CS203196B2 - Method of removing nitrosamines from dinitroanilines by the action of hydrochloric acid or gaseous hydrogen chloride - Google Patents

Description

The present invention relates to a process for the removal of nitrosamines from dinitroanilines by treatment with hydrochloric acid or gaseous hydrogen chloride.

The dinitroaniline group of compounds is present in numerous commercial herbicides. Recently, a new analytical instrument, referred to as a thermal energy analyzer (Te analyzer), has been developed and described in J. Chromatogr. 107 (1975), p. 351, including references, and in the publication "N-Nitroso Compounds in the Environment" (IARC Scientific Publication No. 9, ed., International Cancer Institute, Lyon, 1974, p. 40). The TE analyzer detects specifically the nitroso group (- (NO)) and can be detected at a concentration of 0.02 ppm, ie at a much lower concentration than the previous analytical methods Analysis of various dinitroanilines by the TE analyzer shows that some dinitroanilines contain very small amounts The presence of very small amounts of nitrosamines is considered undesirable because some nitrosamines have been found to have carcinogenic effects on animals.

The present invention provides a method for removing nitrosamines from dinitroanilines.

the chemistry of aliphatic N-nitrosamines is discussed in an article in Russian Chem.

Rev., 40 (1), pp. 34-50 (1971) (Great Britain). On page 40 et seq., The reaction of nitrosamines with inorganic acids is described. It is also discussed: the reaction of hydrochloric acid and hydrogen chloride gas with nitrosamines.

In the journal "Chem. Listy ”, 51, on pages 937 to 945 (1957), there is an article dealing with the kinetics and mechanism of conversion of nitrosamines into the corresponding single amines by the action of strong mineral acids.

In Lieb. Ann., 345, page 277-288 (1906) describes the preparation of di-n-propylamine by the action of hydrogen chloride gas on nitroso-n-propylamine.

None of these sources disclose the use of hydrogen chloride to remove nitrosamines from certain dinitroanilines by the method of the invention. In addition, it is surprising that this removal can be achieved so efficiently using hydrogen chloride.

The amount of nitrosamines present in dinitroamines can be significantly reduced by the method of the invention.

The present invention relates to a process for the removal of nitrosamines from dinitroanilines of formula (I)

where it means

R ^{1 is} hydrogen, C 1 -C 5 alkyl or C 1 -C 5 monohaloalkyl,

R ^{2 is} C 1 -C 5 alkyl, C 1 -C 5 monohaloalkyl or C 1 -C 3 alkylcycloalkyl and C 3 -C 5 alkylcycloalkyl,

R ^{3 is} halogen, hydrogen, C 1 -C 3 alkyl or amino;

R ^{4 is} C 1 -C 5 alkyl, C 1 -C 5 trifluoralkyl, sulfonamide or methylsulfonyl, at least one of R ¹ , R ² , R ³ or R ⁴ being limited to the following groups, namely:

R @ ^{1 is} hydrogen or C1 -C5 monohaloalkyl,

R ² to a monohaloalkyl group having 1-5 carbon atoms or alkylcycloalkyl group having 1 to 3 carbon atoms in the alkyl and 3-5 carbon atoms in the cycloalkyl part,

R ^{3 is} halogen, C 1 -C 3 alkyl or amino;

R ⁴ to a sulfonamide or methylsulfonyl group, according to the invention, is treated with dinitroaniline in the liquid phase at a temperature ranging from 70 ° to 110 ° C with a reagent selected from the group consisting of 28 to 38% hydrochloric acid and hydrogen chloride gas until the nitrosamine concentration is decreased, then dinitroaniline is isolated.

