JPS6372683A - Production of 2-phenylbenzotriazoles - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an ultraviolet absorber, by reducing a specific o-nitroazobenzene derivative with a primary or secondary alcohol in the presence of an aromatic ketone compound catalyst and a base. CONSTITUTION:The objective compound of formula II can be produced by reducing the o-nitroazobenzene derivative of formula I (R1 is H, Cl, 1-4C alkyl, 1-4C alkoxy, COOH or sulfonic acid residue; R2 is H, Cl, 1-4C alkyl or 1-4C alkoxy; R3 is H, Cl, 1-12C alkyl, 1-4C alkoxy, phenyl, phenyl substituted with 1-8C alkyl, phenoxy or phenyl-1-4C alkyl; R4 is H, Cl, OH or 1-4C alkoxy; R5 is H, 1-12C alkyl or phenyl-1-4C alkyl) with a primary or secondary alcohol in the presence of a base and a catalyst consisting of an aromatic ketone compound.

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, R 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 R2 represents a hydrogen or chlorine atom, a carbon Lower alkyl group having 1 to 4 carbon atoms or 1 to 4 carbon atoms
4, R1 represents a hydrogen or chlorine atom, an alkyl group having 1 to 12 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a phenyl group, or a phenyl substituted with an alkyl group having 1 to 8 carbon atoms. group, a fenoquine group, or a phenylalkyl group whose alkyl moiety has 1 to 4 carbon atoms, R4 represents a hydrogen or chlorine atom, a hydroxyl group, or an alkoxyl group having 1 to 4 carbon atoms, and Rs is a hydrogen atom or a phenylalkyl group whose alkyl moiety has 1 to 4 carbon atoms. ~12 alkyl group or a phenylalkyl group in which the alkyl moiety has 1 to 4 carbon atoms;
-Phenylbenzotriazoles are known as ultraviolet absorbers that are added to plastics, paints, oils, etc.

Conventionally, these 2-phenylbenzotriazoles have been produced by chemically or electrolytically reducing an 0-nitroazobenzene derivative represented by the following (where R>-Rx, R3-R4, and Rs are the same as the general formula H). ing. However, the conventional methods have their own advantages and disadvantages and are not completely satisfactory.

For example, in Japanese Patent Publication No. 37-5934 and U.S. Pat. No. 3,773,751, the corresponding 2-phenylbenzene derivative is chemically reduced with zinc powder in an alcoholic sodium hydroxide solution. Although triazoles have been obtained in good yields, this sodium hydroxide-zinc system has the problem of wastewater pollution in that it produces zinc sludge.

Ammonia sulfide, alkali sulfides, zinc-ammonia systems, sodium hydrogen sulfate 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. Although,
This method produces large amounts of sulfites or zinc salts, so
This causes the problem of wastewater pollution, and furthermore, the sulfite salts generate sulfur dioxide gas, and the sulfuric reducing agent used generates toxic hydrogen sulfide, leading to air pollution problems.

JP-A-51-138679 and JP-A No. 51-1386
No. 80 describes a reduction method by adding pressurized hydrogen, and JP-A-50-88072 describes a reduction method using hydrazine, but these methods are unsatisfactory in terms of yield and economy. Moreover, it is impossible to obtain the target product in high purity due to side reactions occurring during the reaction, and this tendency is especially true when obtaining the target product containing chlorine atoms (in this case, side reactions such as dechlorination reactions) reaction occurs).

Furthermore, JP-A-59-170172, filed by the present inventor, describes a method for reducing 0-nitroazobenzene with alcohols, but quinones as catalysts irritate the skin and mucous membranes, and in some cases Since it may cause a rash, care must be taken when handling it to avoid direct contact with the skin or exposure to its vapor. Further, the catalyst after use has the drawback that it is changed or deteriorated and its ability as a catalyst decreases, making it difficult to recover.

