JPS61215378A - Production of 2-phenylbenzotriazole - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an ultraviolet light absorber technologically and economically advantageously, by reducing a specific o- nitroazobenzene derivative as a raw material with an aldehyde in the presence of an aromatic ketone and a base. CONSTITUTION:An o-nitroazobenzene derivative shown by the formula I (R1 is H, Cl, 1-4C lower alkyl, lower alkoxy, carboxy, etc.; R2 is H, Cl, 1-4C lower alkyl, or lower alkoxy; R3 is H, Cl, 1-12C alkyl, 1-4C lower alkoxy, phenyl, phenoxy, etc.; R4 is H, Cl, OH, 1-4C alkoxy) or an N-oxide shown by the formula II which is its intermediate is reduced with an aldehyde shown by the formula RCHO (R is H, alkyl, phenyl, etc.) preferably in a solvent in the presence of an aromatic ketone compound catalyst such as 9-fluorenone, etc., and a base such as NaOH, etc., to give the aimed compound. EFFECT:No problem with respect to pollution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2-phenylbenzotriazoles represented by the following general formula (2), which are useful as ultraviolet absorbers.

General formula ■ (However, R1 represents hydrogen or a chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, or a sulfonic acid group, and R3 represents a hydrogen or chlorine atom, a carbon number 1-4 lower alkyl group or 1-4 carbon atoms
4 represents a lower alkyl group, and R1 is hydrogen or a chlorine atom.

An alkyl group having 1 to 12 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted with an alkyl group having 1 to 8 carbon atoms, a phenoxy group, or an alkyl group having 1 to 4 carbon atoms. represents a phenylalkyl group, R4
is a hydrogen or chlorine atom.

2-phenylbenzotriazoles (representing a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms) are known as ultraviolet absorbers added to plastics, paints, oils, etc.

Conventionally, these 2-phenylbenzotriazoles have been produced by chemically or electrolytically reducing the 0-nitroazobenzene derivative represented by the general formula I (where R, , R, , R, and R4 are the same as the general formula ①). Manufactured by However, the conventional methods have their own advantages and disadvantages and are not completely satisfactory.

For example, the corresponding 2-phenylbenzotriazoles can be obtained in good yield by chemically reducing and reducing the derivatives of Japanese Patent Publication No. 3'7-5934 and US Patent No. 1 with zinc powder in an alcoholic sodium hydroxide solution. However, the di-sodium hydroxide-zinc powder system has the problem of wastewater pollution in that it produces zinc sludge.

Ammonium sulfide, alkali sulfides, zinc-ammonia systems, hydrogen sulfide-sodium systems and zinc-hydrochloric acid systems have also been used as chemical reducing agents in the reduction reaction as disclosed in U.S. Pat. No. 2,362,988. However, this method generates a large amount of sulfite or zinc acid gas, and the sulfuric reducing agent used generates toxic hydrogen sulfide, leading to air pollution problems.

JP-A-5I-138679 and JP-A No. 51-1386
Publication No. 80 describes a reduction method by adding pressurized hydrogen, but these methods are unsatisfactory in terms of yield and economy, and also cause side reactions to occur during the reaction. It is impossible to obtain a product with high purity, and this tendency is particularly strong when obtaining a target product containing chlorine atoms (in this case, side reactions such as dechlorination reactions occur).

An object of the present invention is to provide a method for producing 2-phenylbenzotriazoles that can solve all the problems inherent in the above-mentioned conventional techniques.

In order to solve the above-mentioned problems in the conventional production method of 2-phenylbenzotriazoles, the present inventor conducted various studies and found that: 1) the 0-nitroazobenzene derivative of the general formula I was combined with a catalyst consisting of an aromatic ketone compound; and reduction with aldehydes in the presence of a base, or 2) general formula ■
If the 2-phenylbenzotriazole-N oxide represented by the formula ; has also been found to be advantageous and can be obtained without causing any pollution problems.

Method 1) of the present invention is carried out through the following one or two steps depending on the temperature and the amount of aldehyde used.

In the case of Step 1 (Step a below): The temperature conditions in this case are approximately 20-130°C (preferably 4°C).
0~LQQ°C) is appropriate. The appropriate amount of aldehyde to be used is about 2 to 4 moles per mole of the compound of formula I.

Note that R is hydrogen, an alkyl group, a phenyl group, or an I-substituted phenyl group.

