SU897108A3 - Method of preparing 2,6-dinitroderivatives of n-alkyl or n,n-dialkylanilines - Google Patents

Abstract

Prepn. of herbicidal cpds. of formula (I) (where Y is 1-4C alkyl, halogen CF3; Z is H, halogen; 1-4C alkyl opt. substd. by one halogen or 1-4C alkoxy; 1-4C alkoxy; Ra is 1-6C alkyl, 4-6C cycloalkyl, 1-4C alkoxy - 1-4C alkyl; Rb is H or one of the values of Ra) comprises nitration of the corresp. N-alkylanilines with a mixed acid within the limits 60% HNO3 8% H2SO4, 32% H2O; 50% HNO3, 35% H2SO4, 15% H2O; 2% HNO3, 68% H2SO4, 30% H2O; 2% HNO3, 20% H2SO4, 70% H2O AT 0-70 degrees C. The process avoids the need to block the amino gp. by acylation when Rb is H. This is overcome by denitrosation of the by-prod. N-nitroso cpd. by treating it with HC1 and sulphamic acid.

Description

(54), METHOD OF OBTAINING 2, b-DINITROPRODUCTIVE N-ALKYL OR N, N-DIALKYLANILINES

one

This invention relates to organic synthesis, in particular to the preparation of 2,6-dinitro derivatives of N-alkyl or N, N-dialkylilanines, which can be used as herbicides.

Usually, the nitration of N-alkylated secondary anilines is carried out with the preliminary i protection of the hydrogen atom JQ in the amino group, for example, by acetylation 13

However, this method is multi-staged and does not allow obtaining target products with a sufficiently high yield.

The closest to the proposed technical essence and the achieved result is a method of obtaining 2,6-dinitro-tertiary anilines, 20 in which both N-substituents are haloalkyl, nitrating at least fivefold in excess of the reaction 50-90% - and at the end of the reaction with 50% nitric acid in the presence of a catalytic amount of nitrous acid in the presence of 25%.

However, the known method does not allow obtaining N-alkylated derivatives of secondary anilines from high

output in fairly simple conditions.

The purpose of the invention is to increase the yield and simplify the process.

This goal is achieved by the fact that, according to the method for producing 2,6-dinitro derivatives, N-alkyl or N, N-dialkylaniline of the formula

-alkyl, with the number of carbon atoms Y of 1-4 atoms, halogen;

- hydrogen, halogen, alkyl with

Z is 1-4 carbon atoms, alkoxy or monosubstituted alkyl, in which the substituent is halogen or alkoxy;

-alkyl, monohaloalkyl or alkoxyalkyl with 1-4 carbon atoms, cycloal kil with 4-6 carbon atoms;

 Rj is hydrogen or R; W and V are hydrogen or nitro with the proviso that 4to W and V are not both nit ro;

by nitrating the corresponding N-alkylated aniline with a nitrating mixture, the nitrating mixture has the following composition: 15-78% water, 8-68% 95-98% sulfuric acid, and 2-60% 70-75% nitric acid.

The nitrating agents used in accordance with the proposed method are presented in the form of a trapezium, t, e. the composition of the area defined by the lines connecting the points corresponding to the weight. HNO, 8 HnS04, 50 HNO, 35, 15, 2HN04, 6 HjSO, 30 0 and 2 HNOj, 20., 78 H (,

Three preferred components nitrating the composition are within the trapezium. This area is enclosed between the lines connecting the points corresponding to, wt.%: 45 HNOa, 19 Hi2SOi, 36, 45 HNCU, 19 HnO, 20 HNO, 52 ,, 28 Hijt) and 20 HNOj, 27 ... 53.

The optimal number of moles of nitric acid per mole of compound I will depend on the nitrated compound and the composition of the nitrating agent used. Typically, compounds of the formula are preferably nitrated using from 2.2 to 5.0 mol of nitric acid per mole of M-alkylated aniline. Within this wide area, a level of 2.5 to 3.5 mol of nitric acid is preferred. In cases where W or V is nitro, it is preferable to use from 1.2 to 4.0 mol of nitric acid per mole of N-alkylated aniline. On the inside of this area, a narrow range of 1.5 to 2.5 mol of nitric acid is generally more preferred.

The molar ratio of sulfuric acid to N-alkylated 1-aniline used in the nitrations of the proposed method is from 1.5: 1 to 15: 1, and o is preferably from 12.0: 1 to 10.0: 1. For sulfuric acid, these regions correspond to amounts from 30 to 70 wt.% With a preferred range of about 35 to 65 wt.%.