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

The present inventors have made efforts to solve the above-mentioned problems in the conventional production method of 2-phenylbenzotriazoles, and have made efforts to develop a catalyst that is easy to handle and causes less deterioration.As a result of various studies, 1) Formula I Reducing the 0-nitroazobenzene derivative with a primary alcohol and/or a secondary alcohol in the presence of a catalyst and a base consisting of an aromatic ketone compound, or
Or 2) General formula ■ (However, R1, Rz-Ri, R4, Rs are as described above)
If the 2-phenylbenzotriazole-N-oxide represented by is similarly reduced with a primary alcohol and/or a secondary alcohol in the presence of a catalyst consisting of an aromatic ketone compound and a base, the object of general formula H can be reduced. It was discovered that the product can be obtained technically and economically advantageously, and without causing any pollution problems.

Method 1) of the present invention is carried out through the following one or two steps depending on the reaction temperature, reaction time, and amount of primary alcohol or secondary alcohol consumed.

(i) In the case of 1 step (step a below) In this case, the reaction temperature is 60 to 110 ° C. The appropriate reaction temperature is 3 to 12 hours, and the amount of primary alcohol used at that time is 60 to 110 ° C. O, 1 to 1.3 per mol molecule
molar molecule, and the amount of secondary alcohol used is 1.8~
It is 2.6 mole molecules.

Reaction formula for primary alcohols Reaction formula for secondary alcohols (R' and R″' are the same or different alkyl groups) (
...) In the case of two steps (Steps and C) below, the reaction temperature in this case is approximately 60-100°C for 1 hour for 2-10 hours, then approximately 70-110°C for 1-4 hours. .

Although this method involves two steps, it may be more advantageous in terms of quality and yield than a one-step method.

The amount of alcohol used is 0.4 to 0.7 mol molecule of primary alcohol per mol molecule of the compound of formula I in the step,
Secondary alcohol is 0.8 to 1.4 mol molecules, and in step C, 1 mol of compound 2), primary alcohol is 0.4 to 0.7 mol molecule, and secondary alcohol is 0.8 mol per molecule. 8
~1.4 mole molecules.

(Leaving space below) Reaction formula for primary alcohols R = Alkyl group Step C Reaction formula for secondary alcohols The method of the present invention facilitates the reaction in both cases (i) and (...). For this purpose, the alcohol used for the reduction is usually used as a solvent, and in some cases, the reduction can also be carried out in an inert solvent such as toluene, acetone, dimethyl sulfoxide, or acetonitrile.

General formula l used as a raw material in method (i) of the present invention
Specific examples of the compound include the following.

2-nitro-4-chloro-2'-hydroxy-3'-t
-Butyl-5'-methylazobenzene, 2-nitro-2'-hydroxy-5'-methylazobenzene, 2-nitro-2'-hydroxy-5'-t-octylazobenzene, 2-nitro-2'-hydroxy- 5'-t-butylazobenzene, 2-nitro-4-chloro-2'-hydroxy-3', 5
'-di-t-butylazobenzene, 2-nitro-2'-hydroxy-3',5'-di-t-
Amylazobenzene, 2-nitro-2'-hydroxy-3',5'-di-t
-butylazobenzene, 2-nitro-2'-hydroxy-3''-t-butyl-5
'-Methylazobenzene, 2-nitro-2',4'-dihydroxyazobenzene,
2-nitro-4-chloro-2', 4'-dihydroxyazobenzene, 2-nitro-2'-hydroxy-4'-methoxyazobenzene, 2-nitro-4-chloro-2'-hydroxy-3', 5
'-di-t-amyl azobenzene, 2-nitro-2'-hydroxy-5'-t-amyl azobenzene, 2-nitro-4-chloro-2'-hydroxy-5'-t
-Amyl azobenzene, 2-nitro-2'-hydroxy-3',5'-di(α,
α-dimethylbenzyl)azobenzene.

2-nitro-4-chloro-2'-hydroxy-3',5
'-di(α,α-dimethylbenzyl)azobenzene,
2-nitro-2'-hydroxy-3'-α-methylbenzyl-51-methylazobenzene, 2-nitro-4-chloro-2'-hydroxy-3'-α
-Methylbenzyl-5'-methylazobenzene, 2-nitro-2'-hydroxy-5'-n-dodecyl azobenzene.