In the case of 2nd step (steps S and C below): The temperature conditions in this case are the same as in the method 1), 20~
A temperature of 130°C (preferably 40 to 100°C) is suitable.

Although this method involves two steps, the amount of 6-aldehydes used in the step is from 1 to 1 per mole molecule of the compound of formula I in the step I, which may be more advantageous in terms of quality and yield than the method in step I.
2 mol molecules, and in Step C [this case corresponds to method 2) of the present invention], 1 to 2 mol molecules per 1 mol molecule of compound 2) is suitable.

(I) ○ (I[I) (II) In both cases of L) and 2), in order to facilitate the reaction, an aqueous solution, alcohols, toluene,
The reaction is carried out in an inert solvent such as acetone, dimethyl sulfoxide, acetonitrile, or a mixture of the inert solvent and water.

Further, a surfactant, a phase transfer catalyst, etc. may be further added as necessary.

Specific examples of the compound of general formula I used as a raw material in method 1) of the present invention include the following.

1) 2-nitro-2'-hydroxy-5'-methylazobenzene 2) 2-nitro-2'-hydroxy-5'-cyoctylazobenzene 3) 2-nitro-21-hydroxy-5'-butylazobenzene 4) 2-nitro-2', 4'-dihydroxyazobenzene 5) 2-nitro-4-chloro-2', 4'-dihydroxyazobenzene 6) 2-nitro-2'-hydroxy-4'-methoxyazobenzene 7 ) 2-nitro-2'-hydroxy-5'-t-amyl azobenzene 8) 2-nitro-4'-chloro-22-hydroxy-5
'-t-Amyl azobenzene 9) 2-nitro-2'-hydroxy-5'-〇-dodecyl azobenzene 10) 2-nitro-4-chloro-2'-hydroxy-5
' -n-dodecyl azobenzene 11) 2-nitro-4-chloro-2'-hydroxy-
5'-t-octylazobenzene 12) 2-nitro-4-methyl-2'-hydroxy-5
' ~ methylazobenzene 13) 2-nitro-4,6-dichloro-2'-hydroxy-5'-t-butylazobenzene 14) 2-nitro-4-carboxy-2'-hydroxy-5-methylazobenzene of the present invention Specific examples of the compound of general formula (1) used in the method 2) include 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-oxide 2-(2-hydroxy-5-t,butylphenyl)benzo Triazole-N-oxide 2-(2-hydroxy-5-t-octylphenyl)benzotriazole-N-oxide 2-(2,4-dihydroxyphenyl)benzotriazole-N-oxide 2-(2,4'-dihydroxy phenyl)-5-chlorobenzotriazole-N-oxide 2-(2-hydroxy-4'-methoxyphenyl)benzotriazole-N-oxide 2-(2-hydroxy-5-t-amylphenyl)benzotriazole-N- Oxide 2-(2-hydroxy-5-n-dodecylphenyl)benzotriazole-N-oxide 2-(2-hydroxy-5-n-dodecylphenyl)-
5-chlorobenzotriazole-N-oxide 2-(2
-hydroxy-5-t-octylphenyl)-5-chlorobenzotriazole-N-oxide 2-(2-hydroxy-5-methylphenyl) to 5-methylbenzotriazole-N-oxide 2-(2-hydroxy-5 -methylphenyl)-5-carboxybenzotriazole-N
-Oxide These N-oxides of general formula (1) are preferably prepared using the O-nitroazobenzene derivative of general formula I as a raw material by the method described in step 1) above, but they may also be prepared by other known methods. is also possible.

Specific examples of aldehydes that are reducing agents of the present invention include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, anisaldehyde, etc. Among them, formaldehyde and paraformaldehyde are preferred, and the amount used is as described in 1) above. In the method, 2 to 4 mol molecules are appropriate for 1 mol molecule of the 0-nitroazobenzene derivative of formula I, and in the method 2), 1 to 2 mol molecules are appropriate for 1 mol molecule of the N-oxide of formula is appropriate.

