JPH0710815A - Production of 4-nitrosodiphenylamines - Google Patents

Abstract

PURPOSE:To obtain 4-nitrosodiphenylamine with a single-stage process on an industrial scale at a low cost by using a mixture of nitrogen oxides as a nitrosation agent in the nitrosation of diphenylamines and reacting in an aliphatic alcohol. CONSTITUTION:4-Nitrosodiphenylamines of the formula II are produced by nitrosating hydrochloride of diphenylamines of the formula I (R1 and R2 are H, methyl, ethyl, cyclohexyl, methoxy, ethoxy, Cl or Br) in a 1-10C aliphatic alcohol using a mixture of nitrogen oxides as the nitrosation agent. The reaction may be carried out by continuously supplying the nitrogen oxide mixture and hydrogen chloride gas or an aqueous solution of hydrochloric acid to diphenylamines dissolved in the aliphatic alcohol. The nitrosation agent has an N/O ratio of preferably 0.6-0.85. The most suitable aliphatic alcohol is 2- ethylhexanol. The compound of the formula II is useful as an intermediate for age resistor of natural rubber and synthetic rubber, an azo dye, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 4-nitrosodiphenylamines by nitrosating diphenylamines. The 4-nitrosodiphenylamines obtained by the present invention are important compounds as intermediates for natural rubber, synthetic rubber anti-aging agents, and azo dyes.

[0002]

2. Description of the Related Art As a method for producing 4-nitrosodiphenylamine from diphenylamine, diphenylamine is converted into N-nitrosine using a nitrosating agent such as nitrite in an aqueous solvent.
A method is known in which N-nitrosodiphenylamine is isolated by nitrosation or extracted and separated with an organic solvent, and then hydrogen chloride is added to carry out Fischer-Hepp rearrangement to obtain the desired product (Japanese Patent Publication No. 60-42232 publication, USP
3,728,392).

Further, a one-step method has been proposed in which N-nitrosodilation and rearrangement are simultaneously carried out without performing isolation or extraction separation operation of N-nitrosodiphenylamine. The one-step method involves adding an alcohol solution of hydrogen chloride to a mixture of aromatic solvent containing slightly water, nitrite such as sodium nitrite, and diphenylamine (USP 4,362,893), and carbon number not containing aromatic solvent. A method of reacting diphenylamine with alkyl nitrite and anhydrous hydrogen chloride in a substantially anhydrous aliphatic alcohol solvent of 5 to 10 (Japanese Patent Publication No. 60-4).
No. 2233), and a method of reacting diphenylamine with nitrosyl chloride and anhydrous hydrogen chloride in an aliphatic alcohol solvent having 1 to 10 carbon atoms (JP-A-2-3631).

[0004]

The above-mentioned one-step method is excellent in that 4-nitrosodiphenylamine is obtained in good yield, but it is not always satisfactory for industrial implementation. That is, in the method according to USP 4,362,893, since nitrite is used in the presence of a small amount of water, the inorganic salt such as nitrite is always in a slurry state with poor dispersibility, and the nitrosating agent is forced to undergo a solid-liquid reaction. It In addition, since it is necessary to control a very small amount of water within a certain range in a two-component solvent system, it is necessary to adjust the water content when the solvent is recovered and reused.

Regarding the method according to Japanese Patent Publication No. 60-42233, since alkyl nitrite used as a nitrosating agent has explosiveness and decomposability and is not easily stored and stored,
There are various difficulties in industrial implementation. on the other hand,
Regarding the method according to JP-A-2-3631, the nitrosyl chloride used as the nitrosating agent is an extremely corrosive gas and requires equipment for generation, which is not necessarily industrially advantageous. Not a method.

The object of the present invention is to produce 4-nitrosodiphenylamines by nitrosating diphenylamines without any restrictions on reaction conditions such as solid-liquid reaction and adjustment of water content and operation, and nitrosation. It is an object of the present invention to provide a one-step method which is industrially highly practical and has no handling problems when using the agent.

[0007]

Means for Solving the Problems As a result of intensive studies on the nitrosation of diphenylamines, the present inventors have found that a mixture of nitrogen oxides (hereinafter referred to as NOx gas) is excellent in nitrosation. The inventors have found that it is an agent and have reached the present invention.