The amount of water present in the nitrating mixture is an important factor related to the optimum temperature. Typically, reaction mixtures containing large amounts of water require higher reaction temperatures. The amount of water in the initial nitrous mixture mixture should be approximately from 15 to 78% by weight of the nitrating mixture. To convert any N-alkylated mononitroaniline to N-alkylated-2, 6-dinitroaniline, a sufficiently high temperature must be used.

Compounds 1) Formulas I can be nitrated at temperatures varying from 0 ° C to 70 ° C, however temperatures below 15 ° C tend to prevent the completion of dinitration and therefore are not particularly desirable. Temperatures above are undesirable because the reaction becomes difficult to control. Since the reaction is exothermic, cooling is usually required to maintain the temperature below the upper limit and preferably in an optimal area. The optimum temperature will vary depending on the starting M-alkylated aniline used and on the composition of the nitrating agent. The most preferred temperature region is 35,

When operating in the region of 0-70 ° C (preferably 35-60s), nitration with a mixed acid is easily controlled. In order to avoid an uncontrolled reaction, nitration with concentrated nitric acid should be carried out at a temperature below 10 ° C. Due to the relatively simple control required for mixed acids, this system requires significantly less cooling capacity. In the event of interruptions or shortages of electric power, the mixed acid can be easily processed, and an explosion can occur with a concentrated acid.

Another feature of the mixed acid nitration is a small excess (O, 50-1.50 mol) of nitric acid, necessary to complete the reaction. In the case of concentrated nitric acid, at least 5-10 mol is required. In cases where the extraction of nitric acid is not significant for the economy of the process, the COST and the potential risk of working with concentrated nitric acid will be significantly greater than with a mixed acid.

N-alkylated aniline can react with the nitrating solution in the form of a liquid, a solid, or, being dissolved in an inert solvent such as chloroform ethylene dichloride, carbon tetrachloride or nitromethane. Preferred is the use of N-alkylated aniline in ethylene dichloride, in which the ratio of milliliters of ethylene dichloride per gram of starting compound is about 3, O: 1 - 0.5: 1, preferably 0.75: 1.

The method of addition is not a significant factor. Depending on the specific situation, either a nitrating agent may be added to the initial

compound or the parent compound to the nitrating agent.

The desired product can be separated after completion of the nitration reaction. The termination point is determined by such conventional methods as thin layer chromatographs or nuclear magnetic resonance (NMR) spectroscopy. However, in the case of compounds of the formula I in which R is hydrogen, the additional treatment of the reaction mixture from the nitration stage with a lenitrosing agent, preferably a combination of hydrochloric and sulAamic acids, is highly effective.

The molar ratio of sulLamic acid to N- (nitroso compound is 2: 1. The temperature at the denitrocation step can vary from 20 to 100 ° C and should be between 80 and. Although the denitrocation step can be carried out at atmospheric pressure, it is preferred to be held under pressure to maintain hydrochloric acid. "

Denitrose agents such as hydrochloric acid and ferric chloride can also be used in this process, however, the use of hydrochloric and sulfamic acids is preferred.

The proposed method is usually carried out as a batch process, however, a continuous process is also being developed.

Example 1. The nitration of N-fl-ethylpropyl) -3,4-dimethylaniline.

To the mixed acid solution prepared by adding 145.2 g

Nitration of N- (1-ethylpropyl) -3,4-dimethylaniline

70.5% nitric acid (1.655 mol) and 116.6 g of 94.5% sulfuric acid (1.125 mol) to 58.8 g of water, a solution of is added over 2 hours at 35 ° C. 101.0 g of 94.6% M- (1-ethylpropyl) 5 -3,4-dinitromethylaniline (0.5 mol) 143.5 ml of ethylene dichloride (EDH) The reaction mixture is kept at 35 ° C for 1 h and then the | at water phase is separated. The organic phase is sequentially washed with a ml of 5% caustic solution and 300 ml of water. The organic solution is dried over anhydrous magnesium sulphate, filtered and concentrated at 70 ° C under vacuum to obtain 141.5 g of dry product,

5 containing 117 g (82.62) M- (1-ethylpropyl) -3,4-dimethyl-2,6-dinitroaniline and 14.2 g (10.0%) N-nitrozo-N- (1-ethylpropyl) -3,4-dimethyl-2,6-dinitroaniline. The overall yield of 2,6-dinitroaniline was 72.6%.

Examples 2-10. The results were obtained by nitration with N- (1-ethylpropyl) -3,4-dimethylaniline in reaction mixtures containing

5 identical molar ratios of nitric and sulfuric acid relative to the starting material, but different amounts of water.