Specific examples of aromatic ketone compounds that are catalysts of the present invention include at least one of pencebuenone; benzophenone substituted with an alkyl group, alkoxyl group, a halogen atom, or a hydroxyl group; benzanthrone; anthrone; 9-fluorenone; and 9-xanthenone. Among them are 9 species.
-Fluorenone and anthrone 4-benzanthrone are preferred; two or more of these may be used as a mixture and may be rather preferred. In any case, the amount used is
An appropriate amount is 0.2 to 30% by weight, preferably 2 to 2% by weight, based on the weight of the O-nitroazobenzene derivative of formula (1).
It is 0% by weight. Also, when using the N-oxide of formula (1) as a starting material, the amount is suitably 0.2 to 30%, preferably 2 to 20% by weight, based on the weight of the N-oxide of formula (2).

As the base, sodium hydroxide or potassium hydroxide is preferred, and the appropriate amount of each is 1 to 12 moles per 1 mole of the 〇-nitroazobenzene derivative of general formula I or the N-oxide of general formula ②. and preferably 2
~8 mole molecules.

The present invention will be explained below by way of examples.

Example 1 12.9 g of 2-nitro 2'-hydroxy-5'-methylazobenzene was added to a mixture of 60 ts Q of methanol, 30 Q of water and 12.4 g of 97% caustic soda, and the temperature was raised to 65°C while stirring. , cooled to 40°C, and added 9-
Next to 0.8 g of fluorenone, 2.1 g of 80% paraformaldehyde was added over 1 hour, the temperature was raised to the boiling point (75°C) in 1 hour, and the reaction was stirred at the boiling point for 6 hours. Most of the azobenzene was removed. disappears, producing 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-
Oxide is produced and the reaction in step S is completed.

Next, in order to carry out the reaction in step C, the temperature was cooled to 70°C, 0.2 g of 9-fluorenone and 2.5 g of 80% paraformaldehyde were added over 30 minutes, and the temperature was raised to the boiling point (75°C).
When the reaction is further stirred for 4 hours, the N-oxide disappears and Step C is completed.
reaction ends. Water 50ra 62% after adding Q
It was neutralized to pH 8 with 16 g of sulfuric acid, and the precipitated crystals were separated by suction filtration, thoroughly washed with water, methanol, and dried to yield 9.2 g of 2-(2-hydroxy-5-methylphenyl)benzo. A triazole was obtained. Yield 81
．． 8%, melting point 128-130°C.

Example 2 Instead of 12.9 g of 2-nitro-2'-hydroxy-5'-methylazobenzene, a) 14.9 g of 2-nitro-2'-hydroxy-5'-butylazobenzene, 2-
Nitro 2'-hydroxy-5'-1-octylazobenzene F, 8 g and c) 2-nitro-2',4'-
The same method as in Example 1 was repeated except that 14.9 g of dihydroxyazobenzene was used in each case, and the following results were obtained.

a) Yield of 2-(2-hydroxy-5-t-butylphenyl)benzotriazole 11.0. , Yield 84. θ% melting point 9
5.5-98.0°C) 2-(2-Hydroxy-5-thi-octylphenylbenzotriazole Yield: 12.8g, Yield: 79.0% Melting point: 1
03-105°C c) 2-(2.4-dihydroxyphenyl)benzotriazole Yield: 9.2g, Yield: 70.5% Melting point: 18
7 to 189°C Example 3 17.7 g of 95% caustic potassium was added to a mixture of ethyl alcohol 80+*Q and dissolved, and 2-nitro-2'-hydroxy-5'-methylazobenzene 1 was heated at 50 to 60'C.
2.9 g of 9-fluorenone was added over 30 minutes with stirring, and 0.6 g of 9-fluorenone and 5.6 g of 35% formalin were added to the mixture for 30 minutes.
When the azobenzene is added for 1 minute, stirred for 1 hour at 65 to 70°C, and then reacted at the boiling point (85°C) for 4 hours, most of the azobenzene disappears and the reaction in step S is completed. Next, add 0.4 g of anthrone and 6.4 g of 35% formalin for 30 minutes.
When the mixture is added dropwise over a period of 8 hours and the reaction is stirred for 8 hours, the N-oxide disappears and the reaction in Step C is completed. Next, water 50rs Q
The precipitated crystals were separated by suction filtration, thoroughly washed with water, washed with ethyl alcohol, and dried. hydroxy-5-t-octylphenyl)
Obtained benzotriazole. Yield 77.3%, melting point 13
8-140℃.

Example 4 Methanol 6011 water 30mfl, 97% caustic soda 1
2,4 g and 2-nitro-2'-hydroxy-5'-methylazobenzene were mixed and stirred, 1.2 g of benzanthrone was added at a temperature of 65 to 70°C, and then 4.6 g of 80% paraformaldehyde was added over 2 hours. Add it.