That is, the present invention has the general formula

[Chemical 3] (Wherein 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 NOx gas is reacted using aliphatic alcohol of 10 to 10 as a solvent,

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

The structure of the present invention will be described in detail below. The diphenylamines used in the present invention are compounds represented by the above general formula, and specific examples thereof include diphenylamine, 4-methyldiphenylamine, 4
-Ethyldiphenylamine, 2-cyclohexyldiphenylamine, 4-cyclohexyldiphenylamine, 2
-Methoxydiphenylamine, 3-methoxydiphenylamine, 4-methoxydiphenylamine, 4-ethoxydiphenylamine, 4-chlorodiphenylamine, 4-
Examples include bromodiphenylamine.

In the present invention, an aliphatic alcohol having 1 to 10 carbon atoms is used as a solvent. Specific examples of such alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, secondary butanol, tertiary butanol, pentanol,
Hexanol, heptanol, octanol, 2-ethylhexanol and the like can be mentioned. Preferably, the carbon number is 4
~ 8 aliphatic alcohols are used, and specific examples thereof include butanol, hexanol, 2-ethylhexanol and the like. It is also possible to use a mixture of the above-mentioned several alcohols, or to use a mixture of the above-mentioned alcohol with a solvent such as toluene or chloroform that does not react under the nitrosation reaction conditions. Also, it is possible to coexist with water. The amount of the solvent used is arbitrary, but is usually about 2 to 20 times by weight that of the diphenylamines.

N used as a nitrosating agent in the present invention
The Ox gas contains at least nitric oxide (NO) and nitrogen dioxide (NO ₂ ), and is a mixed gas of dinitrogen trioxide (N ₂ O ₃ ) and dinitrogen tetraoxide (N ₂ O ₄ ). Equilibrium exists in these gases, and the abundance ratio changes depending on temperature and pressure, but the N / O ratio of NOx gas does not change. NOx gas is obtained by mixing NO and NO _2.
2 since it is easily obtained by mixing the O ₂ to NO, NOx gases can be easily obtained by mixing the O ₂ to NO.

The composition of NOx gas is such that the atomic ratio of nitrogen atoms to oxygen atoms in NOx gas is about 0.6 to 0.8.
It is preferably in the range of 5. When the atomic ratio of nitrogen atoms to oxygen atoms is less than about 0.6, by-products of nitric acid increase during the nitrosation reaction, and the unit consumption of NOx gas decreases. If the atomic ratio is greater than about 0.85, the unreacted NOx gas must be recycled many times, which is unsuitable as an industrial production method. The amount of NOx gas used is N
In the composition obtained by regarding Ox gas as a mixed gas of NO and NO ₂ , NO ₂ is usually about 0.4 to 0.7 times mol, preferably about 0.45 to mol of diphenylamines.
Adjust to 0.6 times the mole. If NO ₂ is about 0.4 times or less mol, unreacted diphenylamines increase, and if NO ₂ is about 0.7 times or more mol, the selectivity decreases due to side reaction, which is not preferable.

The diphenylamine hydrochloride used in the present invention is easily obtained by the reaction of diphenylamine with hydrogen chloride, and the diphenylamine is dissolved in the solvent used for the reaction, and then hydrogen chloride or hydrochloric acid aqueous solution is introduced. By doing so, it may be prepared in advance before the nitrosation reaction. It is also possible to simultaneously synthesize the hydrochloride and nitrosate by simultaneously introducing hydrogen chloride or hydrochloric acid aqueous solution and NOx gas into a solution of diphenylamines dissolved in a solvent used for the reaction. The amount of hydrogen chloride used is about 1.2 to 3.0 times mol, preferably about 1.5 to 2.5 times mol, of the diphenylamines.

The reaction temperature in the present invention is usually about 0 to
It is 60 ° C, preferably about 20-35 ° C. The reaction pressure in the present invention may be normal pressure or increased pressure, but sufficient results can be obtained at normal pressure. The reaction time in the present invention varies depending on the amount of hydrogen chloride used with respect to the diphenylamines and the reaction temperature, but usually about 0.5 to 3 hours for blowing NOx and about 0.5 to 5 hours for completion of the reaction. It costs.

The reaction method in the present invention is arbitrary. A batch reaction or a continuous reaction can be carried out. In the batch reaction, a hydrochloric acid solution of diphenylamines is charged in a reactor and NOx gas is blown into the reactor. In the continuous reaction, diphenylamines dissolved in a solvent, NOx gas and hydrogen chloride gas or hydrochloric acid aqueous solution are continuously supplied to a reactor charged with a solvent or a solution after the reaction.

