CS213338B2 - Method of making the derivatives of p-aminodiphenylamine - Google Patents

Description

The invention relates to a process for the preparation of p-aminodiphenylamine derivatives of the general formula I,

(I) where

R ¹ represents a C 3 -C 6 hydrocarbon radical by a one-step reaction of 4-nitro- or 4-nitrosodiphenylamine with a ketone in hydrogen gas in the presence of a catalyst.

Methods for producing these compounds by reducing p-nitro- or p-nitrosodiphenylamine and subsequently alkylating the resulting p-aminodiphenylamine with carbonyl compounds in the presence of hydrogen and catalysts by batch intermittent processes are described in U.S. Patent 2,734,808, British Patent Specification No. 760,315, Belgian patent specification 623,284, French patent specification 1,463,529, Czechoslovak patent specification 119,336, and Polish patent specifications 58,572 and 63,933.

Continuous processes for the preparation of these compounds are described in the patents:

British No. 804113, West German No. 1 077 667 and French No. 1 456 319.

According to the British patent, the reaction is carried out in a tubular reactor in which the reaction products circulate up to 85%.

By the West German patent, the reaction is carried out in columns in which the p-aminodiphenylamine is reductively alkylated at a temperature in the range of 190 to 210 ° C and under a hydrogen pressure of about 15 to 18 MPa, with only a portion being fed to the first column. acetone, while its residue is fed to another column.

According to the French patent, the manufacturing process is carried out in three cascaded autoclaves equipped with mechanical high-speed agitators.

In the known batch production processes, paminodiphenylamine is usually used as the starting material, which is alkylated using catalysts typical of this reaction.

The known continuous processes are not economical at a low production volume due to the complexity of the equipment necessary for their operation. In addition, using p-nitroso- or p-nitrodiphenylamine, the continuous synthesis of alkyl derivatives is complex because the reduction reaction proceeds rapidly, while alkylation of the resulting amine is a much slower operation, requiring large scale equipment. Up to 85% of the recirculation of the reaction products used in some processes increases the energy consumption and, moreover, leads to greater wear on the pumps than normal due to the use of catalysts which are very often deposited on carriers of high hardness.

In addition, p-aminodiphenylamine derivatives containing a large number of contaminants are obtained by the above processes.

SUMMARY OF THE INVENTION It was an object of the present invention to provide a process for the preparation of p-aminodiphenylamine derivatives of the general formula I which, in a one-step reaction, achieves a high yield of pure product and which also allows the use of technical grade reactants.

It has been found that high productivity can be achieved in the production of p-aminodiphenylamine derivatives only slightly contaminated with p-aminodiphenylamine and at the same time reduce catalyst consumption when used as a catalyst in the reaction of a nickel catalyst which is a mixture of fresh catalyst with reused non-regenerated catalyst are exposed to hydrogen gas at a higher temperature and higher pressure in the environment of the ketone prior to use.

Accordingly, the present invention provides a process for the preparation of p-aminodiphenylamine derivatives of formula I wherein R ¹ is as defined above by reacting compounds of formula II,

ID where

R? means a nitro or nitroso group with ketones containing 3 to 6 carbon atoms under hydrogen gas pressure and at elevated temperature in the presence of a catalyst, the method being characterized in that a nickel catalyst is used which is a mixture of fresh and used non-regenerated catalyst in ketone, wherein the catalyst is first subjected to a temperature of from 100 to 200 degrees Celsius and hydrogen gas at a pressure of from 1 to 12.237 MPa, followed by addition of a compound of formula II. Without this initial phase, the course of said self-reaction is impeded. Catalyst consumption is lower despite the use of heavily contaminated p-nitrodiphenylanone as starting material; this is very important since obtaining pure p-nitrodiphenylamine is technologically difficult. This compound decomposes at high temperature and therefore a high vacuum of less than 267 Pa is required for purification by distillation. Also, purification of the compound by recrystallization is associated with the difficulty of selecting a suitable solvent. The impurities of p-nitrodiphenylamine dissolve in this solvent during crystallization. In readily available solvents, both p-nitrodiphenylamine and the accompanying impurities are equally readily soluble, or if impurities do not dissolve in the solvent, the solubility of p-nitrodiphenylamine in the solvent is very low and thus crystallization becomes uneconomic.

The process according to the invention is illustrated by the following examples.

Example 1

For the alkylation with simultaneous reduction, technical p-nitrodiphenylamine is used which contains impurities in an amount of approximately 10% by weight. The reaction is carried out in a 70-liter autoclave equipped with a mechanical stirrer and a heating or cooling jacket and coil. The autoclave was charged with fresh 0.37 kg nickel catalyst, 2.0 kg nickel catalyst recirculated without washing, and technical acetone 9.0 kg. The autoclave is then purged with nitrogen gas. The contents of the autoclave were stirred with a stirrer at 140 rpm while heating to 100 ° C. At the same time, hydrogen is introduced into the autoclave until the pressure in the autoclave reaches 4.04 MPa. Then a solution of 15 kg of technical 4-nitrodiphenylamine in 22 kg of technical acetone at 50 ° C is gradually added to the autoclave via a metering pump. The pressure in the autoclave is maintained between 3.5-4 MPa and the temperature between 138-148 ° C. The total reaction time is 4 hours. The contents of the autoclave are then cooled to 40 ° C, the catalyst is separated from the reaction mixture and the volatile reaction products are distilled off, as well as excess acetone, first under atmospheric, then under 24 kPa.

