RU2323206C1 - Method for preparing 2,3-dimethyl-2,3-dinitrobutane - Google Patents

Abstract

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to chemistry of aliphatic nitro-compounds, in particular, to a method for synthesis of 2,3-dimethyl-2,3-dinitrobutane. Invention describes a method for synthesis of 2,3-dimethyl-2,3-dinitrobutane that involves interaction of 2-nitropropane salts with carbon tetrachloride wherein in first 2-nitropropane is treated with alkaline metal hydroxide aqueous solutions, preferably, potassium or sodium followed by with carbon tetrachloride and without isolation of 2-nitropropane salts. Method provides excluding preparing 2-halogen-nitropropanes (2-chloro-, 2-bromonitropropane) and to enhance the yield of the end product up to 70.4% of 2-nitropropane.

EFFECT: improved method of synthesis.

2 cl, 3 ex

Description

The invention relates to the field of chemistry of aliphatic nitro compounds, in particular to a method for producing 2,3-dimethyl-2,3-dinitrobutane (DMDNB). The literature describes a number of methods for its preparation. A known method developed by Ullman (US Pat. US No. 4032519, publ. 06/28/1977). The essence of the method is the interaction of the sodium salt of 2-nitropropane with bromine, followed by the reaction of the resulting 2-bromo-2-nitropropane with the sodium salt of 2-nitropropane. According to this method, DMDNB is obtained with a yield of 65-70%, but the main disadvantage of the method is the use of highly toxic halogen - bromine, whose MPC is 0.5 mg / m ³ . The irritating effect of bromine on the mucous membranes is clearly manifested even at a concentration of 0.013 ÷ 0.032 mg / l.

For the prototype, we took the method of the authors Sumet Limatibul, Joseph W. Watson (J. Ord. Chem. 37, No. 26, 4491-4492, 1972), in accordance with which the preparation of DMNB is carried out by the interaction of the lithium salt of 2-nitropropane with carbon tetrachloride in a medium anhydrous dimethyl sulfoxide (DMSO) in a nitrogen atmosphere. For the implementation of this method requires a stage of obtaining, separation, drying of the lithium salt of 2-nitropropane. Obtaining the lithium salt of 2-nitropropane is a laborious process using lithium hydride. The reaction takes place in anhydrous ethanol using ether in a nitrogen atmosphere (Robert C. Kerber, Yrant W. Urry, Nathan Komblum, J. Am. Chem. Soc. V 87, No. 20, 4525, 1965). The yield of lithium salt of 2-nitropropane is 80-90% of 2-nitropropane. Then, nitrogen is passed through a stirred solution of the lithium salt of 2-nitropropane in anhydrous DMSO and carbon tetrachloride is added in an amount of 2.5 mol per mol of 2-nitropropane. After exposure, the reaction mixture is diluted with water and extracted with ether. The ether extracts are combined and dried with anhydrous magnesium sulfate. The yield of DMDNB is 50% of the lithium salt of 2-nitropropane. The disadvantages of this method of producing DMDNB are the need for the synthesis and isolation of hydrolytically unstable lithium salt of 2-nitropropane, as well as the need to use an inert gas - nitrogen and anhydrous solvents: DMSO, ethyl alcohol, ether.

The objective of the invention is to develop a method for producing DMDNB, which allows to increase the yield of the target product, to exclude the stage of production, separation, drying of the lithium salt of 2-nitropropane, to exclude the stage of obtaining halide-2-nitropropanes, to simplify the selection of the target product.

The technical result is achieved by carrying out the reaction using potassium or sodium salts of 2-nitropropane obtained by reacting 2-nitropropane with 40% aqueous solutions of an alkali metal hydroxide, preferably potassium or sodium. Further, without isolating the corresponding salt from the reaction mass, DMDNB is obtained by the interaction of salts with carbon tetrachloride in a medium of dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).

The proposed method allows you to:

- increase the yield of the target product to 70.4%;

- exclude the stage of receipt, separation, drying of the lithium salt of 2-nitropropane;

- use carbon tetrachloride produced by industry, excluding the stage of obtaining 2-halide nitropropane

The proposed method for producing DMDB is illustrated by the following examples.

Example 1 (prototype)

In a flask equipped with a stirrer, thermometer, reflux condenser, place 2 g (0.02 mol) of the lithium salt of 2-nitropropane in 30 ml of anhydrous dimethyl sulfoxide. Nitrogen was passed through the suspension for 15 minutes. Next, 5 ml of carbon tetrachloride (8 g, 0.052 mol) are added to the reaction mass, the extract is aged for 15-30 minutes at a temperature of 60 ° C, then 50 ml of water are added, and the reaction mass is extracted with 3 portions of 150 ml of ether. The ether extracts are combined, washed with 100 ml of water, dried with magnesium sulfate. The ether solution was evaporated and 2,3-dimethyl-2,3-dinitrobutane was isolated.

The product yield is 0.925 g (50% of the lithium salt of 2-nitropropane).

Example 2 (the proposed method)

40 ml of dimethyl sulfoxide and 10 ml (9.9 g, 0.11 mol) of 2-nitropropane are placed in a flask equipped with a stirrer, thermometer and reflux condenser. With stirring and at a temperature not exceeding 30 ° C, 8 ml of a 40% aqueous sodium hydroxide solution (11.44 g, 0.11 mol) are metered in for 10-15 minutes. At the end of the dosage, an extract is allowed to stand for 40-60 minutes at a temperature of 30 ° C, then 13 ml of carbon tetrachloride (20.8 g, 1.2 mol per 1 mol of 2-nitropropane) are poured, the reaction mass is heated to a temperature of 55-60 ° C and give exposure at this temperature for 2 hours. The reaction mass is cooled to a temperature of 15 ° C and diluted with 100 ml of water. The product is filtered off, washed with water, and dried.

The yield of DMDB is 70.4% of 2-nitropropane. Melting point 209-210 ° C.

Example 3 (the proposed method)

30 ml of dimethylformamide and 10 ml (9.9 g, 0.1 mol) of 2-nitropropane are placed in a flask equipped with a stirrer, thermometer and reflux condenser. With stirring and at a temperature not exceeding 30 ° C, 12 ml of 40% aqueous potassium hydroxide solution (16.8 g, 0.12 mol) are dosed for 10-15 minutes. At the end of the dosage, an extract is allowed to stand for 40-60 minutes at 30 ° C, then 8 ml of carbon tetrachloride are poured (12.8 g, 0.75 mol per 1 mol of 2-nitropropane), the reaction mass is heated to a temperature of 55-60 ° C and give holding at this temperature for 2 hours. Next, the reaction mass is cooled to a temperature of 5-10 ° C, 100 ml of water are poured and the extract is allowed to stand for 30 minutes. The product is filtered off, washed with water, and dried.

The yield of DMDMB is 68.3% of 2-nitropropane. Melting point 209-210 ° C.

Claims (2)

1. The method of producing 2,3-dimethyl-2,3-dinitrobutane by the interaction of salts of 2-nitropropane with carbon tetrachloride, characterized in that 2-nitropropane is treated first with aqueous solutions of an alkali metal hydroxide, preferably potassium or sodium, then with carbon tetrachloride without evolution of salts 2-nitropropane. 2. The method according to claim 1, characterized in that carbon tetrachloride is taken in an amount of 0.75 ÷ 1.2 mol per mole of 2-nitropropane.