Various methods are possible for the isolation operation. For example, after the completion of the reaction, when the hydrochloride of 4-nitrosodiphenylamine is in the form of slurry, it can be filtered as it is to obtain the desired product as the hydrochloride, or after neutralization with an alkaline aqueous solution according to a conventional method. It is also possible to obtain free 4-nitrosodiphenylamines by crystallization or the like. Further, depending on the case, it is also possible to obtain an aqueous solution of 4-nitrosodiphenylamines by forming a base with an excess alkaline aqueous solution. In any method, the obtained 4-nitrosodiphenylamines can be used as a raw material for a rubber anti-aging agent such as N-alkyl-N-phenyl-P-phenyldiamine.

[0017]

According to the present invention, 4-nitrosodiphenylamine can be easily produced from diphenylamines in good yield.

[0018]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1 33.8 g (0.20 mol) of diphenylamine was added to a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and 14.6 g (0.40) of hydrogen chloride gas with stirring. Mol) was blown in through the gas introduction tube for about 30 minutes. Then, at the same temperature, NO (2
NOx gas (N _0.83 O ₁ ) prepared by previously mixing 50 cc / min) and O ₂ (25 cc / min) was blown into the reaction mixture for 60 minutes through a gas introduction tube. After blowing, 3
The reaction was continued at 0 ° 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 37.6 g (0.190 mol, yield 95%). 0.8 g (0.004 mol) of N-nitrosodiphenylamine remained in the oil layer.
This can be recovered and used as a raw material for 4-nitrosodiphenylamine.

Example 2 33.8 g (0.20 mol) of diphenylamine was added to a mixed solvent of 100 ml of toluene and 100 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and 14.6 g (0.40) of hydrogen chloride gas with stirring. Mol) was blown in through the gas introduction tube for about 30 minutes. Then, at the same temperature, NO
NOx gas (N _0.67 O ₁ ) prepared by previously mixing (100 cc / min) and O ₂ (25 cc / min) was blown into the reaction mixture through the gas introduction tube for 60 minutes. After blowing, the reaction 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. 4-in the water layer
The amount of nitrosodiphenylamine was 37.2 g (0.188 mol, yield 94%). 0.8 g (0.004 mol) of N-nitrosodiphenylamine remained in the oil layer.

Example 3 Diphenylamine (33.8 g, 0.20 mol) was added to a mixed solvent of toluene (100 ml) and 2-ethylhexanol (100 ml), and 36% hydrochloric acid (40.40%) was added while maintaining the temperature at 30 ° C.
6 g (0.40 mol as HCl) was added dropwise. Then 2
NO (100cc / min) and O ₂ (25cc / min at 0 ℃
NOx gas (N _0.67 O ₁ ) prepared by previously mixing
Was bubbled through the gas inlet tube into the reaction mixture for 60 minutes. After blowing, the temperature was raised to 30 ° C. and the reaction was continued for 4 hours. After the reaction, as in Example 1, 4-nitrosodiphenylamine was extracted into the aqueous layer. The amount of 4-nitrosodiphenylamine in the aqueous layer was 30.9 g (0.156 mol, yield 78).
%)Met. 5.1 g (0.026 mol) of N-nitrosodiphenylamine remained in the oil layer. The total yield of 4-nitrosodiphenylamine and N-nitrosodiphenylamine is 91%.

Example 4 14.5% by weight of diphenylamine toluene and 2-ethylhexanol (weight ratio 1:
699 g of mixed solution of mixed solvent of 1) at 30 ° C., hydrogen chloride at a rate of 14.6 g / hour, and a mixture of nitrogen oxides (volume ratio of NO and O ₂ 4: 1) at a rate of 9.1 g / hour. Supply,
The reaction was carried out for 3 hours. After completion of the reaction, the feed rate of the mixture of hydrogen chloride and nitrogen oxide was kept the same as above, and the mixed solution of toluene of diphemylamine and 2-ethylhexanol was adjusted to 23%.
A continuous reaction was started by feeding at a rate of 3 g / hour. The reaction solution flowing out of the reactor is introduced into an aging unit and kept at 30 ° C. for a residence time of 3 hours.

In Table 1 below, 4-nitrosodiphenylamine (abbreviated as PNDA), N-nitrosodiphenylamine (abbreviated as NNDA) in the reaction mixture flowing out of the aging device during the reaction time after the start of the continuous reaction, The concentration of diphenylamine (abbreviated as DPA) is shown. As a result of continuous reaction for 18 hours, the PNDA yield was 96.2%, the NNDA yield was 1.78%, and the unreacted DPA was 0.85%.

