KR910002370B1 - Process for the preparation of 4-nitrodiphenyl amines - Google Patents

Abstract

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Description

Method for preparing 4-nitrodiphenylamine

The present invention relates to a process for preparing 4-nitrodiphenylamine of general formula (I) by reacting 4-nitrohalogenbenzene with a primary aromatic amine in the presence of potassium carbonate and a copper compound.

Wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are hydrogen or an alkyl radical having 1 to 9 carbon atoms.

The reaction of halogen nitrobenzene with aromatic amines has long been known. That is, DE-PS 185,663 discloses carrying out the reaction in the presence of alkali carbonate and copper compounds as catalysts.

It is also known that extremely slow reactions can be promoted when potassium carbonate is added and the water of the reaction is removed by azeotropic distillation. According to Example 1 of US Pat. No. 2,927,943, suitably pure 4-nitrodiphenylamine is obtained in 73% yield of theoretical yield under these conditions for 21 hours, and also in US Pat. No. 4,155,936 During the reaction of halogen nitrobenzene with primary aromatic amines, such as the formation of nitrobenzene, due to reductive halogen elimination reactions (see US Pat. No. 3,313,854, column 3, lines 64 and 65), Contamination of nitrodiphenylamines due to disadvantages has been described as causing long reaction times.

To solve this drawback, polar solvents are added to the reaction mixture as co-catalysts. However, all polar solvents used up to now also result in loss. Because of this, the dimethylformamide used according to US Pat. No. 3,055,940 is volatile under the reaction conditions, which forms easily inseparable from the by-products. Hexamethyl-phosphate triamides used according to US Pat. No. 3,055,940 and formanilides used according to US Pat. No. 3,313,854 have only insufficient acceleration in the amount of catalyst in the presence of copper compounds. Dimethylsulfoxide, acetanilide and salicylicanilide used according to US Pat. No. 3,277,175, DE-AS 1,518,307 and DE 1,117,594 also have some effect. . This also applies to the use of N-methylpyrrolidone according to DE-OS 2,633,811 or 2-caprolactam according to Japanese patent (JP) 56/022751.

The addition of polyethers described in US Pat. No. 4,155,936 also results in losses. Depending on the finishing method, the adduct remains in the final product or wastewater.

U. S. Patent No. 3,121, 736 describes another possibility of reducing the product of tar, including aminocarboxylic acids, alkyldiaminopolycarboxylic acids and salts thereof, disalicyl aldiaminoalkyl, O-hydroxy-benzalaminophenol, polyphosphates, carboxymethylmers. The addition of a capto succinic acid or a schiff base of salicylic acid is recommended.

Problems arise in finishing operations when all of these materials are used.

The present invention is characterized by the addition of a rubidium or cesium compound or a mixture of both, by reacting the halogen nitrobenzene of formula (II) with the primary aromatic amine of formula (III) in the presence of a mixture of potassium carbonate and copper It is to provide a method for producing 4-nitrodiphenylamine of formula (I).

Wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are hydrogen or an alkyl radical having 1 to 9 carbon atoms; X is chlorine or fluorine.

As an alkyl radical of general formula (I), a C1-C3 alkyl radical is preferable.

Preferably a method of preparing 4-nitrophenylamine from 4-nitrochlorobenzene and aniline is used.

The following are examples of copper catalysts that can be used in the process of the present invention: copper iodide (I), copper chloride (I), copper chloride (II), copper bromide (I), copper bromide (II), copper cyanide (I) ), Copper oxide (I), copper oxide (II), copper carbonate (II), basic copper carbonate (II), copper sulfate (II), copper nitrate (II), copper formate (II), copper acetate (II) and Organic and inorganic coordination compounds of copper (I) or (II). Oxygen-containing copper compounds such as copper (II), copper carbonate (II), copper carbonate (II) or copper (I) are preferred, and the copper catalyst is 0.001 to 0.1 per mole of halogen nitrobenzene used, preferably Is added in an amount of 0.01 to 0.05 mol. The copper catalyst can be used on its own or mixed.

The following are examples of halogen nitrobenzenes: 4-nitrochlorobenzene, 4-nitrobromobenzene, 4-nitro-2-methyl-chlorobenzene and 4-nitro-3-methyl-chlorobenzene.

The following are examples of primary aromatic amines: aniline, O-toluidine, m-toluidine, p-toluidine, 4-ethylaniline, 4-butylaniline, 4-isopropyl-aniline, 3, 5-dimethylaniline and 2, 4-dimethylaniline.

Of course, aromatic amines can be used in the form of mixtures, in particular isomer mixtures. About 1 to 6 moles, preferably 1.5 to 3 moles, in particular 1.7 to 2.5 moles of aromatic amine are generally used per mole of halogen nitrobenzene.

The following are examples of rubidium or cesium compounds: chloride, bromide, iodide, sulfate, oxide, hydroxide, carbonate, hydrogen carbonate, formate, acetate, propionate, cyanide, phosphate and mixtures thereof, but especially organic And salts of inorganic acids such as carbonates, acetates, formates and cyanides. Cesium compounds are preferred. The salts used may be formed in the reaction vessel from the hydroxides and the corresponding acids or suitable acid derivatives.

The rubidium and cesium compounds are added in molar amounts corresponding to 0.05 to 5 g, preferably 0.1 to 1 g of cesium carbonate per mole of halogen nitrobenzene.

Potassium carbonate can be used in the equivalent amount or 1.5 times or less.