After the addition is complete, stir the reaction at the boiling point (75°C) for 5 hours, and the 0-nitroazobenzene will disappear, completing the reaction in step S. To carry out the reaction in step C, the reaction is continued with stirring for 6 hours, and the N-oxide disappears, completing the reaction in step C. Next, add 50mQ of water, 62%H, So416g
Neutralize to pH 8 with
2-(2-hydroxy-5-methylphenyl)benzotriazole was obtained in a yield of 8.4 g. Yield 74.7%.

Melting point: 128-130°C.

Example 5 2-nitro-2'-hydroxy-5 was added to a mixture of 601 L methanol, 30 m water, Q and 124 g of 97% caustic soda.
12.9 g of '-methylazobenzene was added, and the temperature was raised to 65°C with stirring, then 1.2 g of 9-fluorenone and 6.5 g of 90% acetaldehyde were added over 1 hour, and the mixture was heated at the boiling point (75°C) for 6 hours. When stirred and reacted.

Most of the azobenzene disappears, 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-oxide is produced, and the reaction in step S is completed. In order to carry out the reaction in step C, if the reaction is continued with stirring at the boiling point for 5 hours, N
-Oxide disappears.

The reaction in step C is completed. After adding water SOm ft, it was neutralized to pH 8 with 16 g of 62% sulfuric acid, and the precipitated crystals were separated by absorption filtration, thoroughly washed with water, washed with methanol, and dried. 9.1. 2-(2-hydroxy-5-methylphenyl)benzotriazole was obtained in a yield of . Yield 80.9%, melting point 128-130°C.

Example 6 Methanol 110■a, water 20■2, 97% caustic soda 12.4g and 2-nitro-2'-hydroxy~5'
- 17.8 g of t-octyl azobenzene was mixed and stirred,
After adding 2.4 g of 9-fluorenone at a temperature of 65 to 70 °C, 6 g of 80% paraformaldehyde was added over 4 hours, and then the reaction was stirred at the boiling point (73 °C) for 6 hours, and the ring reaction was completed. do. Next, add 50 ta of water to the reaction solution.
Q was added to neutralize to 416 g of 62% H*I O to pH 8, and the precipitated crystals were separated by suction filtering, thoroughly washed with water, and then washed with methanol.

2-(2-hydroxy-5-t-octylphenyl)benzotriazole was obtained in a yield of 13.1 g. Yield 81
, θ%, melting point 103-105°C.

Claims (1)

[Claims] 1. General formula I ▲ Numerical formulas, chemical formulas, tables, etc.▼ (However, R_1 is a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, Represents a carboxyl group or a sulfonic acid group, R_2 represents hydrogen or a chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, or a lower alkoxyl group having 1 to 4 carbon atoms, and R_3 represents hydrogen or a chlorine atom, or a lower alkyl group having 1 to 4 carbon atoms. represents an alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted with an alkyl group having 1 to 8 carbon atoms, a phenoxy group, or a phenylalkyl group having 1 to 4 carbon atoms in the alkyl part. , R_4 represents a hydrogen or chlorine atom, a hydroxyl group, or an alkoxyl group having 1 to 4 carbon atoms) is reduced with an aldehyde in the presence of an aromatic ketone compound and a base. A method for producing 2-phenylbenzotriazoles represented by general formula II ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_2, R_3, and R_4 are the same as in general formula I). 2. General formula III ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 is a hydrogen or chlorine atom, a lower alkyl group with 1 to 4 carbon atoms, a lower alkoxyl group with 1 to 4 carbon atoms, a carboxyl group, or a sulfonic acid group. , R_2 represents a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, or a lower alkoxyl group having 1 to 4 carbon atoms, and R_3 represents a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, and R_3 represents a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, and
12 alkyl group, lower alkoxyl 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. In the formula, R_4 represents a hydrogen or chlorine atom, a hydroxyl group, or an alkoxyl group having 1 to 4 carbon atoms. ) General formula II characterized by reducing 2-phenylbenzotriazole-N-oxides represented by aldehydes in the presence of an aromatic ketone compound and a base ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (However, A method for producing 2-phenylbenzotriazoles represented by formula III (R_1, R_2, R_3, R_4 are the same as in general formula III).