipitated crystals were filtered. This was washed with 4 g of cold isopropanol and dried under reduced pressure. Yield was 7.6g.

Purification yield was 95%.

The melting point of the purified product was 128-130''C.

Comparative Example 3 (Purification of Exemplified Compound 1 by the Comparative Method) 40 d of isopropanol was added to 8 g of the same crude product as in Comparative Example 1, and after stirring under reflux for 1 hour, it was cooled to 0 to 5 ''C and precipitated. The resulting crystals were filtered. After washing with 4 g of cold isopropanol, they were dried under reduced pressure. Yield: 7.6 g
The purification yield was 95%.

The melting point of the obtained purified product was 128 to 130°C.

Example 1 (Purification of Exemplified Compound 1 by the method of the present invention) Impropatol 40d was added to 8 g of the same crude product as in Comparative Example 1, and then 8 g of Galleon Earth NSO was added.
After stirring under reflux for 1 hour, when heated, Galleon Earth NS
was filtered. The filtrate was cooled to 0-5°C, and the precipitated crystals were filtered. The crystals were washed with 4 g of cold inproper tool and dried under reduced pressure to obtain a purified product. The yield was 7.6 g, and the purification yield was 95%. The melting point of the purified product obtained is 1
The temperature ranged from 31.0 to 132.0°C. (The melting point of the pure substance is 131.5-132.0°C).

Comparative Example 4 (Purification of Exemplified Compound 2 by Comparative Method) Exemplified Compound 2 was produced as follows according to the synthesis method described in U.S. Patent No. 4,041,044, and a crude product was obtained. Ta.

That is, 119 g of isopropyl alcohol and 80 g of groin were added to 155 g of 2-nitro-2'-hydroxy-3'5'-di-tert-amyl azohenzene.
While stirring and introducing nitrogen gas, 13.5 g of a 50% aqueous solution of caustic soda was added. Next, add 222 parts of water and add 54 parts of water.
104 g of zinc powder was added in 5 portions at 25 minute intervals at °C. After adding the zinc powder, the temperature was raised to 60"C, and after reacting for 4 hours, the temperature was raised to 65°C, 100 d of an aqueous solution containing 62.5 g of sodium sulfate was added, and the temperature was raised to 70°C, and the reaction was continued for 15 minutes. , stop stirring, collect the top two layers, 7.5%
The organic layer was washed twice with 175 d of hydrochloric acid, and 14 g of 32% hydrochloric acid was added to the organic layer, followed by 220 g of isopropanol, crystallized, filtered and dried to obtain 128 g of a yellow crude product.

After dissolving 50 g of the yellow crude product obtained above in 70 g of toluene, 55 g of Galleon Earth N was added, and 1
After stirring at reflux for an hour, the Galleon Earth NS was filtered and the filtrate was cooled to 0-5°C. The precipitated crystals were filtered, washed with 20 mfl of cold toluene, and then dried under reduced pressure. Yield is 2
At 5 g, the purification yield was 50%.

The melting point of the obtained purified product was 80-82°C.

Comparative Example 5 (Purification of Exemplary Compound 2 by Comparative Method) After dissolving 50 g of the same crude product as Comparative Example 4 in 7M ligroin, 510 g of Galleon Earth N was added, and after stirring under reflux for 1 hour, the Galleon Earth NS was filtered. and reduce the filtrate to 0~
Cooled to 5°C. The precipitated crystals were filtered, washed with cold ligroin 20d, and then dried under reduced pressure. The yield was 30 g, and the purification yield was 60%.

The melting point of the obtained purified product was 80-82°C.

Comparative Example-6 (Purification of Exemplary Compound 2 by Comparative Method) 200 d of isopropanol was added to 50 g of the same crude product as in Comparative Example-4, stirred under reflux for 1 hour, and then cooled to 0 to 5°C. Filter the precipitated crystals and add 20 ml of cold isoprobanol.
After washing with water, it was dried under reduced pressure. The yield was 47.5 g, and the purification yield was 95%.

The melting point of the obtained purified product was 79.5-82°C.

Example 2 (Purification of Exemplified Compound 2 by the method of the present invention) Same as Comparative Example 4 - 200 d of isopropanol was added to 50 g of the crude product, then 2.5 g of Galleon Earth NS was added, and the mixture was stirred under reflux for 1 hour. After that, the Galleon Earth NS was filtered and the filtrate was cooled to 0-5°C. The precipitated crystals were filtered, washed with 20 drops of cold isopropanol, and then dried under reduced pressure. The yield was 48 g, and the purification yield was 96%.

The melting point of the obtained purified product was 82.0 to 82.5°C. (The melting point of the pure substance is 82.5-83.0°C).

Evaluation of Examples and Comparative Examples 2-aryl- obtained by purification in each of the above Examples and Comparative Examples
Table 1 shows the measured values of the transmittance of 2H-benzotriazoles and the pure charcoal measured by liquid chromatography.

The surface transmittance is 2-aryl-2H-hencytriazole 1
．． 00g dissolved in 10.0d of ethyl acetate. The transmittance measuring device used was Hitachi Spectrophotometer 320.

Liquid chromatography manufactured by JASCO Corporation was used.

From Table 1, it can be seen that the purification method of the comparative example shows no purification effect at all (see comparison of data with crude product).

It can be seen that only the examples of the present invention showed significant purification effects and were able to provide 2-aryl-2H-penztriazoles with high purification yields.

When other compounds were similarly purified, purified products could be obtained with high purity and high purification yield, as in Examples 1 and 2.

〔Effect of the invention〕

As mentioned above, according to the purification method of the present invention, diaryl-
Since 2H-benzotriazoles can be purified with high purity and high purification yield, and can be obtained using inexpensive activated clay and alcoholic solvents, they can be purified at low cost.

Claims (1)

[Claims] (1) A method for purifying 2-aryl-2H-benzotriazoles, which comprises treating 2-aryl-2H-benzotriazoles using an alcoholic solvent and activated clay.