The water produced during the reaction can be removed well from the reaction mixture by distillation of the entrainer. The following are examples of entrainers: xylene, toluene, benzene, chlorobenzene, chlorotoluene, aniline and / or toluidine, preferably xylene or toluene.

If necessary, the process according to the invention can be carried out in the presence of a diluent, for example an inert organic hydrocarbon (eg xylene). Moreover, aromatic primary amine itself can also be used as a solvent.

The reaction temperature of the process spans a wide range, generally 140 to 225 ° C, preferably 180 to 210 ° C.

The present invention can be carried out continuously or discontinuously according to conventional methods.

Likewise, the reaction mixture can be finished in different ways. Salts in the reaction mixture may be physically separated by centrifugation or filtration at elevated temperature. After washing with warm xylene and drying, a light gray powder solid remains. Unreacted halogen nitrobenzene and primary aromatic amines are removed from the filtrate using steam, and nitrodiphenylamines are mostly obtained in particulate form. The filtrate can be partially distilled under vacuum, then the product can be obtained in the residue or crystallized to actually separate 4-nitrodiphenylamine and / or the filtrate can be mixed with a precipitant such as xylene. In this case, 4-nitrodiphenylamine is produced in extremely pure form and can be immediately further processed under these conditions.

The copper catalyst can be used repeatedly. To obtain sufficient activity, the catalyst is optionally added in new form in an amount less than the amount originally used. In order to drain the by-products, a small amount of the mother liquor is separated as necessary. To remove the salt, the reaction mixture may be stirred with the amount of water required to dissolve the salt, preferably at elevated temperature (85 ° to 95 ° C.). After phase separation, the organic layer is further finished by steam distillation or by removing volatile components more readily than 4-nitrodiphenylamine.

According to the method, 4-nitrodiphenylamine can be produced in high purity and yield of 85% or more for a short reaction time. By-products are produced in this method very little.

4-nitrodiphenylamine produced according to the process of the present invention can be easily reduced to aminodiphenylamine according to known methods, for example an important intermediate product for the preparation of dyes or stabilizers of rubbers (US patents). 3,163,616).

Example 1

3구 플라스크에 400r.p.m.의 교반속도로 도입한다.1 mole of 4-chloronitrobenzene, 1.9 moles of aniline, 1.25 moles of anhydrous potassium carbonate, 1/42 moles of copper (II) oxide 1/950 moles of anhydrous cesium carbonate, and 1/10 moles of xylene, 2 with fractionation column with water separator

Into a three-necked flask is introduced at a stirring speed of 400 r.pm.

The reaction mixture is heated to 195 ° C. with stirring. The contents in the flask are kept at this temperature until 10 to 10.5 ml of water is separated and the 4-chloronitrobenzene content of the sample is measured by liquid chromatography. If this content is less than 15% of the original amount, the reaction is stopped by cooling. Otherwise, the reaction continues until this value is reached. The completion time of the reaction is 5 to 6 hours.

50 ml of water is added at 100 ° C. and volatile components are removed by steam. The aqueous phase of the contents of the flask is separated and the organic phase solidifies during cooling. Analysis by liquid chromatography yields 216 g of green gray particulate matter, containing 86% by weight of 4-nitrodiphenylamine, corresponding to 87% yield based on 4-chloronitrobenzene.

Example 2

Example 1 is repeated using 1/930 moles of cesium cyanide instead of cesium carbonate.

4-nitrodiphenylamine is obtained in a yield of 88.7% based on the 4-chloronitrobenzene used.

Example 3

Except using 1.95 moles of aniline, 1.3 moles of potassium carbonate, 1/45 moles of copper (II) oxide, 1/850 moles of cesium acetate, 1/20 moles of water, and 1/12 moles of xylene Example 1 is carried out as before. Remove about 11 ml of water. The yield of 4-nitrodiphenylamine amount based on 4-nitrochlorobenzene is 89.2%.

Claims (10)

A process for preparing 4-nitrodiphenylamine by reacting 4-nitrohalogen benzene with a primary aromatic amine in the presence of potassium carbonate and a copper compound, characterized by adding a rubidium or cesium compound or a mixture of both to the reaction mixture. How to. 2. Process according to claim 1, characterized in that 4-nitrodiphenylamine corresponds to formula (I).

Wherein R ¹ , R ² , R ³ and R ⁴ are the same or different and are hydrogen or an alkyl radical having 1 to 9 carbon atoms. The method of claim 1 wherein 4-nitrochlorobenzene is reacted with aniline to produce 4-nitrodiphenylamine. The method of claim 1 wherein a salt of a weak organic or inorganic acid is used as the rubidium or cesium compound. The method according to claim 1 or 4, characterized in that a cesium compound is used. The rubidium or cesium compound is used in a molar amount corresponding to 0.05 to 5 g of cesium carbonate and the copper catalyst is used in an amount of 0.001 to 0.1 molar based on 1 mole of the halogen nitrobenzene used in each case. How to. The rubidium or cesium compound is used in a molar amount corresponding to 0.1 to 1 g of cesium carbonate and the copper catalyst is used in an amount of 0.01 to 0.05 molar based on 1 mole of the halogen nitrobenzene used in each case. How to. The process according to claim 1, wherein the reaction is carried out at 140 to 225 ° C. The process according to claim 1, wherein the reaction is carried out at 180 to 210 ° C. The method of claim 1 wherein the water produced during the reaction is removed by distillation using an entrainer.