RU2436763C1 - Method of producing 2,3-dimethyl-2,3-dinitrobutane - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing 2,3-dimethyl-2,3-dinitrobutane via nitration of tetramethylethylene with nitrogen tetraoxide in ethyl acetate medium or tetrachloromethane. The disclosed method enables to obtain 2,3-dimethyl-2,3-dinitrobutane with higher output than in the existing analogue method, where the reaction is carried out at low temperature in diethyl ether medium.

EFFECT: method enables to avoid use at low temperatures of minus 16 to minus 20°C and carry out said reaction at temperature 20-60°C, which considerably simplifies the process of obtaining 2,3-dimethyl-2,3-dinitrobutane.

2 cl, 5 ex, 2 tbl

Description

The present invention relates to the field of chemistry of aliphatic nitro compounds, in particular to a method for producing 2,3-dimethyl-2,3-dinitrobutane (DMNB).

Of the known ways of synthesizing DMNB, the main one is the method proposed by Seigle and Hess (Seigle J.W., Hass H.W. // J.Org.Chem., 1940. V5, P100), according to which dinitroparaffins can be obtained from secondary nitroparaffins. The method is based on the reaction of the interaction of the sodium salt of 2-nitropropane with 2-halide-2-nitropropane according to the scheme

The authors heated the sodium salt of 2-nitropropane with 2-chloro-2-nitropropane in absolute alcohol for 7 hours. The yield of DMNB was only 9% (of theory). When carrying out the reaction using 2-bromo-2-nitropropane in ethyl alcohol for 3.5 hours, the yield of DMNB was 29%. This method was subsequently improved by Ullman (US patent No. 4032519, Ullman Edwin, publ. 06/28/77). According to this method, the preparation of DMNB is carried out by 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 in ethyl alcohol.

The authors (patent RU No. 23233206, N.P. Tikhomirova, S.I. Valeshniy, V.P. Ilyin et al., Applications. 03.10.06, publ. 27.04.08) developed a method for producing DMNB by condensation of sodium or potassium salt 2 -nitropropane with carbon tetrachloride, which eliminates the stage of obtaining 2-halogen nitroparaffins.

The literature describes methods for producing DMNB by nitration of tetramethylethylene (TME) with nitrogen oxides: NO ₂ , N ₂ O ₄ , N ₂ O ₅ . The use of TME as an alternative raw material for the production of DMNB is of interest, since it allows eliminating the deficient 2-nitropropane from the process.

The nitration of tetramethylene was studied by adding nitrogen tetraoxide under pressure to TME at 24 ° C (C.A. Burkhard, J.F. Brown // J. Org. Chem., 1940, V.29, P.2235-2239). The reaction product was cooled in an acetone bath and dry ice, filtered. The filtrate was subjected to distillation at 1 mm (100 ° C). The yield of DMNB was ~ 28% (from TME). This method requires a special apparatus for working under pressure, cooling the reaction mass with acetone with dry ice, distillation under vacuum (1 mm, 100 ° C).

Also known is a method for producing DMNB with a rather high yield by nitration of tetramethylene with nitrogen dioxide (NO ₂ ) in hexane (Golding P., Powell JL, Ridd JH // J. Chem. Soc. Perkin Trans 2, 1996. P.813-818). It should be noted that all the starting materials (nitrogen dioxide, TME and solvents) were of high purity: nitrogen dioxide was purified by distillation over phosphorus pentoxide, TME was used with the grade “hch”, and hexane was dried over phosphorus pentoxide. All this complicates the process of obtaining DMNB, making it unsuitable for industrial use.

As the closest analogue, we took the method of the authors A.Michael, JHCarison (J.Org.Chem., 1940, V.5, P.14, 21) in accordance with which DMNB is produced by nitration of TME with gaseous nitrogen tetroxide (N ₂ O ₄ ).

The authors investigated the effect of gaseous nitrogen tetroxide on TME under various experimental conditions. DMNB with yields of 19.6-22.0% was obtained with an excess of TME in diethyl ether as a solvent. The results of the experiments are presented in table 1.

Table 1 Process parameters Parameter value TME, g 4.0 5.5 5.5 N ₂ O ₄ , g 4.0 4.8 5.1 Diethyl ether, ml 25.0 30,0 30,0 T, ° С -18.0 -20.0 -16.0 Time min 30,0 10.0 20,0 Exit, % 19.8 19.6 22.0 T _pl , ° C 210.0-211.0 208.0-210.0 208.0-210.0

The data shown in table 1 show that DMNB is obtained by nitration of TME with nitrous oxide at a temperature of minus 16 to minus 18 ° C for 20-30 minutes with a maximum yield of 22%.

