CS221339B1 - Method of making the 2-nitrodiphenylamine - Google Patents

Abstract

Process for producing 2-nitrodiphenylamine by condensation 2-nitrochlorobenzene with aniline is indicated by providing a mixture of aniline and acidic sodium carbonate by weight ratio 1: 0.1-1.5 at 130-150 ° C while distilling off the reaction water, then gradually to the reaction mixture introduces a pre-prepared solution of 2-nitrochlorobenzene and aniline by weight ratio 1: 0.5 to 1.5 and at 170 ° C to 200 CCs are condensed, after they are done by condensation, the reaction mixture is cooled to 80 ° Centigrade to 130 ° C, diluted 1: 1 with water : 0.1 to 0.8 wt.% Followed by separation solution of the salts, then the reaction mixture was then \ t vacuum distillation at 70 ° C to 140 ° C Celsius and a pressure of 1 kPa to 3 kPa separate the starting unreacted raw material, purified product is extracted with toluene (1: 1) up to 1.5 wt agents such as diatomaceous earth, diatomaceous earths or carborafine, saturated with concentrated sulfuric acid is cloned, distilled off from the purified reaction mixture toluene, the reaction mixture is cooled to room temperature From 80 ° C to 90 ° C, ethanol is introduced into it, from which it is cooled to 20 ° C to 0 ° C 2-nitrodiphenylamine crystallizes.

Description

The present invention relates to a process for the preparation of 2-nitodiphenylamine, which is an important dye intermediate and has recently found use as a stabilizing agent for particular manufacture.

As a technologically feasible method of preparing 2-nitrodiphenylamine, the action of aniline on 2-nitrochlorobenzene is at temperatures close to the boiling point of aniline in the presence of substances capable of binding the resulting hydrochloric acid. The known preparation process uses sodium acetate, but at the same time a considerable proportion of acetanilide is formed by the action of the liberated acetic acid on the aniline.

Among other reagents, ammonia has been proposed to be used in large excess due to its insolubility at temperatures necessary for condensation. Soda as a hydrochloric acid binding agent does not have the necessary reaction surface.

The present process is overcome by the process for the preparation of 2-nitrodiphenylamine by the condensation of 2-nitrochlorobenzene with aniline which is the object of the invention, which comprises the mixture of aniline and sodium bicarbonate having a weight ratio of 1: 0.1 to 1.5 at 130 ^C to 150 ° C while distilling off the reaction water, then a preformed solution of 2-nitrochlorobenzene and aniline in a weight ratio of 1: 0.5 to 1.5 is successively introduced into the reaction mixture at 170 to 200 ° C. condensation, after the condensation has been carried out, the reaction mixture is cooled to 80 to 130 ° C, diluted with water in a weight ratio of 1: 0.1 to 0.8, followed by separation of the salt solution, from the reaction mixture is then vacuum distilled at 70 to 140 ° C at a pressure of 1 to 3 kPa, separates the starting unreacted raw materials, the purified product is extracted with toluene in a weight ratio of 1: 1 to 1.5, after A clering agent such as diatomaceous earth, diatomaceous earth or carboraffin saturated with concentrated sulfuric acid is clerified, toluene is distilled off from the purified reaction mixture, the reaction mixture is cooled and ethyl alcohol is introduced at 80-90 ° C. 20 DEG-0 DEG C. 2-nitrodiphenylamine crystallizes.

The principle of the invention is in particular the use of sodium bicarbonate which decomposes into carbon dioxide and water at temperatures of 130 to 150 ° C, i.e. even below the condensation temperature itself, both decomposition products escape at decomposition temperature leaving finely dispersed sodium carbonate with a large reaction surface. acts as a neutralizing agent in the reaction, binding hydrogen chloride formed. This decomposition is preferably carried out directly in the aniline solution. Upon completion of the decomposition of sodium bicarbonate to finely divided soda by raising the temperature of the reaction mixture to near the boiling point of aniline, condensation takes place to form carbon dioxide and water, which are removed from the reaction mixture. Condensation requires efficient mixing and sensitive control of the temperature of the heating medium to prevent the reaction mixture from overheating. At the ratio of reaction components:

aniline 3 moles,

2-nitrochlorobenzene 1 mol, sodium bicarbonate 1 to 1.2 mol, formation of 2-nitrodiphenylamine occurs at a reaction temperature of 182 to 185 ^° C as follows:

Reaction time Sample of 2-nitrodiphenylamine (hours) (% conversion) ^{1 2}

12.07

57.73

73.55

84.02

89.00

The condensation reaction at a given temperature with measures to prevent overheating of the reaction mixture is accompanied by side reactions leading to the formation of dark resinous fractions. By sensitively maintaining the optimal reaction temperature, the formation of these by-products is strongly suppressed, but the resulting product is colored brown. It has been found that constant maintenance of the optimum temperature is critical to successful condensation, for example, increasing the reaction temperature by 10-15 ° C leads to a rapid increase in the resins, which ultimately predominate. These resins can be chromatographically separated into 10 to 12 dyes from blue, violet and red to orange and yellow.