[0024]

[Table 1]

Example 5 67.6 g (0.40 mol) of diphenylamine was added to a mixed solution of 170 ml of toluene and 170 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and 29.2 g (0. 80 mol) was blown in through the gas introduction tube for about 2 hours. Then, NO at the same temperature
(104.5 cc / min, 0.56 mol) and O ₂ (2
NO _x gas (N _0.7 O ₁ ) prepared by previously mixing 1.8 cc / min, 0.12 mol) was blown into the reaction mixture through the gas introduction tube for 2 hours. After blowing, the reaction was continued at 30 ° C. for 2 hours.

14% of the resulting slurry was cooled to 5 ° C.
It was added dropwise to 411 g of an aqueous sodium hydroxide solution over 2 hours to form a base. The amount of 4-nitrosodiphenylamine in the aqueous layer was 71.2 g (0.36 mol, selectivity 95%). The oil layer contained 3.8 g of diphenylamine (0.
(02 mol, 5%) remained. This can be reused as a raw material.

Comparative Example 1 33.8 g (0.20 mol) of diphenylamine was added to a mixed solution of 85 ml of toluene and 85 ml of 2-ethylhexanol, and the mixture was kept at 30 ° C. and stirred with 14.6 g of hydrogen chloride gas (0. 4 mol) was blown in through the gas introduction tube for about 1 hour. Then, at the same temperature, NO (7
(4.7 cc / min, 0.2 mol) was bubbled into the reaction mixture through a gas inlet tube over 1 hour. After blowing, the reaction was continued at 30 ° C. for 2 hours.

The resulting slurry was cooled to 5 ° C., 14%
It was dropped into 206 g of an aqueous sodium hydroxide solution over 1 hour to form a base. The amount of 4-nitrosodiphenylamine in the aqueous layer was 1.4 g (0.007 mol, yield 4%). 32 g of unreacted diphenylamine in the oil layer
(0.19 mol, 95%) remained.

Comparative Example 2 Diphenylamine (33.8 g, 0.20 mol) was added to a mixed solution of toluene (85 ml) and 2-ethylhexanol (85 ml), and the mixture was kept at 30 ° C. and stirred with hydrogen chloride gas of 14.6 g (0. 4 mol) was blown in through the gas introduction tube for about 1 hour. Then, at the same temperature, NO (7
4.7 cc / min, 0.2 mol) and O ₂ (37.3 c)
c / min, was bubbled NO _X gas prepared by previously mixing 0.1 mol) (N _0.5 O ₁₎ over 1 hour into the reaction mixture through a gas inlet tube. After blowing, 30
The reaction was continued for 2 hours at ℃.

The resulting slurry was cooled to 5 ° C., 14%
It was dropped into 206 g of an aqueous sodium hydroxide solution over 1 hour to form a base. The amount of 4-nitrosodiphenylamine in the aqueous layer was 16.8 g (0.084 mol, yield 42%). In the oil layer, unreacted diphenylamine 13.
1 g (0.078 mol, 39%) remained.

Claims (6)

[Claims] 1. The general formula: (Wherein 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 ## STR00002 ## wherein a mixture of nitrogen oxides is reacted using an aliphatic alcohol of 10 to 10 as a solvent. (In the formula, R ₁ and R ₂ are the same as the above-mentioned groups) A method for producing 4-nitrosodiphenylamines. 2. A mixture of diphenylamines dissolved in an aliphatic alcohol having 1 to 10 carbon atoms, a mixture of nitrogen oxides, and hydrogen chloride gas or an aqueous hydrochloric acid solution is continuously supplied to react. And a method for producing 4-nitrosodiphenylamines. 3. The method for producing 4-nitrosodiphenylamines according to claim 1, wherein the nitrogen atom ratio to the oxygen atom in the mixture of nitrogen oxides is 0.6 to 0.85. 4. The amount of the mixture of nitrogen oxides used is such that the mixture of nitrogen oxides is regarded as a mixed gas of nitric oxide and nitrogen dioxide, and nitrogen dioxide is 0.4 to 0. It is 7 mol, The manufacturing method of 4-nitrosodiphenylamines of Claim 1 or Claim 2. 5. The method for producing 4-nitrosodiphenylamines according to claim 1 or 2, wherein the diphenylamines are diphenylamines. 6. The method for producing 4-nitrosodiphenylamines according to claim 1 or 2, wherein the aliphatic alcohol is 2-ethylhexanol.