2-nitro-4-chloro-2'-hydroxy-5'-n
-dodecyl azobenzene, 2-nitro-2'-hydroxy-3',5'-di-t-
Octyl azobenzene, 2-nitro-4-chloro-21-hydroxy-3', 5
'-di-t-octylazobenzene, 2-nitro-4-chloro-2'-hydroxy-5'-t
-octylazobenzene, 2-nitro-4-methyl-2'-hydroxy-5'-methylazobenzene, 2-nitro-4-methyl-2'-hydroxy-3'-t
-butyl-5-methylazobenzene, 2-nitro-4-n-butyl-2'-hydroxy-3'
, 5'-di-t-butylazobenzene, 2-nitro-4-n-butyl-2'-hydroxy-3'
-5aC-butyl-5'-t-butylazobenzene.

2-nitro-4-t-butyl-2'-hydroxy-3'
-3eC-butyl-5'-t-butylazobenzene, 2
-nitro-4,6-dichloro-22-hydroxy-5'
-t-butylazobenzene, 2-nitro-4,6-dichloro-2'-hydroxy-3
'.

5'-di-t-butylazoben, and 2-nitro-4-carboxy-2'-hydroxy-5-
Methylazobenzene.

The general compound 2) used in the method 2) of the present invention can be obtained, for example, by reducing the compound of formula I above to an N-oxide, and specific examples thereof include the following.

2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole-N-oxide, 2-(2-hydroxy-3,5-di-t-butylphenyl)-5- Chlorbenzotriazole-N-oxide,
2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole-N-oxide, 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-oxide, 2-(2-hydroxy -5-t-butylphenyl)benzotriazole-N-oxide, 2-(2-hydroxy-5-t-octylphenyl)benzotriazole-N-oxide, 2-(2-hydroxy-3,5-di-t -butylphenyl)benzotriazole-N-oxide, 2-(2-hydroxy-3-t-butyl-5-methylphenyl)benzotriazole-N-oxide, 2-(2
,4-dihydroxyphenyl)benzotriazole-N
-oxide, 2-(2,4-dihydroxyphenyl)-5-chlorobenzotriazole-N-oxide, 2-(2-hydroxy-4-methoxyphenyl)benzotriazole-N-oxide, 2-[2-hydroxy- 3,5-di(α,α-dimethylbenzyl)phenyl]benzotriazole-N-oxide, and

In addition, these N-oxides of general formula (2) are 0 of general formula (I)
Although it is preferable to use the -nitroazobenzene derivative as a raw material and produce it by the method described in step (i) above, it is also possible to produce it by other known methods.

Examples of alcohols that are reducing agents of the present invention include:

Methanol, ethanol, n-propanol, n-butanol, isobutanol, n-amyl alcohol, isoamyl alcohol, n-hexanol, 2-ethylbutanol, n-heptyl alcohol, n-octatool,
2-ethylhexanol, 3,5.5-trimethylhexanol, n-decanol, dodecanol, tetradecanol, isopropyl alcohol, sec-butanol,
Examples include 3-pentanol, methylamyl alcohol, 2-hebutanol, 3-heptatool, 2-octatool, nonanol, undecanol, among others, n-propanol, n-butanol, n-amyl alcohol,
Isopropyl alcohol, sec-butanol, 27-myl alcohol, and n-octatool are preferred.

It is preferable to use the primary or secondary alcohol in a chemical manner, and since it is generally used as a solvent for the reaction, the starting material, 0-nitroazobenzenes of formula (1), or the formula (I[[) It is used in an amount of 1 to 20 times, preferably 2 to 8 times, the weight of the N-oxide.

Furthermore, even if two or more types of alcohols are mixed, there is no adverse effect on the reaction, and favorable results may be obtained in some cases.

Furthermore, alcohols can also be used as aqueous solutions, and in this case, a concentration of 50% by weight or more is preferred. Being able to use alcohols in the form of an aqueous solution is industrially advantageous in that the recovered alcohol can be reused without dehydration. It is very advantageous for manufacturing.

Specific examples of the aromatic ketone compound that is the catalyst of the present invention include at least one of benzophenone; benzophenone substituted with an alkyl group, alkoxyl group, a halogen atom, or a hydroxyl group; benzanthrone; 9-fluorenone; and 9-xanthenone. Among these, 9-fluorenone and benzanthrone are preferred, and two or more of these may be used in combination, which may be preferable in some cases.

In any case, the amount used is suitably 0.2 to 30% by weight, preferably 2 to 20%, based on the weight of the 0-nitroazobenzene derivative of formula (1).