The condensation reaction mixture contains, besides aniline, a proportion of unreacted 2-nitrochlorobenzene as desired product, 2-nitrodiphenylamine in addition to an inorganic portion of soda and sodium chloride.

The products were isolated by distilling off the aniline in vacuo and extracting the residue with an aromatic hydrocarbon, benzene or toluene, distilling off the solvent and crystallizing the crude product from ethanol. It was also tried to obtain the product by vacuum distillation.

A second variant of isolation was to add enough water to the reaction mixture at 80 [ ^deg .] C. with stirring to dissolve the inorganic fraction to a nearly saturated solution which is heavier than the reaction mixture. Crystallization from ethanol yields a regular brown to dark brown product, and it has been found that the condensation formed resinous dyes from the product can be removed very advantageously and quantitatively by cleaving the toluene solution of the crude product after distilling aniline in an aromatic solvent such as toluene, by simple mixing with diatomaceous earth, diatomaceous earth or carboraffin, in which concentrated sulfuric acid is attached up to 50% by weight, in this process the resin dyes are bound to the sulfuric acid connected in the absorption agent without the sulfuric acid from the reagent being transferred P by the gradual addition of this cleric agent, a complete clarification of the solution is achieved within a short time, which is then red-orange. The clering temperature is 20 to 50 ° C. After completion of the cleration, the reagent is filtered off, washed with solvent and the purified solution is treated by evaporation of the solvent and crystallization. The product thus obtained is brick-orange, crystalline and chromatographically pure. The mother liquors, after crystallization of the final product, give a residue which, after vacuum distillation of aniline and 2-nitrochloribenzene, again yields a satisfactory product in all parameters. The yield of pure 2-nitrodiphenylamine having a pour point of 73.8-74 ° C and a melting point of 74.8-76 ° C is 79.5 percent of theory to 2-nitrochlorobenzene and 65.0% of theory to aniline, respectively.

He did

The operating condensing boiler is a duplicator with good insulation against heat loss, equipped with an efficient stirrer, 1.5 rn high column, downstream cooler and wells. The boiler is heated by reaction medium (dowtherm), whose temperature is within the range of 1 ± 2 ° C automatically regulated to the desired temperature, which is registered during the reaction.

138 kg of technical aniline are added to the condensing boiler and 87.5 kg of sodium bicarbonate are added. The contents of the boiler are heated to 130 ° C with heating medium while stirring. At 130 ° C the decomposition of sodium bicarbonate begins, which after 3 hours at 150 ° C is virtually complete and the water with aniline stops (about 9 L).

The temperature of the mixture is now slowly raised to 180 ° C and a previously prepared solution of 157.9 kg of 2-nitrochlorobenzene in 140.0 kg of aniline is added to the suspension. 4 hours. The temperature in the condensing boiler is maintained at 183-186 ^° C for 20 hours. The medium temperature is at most 10 ^° C higher. Reaction water is produced which flows out of the column at a temperature in the range of 55 to 85 ° C in admixture with aniline in an amount of 6 to 9 L. At the end of the condensation period, the contents of the boiler are allowed to cool to 120 ° C under nitrogen and, while stirring, the 180 liters of water are introduced into the boiler. The contents of the boiler are then maintained at 85 ° C to 95 ° C for 2 hours, then the bottom aqueous layer, the salt solution is allowed to settle and after 4 hours the bottom layer is drained from the boiler. The aniline is distilled off from the salt-free reaction mixture thus obtained, possibly with 2-nitrochlorobenzene.

Toluene (400 L) was then added to the residual melt of the crude 2-nitrodiphenyl-6 amine at 60 ° C.

The resulting solution is then charged portionwise at 60 ° C with a portion of about 1 kg of powdered cleric reagent (50% sulfuric acid mixture at 96% by weight in diatomaceous earth). After each addition of the cleaving agent, the contents of the boiler were stirred for 1 hour, filtered, and the filtrate was judged visually or sensitively by the trace it left after being spiked onto the silufol plate. Consumption according to resin content 10 kg of clering agent. After the solution has cleared, the solution is filtered at 60 DEG C. with a pressure filter, the clering agent is washed with 150 l of toluene and the toluene filtrate is evaporated. 200 kg of ethanol are then added to the remaining orange melt at 90 ^DEG C. with stirring, and the contents of the boiler are slowly cooled to 30 DEG C. while stirring, and then to 10 DEG C. with cold water. The crystallized 2-nitrodiphenylamine, orange crystals, is isolated on suction, washed with ethanol and dried at room temperature. The mother liquor is again evaporated and the residue is reprocessed as described by vacuum distillation after removal of the aniline and 2-nitrochlorobenzene.