. The crude product is then distilled under reduced pressure to give 14.5 kg of a product containing approximately 94.5% N-isopropyl-N‘-phenyl-p-phenylenediamine and less than 1% p-aminodiphenylamine.

Example 2

As in Example 1, fresh nickel catalyst (0.37 kg), recirculated catalyst (2.0 kg) and methyl isobutyl ketone (9.00 kg) were charged to the autoclave. The contents of the autoclave are then heated to 140 ° C. While stirring, hydrogen is admitted to a pressure of 5 MPa. Then, a solution of p-nitrodiphenylamine in methyl isobutyl ketone is gradually added via a metering pump. The temperature is maintained between 135 and 150 ° C and the pressure between 3 and 5 MPa. After completion of the reaction, excess ketone and the other volatile components are distilled off first at atmospheric pressure, then the remainder under reduced pressure. This gives 17.1 kg of technical N-1,3-dimethylbutyl-N '-phenyl-p-phenylenediamine of approximately 94.5% of the desired product and less than 1% of p-aminodiphenylamine.

Example 3

Approximately 9 kg of technical acetone, 0.37 kg of fresh nickel catalyst and 2 kg of unregenerated catalyst used are introduced into the autoclave and then purged with nitrogen gas. The autoclave was then filled with hydrogen to a pressure of 3.04 MPa, the stirrer was set in motion and the contents of the autoclave started to heat. At a temperature of about 130 ° C, the hydrogen pressure was adjusted to 4.05 MPa. Then a solution of 15 kg of technical 4-nitrosodiphenylamine (having an impurity content of approximately 15% based on the weight of technical 4-nitrosodiphenylamine) in 22 kg of technical acetone at 50 ° C is added to the autoclave via a metering pump. During the addition of the solution (about 1 hour), the hydrogen pressure was maintained at a pressure of 5 to 5 bar and a temperature of 138 to 148 ° C.

After the entire amount of the solution has been introduced, the pressure and temperature are maintained within these ranges for approximately 3 hours. After the reduction and alkylation reaction, the temperature is lowered to about 40 ° C, the catalyst is separated and excess acetone as well as volatile reaction products are distilled off, first at atmospheric pressure, then under reduced pressure of about 24 kPa. The crude product is subjected to a simple vacuum distillation to yield approximately 15 kg of the product containing 4-aminodiphenylamine isopropyl derivative in an amount by weight

94.5% and a trace amount of 4-aminodiphenylamine.

Example 4

In this example, technical reductive p-nitrodiphenylamine containing 80% pure p-nitrodiphenylamine is used for reductive alkylation. The reaction is carried out in a reactor equipped with a mechanical stirrer and a double jacket and a coil for heating and cooling. The reactor is charged with 4.5 g fresh nickel catalyst, 22.5 g of unsupported nickel catalyst and 345 ml of cyclohexanone. The reactor is then purged with nitrogen gas. The contents of the reactor were mixed, the reactor was filled with hydrogen, and the whole was heated to 160 ° C, bringing the hydrogen pressure to 4 MPa. Thereafter, 150 g of technical p-nitrodiphenylamine dissolved in 180 ml of cyclohexanone was gradually introduced into the reactor via a metering pump. The pressure in the reactor is maintained between 3.5 and 4 MPa, the temperature between 160 and 170 ° C. The total reaction time is 5 hours. The contents of the reactor are cooled to 40 DEG C., the catalyst is separated and the volatile products as well as the excess cyclohexanone are distilled off, initially under normal, then under reduced pressure. N-cyclohexyl-N '-phenyl-p-phenylenediamine is obtained in a yield of 95%, based on pure p-nitrodiphenylamine used.

Claims (1)

A process for the preparation of p-aminodiphenylamine derivatives of the general formula I, wherein: R @ ¹ represents a hydrocarbon radical having from 3 to 6 carbon atoms, by reacting compounds of the formula II wherein R ² is nitro or nitroso group, with a ketone containing 3-6 carbon atoms under a pressure of hydrogen gas at elevated temperature in the presence of catalysts, characterized in that a nickel catalyst which is a mixture of fresh and already used neregenerovaného catalyst mixture catalysts in a ketone environment, first subjected to a temperature in the range of from 100 to 200 ° C and hydrogen gas at a pressure in the range of from 1 to 12,237 MPa, followed by the addition of a compound of formula II.