The dinitroanilines in which the method of the invention can be used are

(1) 4-trifluoromethyl-2,6-dinitro-N-N-di-n-propylaniline ('tritluoralin');

(2) 4-isopropyl-2,6-dinitro-N, N-di-n-propylaniline ('isopropalin');

3) 4-trifluoromethyl-2,6-dinitro-N-n-butyl-N-ethylaniline ('benefin'),

4) 4-trifluoromethyl-2,6-dlnitro-N-ethyl-N-methalylaniline ('ethalfluralin'), 4'-tert-butyl-2,6-dinitro-N-sec-butylaniline ('butralin'),

6) 3,4-dimethyl-2,6-dinitro-N- (1-ethylpropyl) -aniline ("tendimethalin"),

7) 4-trifluoromethyl-1,2,6-dinitro-N-propyl-N- (2-chloroethyl) aniline ('fluchloralin'),

8) 4-trifluoromethyl-2,6-dinltro-N-propyl-N- (cyclopropylmethyl) -aniline ("profluarine"),

(9) 4-trifluoromethyl-2,6-dinitro-3-amino-Ν, Ν-diethylaniline ('dinitramine'),

(10) 4-trifluoromethyl-2,6-dinitro-3-chloro-Ν, Ν-diethylaniline (intermediate 'ditramine'),

11) 4-methyl-2,6'-dinitro-N, N-bis-

- (2-chloroethyl) aniline,

12) 4-sulfamoyl-2,6-dlnitro-N, N-di-n-propylaniline ("oryzalin"); and

13) 4- (methylsulfonyl) -2,6-dinitro-N, N-di-n-propylanine ("nitraline").

The dinitroanilines which can preferably be processed according to the process of the invention are 4-trifluoromethyl-2,6-dinltro-N, N-dl-n-propylaniline (trifluralin), 4-isopropyl-2,6-dinltro-N, N'dl- n-propylanine (Isopropalin), 4-trifluoromethyl-2,6-di-nitro-N-butyl-N-ethylaniline (benefin) and 4-trifluoromethyl-2,3-dinitro-N-ethyl-N-methallylaniline (ethalfiuralin).

As a rule, prepare dinitroaniline.y! as shown for 4-trifluoromethyl-2,6-dlnitro-N, N-di-n-propylaniline (trifluralin) by the following scheme:

It is believed that small amounts of nitrogen oxides remaining after nitration react with the moiety. amine during the amination to give a small amount of nitrosamine which may be contained in the resulting dinitroaniline product. Therefore, any contaminating nitrosamine is expected to be a nitrosamine derivative. of the alkylamine used. However, it is also possible that small amounts of other nitrosamines may also be formed. The removal of nitrosamines, whatever, is desirable and can be achieved by the method of the invention.

The mechanism by which. the process according to the invention is carried out, it is not known precisely, however, it is believed that hydrogen chloride denitroses nitrosamine into some other substance, probably the hydrochloride salt of the corresponding amine. It is also likely, but not yet proven, that as. part of the denitrosing product may be formed by nitrosyl chloride NOCI. However, the net result is the conversion of the undesired nitrosamine into a water-soluble substance which can be easily separated from the dinitroanilines.

The process of the invention allows a substantial reduction in the nitrosamine concentration regardless of the original amount. The process was carried out using dinitroanilines containing from only 10 ppm of nitrosamine to several thousand ppm of nitrosamine; the nitrosamine concentration is generally reduced to about one tenth of the original amount or even below. border. In many cases, the nitrosamine concentration is reduced to less than about 1 ppm.

The process according to the invention is carried out in the liquid phase. For many dinitroanilines, this can be accomplished by heating the nitrosamine-containing dinitroaniline to its melting point or to a higher temperature and conducting the reaction in a pure manner. . state, without. Use of a solvent The liquid phase can also be achieved by dissolving dinitroanilines containing nitrosamine. in a solvent. Suitable solvents include alcohols such as ethanol, ketones such as. It is acetone, and hydrocarbons, both aliphatic and aromatic. The use of solvents containing a group capable of reacting with hydrogen chloride should be avoided. For example, the use of secondary and tertiary alcohols should be avoided because of their ability to react with hydrogen chloride.

