JPH06234718A - Production of n-nitrosodiphenylamines - Google Patents

Abstract

PURPOSE:To obtain N-nitrosodiphenylamines in good yield by nitrosating diphenylamines with an inexpensive nitrogen oxide usable in a solvent without any explosiveness and decomposability as a nitrosating agent in the solvent. CONSTITUTION:Diphenylamines expressed by formula I [R1 and R2 are H, methyl, ethyl, cyclohexyl, methoxy, ethoxy, Cl or Br) are nitrosated with an inexpensive nitrogen oxide (a mixture of NO with NO2 is usually used) as a nitrosating agent in a solvent to afford the objective N-nitrosodiamines expressed by formula II. An aromatic hydrocarbon or a mixed solvent thereof with an alcohol is preferred as the solvent used. The atomic ratio of O to N in the mixture of the nitrogen oxides is preferably 1.1-1.6. Furthermore, when the composition of the NOx gas is NO and NO2, the molar amount of the NO2 is preferably 0.4-0.8 based on the diphenylamines. The reactional temperature is preferably 0-40 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing N-nitrosodiphenylamines by nitrosating diphenylamines. The N-nitrosodiphenylamines obtained by the present invention are important as an antiaging agent for natural and synthetic rubbers or an intermediate for azo dyes and the like. For example, the obtained N-nitrosodiphenylamines can be rearranged with hydrogen chloride to produce 4-nitrosodiphenylamines, which can be used as a raw material for rubber anti-aging agents such as N-alkyl-N'-phenyl-p-phenylenediamine. It is possible to use.

[0002]

2. Description of the Related Art Conventionally, a method for producing N-nitrosodiphenylamine is a method of using a mineral acid such as sulfuric acid and an aqueous nitrite solution such as sodium nitrite in an aqueous solvent (Japanese Patent Publication No. 60-42232). Also known are methods using alkyl nitrite (Japanese Patent Publication No. 60-42233), methods using a mixture of nitrogen oxides in the absence of solvent (GB-772081), and the like.

[0003]

The nitrosation method using a mineral acid and nitrite is the most commonly used nitrosation method at present, but it includes salts formed by the reaction of nitrite and acid. When a large amount of waste water is discharged, or when a rearrangement reaction is subsequently performed to obtain 4-nitrosodiphenylamines, it is necessary to separate the aqueous layer by an operation such as extraction and separation.

On the other hand, in the method using alkyl nitrite,
Alkyl nitrite is explosive and decomposable, and is not easy to store and store, so various industrial difficulties are encountered.

In the method using a mixture of nitrogen oxides in the absence of solvent, the reaction temperature must be set above the melting point of diphenylamines in order to dissolve the diphenylamines. Therefore, the stability of the N-nitrosodiphenylamines is lowered, and the yield is lowered.

It is an object of the present invention to convert diphenylamines into N
An object of the present invention is to provide a highly practical N-nitrosation method, which solves the above-mentioned drawbacks in producing N-nitrosodiphenylamines by nitrosation.

[0007]

[Means for Solving the Problems] The inventors of the present invention have made diligent investigations for a nitrosating agent which does not have explosiveness or decomposability and can be used in a solvent during N-nitrosation. , NOx gas) was made to react in the presence of a solvent, and it was found that the above object was satisfied, and the present invention was reached.

That is, the present invention has the general formula

[Chemical 3] (In the formula, R ₁ and R ₂ each represent a hydrogen atom, a methyl group, an ethyl group, a cyclohexyl group, a methoxy group, an ethoxy group, a chlorine atom or a bromine atom), and nitrogen oxidation is performed in the presence of a solvent. N-nitrosation using a mixture of compounds

[Chemical 4] (In the formula, R ₁ and R ₂ are the same as the above-mentioned groups.) The method for producing N-nitrosodiphenylamines.

