RU2506255C1 - Method of obtaining n-nitrosodialkylamines - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: relates to field of obtaining N-nitrosodialkylamines. Method of obtaining N-nitrosodialkylamines consists in interaction of water solutions of dialkylamines with carbon dioxide with molar ratio of dialkylamine to carbon dioxide (1÷2):1 with further processing of carnonates of dialkylamines with gas mixture of nitrogen with equimolecular mixture of nitrogen oxide and dioxide or gas mixture of nitrogen with nitrous anhydrite with molar ratio of dialkylamine to nitrogen oxides, in terms of nitrous anhydrite, not less than 1:1, reaction mass being kept at temperature 30-60°C, with support of pH of reaction mixtures 3-6.5 for 15-60 minutes.

EFFECT: invention makes it possible to reduce energy consumption, ensure ecological safety of technological production, with simultaneous increase of end product.

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Description

The invention relates to the field of production of N-nitrosodialkylamines used as intermediates for the synthesis of biologically active substances, drugs, surfactants, components of rocket fuels and other raw materials of chemical and related industries.

A known method of producing N-nitrosodialkylamines by the interaction of salts of strong mineral acids of the corresponding N-dialkylamines with nitrous acid salts of alkali metals [US Patent 2981752, NCI 260-583, publ. 04/25/1961]. The reaction is carried out in an aqueous medium when heated to 100 ° C, sodium nitrite is used as a nitrosating agent, and as an acid that binds amine, hydrochloric or sulfuric acid. The method is characterized by high yield (90% and higher), availability and low cost of starting materials. The disadvantage of this method of producing N-nitrosodialkylamines is the generation of waste by-products in the form of the corresponding sodium salts. The amount of waste generated in this process is quite high and amounts to 1.0-1.5 tons per ton of N-nitrosodialkylamine, depending on the mineral acid used in the process. The need to separate the main product from the side increases the number of stages and increases the cost of the process.

The use of nitrogen oxides as a nitrosating agent eliminates the formation of inorganic salts. In US patent 3090786, IPC C08L 21/00, publ. 05/21/1963 the process of nitrosation of secondary amines with nitrogen dioxide is carried out in an autoclave at a temperature of from -30 to 200 ° C and a pressure of from 1.5 to 10 atm in an organic solvent. The yield after distillation is not more than 66.5%. The process is carried out at elevated temperatures, pressure, with a low yield of N-nitrosodialkylamines.

In US patent 3065270, NKI 260-583, publ. 11/20/1962 the process of nitrosation of lower dialkylamines with a mixture of nitrogen dioxide and oxygen is carried out in excess of dialkylamine at a temperature from 0 to 100 ° C. The yield after isolation is not more than 66%.

The disadvantage of the considered methods is the low yield of the finished product, the use of the increased pressure necessary to prevent the evaporation of volatile components at elevated temperatures - this greatly complicates and increases the cost of the process.

Known gas-phase process of nitrosation of N-dialkyl- and N-alkyl-N-arylamines with an equimolar mixture of oxide and nitrogen dioxide in a stream of nitrogen [US Patent 3340303, NCI 260-583, publ. 09/05/1967]. The method of nitrosation of dialkylamines in the vapor phase, which consists in initiating a nitrosation reaction by contacting a gaseous stream of dialkylamine with a gaseous mixture of nitrogen oxides until the temperature in the reaction zone rises, after which the addition of nitric oxide is stopped, continuing to add nitric dioxide and dialkylamine, maintaining a temperature of from 80 to 225 ° C, continuously removing the resulting dialkylnitrosoamine. The yield of N-nitrosodialkylamines is 65-80%. The disadvantage of this method is the low yield of the finished product, maintaining high temperatures, which complicates the technological installation of this production.

The task of the invention is to simplify the process, increase environmental safety and increase the yield of the finished product.

To solve this problem, a method for producing N-nitrosodialkylamines by the interaction of aqueous solutions of dialkylamines with carbon dioxide at a molar ratio of dialkylamine to carbon dioxide (1-2): 1, followed by treatment of the obtained dialkylamine carbonates with an equimolecular mixture of nitric oxide with nitrogen dioxide or nitrous anhydride with a molar the ratio of dialkylamine to nitrogen oxides, in terms of nitrous anhydride, is not less than 1: 1, while the reaction mass is maintained at a temperature of 30-60 ° C and the pH of the reaction x 3-6.5 mixtures within 15-60 minutes.

Pretreatment of aqueous solutions of dialkylamines with carbon dioxide, the proposed method, carries out chemical binding and retention in the reaction mixtures of N-dialkylamines in the form of carbonic salts, followed by nitrosation with nitrogen oxides, which allows the nitrosation process at a temperature of 30-60 ° C at normal pressure for 15 -60 minutes and reduces the number of stages of the process, significantly reduces energy consumption, ensures environmental safety of the whole production. As nitric oxides can be used industrial nitrous gases generated during the catalytic oxidation of ammonia.