The reagent used in the process of the present invention is either hydrochloric acid or hydrogen chloride gas. If it is hydrochloric acid, it should contain at least 20% by weight of hydrogen chloride. Better results were obtained by using more concentrated hydrochloric acid, for example 33-38%. Hydrogen chloride gas may also be used, which is a preferred embodiment of the process of the invention. In the case of 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methyllylamine (ethalfluralin, the use of hydrogen chloride gas is preferable to the use of hydrogen chloride, since addition to the methallyl double bond is avoided.

The amount of hydrochloric acid or hydrogen chloride gas to be used is not critical as long as it is effective to reduce the original. lower nitrosamine levels. Using hydrochloric acid, it was found that 0.04 g per 100 g dinitroanilines was sufficient. When using hydrogen chloride gas, 250 ml per 100 g of dinitroaniline is sufficient. Using larger quantities (three times) also produced successful results, but did not yield. it has no advantage. When reacting with hydrogen chloride gas on a laboratory scale was. successfully worked with additions ranging from 5 to 90 ml per 100 g dinitroaniline. Preferred amounts are in the range of 8 to 12 ml per 100 g of dinitroaniline.

The reaction can be carried out at a wide range of temperatures. Generally, temperatures below 140 ° ^C, preferably below 100 ° C because of the greater risk of side reactions at higher temperatures. When the process of the invention is carried out in a solvent, suitable temperatures vary within wide ranges depending on the type of solvent, but are usually in the range of room temperature to 100 ° C. When the process according to the invention is carried out without solvent, the reaction is carried out at temperatures above the melting point of the respective dinitroaniline. There were good results. reached at temperatures in the range 70-90 ° C when the process of the invention was carried out with 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propyl-aniline (trifluralin) with a melting point of 54-55 ° C, with 4-isopropyl-2,6-dinitro-N, N-di-n-propylaniline (isopropalin), m.p. 30 ° C, with 4-trifluoromethyl-2,6-dinitro-Nn-butyl-N -ethylaniline (benefin), m.p. 65-66 ° C, and with 4-trifluoromethyl-2,6-dinitro-N-ethyl-N, N-allylaniline (ethnalfluralin), m.p. ° C without solvent.

The reaction may be carried out at atmospheric pressure or at elevated pressure. .Bylo found that it is advantageous to conduct the reaction with hydrogen chloride gas at a temperature ranging from 70 to 90 ° ^C under a positive pressure of hydrogen chloride gas in the range of 6.86 to 68.6 kPa, in particular in the range of 20.58 to 34.3 kPa.

The presence of water in nitrosanin-containing dinitroanilines has an adverse effect on the process of the invention. This is particularly the case when hydrogen chloride gas is used, since more hydrogen chloride is required for denitrosation. Therefore, when hydrogen chloride gas is used, it is preferred that dinitroaniline. % containing nitrosamine is relatively dry, i.e. it contains less than 0.2 wt. water.

The rate at which the process of the present invention proceeds will vary with the nitrosamine concentration, temperature, reagent form, i.e., hydrogen chloride, rate of addition, and other agents. The progress of nitrosamine removal can be monitored by gas chromatography or a TEC analyzer. Denitrosation is usually completed in less than 1 hour. A time study of the process of the invention has shown that soon after the initiation of the reaction, the nitrosamine content is reduced, which in some cases is followed by a slight increase in its content over a longer reaction time. Prolonged exposure of the di-nitroaniline and the predicted alkylamine denitrosation product to the reaction conditions is likely to result in further nitrosamine formation. Therefore, it is desirable to carry out the reaction only for an essentially long time.

Work-up of the reaction mixture is carried out by conventional methods. The treatment suitably depends on washing with water, followed by washing with a weakly alkaline medium to remove the last traces of hydrogen chloride. Measures should also be taken to remove gaseous by-products during the denitrosing process.

The following examples illustrate the process of the invention in more detail and allow those skilled in the art to practice it.