The structure of the present invention will be described in detail below. Specific examples of the diphenylamines used in the present invention include diphenylamine, 4-methyldiphenylamine, 4-ethyldiphenylamine, 2-cyclohexyldiphenylamine, 4-cyclohexyldiphenylamine, 2-methoxydiphenylamine, 3-methoxydiphenylamine, 4-methoxydiphenylamine, 4-ethoxydiphenylamine, 4-chlorodiphenylamine, 4-bromodiphenylamine and the like can be mentioned. Preferred examples include diphenylamine, 4-cyclohexyldiphenylamine, 3-methoxydiphenylamine, 4-methoxydiphenylamine and the like.

As the solvent used in the present invention, an aromatic hydrocarbon is usually used, specifically, benzene, toluene,
Xylene etc. are mentioned.

The amount of the solvent used may be such that the diphenylamines are dissolved.

It is also possible to use a mixed solvent with alcohols. As the alcohols used,
Methanol, ethanol, propanol, isopropanol, butanol, 2-ethylhexanol and the like can be mentioned.

For example, when N-nitrosodiphenylamines are not isolated but N-nitrosodiphenylamines are added and rearranged to give 4-nitrosodiphenylamines by rearrangement, the mixed solvent with alcohols is used. Is preferably used.

The presence of water in the reaction system does not hinder the N-nitrosation reaction. However, after the N-nitrosation, hydrogen chloride is added as it is and rearranged to give 4-nitrosodiphenylamines. However, it is not desirable to have a large amount of water, so it is not necessary to intentionally exist.

The mixture of nitrogen oxides used as the nitrosating agent in the present invention is usually obtained by mixing nitric oxide (NO) and nitrogen dioxide (NO ₂ ). NO ₂ is O for NO
_Since it is obtained by mixing ₂ , a mixture of nitrogen oxides can be easily obtained by mixing O ₂ with NO. There is an equilibrium in nitrogen oxides, and the components of the resulting mixture of nitrogen oxides are NO, NO ₂ , N
₂ O ₃ , N ₂ O _4, etc.

The composition of the NOx gas is such that the atomic ratio X of oxygen atoms to nitrogen atoms in the mixture of nitrogen oxides is 1.1 to.
It is preferably in the range of 1.6. When X is larger than 1.6, the by-product of nitric acid increases during the N-nitrosation reaction, and the basic unit of NOx gas deteriorates. Further, when X is smaller than 1.1, it is necessary to recycle the unreacted NOx gas many times, which is not preferable as an industrial production method.

The amount of NOx gas used is such that when the composition of NOx gas is regarded as a mixed gas of NO and NO ₂ , NO ₂ is about 0.4 to 0.8 times mol, preferably about 0. It should be 45 to 0.7 times the molar amount. NO
_{When 2} is about 0.4 times or less, unreacted diphenylamines increase, and when NO ₂ is about 0.8 times or more, the selectivity decreases due to side reaction.

The reaction temperature in the N-nitrosation of the present invention is about 0-40 ° C. At a temperature of about 40 ° C. or higher, the reaction rate decreases due to the decrease in gas absorption rate and the selectivity decreases due to side reactions, resulting in a decrease in yield. The reaction rate decreases at about 0 ° C or lower.

The reaction pressure in the present invention may be normal pressure or increased pressure, but normal pressure gives sufficient results.

The reaction is carried out by dissolving diphenylamines in a solvent and blowing NOx gas into the reaction mixture while maintaining it at a predetermined temperature. The reaction of the present invention is very fast, NOx
After the gas is blown in, the reaction is completed by stirring for 5 to 60 minutes. It is not preferable to blow the NOx gas so rapidly that NO ₂ cannot be completely absorbed because the reaction is fast.

The reaction method in the present invention is arbitrary. A batch reaction or a continuous reaction can be carried out.

After the N-nitrosation, usually, for example, hydrogen chloride is further added to the reaction solution for rearrangement and then neutralized with an aqueous sodium hydroxide solution to separate 4-nitrosodiphenylamines.