In all cases, the main reaction conditions were the same as

0 and in Example 1. In some cases, the starting material was added without solvent and the reaction mixtures were extracted with toluene or xylene cmol and processed in the usual manner.

The results of the nitration of M- (1-ethyl-, propyl) -3,4-dimethylaniline are given in table. one.

Table at 35 ° C

2.0 27.0 48.6 43.1 2 3.0

2.0 31.1 31.9 61.0 29.5 48.0

3 3,0

77.5 41.2 40.3- 81.5

Examples 11-13. Nitration of N- (1-ethylpropyl-3,4-dimethylaniline.

Nitration of N - (1-ethylpropyl) -3,4-dimethyl aniline and at 20-25 0 in mixtures containing 16.7, 21.7 and 48.7% of water, respectively, leads to low yields as N- (1 -ethylpropyl) -3, -dimethyl-2, b-dinitroaniline, so

to M ;; NITROZO-M- (1-ETYLPROPIL) -3, 4-dimethyl-2,6-dinitroaniline.

Continued table. one

.

This example shows the effect of molar ratios and water content on the yield of the product compositions.

The technique was the same. as in example 1.

The results of the nitration of N- (1-ethylpropyl) -3, 4-dimethylaniline at 2025 ° C in examples 11-13 are given in table. 2. 9 Nitration N In all cases, the addition time is 2 hours, the yield. The conditions are mainly higher; the holding time is 1 h. 30, the same as in Example 1. Examples 14 and 15. Result-. max (g) -.

Tables of these examples show the effects of the N-nitration of H- (1-ethyl of elevated temperatures and condensation) of 3,4-dimethylaniline on the approximations of water on the composition of the product and range 35 and 14 are given in table. 3. Nitration of N- (1-ethylpropyl) -3,4-dimethylaniline

43.3 0.75

2.25

14 3.25

49.1

2.25

3.25

15

The compositions are given in moles x (m) and grams. Table 3

88.0

64.5

23.5

60

87.0

73.5

13.5

70 {1-ethylpropyl) -3,4-dimethylaniline at 20-25 with 89710810 Ta b. 2

Example 16: Denitroosing a crude, nitrated product from N- (1-eth propyl) -3.4 dimethylaniline.

To the crude nitrous solution containing 1550 g of 2, 6-dinitro-N .- (l-ethylpropyl-3,4-dimethylayl and 340 g 2, b-dinitro - M-nitroso-M- (1-ethylpropyl-3, 4-dimethylaniline in 3700 MP of ethylene dichloride, 212 g of sulfamic acid and 2850 ml of 37.7% hydrochloric acid were added. The mixture was refluxed at 80 ° C for b, 2 l of water was added and the aqueous phase was separated. The aqueous phase was extracted with 500 ml of ethylene dichloride and organic faDenitrosis of crude nitration products from -3,4-dimethylaniline

17 17.2

22

3.1

2.5

23

24

2.5

The reaction was carried out in an autoclave. In all cases, the percentage of Ni-nitroso (1-ethylpropyl) -3,4-dimethyl-2,6-dinitroaniline in the final product was less than 0.1 wt.%.

PS combined. The combined organic phase was washed with 3 l of water, the aqueous phase was separated and the ethylene dichloride was removed under vacuum with the extraction of 1915 g of a product containing 1820 g 2, b-dinitro-N- (l-ethylpropin) 3, 4-dimethylaniline and less than 0.1% 2, b-dinitro - M-nitroso-M- (1-ethylpropyl) -3,4-dimethylpnilin.

Examples 17-24. Denitration of the crude products of nitration of N- (1 ethyl propyl-3, 4-dimethylaniline was carried out under the conditions of example 16.

The results of denitrosation are given in table. four.

90

97.0 94.3 97.0 97.2 95.5 96.4 96.5 Table 4 N - (1-ethylpropyl) 4 molar ratios express the number of salts of the reagent per mole of the N-nitroso by-product. In most cases, the reaction was carried out in an autoclave. Example 25. The nitration of N- (2-: -butyl) - 3,4-dimethylaniline. To a solution of a mixed acid prepared by adding 134.1 g of 70.5% nitric acid (50 ml) and 101.1 g of 96.9% sulfuric acid (1.0 mol) to 87.2 g of water with SO A solution of 92.3 95.9% N- (2-butyl) -3,4-dimethylaniline in 66.5 ml of ethylene dichloride was added over 2 hours. The reaction was carried out at 35 ° C for an additional hour and then the aqueous phase was separated.