Unless otherwise stated, the determination of nitrosamine concentration in the following examples was carried out by gas chromatography sensitive to about 0.5 ppm. An "undetectable amount" was considered to be less than about 0.5 ppm nitrosamine. Hewlett-Packard Model 5711A gas chromatograph was used; however, this method can be carried out with any gas chromatography apparatus equipped with a flame ionization detector. The column consisted of a glass snake 122 cm long and 3.2 mm in internal diameter, packed with 3% Carbowax 20 M on an AW DMCS Chromosorb G having a grain size of 100 to 120 mesh; the operating temperature was 100 ° C. After elution of the nitrosamine peak, the column was heated to 230 ° C and held for about 15 minutes. The amount of helium passing was maintained at 60 ml / min. A standard of approximately the same nitrosamine concentration as expected in the sample was used. Both standard and sample were prepared in methylene chloride.

In those cases where the TEN analyzer has been used, this is indicated. Analyzes with this method were carried out in essentially the same manner as described in J. Chromatogr., 109, p. 271 (1975). In the context of the present invention, the method is considered to be sensitive to a nitrosamine concentration of only 0.05 ppm. Where no nitrosamine has been detected by the T analysis of the samples, this is indicated as 'not detected'.

In Example 2, combined gas chromatography and mass spectrometry were used as analytical methods. In this method, the samples are dissolved in benzene and purified by chromatography on a column of oxygen.

Aluminum is eluted using benzene as the elution solvent. The nitrosamine content of the sample is determined using an LKB-9000 instrument consisting of a gas chromatograph and a mass spectrometer equipped with a 5% Carbowax 20 M column. The column temperature is adjusted to 130 ° C, resulting in a nitrodi residence time -n-propylamine for 2 minutes. The measurement is performed by setting the magnet to the molecular ion (m / e = 130) and the resulting ion current is captured on the recorder strips.

Example 1

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) with 20% hydrochloric acid using ethanol as solvent g 4-trifluoromethyl-2,6-dinitro-N, N-di of n-propylaniline (trifluralin), containing 256 ppm of nitrosamine, is mixed with 20 ml of 20 why, hydrochloric acid and 5 ml of ethanol. The mixture is heated to 90 ° C, where it is kept under stirring for 3 hours. The resulting layers were separated and the organic layer was washed with 10% sodium bicarbonate solution. The product is analyzed for nitrosamine; none can be detected.

Example 2

Removal of the nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (tri fluralin) with hydrogen chloride gas using benzene as solvent.

4-Trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (10 g sample containing 480 ppm nitrosamine) was dissolved in 200 mL benzene and the solution was heated to 80 ° C under reflux. Hydrogen chloride gas was continuously added to the solution under reflux for 1 hour. The reaction mixture was cooled slightly and washed twice with equal volumes of water. The tan layer was separated, dried over anhydrous magnesium sulfate and filtered, and the benzene was removed by rotary evaporation. The resulting 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) was analyzed for nitrosamine content by a combined method of gas chromatography and mass spectrometry. According to the analysis, the nitrosamine content is less than 1 ppm.

Example 3

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) with hydrogen chloride gas.

g of 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) was heated to 70 ° C. Hydrogen chloride gas is introduced into the melt at 8-12 ml / mln. After 0, 30 and 60 minutes, samples were collected. Each sample was washed with 10% sodium carbonate solution, then dried and analyzed for nitrosamine content. The results are as follows:

the sampling time x minutes after the start of bubbling the nitrosamine hydrochloride concentration was bubbled through the hydrogen chloride gas at a rate of 90 ml / min. Each sample is washed with 2 ml of 10% sodium carbonate solution, then dried and analyzed for nitrosamines. The results of the analyzes are as follows:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration in minutes minutes

32.6 ppm

2.9 ppm not detected

Example 4

10.2 ppm min not found min not found hour not found

Example 7

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N-n-butyl-N-ethylaniline (benefin) with 38% hydrochloric acid.

g of 4-trifluoromethyl-2,6-dinitro-N-n-butyl-N-ethylaniline (benefin) containing 130 ppm nitrosamine is heated to 70 ° C. 1.5 g of 38% concentrated hydrochloric acid are added and the reaction mixture is stirred for 15 minutes. The resulting organic layer was separated and washed with 10% sodium carbonate solution. The nitrosamine content of the final product is 17 ppm.