[0023]

In the conventional method using nitrite, a large amount of wastewater containing unreacted nitrite and diphenylamines was discharged, which required complicated treatment. N-nitrosodiphenylamines can be produced in good yield using an inexpensive mixture of nitrogen oxides without discharging.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 33.8 g (0.20 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and stirred while NO.
Of NOx gas prepared by previously mixing 100 cc / min of oxygen with 25 cc / min of O ₂ (x = 1.50, NO / N
O ₂ = 1) was bubbled through the gas inlet tube into the reaction mixture for 60 minutes. When the composition of the NOx gas is regarded as a mixed gas of NO and NO _2, blowing amount of NO ₂ is 0.134 mol, NO ₂ amount for diphenylamine 1 mole is 0.67 moles. After blowing, the reaction was continued at 30 ° C. for 10 minutes. 210 g of the reaction solution was obtained and analyzed by liquid chromatography. As a result, N-nitrosodiphenylamine was 39.2 g (0.198 mol, yield 99%).

Reference Example 1 210 g of the reaction solution obtained in Example 1 was kept at 30 ° C.
Hydrogen chloride gas of 14.6 g (0.4 mol) was blown in through the gas introduction tube for 60 minutes. After blowing, stirring was continued at 30 ° C. for 2 hours. An aqueous sodium hydroxide solution was added to the generated slurry to form a base, and 4-nitrosodiphenylamine was extracted into the aqueous layer.

The amount of 4-nitrosodiphenylamine in the aqueous layer was 35.6 g (0.18 mol, yield 90% calculated from diphenylamine). The oil layer contained 0.68 g (0.004 mol) of diphenylamine and 1.19 g (0.006 mol) of N-nitrosodiphenylamine. In addition, these can be recovered and used as a raw material of 4-nitrosodiphenylamine.

Example 2 33.8 g (0.20 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and stirred while NO.
Of NOx gas (x = 1.20, NO / N) prepared by previously mixing 250 cc / min of O ₂ and 25 cc / min of O _2.
O ₂ = 4) was bubbled through the gas inlet tube into the reaction mixture for 60 minutes. When the composition of the NOx gas is regarded as a mixed gas of NO and NO _2, blowing amount of NO ₂ is 0.134 mol, NO ₂ amount for diphenylamine 1 mole is 0.67 moles. After blowing, the reaction was continued at 30 ° C. for 10 minutes. 210 g of the reaction solution was obtained, and as a result of analysis by liquid chromatography, N-nitrosodiphenylamine was 39.0 g (0.197 mol, yield 98%).

Reference Example 2 The reaction liquid obtained in Example 3 was kept at 30 ° C., and 14.6 g (0.4 mol) of hydrogen chloride gas was passed through a gas inlet pipe to obtain 6
Blow in 0 minutes. After blowing, stirring was continued at 30 ° C. for 2 hours. An aqueous sodium hydroxide solution was added to the generated slurry to form a base, and 4-nitrosodiphenylamine was extracted into the aqueous layer.

The amount of 4-nitrosodiphenylamine in the aqueous layer was 35.2 g (0.177 mol, yield 89% calculated from diphenylamine). The oil layer contained 0.70 g (0.004 mol) of diphenylamine and 1.25 g (0.006 mol) of N-nitrosodiphenylamine.

Example 3 50.7 g (0.30 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 50 ml of water, and 12
NOx prepared by previously mixing 228 cc / min of NO and 23 cc / min of O ₂ while maintaining the temperature at 0 ° C. with stirring
Gas (x = 1.20, NO / NO ₂ = 4) was bubbled through the gas inlet tube into the reaction mixture for 80 minutes. When the composition of NOx gas is regarded as a mixed gas of NO and NO ₂ , NO
The amount of ₂ blown in was 0.164 mol, and the amount of NO ₂ per 0.5 mol of diphenylamine was 0.55 mol. After blowing, the reaction was continued at 12 ° C for 60 minutes. As a result of analyzing the obtained reaction liquid by liquid chromatography, diphenylamine was found to be 10.5 g (0.062 mol, reaction rate 79).
%), N-nitrosodiphenylamine 58.8 g
(0.297 mol, yield 98%) was contained.