The yield of chromatographically pure 2-nitrodiphenylamine satisfying the desired parameters is 79.5% of theory to 2-nitrochlorobenzene and 65.0% of theory to aniline, respectively.

Regenerated aniline, 2-nitrochlorobenzene and regenerated solvents (toluene, ethanol) can be used for further production operations. In addition to the waste salt solution (sodium chloride, sodium carbonate), which does not contain aniline or 2-nitrochlorobenzene, only a relatively small amount of the cleric mixture used is produced.

Example 2

200 kg of technical aniline are added to the condensing boiler and 150 kg of sodium bicarbonate are added. The contents of the boiler are heated to 130 ° C with heating medium while stirring. At 130 ° C the decomposition of sodium bicarbonate begins, which after 3 hours at 150 ° C is virtually complete and the water and aniline cease to pass (approx. 14 L). The temperature of the mixture is now slowly raised to 180 ° C and a previously prepared solution of 236 kg of 2-nitrochlorobenzene in 219 kg of aniline is introduced into the suspension. 4 hours. The temperature in the condensing boiler is then maintained at 183-186 ° C for 20 hours. The temperature of the medium is at most 10 ° C higher. Reaction water is produced which flows through the column at a temperature in the range of 55-85 ^° C in admixture with aniline in an amount of 9-113 L. The course of the condensation can be monitored by chromatography, e.g. At the end of the condensation period, the contents of the boiler are allowed to cool to 120 ° C under nitrogen and, with constant stirring, are introduced into the boiler via a water meter of 350 L of water. The contents of the boiler are then maintained at 85-95 ° C for 2 hours, then the bottom aqueous layer, salt solution is allowed to settle and after 4 hours the bottom layer is drained from the boiler. The aniline is distilled off from the salt-free reaction mixture thus obtained, possibly with 2-nitrochlorobenzene.

700 L of toluene is then added to the residual melt of the crude 2-nitrodiphenylamine at 60 ° C. The resulting solution is then charged in portions of about 3 kg at 60 [deg.] C. with a powdered cleric agent (50% by weight 96% sulfuric acid in diatomaceous earth). After each addition of the cleaving agent, the contents of the boiler were stirred for 1 hour, filtered, and the filtrate was judged visually or sensitively according to the trace it had left on the silufol plate. Consumption according to resin content 15 kg of clering agent. After clarifying the solution, the solution was filtered at 60 ° C with a pressure filter, washed with 150 L of toluene and the toluene filtrate was evaporated. 300 kg of ethanol are then added to the remaining orange melt at 90 ° C with stirring and the contents of the boiler are slowly cooled to 30 ° C with stirring and further to 10 ° C with cold water. The crystallized 2-nitrodiphenylamine, orange crystals, is isolated on suction, washed with ethanol and dried at room temperature. The mother liquor is again evaporated and the residue after the removal of aniline and 2-nitrochlorobenzene by vacuum distillation is reprocessed as described.

The yield of chromatographically pure 2-nitrophenylamine satisfying the desired parameters is 79.5% of theory on 2-nitrochlorobenzene, respectively. 65.0% of the theory for aniline.

Claims (1)

SUBJECT A process for the preparation of 2-nitrodiphenylamine by condensation of 2-nitrochloribenzene with aniline, characterized in that the mixture of aniline and sodium bicarbonate in a weight ratio of 1: 0.1 to 1.5 is heated at 130 to 150 ° C while distilling off the reaction water, then the reaction mixture is gradually introduced with a pre-prepared solution of 2-nitrochlorobenzene and aniline in a weight ratio of 1: 0.5 to 1.5 and condensation is carried out at 170 to 200 ° C, after the condensation the reaction mixture is cooled to 80 to 130 ° C, Dilute with water at a ratio of 1: 0.1 to 0.8, followed by separation (YNÁLEZU of the salt solution), from the reaction mixture, the starting unreacted raw materials are separated from the reaction mixture by vacuum distillation at a temperature of 70 to 140 ° C and a pressure of 1 to 3 kPa. is extracted with toluene in a weight ratio of 1: 1 to 1.5, after addition of a clerifying agent such as diatomaceous earth, diatomaceous earth or carboraffin, saturated The reaction mixture was cooled, and ethanol was added at 80-90 ° C, from which 2-nitrodiphenylamine crystallized upon cooling to 20 ° C - 0 ° C. Severografia, n. P „plant 7 Most price 2, <0 Code no