Example 5

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N-n-butyl-N-ethylaniline (benefin) with hydrogen chloride gas.

g of 4-trifluoromethyl-2,6-dinitro-N-n-butyl-N-ethylaniline (benefin) containing 130 ppm. The nitrosamine is heated to 70 degrees Celsius. Hydrogen chloride gas was bubbled through the resulting melt at a rate of 8 to 12 ml / min. Samples are taken 10, 20, 30 minutes after the start of bubbling. Each sample was washed with 10% sodium carbonate solution and analyzed for nitrosamine content. The results are as follows:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration minutes 65 ppm minutes 38 ppm minutes 14 ppm

Example 6

Removal of nitrosamine from 4-trifluoromethyl-2,6-dimethyl-N, N-di-n-propylaniline · (trifluralin) with hydrogen chloride gas added at a higher rate.

4-Trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) was washed with water for 30 minutes and air dried for a further 30 minutes. It is then heated to 70 ° C and hydrogen chloride gas is bubbled through the resulting melt at a rate of 35 ml / min. Samples are taken after 0, 15, 30 and 60 minutes from the start of the bubbling. Each the sample is washed with ^10:% sodium carbonate solution and analyzed for nitrosamine content. The results are as follows:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration min min hour

Example 8

9.3 ppm <1 <1 <1

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) with hydrogen chloride gas, effect of added water.

100 g of 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) is heated to 70 DEG C. and 0.5 ml of water are added. Hydrogen chloride gas was then bubbled through the mixture at a rate of 8 ml / min. Occasionally samples are taken. Each sample was washed with 10% sodium carbonate solution, dried and analyzed for nitrosamine content. The results of the analyzes are as follows:

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinltro-N-ethyl-N-methallylaniline (ethalfluralin) with hydrogen chloride gas.

100 g of 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methallylaniline (ethalfluralin) was heated to 70 ° C. The resulting melt

203198 sampling time after x minutes from the start of bubbling nitrosamine hydrogen concentration cl or j min min min min

Example 9 ppm ppm

6.8 ppm

3,2 ppm not identified

Removal of the nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) with gaseous hydrogen gas introduced over a longer period.

100 g of 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) was heated to 70 ° C. Hydrogen chloride gas was bubbled through the resulting melt at a rate of 8 to 12 ml / min. Samples are taken every 2 hours. Each sample was washed with 10% sodium carbonate solution, then dried and analyzed for nitrosamine content. The results of the analyzes are as follows:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration hours hours hours hours ppm not identified not detected not detected 1.3 ppm

Example 10

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methylaniline (ethalfluralin) with 38% hydrochloric acid.

g of 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methallylaniline (ethalfluralin) containing 9 ppm of nitrosamine is heated to 70 ° C according to TE analysis, 15 g of concentrated 38% hydrochloric acid are added and the reaction mixture is stirred for 30 minutes. The resulting layers were separated and the organic layer was washed with 15 mL of water. The layers were separated again and the organic layer was washed with 15 ml of 10% sodium carbonate solution and then with 15 ml of water. The organic layer was dried at 120 ° C for 15 minutes. A sample is taken and analyzed with a TE analyzer. No nitrosamine is detected.

4-Trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluoraline) containing 13 ppm nitrosamine is heated to 70 g. Hydrogen chloride gas is bubbled through the melt for 5 minutes at a rate of 90 ml / min. Trifluarin is then washed with 5 ml of 10% sodium carbonate solution and dried. The sample is analyzed for nitrosamine content. No nitrosamine could be detected by analysis.