Example 4 50.7 g (0.30 mol) of diphenylamine was dissolved in a mixed solvent of 120 ml of toluene and 90 ml of 2-ethylhexanol, and the mixture was kept at 5 ° C. and NO 2 was added while stirring.
NOx gas (x = 1.20, NO / NO ₂ prepared by previously mixing 28 cc / min and O ₂ at 23 cc / min)
= 4) was bubbled through the gas inlet tube into the reaction mixture for 90 minutes. When the composition of NOx gas is regarded as a mixed gas of NO and NO ₂ , the blowing amount of NO ₂ is 0.185 mol, and the amount of NO ₂ per 1 mol of diphenylamine is 0.
62 mol. After blowing, the reaction was continued at 5 ° C. for 60 minutes. As a result of analyzing the obtained reaction liquid by liquid chromatography, N-nitrosodiphenylamine was 58.0 g.
(0.293 mol, yield 98%).

Comparative Example 1 33.8 g (0.20 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and stirred while NO.
NOx gas (x = 2.0) prepared by previously mixing 75 cc / min of oxygen with 37 cc / min of O ₂ was blown into the reaction mixture through the gas introduction tube for 60 minutes. The amount of NO ₂ blown in was 0.20 mol, and diphenylamine 1
The amount of NO _{2 with} respect to mol is 1.0 mol. After blowing, the reaction was continued at 30 ° C. for 60 minutes. As a result of analyzing the reaction solution by liquid chromatography, 12.4 g (0.063 mol, yield: 32) of N-nitrosodiphenylamine was obtained.
%) And diphenylamine were 19.6 g (0.116 mol, 58%).

Comparative Example 2 33.8 g (0.20 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and stirred while NO.
Was bubbled into the reaction mixture through a 75 cc / min gas inlet tube for 60 minutes. The blowing amount of NO ₂ is 0 mol. After blowing, the reaction was continued at 30 ° C. for 60 minutes. As a result of analyzing the reaction liquid by liquid chromatography, N-nitrosodiphenylamine was 0.6 g (0.003 mol, yield 1.5%), and diphenylamine was 33.3 g (0.1%).
97 mol, 98.5%).

Comparative Example 3 33.8 g (0.20 mol) of diphenylamine was dissolved in a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 50 ° C. and stirred while NO.
Is 98.6 cc / min and O ₂ is 22.4 cc / min
NOx gas (x = 1.45, N
O / NO ₂ = 1.20) was bubbled through the gas inlet tube into the reaction mixture for 60 minutes. When the composition of NOx gas is regarded as a mixed gas of NO and NO ₂ , the blown amount of NO ₂ is 0.120 mol, and the amount of NO ₂ per 1 mol of diphenylamine is 0.60 mol. After blowing, 50 ℃
The reaction was continued for 30 minutes. As a result of analyzing the obtained reaction liquid by liquid chromatography, N-nitrosodiphenylamine was 28.1 g (0.142 mol, yield 71%),
Diphenylamine is 9.16 g (0.0542 mol, 2
7%) was included.

Claims (6)

[Claims] 1. The general formula: (In the formula, R ₁ and R ₂ each represent a hydrogen atom, a methyl group, an ethyl group, a cyclohexyl group, a methoxy group, an ethoxy group, a chlorine atom or a bromine atom), and nitrogen oxidation is performed in the presence of a solvent. N-nitrosation using a mixture of compounds of the general formula: (In the formula, R ₁ and R ₂ are the same as the above-mentioned groups) A method for producing N-nitrosodiphenylamines. 2. The method for producing N-nitrosodiphenylamines according to claim 1, wherein the solvent is an aromatic hydrocarbon. 3. The method for producing N-nitrosodiphenylamines according to claim 1, wherein the solvent is a mixed solvent of aromatic hydrocarbon and alcohol. 4. The method for producing N-nitrosodiphenylamines according to claim 1, wherein the atomic ratio of oxygen atoms to nitrogen atoms in the mixture of nitrogen oxides is 1.1 to 1.6. 5. When the composition of the NOx gas is regarded as a mixed gas of NO and NO _2, NO ₂ is according to claim 1, wherein NO ₂ amount is 0.4 to 0.8 mol per mol of diphenylamine A method for producing N-nitrosodiphenylamines. 6. The method for producing N-nitrosodiphenylamines according to claim 1, wherein the reaction temperature is 0 to 40 ° C.