Also, when using N-oxides of general formula (m) as starting materials, 0.2 to 30% of the weight of N-oxides is used.
%, preferably 2 to 20%.

The aromatic ketone compound that is the catalyst of the present invention is generally soluble in organic solvents such as benzene, toluene, xylene, alcohol, etc., or has a boiling point, so it is easy to remove the used catalyst from the reaction system by extractive distillation. can be recovered and reused for the next reaction. The use of a semi-permanent catalyst is also one of the most significant features of the present invention.

As the base, sodium hydroxide or potassium hydroxide is preferred, and the amount used is as shown in general formula (1). , 1 to 12 mol molecules each per 1 mol molecule of the nitroazobenzene derivative or the N-oxide of general formula (III),
Preferably it is 2 to 8 mol molecules.

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

Example 1 To a mixture of 80 g of n-butanol, 14 g of water, and 8.2 g of 97% caustic soda was added 25.5 g of 2-nitro-2'-hydroxy-3',5'-di-t-amylazobenzene.
g was added, the temperature was raised to 65°C with stirring, then cooled to 50°C, 2.0g of 9-fluorenone was added, and the temperature was raised to 90°C for 1 hour.
When the temperature is raised to 90-96℃ for 4 hours with stirring, most of the azobenzene disappears and 2-(2-hydroxy-3,
5-di-t-amylphenyl)benzotriazole-N
- oxide is formed and the reaction in step S is completed.

Next, in order to carry out the reaction in step C, it was cooled to 60°C and 97%
8.2 g of caustic soda followed by 1.0 g of 9-fluorenone
was added, the temperature was raised to 90℃ for 1 hour, and further heated at 90 to 97℃ for 2 hours.
When the reaction is stirred for a period of time, the N-oxide disappears and the reaction in step C is completed. 80m water Add Q and then 62% sulfuric acid 2
When 6.0 g of P) is neutralized to 18 to 9 and left at 60 to 70°C, 2-(2-hydroxy-3,5-di-t) is added to the upper layer.
A butanol layer containing -amylphenyl)benzotriazole is formed in the upper layer, and an aqueous layer is formed in the lower layer. After removing the lower aqueous layer, the upper butanol layer is transferred to a distiller and most of the butanol is recovered under normal pressure or light vacuum.
The degree of vacuum was 2-4+*m) Ig, and 2.9 g of the 120-140°C fraction was collected. This is the catalyst 9-fluorenone used and can be reused as the next catalyst. After recovering the catalyst, the residue was washed with methanol to obtain the desired product, 2-(2-hydroxy-3,5-di-amylphenyl)benzotriazole, in a yield of 20.0 g.

Yield 85.4% Melting point 78-80°C Example 2 2-nitro-2'-hydroxy-3',5'-di-t-
Instead of 25.5 g of amyl azobenzene, 2-nitro-2'-hydroxy-5'-t-octylazobenzene 2
The catalyst was recovered in the same manner as in Example 1, except that 3.7 g was used, and washed with methanol to obtain 2° (2-hydroxy-5-t-octylphenyl)benzotriazole in a yield of 18.0 g. .

Yield: 83.7% Melting point: 103-105°C Example 3 Instead of 80 g of n-butanol, 80 g of n-propanol
The same method as in Example 1 was repeated except for using g, and the desired product was obtained in the same yield as in Example 1.

(9-fluorenone used in this example was used in Examples 1 and 2.
I used what I collected. ) Example 4 Instead of 9-fluorenone a) Benzanthrone, mouth)
The same method as in Example 1 was repeated except that benzophenone was used, and 2-(2-hydroxy-3,
5-di-t-7mylphenyl)benzotriazole was obtained.

b) 19.4g, yield 83%, melting point 77-80℃)
14.3 g, yield 61%, melting point 76-79°C Example 5 2-nitro-4-chloro-2' was added to a mixture of 60 g of n-butanol, 10.6 g of water, and 6.9 g of 97% caustic soda.
After adding 23.2 g of -hydroxy-3'-t-butyl-5'-methylazobenzene and raising the temperature to 65°C while stirring,
Cool to 50°C, add 1.5g of 9-fluorenone,
The temperature was raised to 90° C. in 1 hour, and the reaction was stirred at 90 to 96° C. for 5 hours, whereby azobenzene disappeared and the reaction in step S was completed. Add 50m of water, then add 10% 62% sulfuric acid.
g to pH 8-9, cooled to 20°C, precipitated crystals were separated by passing, and 2-(2-hydroxy-3-t
A wet amount of 22.9 g (20.6 g of dry product, yield 93.0%, melting point 160-163°C) of -butyl-5-methylphenyl)-5-chlorobenzotriazole-N-oxide was obtained.