Nitration of N- (2-butyl) -3,4-dimethylaniline

20.6 70.8

4.0

26

2.0

27.6 19.8

2.5

27

3.5

31.7 10.5

2.5

3.5

28

The use of a mixed acid containing more water and a lower molar ratio of nitric acid results in a lower by-product content of the N-nitroso compound.

In all cases, the basic procedure of Example 1 was used at 35 ° C. A solution of 4.53 g of (2-butyl) -3, 4-dimethylaniline in 15 ml of ethylene was added.

Table 5

18.2

54.3

72.5

21.4

16.7

83.3

70,6

66.6

80.9

72.0

8.9

76.3

dichloride as a starting material for 2 hours and then the reaction mixture was maintained at 35 ° C. Examples 29-31. The examples given in table. 6 shows the change in the overall yield and composition of the product depending on the change in the water content and the temperature of the reaction mixture during the nitration of N- (2-6-yl) -37 4-cymethylaniline. The organic Laza was successively washed with 500 ml of a 5% aqueous solution of caustic and 500 ml of water; The organic phase was then dried over anhydrous magnesium sulphate, filtered and concentrated at 70 s under vacuum to obtain 130.0 g of a crude product containing 100 g (yield 75.5%) 2, b-dinitro-N- (2-butyl) -3 , 4-dimethylaniline and 22.0 g (yield 14.9%) of 2,6-dinitro-N-nitroso-M- (2-butyl) -3,4-dimethylaniline. The overall yield of the desired 2,6-dinitroaniline product is 90.4%. Examples 26-28. Nitration of N- (2-butyl) -3.4 dimethylaniline shows the effect of the water content in the nitro-ary mixture on the composition of the product. The results of nitration of N- (2-butyl) -3, 4-dimethylaniline are given in table 5.

Nitration of N- (2-butyl) -3. dimethylaniline

3.25

2.25

38.8 0.75

29

2.25

3.25

thirty

43.8 0.75

49.1 0.75

2.25

31

3.25

From tab. 6, it follows that the preferred temperature is about and the water content is about 40% for stoichiometric nitration of N- (2-butyl) -3,4-dimethylaniline.

Example 32. Denitroheathing a crude nitration product from (2-butyl-3.4-dimethylaniline,

To a solution of 30 g of a crude product of nitration, containing 20.2 g. Of 2,6-dinitro-N- (2-butyl) -3,4-demethylaniline and 6.84 g of 2,6-dinitro-M-nitroso- (2-butyl) -3,4-dimethylaniline in 15 ml of ethylene dichloride were added 3.94 g of sulfamic acid and 9.84 g of 37.6% hydrochloric acid. The mixture was stirred and heated for 6 hours under pressure at and at the end of this period 20 ml of water was added and the pH of the mixture was adjusted to 9-11 by careful addition of a 50% aqueous solution.