Example 12

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (tri * fluralin) with 38% hydrochloric acid over extended periods g 4-trifluoromethyl-2,6-dinitro-N, N- The di-n-propylaniline (trifluoroaline) was heated to 70 ° C, 6 g of concentrated 38% hydrochloric acid was added and the reaction mixture was stirred. Occasionally, samples are taken and analyzed for nitrosamine content. The results of the analyzes are as follows:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration

0 10 ppmi 30 min 1.4 ppm 1 hour 1.5 PPm 2 clock <1 ppm 3.5 clock 1.4 ppm 4 clock 1.4 PPm

Example 13

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (tri-fluralin) with gaseous hydrogen chloride at higher temperature

100 g of 41-trifluoromethyl-2,6-di-nitro-N, N-di-n-propylaniline (trifluralin) are dried for 30 minutes at 120 DEG C. while air is blown onto the surface. Hydrogen chloride gas was bubbled through the melt at 85 ° C at a rate of 12 ml / min. At 20, 40, 60 and 90 minutes after the beginning of the bubbling, 10 grams samples were taken. Each sample was washed with 5 ml of 5% sodium carbonate solution and dried on a rotary evaporator at 90 ° C for 15 minutes. The results of these samples are:

sampling time x minutes after the start of bubbling nitrosamine HCl concentration minutes minutes minutes minutes

11,1 ppm not identified not found not found not found

Example 11

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (fluralin) by gaseous hydrogen chloride added at a higher rate

Example 14

Removal of nitrosamine from 4-isopropyl-2,6-dinitro-N, N-di-n-propylaniline (isopropalin) with gaseous hydrogen chloride at higher pressure

To 1 liter of the isopropalin xylene solution (representing approximately 700 g of isopropalin containing 22 ppm of nitrosamine as determined by TE analysis) hydrogen chloride gas is added up to a pressure of 34.5 kPa at 70 ° C. Occasionally a sample is taken and washed with 50% by volume 5% sodium carbonate solution. The resulting layers were separated and the organic layer was dried on a rotary evaporator at 60 ° C for 10 minutes. The results of the analyzes performed by the TE analyzer are as follows:

sampling time x minutes after the start of hydrogen chloride bubbling nitrosamine concentration 0 22 pm 30 minutes 0.22 ppm 60 minutes 0.19 ppm 90 minutes 0.4 ppm 120 minutes 0.52 ppm 2.5 hours 0.40 ppm 3 hours 0.28 ppm 3.5 hours 0.24 ppm

Example 15

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methallylaniline (ethalfluralin) by hydrogen chloride gas

100 g of 4-trifluoromethyl-2,6-dinitro-N-ethyl-N-methallylaniline (ethalfluarin) containing 10.5 ppm of nitrosamine are heated to 70 ° C and hydrogen chloride gas is bubbled through the resulting melt at a rate of 8 ml / min. Occasionally samples are taken and analyzed for nitrosamine content by a TE analyzer. The results of the analyzes are as follows: sampling time

after x minutes from start bubbling concentration hydrogen chloride nitrosamine 10 min 10.9 ppm 20 min 6.6 ppm 30 min not identified 40 min not identified

Example 16

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) by 39% recycled hydrochloric acid

100 g of 4-trifluoromethyl-2,6-dinitro-N, N-dinopropylaniline (trifluralline) containing 18 ppm of nitrosamine are heated to 70 DEG C. and 20 g of 38% hydrochloric acid are added. The reaction mixture was stirred at 70 ° C for 30 minutes. The layers were separated, the organic layer was washed with 10 mL of 10% sodium carbonate solution and analyzed for nitrosamine concentration. The acidic layer was saturated with hydrogen chloride gas and used in the next nitrosamine reaction with an additional 100 g of 4-trifluoromethyl-2,6-dinitro-Ν, Ν-di n-propyaniline (trifluoraline), which was carried out under the same conditions as described above (first repeat) . Two additional acid recycles were performed. The results of the analyzes are as follows:

nitrosamine concentration control (starting 4-trifluoromethyl-2,6-dinitro-N, N-n-propylaniline (trifluralin) 18 ppm first treatment not detected by acid first recycle not detected second recycle not detected third recycle not detected