Next, 90% n-butanol 66 g was added to this wet amount of 22.9 g.
．． 7g of 97% caustic soda, and 1.5g of 9-fluorenone were added, and the temperature was raised to 90°C for 1 hour.
When reacted at 97°C for 3 hours, N-oxide disappeared,
The reaction of step C was completed.

Add 80+aQ of water to the reaction solution, then add 28% of 62% sulfuric acid.
After cooling to 20°C, the precipitated crystals were separated by filtration, thoroughly washed with water, further washed with a small amount of methanol, and dried to obtain 2-(2-
Hydroxy-3-t-butyl-5-methylphenyl)-
Pale yellow crystals of 5-chlorobenzotriazole were obtained.

Yield 87% (yield from azobenzene), melting point 139~
140℃ (To recover the used catalyst, the butanol layer will separate if left to stand after filtering the N-oxide and the target product, so collect it in a distiller, and after recovering the butanol by distillation,
Collecting the 120-140° C. fraction under a vacuum of 4+uiHg recovers more than 80% of the catalyst used. ) Example 6 In a mixture of 80 g of isopropyl alcohol, 14 g of water, and 11.0 g of 97% caustic soda, 26.0 g of 2-nitro-4-chloro-2'-hydroxy-3',5'-di-t-butylazobenzene and When 2.0 g of 9-fluorenone was added and the reaction was stirred for 8 hours at a boiling point of 79°C, azobenzene disappeared and 2-(2-hydroxy-3,5-di-t-butylphenyl)-5-chlorobenzotriazole-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 60°C, 8.2g of 97% caustic soda was added, followed by 1.0g of 9-fluorenone, and the reaction was stirred for 6 hours until the boiling point (79-82°C) was reached.
-The oxide disappears and the reaction of step C is completed. water 80
+ mΩ, neutralized to pH 8-9 with 36 g of 62% sulfuric acid, cooled to 20°C, and separated the precipitated crystals by passing through.
After thorough washing with water, washing with a small amount of isopropyl alcohol and drying yielded 18.6 g of 2-(2-hydroxy-3,5-di-t-butylphenyl)-5-chlorobenzotriazole.

Yield: 78%, melting point: 153-155°C Example 7 Sec-butanol 80g, water 14g, 97% caustic soda 2
2.4. Add 2.5 g of 9-fluorenone to the mixture of
2-nitro-2'-hydroxy- while stirring at 80°C.
After adding 19.9 g of 5'-t-butylazobenzene over 1 hour and stirring at 90-97°C for 4 hours, azobenzene disappeared and 2-(2-hydroxy-5-t-butylphenyl)benzotriazole was produced. -N-oxide is produced and the reaction in step S is completed. When stirring is continued for a further 4 hours, the N-oxide disappears and the reaction in Step C is completed.

After adding 80 Ω of water and recovering excess secondary butanol by distillation, 50 Ω of toluene was added to the remaining liquid.
When neutralized to P) 18 with 2% sulfuric acid 31 and left to stand at 70°C, a toluene layer containing the target substance is formed in the upper layer, and an aqueous layer containing potassium sulfate is separated in the lower layer. Transfer the toluene layer to a distiller.

After removing most of the toluene by distillation at normal pressure,
2.5 g of distillate at 120-140°C under vacuum of 4+*mHg
Collect. This is the catalyst 9-fluorenone used and can be reused as the next catalyst. After recovering the catalyst, the target product, 2-(2-hydroxy-5-t-butylphenyl)benzotriazole, remains as 13
．． A yield of 5g was obtained.

Yield 76%, melting point 96-98°C Example 8 2-nitro 2'-hydroxy-3 in a mixture of 50 g n-octatool, 14 g water, and 8.2 g 97% caustic soda
'.