Table 6

15.3

88.6

73.3

50

87.0

18.1

68.0

60

85.7

65.0

20.7

70

sodium hydroxide. This allowed to separate the phases and remove the aqueous layer. The organic layer was washed with 20 ml of water, dried over anhydrous sulf | 1) magnesium atom, filtered and concentrated under vacuum at 70 ° C to obtain 28.2 g, containing 24.6 g (yield 93%) 2,6-dinitro ( 2-butyl) -3,4-dimethylaniline and less than 0.1% of 2,6-dinitro-N-nitroso-N- (2-butyl) -3,4-dimethylaniline. Example 33. A mixture of 1.83 g of water, 6.83 g of 96.9% sulfuric acid (0.0675 mol) and 8.71 g of 70.5% nitric acid (0.0975 mol) were prepared acid solution. A solution of 5.93 g (0.03 mol) of 2-butyl-3-chloro-4-methylaniline in 4 g of ethylene dichloride was added to this solution over 75 minutes at 35–40 ° C. The mixture was heated for 2.25 h at 40-45 ° C and eL, e .0.75 h at. The mixture was diluted with ethylene dichloride and washed with a dilute aqueous solution of caustic (to pH 1012), washed with fresh water, dried over magnesium sulfate and filtered. After concentration, 7.8 oils were obtained. When analyzing this oil by thin layer chromatography, it was found that it contains a lot of one component and a small amount of the other three components. This oil was dissolved in 20 ml of ethylene dichloride, 13 ml of concentrated hydrochloric acid and 1 g of sulfamic acid were added to the solution. The mixture was heated at reflux for 7 hours. Analysis of the aliquot by thin-layer xp mathematics showed that one of the three components present in a small amount had disappeared. The mixture was cooled and the aqueous component was discarded. The organic layer was washed with water, dried over magnesium sulfate, filtered and concentrated to obtain 5.7 g of oil. The main component of this oil was separated in its pure form by liquid chromatography and proton magnetic resonance spectroscopy. It has been shown to be the desired N- (2-butyl) -2,6 dinitro-3-chloro-p-toluidine. Example 34. By mixing 2.55 g of water, 6.91 g of 95.7% sulfuric acid and 8.71 g of 70.5% nitric acid, an acidic solution was prepared. A solution of 6.3 g of N-2-butyl-4-M-butylaniline was added to this solution over a period of about 2 hours. 19 ml of ethylene dichloride at 33-37 ° C. The reaction mixture was stirred for 1.5 hours at 40-45 ° C and 1 hour at. Additionally, 1.93 g of 95.3% sulfuric acid was added and the mixture was stirred for more than 0.5 h at 50 ° C. Tests have shown that unreacted N-2-but.yl-4-Mbutylaniline or its mono-nitro derivatives have remained in the reaction mixture. The mixture was cooled, the organic phase was separated and washed with a dilute caustic aqueous solution and then with water. Then 13 ml of concentrated hydrochloric acid and 1.0 g of sulfamic acid were added to the organic phase. This mixture was heated by refluxing for 4 hours, then it was cooled and the acidic layer was discarded. The organic phase was washed with water and concentrated to give 14.4 g of oil. This oil was placed in a column of silica gel and eluted with toluene. The most strongly retained component was extracted from silicon using methylene chloride. The extract was concentrated to obtain 3.4 g (more than 38% of the theoretical amount) of a yellow solid, which was identified as K-2-butyl-2, b-dinitro-4-M-butylaniline. Example 35. Obtaining N-fluoro-butyl-2-nitro-3, 4-dimethylaniline and N-fluoro-butyl-b-nitro-3, 4-dimethylaniline. N-Fluoro-butyl-3,4-dimethylaniline (5.3 g, 0.03 mol) was dissolved in 10 ml of dichloroethane and carefully treated with mixed acid (6 ml of concentrated sulfuric acid and 2.7 g of concentrated nitric acid) at 15 25 C. After completion of the dissolution, the mixture was poured into water. The organic layer was separated and purified by column chromatography on silica gel using hexane as the elgent. The first eluted compound was M-fluoro-butyl-2-nitro-3,4-dimethylaniline, identified by NMR and IR spectra. The second eluted compound was M-Fluoro-butyl-6-nitro-3, 4-dimethylaniline, which was also characterized by its NMR spectrum. Example 36. Obtaining N- (1 ethylpropyl) -2, b-dinitro-3,4-dimethylaniline. N- (1-Ethylpropyl) -2-nitro-3, 4-. -dimethylaniline was prepared according to the procedure of Example 35 using an interchange of N-fluoro-butyl-3,4-dimethylanate {N- (1-ethylpropyl) -3,4-dimethylaniline. The target 2,6-dinitro compound was obtained in good yield and purity by nitration of the 2-nitro compound using the procedure of Example 1. Example 37. In a manner analogous to Example 36, using the procedure of Example 35 replacing N-fluoro-butyl-3 4- dimethylaniline on N- (1-ethylpropyl) -3,4-dimethaniline prepared N - (1-ethylpropyl) -6-nitro-3,4 dimethylaniline. Using the procedure of Example 1, the 6-nitro compound was converted to N- (1-ethylpropyl) -2,6-dinitro 3, 4-dimethylaniline. Example 38. A mixed acidic solution was prepared by adding 95.3% sulfuric acid (5.79 g; 0.056 mol) and 70.5% nitric acid (7.27 g; 0.081 mol) to water (1.27 g). solution. To the mixed acids, while stirring, a solution of N, H-bis- (2-chloroethyl) 3, 4-dimethylaniline (6.15 g; 0.025 mol) in 15 ml of ethylene dichloride was added. The addition was carried out for 90 minutes at 35-45 ° C. After the addition was complete, the mixture was stirred for an additional 2 hours at 30-40 seconds. The bottom layer is then separated and dropped. The upper layer was washed with 10 ml portions of a dilute solution of caustic and water alternately. The organic solution was dried over anhydrous magnesium sulphate and then subjected to chromatographic separation on a column of silica gel. Elution with benzene allowed us to isolate 3.73 g (44.5%) of yellow solid

substances that NMR spectroscopy was defined as M, M-bis- (2-Chlorate) -2, b-dinitro-3,4-dimethylaniline.

Claims (2)

1. Topchiev A.V. Nitration, Science, 1965. 2.Patent of Belgium No. 762232, cl. C 07 C 87/60, 1967 (prototype).