Example 17

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N ^; , N-di-n-propylaniline (trifluralin) with hydrogen chloride gas at elevated pressure in pilot plant

210.0 kg of 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluralin) are melted at 70 ° C overnight (approximately 20 hours) and the resulting melt is introduced into a distillation device inside the enamelled apparatus. with a capacity of 284 liters. Then trifluralin is heated to 90 ° C and hydrogen chloride gas is pressurized to the melt. The reaction conditions are as follows:

203196 1S 19 Dec time temperature ° C overpressure of HCl, kPa sample no. nitrosamine concentration

0 90 0 1 22 ppm 8 minutes 91 17.2 2 3 ppm 16 minutes 90 17.2 3 not identified 22 minutes 89 17.2 4 not identified 39 minutes 90 17.2 5 not identified 65 minutes 90 17.2 6 not identified 71 minutes 90 17.2 7 not identified

The reaction mixture is neutralized with sodium carbonate and another sample is taken; no nitrosamine can be detected in the sample.

The total amount of hydrogen chloride used is 0.38 kg.

Example 18

Removal of ntrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (tri * fluralin) with hydrogen chloride gas using ethanol as solvent

To a mixture of 50 ml of 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluoroaline) and 25 ml of ethanol at > 70 ° C was added hydrogen chloride gas at a rate of 12 ml / min. Samples are taken 1 hour and 30 minutes after the start of bubbling. Each sample was treated at 30 ° C for 15 minutes on a rotary evaporator and then washed with 5 mL of 5% sodium carbonate solution. The resulting layers were separated and the organic layer was worked up in a rotary evaporator at 90 ° C for 15 minutes. The results of the analyzes are as follows:

sampling time x minutes after the start of concentration bubbling

hydrogen chloride nitrosamine 0 44 ppm 30 min 20 ppm. 60 min 14 ppm

Example 19

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-N, N-di-n-propylaniline (trifluoroaline), two treatments with 38% hydrochloric acid

A mixture of 20 g of 4-trifluoromethyl-2,6-dinitro-N, N di-n-propylaniline (triflurine) containing 68 ppm of nitrosine and 5 ml of 38% hydrochloric acid is prepared, which is stirred for 20 minutes at 70 ° C. . The resulting layers were separated and an additional 5 mL of 38% hydrochloric acid was added to the organic layer. The reaction mixture was then stirred again at 70 ° C for 20 minutes. The layers were separated and the organic layer was washed with 10 mL of 10% sodium carbonate solution. The product is analyzed for nitrosamine content. The presence of nitrosamine cannot be detected by either gas chromatography or the TEC analyzer.

Example 20

Removal of nitrosamine from 4-trifluoromethyl-2,6-dinitro-3-amino-N, N-diethylaniline (dinitramine) with hydrogen chloride gas g 4-trifluoromethyl-2,6-dinitro-3-amino-Ν, Ν-diethylaniline (dinitramine) with with a nitrosamine content of 138 ppm, it is heated to a temperature of about 110 ° C and hydrogen chloride gas is introduced into the melt for 45 minutes at a rate of 35 ml / min. After taking a sample of 2 g (sample 1), the hot remaining liquid is slowly added to 60 ml of methylene chloride. To the resulting mixture was added 15 mL of 10% sodium carbonate solution. The resulting organic phase was separated and the solvent was removed in a rotary evaporator for 15 minutes at 45 ° C. Evaporation gave 8 g of a yellow solid (sample 2).

