RU1817772C - Process for preparing 2-chloro-4-nitroaniline - Google Patents

Abstract

The inventive product 2-chloro-4-nitro / aniline bF CeHsCINzOz, so pl. 99.6 ° C. Reagent 1: 4-nitroanaline. Reagent 2: HCI. Reagent 3: H202. Reaction conditions: the ratio of reagents 1.2 and 3 is 1: 2.0-3.0: 1.20-1.25 and the process is carried out in an aqueous medium in the presence of a catalyst - dimethylformamide, N-methylpyrrolidone or dimethyl sulfoxide, in quantity 0.18-0.22 mol, or sodium chloride, taken in an amount of 0.02-0.3 mol per 1 mol of 4-nitroaniline, at 45-60 ° C. 1 tab.

Description

The invention relates to organic chemistry, in particular to a method for producing 2-chloro-4-nitroaniline, which is used as an intermediate in the synthesis of anthelmintic preparations, and can be used in organic chemistry.

The aim of the invention is to increase the yield of the target product, simplify the technology, improve working conditions, eliminate chlorine gas from production, and reduce the amount of wastewater.

The goal is achieved in that in the method for producing 2-chloro-4-nitroaniline by chlorination of 4-nitroaniline in an aqueous medium in the presence of hydrochloric acid, according to the invention, chlorination is carried out with a mixture of 2-3 mol of hydrochloric acid with 1.20 -1.25 mol of hydrogen peroxide in the presence of. 0.18-0.22 mol% of the catalyst: dimethylformamide or N-methylpyrrolidone, or dimethyl sulfoxide, or 0.02-0.3 mol of sodium chloride at a temperature of 45-60 ° C.

If the above mixture contains an amount of hydrochloric acid less than the lower limit value, then the reaction is incomplete, which leads to a decrease in yield and deterioration of product quality, and if a higher upper limit value, the consumption of hydrochloric acid and the likelihood of corrosion of the equipment increase.

If the mixture contains an amount of hydrogen peroxide less than the lower limit value, then the reaction does not reach the end, which leads to a decrease in yield, and if a higher upper limit value, an admixture of re-chlorinated product is formed, which leads to a decrease in the content of the basic substance.

If the chlorination process is carried out at a temperature lower than the lower limit value, then the reaction does not reach the end, which reduces the yield and increases the duration of the process, and if at a temperature is higher than the upper limit value.

with

with

with

 vj vi y

Oj

This accelerates the formation of the re-chlorinated product.

If we take the amount of catalyst less than the lower limit value, the yield decreases and the quality of the product deteriorates, and if a higher limit value, the yield also decreases and the quality of the product deteriorates.

The essence of the proposed technical solution is confirmed by examples of the specific implementation of the method.

EXAMPLE 1 70 ml water or a mother liquor from a previous experiment is introduced into a 100 ml flask. 1.43 g of dimethylformamide (0.0197 mol), 13.8 g of 4-nitroaniline (0.1 mol) and 10.49 g of 31.5% 4 hydrochloric acid (0.29 mol). The resulting mixture was heated to 55 ° C and stirred until p-nitroaniline was completely dissolved. At this temperature, 4 t4 g of 35% hydrogen peroxide (0.122 mol) was added over 3 hours, then at 55 ° C the mass was stirred for 3 hours until the oxidizing agent disappeared (according to iodine starch paper). Filter at 25 ° C. A small amount of hydrochloric acid and dimethylformamide was added to the filtrate and used for subsequent experiments. The precipitate is washed with water at 20 ° C until neutral. The yield of 2-chlorr-4-nitroaniline is 99.8%, and the melting point is 99.6 ° C.

Examples 2-28. Performed as in Example 1. The process conditions and the results obtained are shown in the table.

The proposed technical solution in comparison with the prototype has the following advantages: increases the yield of the target product by 17.2% (prototype

81%, by the proposed method 99.3%) working conditions are improved due to the exclusion of gaseous chlorine; eliminating the possibility of emissions of gaseous chlorine into the environment; technology is simplified

by omitting the preparation of sodium hypochlorite; the amount of wastewater is reduced (according to the prototype 34500 kg. according to the proposed method, 69QO kg).

fifteen

Claims (1)

The claims A method of producing 2-chloro-4-nitroaniline by chlorination of 4-nitroaniline in an aqueous medium in the presence of hydrochloric acid subsequent isolation of the target product by filtration, characterized in that, in order to simplify the process and increase the yield of the target product, chlorination is carried out with a mixture of hydrochloric acid and hydrogen peroxide in a molar ratio of 4-nitroaniline, hydrochloric acid and hydrogen peroxide equal to 1: 2.0-3.0: 1.20-1.25, in the presence of a catalyst of dimethylformamide, N-methylpyrrolidone or dimethyl sulfoxide, in an amount of 0.18-0.22 mol, or sodium chloride, in an amount of 0.02-0.3 mol per 1 mol of 4-nitroaniline, at a temperature of 45-60 ° C.