Add 23.7 g of 5'-di-t-butylazobenzene,
After heating to 65°C and cooling to 50°C, 9-fluorenone 2
．． After adding 0 g and stirring at 90 to 97°C for 2 hours, azobenzene disappeared and 2-(2-hydroxy-3,5-
Di-butylphenyl)benzotriazole-N-oxide is formed and the reaction in step S is completed.

Next, in order to carry out the reaction in step C, it was cooled to 60°C and 97%
8.2 g of caustic soda followed by 1.0 g of 9-fluorenone
was added, the temperature was raised to 90℃ for 1 hour, and further heated at 90 to 97℃ for 2 hours.
After stirring for a period of time, the N-oxide disappears and the reaction in step C is completed.

Add 80IlIQ of water, 26g of 62% sulfuric acid''cPH8
When the crystals are neutralized and cooled at 20°C, they are separated by filtration, thoroughly washed with water, washed with a small amount of methanol, and then dried. The yield of 2-(2-hydroxy- 3,5'-di-t-butylphenyl)benzotriazole was obtained.

Yield: 79%, melting point: 150-152°C Example 9 2-nitro-2'-hydroxy-5'-t-octylazobenzene was added to a mixture of 60 g of n-butanol, 12 g of water, and 16.5 g of 97% caustic soda. After adding 7 g of the mixture and raising the temperature to 50° C. while stirring, 2.0 g of 9-fluorenone was further added and the temperature was raised to 80° C. over 2 hours. 80℃～84
When the reaction is stirred at ℃ for 3.5 hours, the reduction reaction is completed.

After adding 80 m of water 12, add 28 g of 62% sulfuric acid to pH 8.
When neutralized and left at 60-70℃, 2-(2
A butanol layer containing -hydroxy-5-t-octylphenyl)benzotriazole is formed in the upper layer, and an aqueous layer is formed in the lower layer. After removing the lower aqueous layer, the upper butanol layer was transferred to a distiller, and after recovering most of the butanol under normal pressure or light vacuum, 2~3e-1 (g and
Collect 1.8 g of the 120-140°C fraction. This is the catalyst 9-fluorenone used and can be reused as the next catalyst. After recovering the catalyst, washing the residue with methanol yields the target product, 2-(2-hydroxy-5
-t-octylphenyl)benzotriazole is 17.
A yield of 4g was obtained.

Yield 81.0%, melting point 103-105°C Example 10 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole-N-oxide 23.2 g'#
60 g of tn-butanol, 12 g of water and 16.5 g of 97% caustic soda were added to the mixture, then 2.0 g of 9-fluorenone was added, and the temperature was raised to 80°C, and the mixture was heated at 80-85°C for 2 hours.
．． After stirring and reacting for 5 hours, the reduction reaction is completed. Example 9
After recovering butanol through post-treatment in the same manner as above, reduce the degree of vacuum to 2~
3 Peng Hg and 9- as a fraction of 120-130℃
1.8 g of fluorenone catalyst was recovered. After recovering the catalyst, the residue was washed with methanol and was found to be the desired product. 2-(
A yield of 20.5 g of 2-hydroxy-3,5-di-t-amylphenyl)benzotriazole was obtained.

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. Alkyl group, carbon number 1~
4 represents a lower alkoxyl group, 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 is hydrogen or a chlorine atom, It represents a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms, and R_5 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. ) General formula II characterized in that the o-nitroazobenzene derivative represented by is reduced with at least one of a primary alcohol and a secondary alcohol in the presence of a catalyst consisting of an aromatic ketone compound and a base ▲Math. , chemical formulas, tables, etc. ▼ (However, R_1, R_2, R_3, R_4, R_5 are the same as general formula I) A method for producing 2-phenylbenzotriazoles. 2. General formula II ▲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 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 an alkyl group having 1 to 12 carbon atoms. Represents 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, and R_4 is hydrogen or chlorine. represents an atom, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms,
R_5 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. ) is characterized by reducing the 2-phenylbenzotriazole-N-oxide represented by the following formula with at least one of a primary alcohol and a secondary alcohol in the presence of a catalyst consisting of an aromatic ketone compound and a base. General formula II ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_2, R_3, R_4, R_5 are the same as in general formula I) A method for producing 2-phenylbenzotriazoles.