Each of these samples is analyzed with a nitrosamine analyzer. The results of the analyzes are:

sample of nitrosamine concentration <0.2 <0.2

Claims (20)

A process for removing nitrosamine from dinitroanilines of the general formula I, R 1 is hydrogen, C 1 -C 5 alkyl or C 1 -C 5 monohaloalkyl, R ^{2 is} C 1 -C 5 alkyl, C 1 -C 5 monohaloalkyl or C 1 -C 3 alkylcycloalkyl and C 3 -C 5 alkylcycloalkyl, R 3 is halogen, hydrogen, C 1 -C 3 alkyl or amino; R4 is alkyl having 1-5 carbon atoms, trifluoroalkyl of 1-5 carbon atoms, a sulfonamide group, or · a methylsulfonyl group, wherein at least one of R ^1, R ^2, R 3 or R ⁴ is limited to the following groups, namely R @ ^{1 is} hydrogen or C1 -C5 monohaloalkyl, R2 to a monohaloalkyl group having 1 to 5 carbon atoms or an alkylcycloalkyl group having 1 to 3 carbon atoms in the alkyl and 3 to 5 carbon atoms in the cycloalkyl moiety, R 3 is halogen, C 1 -C 3 alkyl or amino; R4 to a sulfonamide or methylsulfonyl group, characterized in that dinitroaniline in the liquid phase at a temperature ranging from 70 ° C to 110 ° C is treated with a reagent selected from the group consisting of 20 to 38% hydrochloric acid and hydrogen chloride gas until the nitrosamine concentration is lowered, whereupon the dinitroaniline is isolated. 2. Process according to claim 1, characterized in that it is operated at a temperature in the range of from 70 to 90 ° C. Method according to claim 1 or 2, characterized in that molten dinitroaniline is used as the liquid phase. 4. Process according to claim 1 or 2, characterized in that the reaction is carried out in a primary alcohol, ketone, xylene or benzene medium. 5. A process as claimed in any one of claims 1 to 4, wherein 33 to 38% hydrochloric acid is used as the reagent. 6. The method according to claims 1 to 4, characterized by: OF THE INVENTION using hydrogen chloride gas as the reagent. 7. A process as claimed in claim 6, wherein the hydrogen chloride gas at an overpressure in the range of 6 to 6 psig is used. 8. A process according to claim 7, wherein the hydrogen chloride gas at an overpressure in the range of 20.58 to 34.3 kPa is used. 9. The method of claim 1 for removing nitrosamines from dinitroanilines of formula I wherein R1 is alkyl having 1-5 C atoms, R2 is alkyl having 1-5 carbon atoms, ^R5 is hydrogen and R4 is alkyl having 1-5 carbon atoms or a C 1 -C 5 trifluoroalkyl group, characterized in that dinitroaniline in the liquid phase at a temperature ranging from 70 to 110 ° C is treated with a reagent selected from the group consisting of 20 to 38% hydrochloric acid and gaseous hydrogen chloride, when the nitrosamine concentration is reduced, the dinitroaniline is then isolated. 10. The process of claim 9 wherein the temperature is in the range of from 70 to 90 [deg.] C. Process according to Claim 9 or 10, characterized in that molten dinitroaniline is used as the liquid phase. 12. The process of claim 9 or 10 wherein the reaction is carried out in a primary alcohol, ketone or benzene environment. 13. A process as claimed in claim 9, wherein 33 to 38% hydrochloric acid is used as the reagent. 14. A process according to any one of Claims 9 to 12 wherein the reagent is hydrogen chloride gas. 15. The process of claim 14 wherein hydrogen chloride gas at an overpressure in the range of about 10 to about 50 psi is used. 16. The process of claim 15 wherein hydrogen chloride gas at an overpressure in the range of 20.58 to 34.3 kPa is used. 17. The process of claims 9-11, wherein molten trifluralin is treated with hydrogen chloride gas at a temperature in the range of from 70 to 90 ° C under a positive pressure of 13.72 to 34.3 kPa until the nitrosamine concentration is reduced, then trifluralin is isolated. 18. The process of claims 9 to 11, wherein the molten trifluralin is treated with 38% hydrochloric acid at a temperature ranging from 70 to 90 [deg.] C. until the nitrosamine concentration is lowered and the trifluralin is isolated. 19. A process according to claim 9, wherein the dinitroaniline is trifluralin. 20. The process of claim 9, wherein the dinitroaniline is isopropalin.