Under all experimental conditions studied, 2-nitro-2,3-dimethylbutanol-3 nitrate is formed as a by-product.

Reaction scheme for producing DMNB

The objective of the invention is to develop a method for producing DMNB, which allows to increase the yield of the target product, to exclude from the process the use of flammable explosive diethyl ether and the use of low temperatures (minus 16 ÷ minus 20 ° C).

The technical result is achieved by nitration of TME with nitrogen tetroxide in an environment of carbon tetrachloride, ethyl acetate. As solvents, hexane, ethyl acetate, carbon tetrachloride, nefras 80/120 (catalytic reforming gasoline with a start temperature of distillation from 80 to 120 ° C), benzene, toluene, methylene chloride, etc. were studied. The nitration temperature varied in the range from 20 to 60 ° C. The results of the experiments are presented in table 2.

table 2 No. p / p Solvent name DMNB output Note g % one hexane 3.9 43.8 Amount: solvent 60 ml. TME - 6 ml (4.25 g) 2 ethyl acetate 4.4 49.8 3 Nefras 80/120 3.8 42.7 N ₂ O ₄ 3.5 ml (composition: N ₂ O ₄ 94.67% four carbon tetrachloride 4,55 51.0 HNO ₃ 5.25%) Holding time: 1 hour at 20 ÷ 24 ° C 2 hours at 55 ÷ 60 ° C

The data shown in table 2 show that DMNB is obtained with a yield of 42.7 ÷ 51.0% using various solvents. The maximum yield was obtained using carbon tetrachloride and ethyl acetate.

The proposed method allows you to:

- increase the yield of the target product;

- eliminate the use of diethyl ether, which is a flammable liquid;

- carry out nitration of TME at temperatures of 20 ÷ 60 ° C, which eliminates the use of refrigerants used to achieve temperatures of minus 16 ÷ minus 20 ° C.

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

Example 1 (prototype).

5.5 g (0.065 mol) of TME are placed in a flask equipped with a stirrer and reflux condenser. With stirring and cooling to minus 16 ° C, 5.1 g (0.055 mol) of nitrogen tetroxide in 30 ml of diethyl ether are dosed. Give an exposure of 20 minutes at a temperature of minus 16 ° C. The precipitated product is filtered off, washed with ether, and dried. The yield of DMNB is 22% (of TME), so pl. 208-210 ° C.

Example 2 (the proposed method).

In a flask equipped with a stirrer, a thermometer and a reflux condenser, 30 ml of ethyl acetate and 6 ml (4.25 g, 0.05 mol) of tetramethylene (TME) are placed. With stirring and a temperature of 20-24 ° C, a solution of 3.0 ml (4.32 g, 0.047 mol) of nitrogen tetroxide in 30 ml of ethyl acetate is metered in under a layer of a mixture of ethyl acetate with TME for 30 minutes. Further, the temperature is increased to 55-60 ° C for 15-30 minutes and the extract is allowed to stand for 2 hours. Then ethyl acetate is distilled off and the precipitated product is filtered off, washed with alcohol, and dried. The yield of DMNB is 49.8% (of TME), mp 209-210 ° C.

Example 3

The experiment is carried out by analogy with example 2, using carbon tetrachloride as a solvent.

The yield of DMNB is 51.0% (of TME), mp 209-211 ° C.

Example 4

In a flask equipped with a stirrer, thermometer and reflux condenser, 30 ml of hexane and 6 ml (4.25 g, 0.05 mol) of tetramethylene (TME) are placed. With stirring and a temperature of 20 ÷ 24 ° C, a solution of 3.0 ml (4.32 g, 0.047 mol) of nitrogen tetroxide in 30 ml of hexane is metered in under a layer of a mixture of hexane with TME for 30 minutes. Next, the temperature is increased to 55 ÷ 60 ° C for 15-30 minutes and the extract is held for 2 hours. The precipitated product is filtered off, washed with alcohol, and dried. The yield of DMNB is 43.8% (from TME), mp 209-211 ° C.

Example 5

The experiment is carried out by analogy with example 4, using nephras 80/120 as a solvent.

The yield of DMNB is 42.7% (from TME), mp 209-210 ° C.

Claims (2)

1. A method of producing 2,3-dimethyl-2,3-dinitrobutane by nitration of tetramethylene with nitrogen tetroxide in a solvent medium, characterized in that carbon tetrachloride or ethyl acetate is used as the solvent. 2. The method according to claim 1, characterized in that the process is carried out at a temperature of from 20 to 60 ° C.