The process is carried out on a plant operating in a semi-continuous mode with periodic loading of a liquid reagent and continuous supply of a gaseous reagent. To obtain dialkylamine carbonate, a measured amount of an aqueous solution of dialkylamine is poured into the reactor. Carbon dioxide is fed into the reactor via a bubbler installed inside the reactor through a porous glass plate located at the bottom of the reactor over its entire cross section. The pore diameter of the plate is 0.1 mm, which ensures a high dispersion of the bubbling gas (bubble diameter of not more than 0.1 mm) and a sufficient contact time (bubble rise time of 20-25 seconds) for the complete conversion of dialkylamine to carbonate.

The amount of dialkylamine and dialkylamine carbonate in the solution is determined by potentiometric titration with a 0.1N hydrochloric acid solution. At the end of the carbon dioxide supply, a gas mixture of nitrogen with an equimolecular mixture of nitrogen oxide and dioxide or a gas mixture of nitrogen with nitrous anhydride is fed into the reactor at a predetermined flow rate. The mixture was bubbled through an aqueous solution of dialkylamine carbonate. Upon reaching a solution pH of 3-6.5, the reaction mass is maintained at a temperature of 30-60 ° C for 15-60 minutes.

Example.

A method of producing N-nitrosodimethylamine. An aqueous solution of dimethylamine is loaded into the reactor with a jacket to maintain the desired temperature, equipped with a stirrer, bubbler and thermometer, and carbon dioxide is bubbled through it. The volume of carbon dioxide is calculated so that the molar ratio of dimethylamine to carbon dioxide is 1: 1. At the end of dosing of carbon dioxide through a bubbler, a nitrogen gas mixture with an equimolecular mixture of nitrogen oxide and dioxide is fed into the reactor. The mixture was bubbled through an aqueous solution of dimethylamine carbonate. Upon reaching a solution pH of 3, the reaction mass is maintained for 45 minutes at a temperature of 60 ° C. The solution is analyzed for the content of N-nitrosodimethylamine according to UV spectrometry and gas-liquid chromatographic analysis of the reaction mixtures. The yield of N-nitrosodimethylamine is 93%.

The table shows the methods for producing N-nitrosodialkylamines by the example of dimethylamine, diethylamine, methylethylamine, dipropylamine, diisopropylamine, diisobutylamine.

The proposed method for the production of N-nitrosodialkylamines allows to increase the yield of the finished product up to 96%, to simplify the process by reducing a number of production stages and to ensure environmental safety of the whole production.

Table Methods of nitrosation of dialkylamines (DAA) and obtaining N-nitrosodialkylamines (NDAA) No. p / p Starting reagents Experience Conditions The yield of NDAA,% wt. an aqueous solution of DAA, g (mol) CO ₂ ndm ³ (mol) NO, dm ³ (mol) NO ₂ , DM ³ (mol) N ₂ O ₃ , g (mol) N ₂ , NDM ³ Holding time, min Holding temperature, ° С PH one dimethylamine 50 (0.27) 4.50 (0.20) 3.15 (0.14) 3.20 (0.14) - 60.0 45 60 3.0 93.0 2 dimethylamine 50 (0.27) 4.00 (0.18) - - 10.00 (0.13) 62.0 60 60 5.5 96.0 3 diethylamine 50 (0.41) 5.60 (0.25) 4.50 (0.20) 4.60 (0.20) - 70.0 thirty 60 6.0 88.3 four diethylamine 50 (0.41) 5.5 (0.25) 20.00 (0.26) 80.0 55 60 6.5 89.7 5 methylethylamine 50 (0.51) 5.60 (0.25) 6.20 (0.26) 6.00 (0.26) - 80.0 twenty fifty 5,0 90.0 6 methylethylamine 50 (0.51) 6.0 (0.26) - - 24.00 (0.32) 100.0 fifty fifty 5,0 92.3 7 dipropylamine 50 (0.32) 3.50 (0.16) 3.60 (0.16) 3.60 (0.16) - 60.0 thirty 40 4,5 93.0 8 dipropylamine 50 (0.32) 3.6 (0.16) - - 15.00 (0.2) 70.0 60 40 5,0 94.5 9 diisopropylamine 50 (0.32) 7.00 (0.32) 3.60 (0.16) 3.60 (0.16) - 65.0 fifteen 60 4.0 89.0 10 diisopropylamine 50 (0.32) 7.00 (0.32) - - 16.00 (0.21) 80.0 45 60 5.5 91.0 eleven diisobutylamine 50 (0.23) 6.00 (0.26) 3.00 (0.13) 3.00 (0.13) - 55.0 60 thirty 5.5 92.0 12 diisobutylamine 50 (0.23) 6.00 (0.26) - - 11.00 (0.15) 60.0 60 thirty 5,0 94.3

Claims (1)

A method of producing N-nitrosodialkylamines, including the interaction of dialkylamines with nitrogen oxides, characterized in that the aqueous solutions of dialkylamines are treated with carbon dioxide at a molar ratio of dialkylamine to carbon dioxide (1 ÷ 2): 1, followed by treatment of dialkylamine carbonates with a nitrogen gas mixture with an equimolecular oxide mixture and nitrogen dioxide or a gas mixture of nitrogen with nitrous anhydride at a molar ratio of dialkylamine to nitrogen oxides, in terms of nitrous anhydride, not less than 1: 1, while the reaction Assa maintained at a temperature of 30-60 ° C, keeping the pH of the reaction mixtures 3-6.5 for 15-60 minutes.