PL231526B1 - Alkyl[2-(2-hydroxyethoxy)ethyl]dimethylammonium 3,6-dichloro-2-methoxybenzoates, method for obtaining them and application as herbicides - Google Patents

Description

Description of the invention

The present invention relates to alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoates, a method for their preparation and use as herbicides.

Ionic liquids are organic chemicals, consisting of a cation and an anion, which are characterized by a melting point lower than the boiling point of water. Organic salts, which include anions derived from organic acids showing herbicidal activity, belong to the group of herbicidal ionic liquids (HIL's).

Weeds are a major problem in plant cultivation. They harm agriculture by taking away from crops space to grow, nutrients from the soil, and water and light. In addition, they make harvesting difficult, which becomes more energy-consuming and costly due to the need to thoroughly clean the crop from possible weed seeds. Earlier methods of fighting undesirable plants were by manual removal or burning. Currently, chemical plant protection products are used, which are of greater practical importance, because they remove many species of harmful plants extremely effectively.

Herbicidal ionic liquids, thanks to their unique properties such as low vapor pressure, non-flammability and non-volatility, become promising plant protection products. In addition, the high biological activity, often exceeding the effect of commercial preparations, allows for lowering the dose of the preparation during the spraying procedure. This is beneficial for the protection of the natural environment due to the lower possibility of pesticide accumulation in the soil and lower likelihood of chemical substances being released into groundwater and natural water bodies. Low volatility prevents chemicals from getting into adjacent fields, and the person conducting the spraying treatment is not exposed to inhalation of harmful vapors.

Herbicide ionic liquids were first described in 2011 in the publication of J. Pernak, A. Syguda, D. Janiszewska, K. Materna, T. Praczyk, Tetrahedron 2011, 67, 4838-4844. The wide application potential and unusual, multifunctional properties have resulted in an increased interest in these compounds in the scientific community, which has been presented in the publications of: T. Praczyk, P. Kardasz, E. Jakubiak, A. Syguda, K. Materna, J. Pernak, Weed Sc. 2012, 60, 189-192; J. Pernak, A. Syguda, K. Materna, E. Janus, P. Kardasz, T. Praczyk, Tetrahedron 2012, 68, 4267-4273; J. Pernak, J. Shamshina, T. Praczyk, A. Syguda, J. Dominika, M. Smiglak, G. Gurau, D. T. Daly, R. D. Rogers, PCT Int. Appl. (2012), WO 2012006313 A2 20120112; J. Pernak, M. Niemczak, K. Zakrocka, T. Praczyk, Tetrahedron 2013, 69, 8132-8136; J. Pernak, M. Niemczak, K. Materna, K. Marcinkowska, T. Praczyk, Tetrahedron 2013, 69, 4665-4669; R. Kordala-Markiewicz, H. Rodak, B. Markiewicz, F. Walkiewicz, A. Sznajdrowska, K. Materna, K. Marcinkowska, T. Praczyk, J. Pernak, Tetrahedron 2014, 70, 47844789; J. Pernak, K. Czerniak, M. Niemczak, Ł. Chrzanowski, Ł. Ławniczak, P. Fochtman, K. Marcinkowska, T. Praczyk, New J. Chem., 2015, 39, 5715-5724; J. Pernak, M. Niemczak, K. Materna, K. Żelechowski, K. Marcinkowska, T. Praczyk, RSC Adv., 2016, 6, 7330-7338 and patents: J. Pernak, J. Shamshina, T. Praczyk, A. Syguda, J. Dominika, M. Smiglak, G. Gurau, DT Daly, RD Rogers, PCT Int. Appl. (2012), WO 2012006313 A2 20120112; J. Pernak, T. Praczyk, A. Syguda, M. Urbanek, W. Warchoł, B. Loryś, Leżajsk, J. Peć, Nowa Sarzyna, A. Szałajewicz, PL 211855 B1; J. Pernak, A. Syguda, M. Kukuć, PL 218145 B1; J. Pernak, A. Syguda, M. Kukuć, PL 218425 B1; J. Pernak, M. Niemczak, S. Giertych, PL 218453 B1, J. Pernak, M. Niemczak, S. Giertych, R. Giszter, T. Praczyk, PL 218454 B1, J. Pernak, M. Niemczak, S. Giertych, PL 218511 B1.

One of the organic acids showing good herbicidal activity is acid

3,6-dichloro-2-methoxybenzoic acid with the popular name Dikamba. It is a systemic herbicide belonging to growth regulators. Used to protect crops of wheat, oats and corn. Weeds that show sensitivity to this herbicide include: field mustard, field poppy, white quinoa and cornflower.

The subject of the synthesis were ionic liquids with the alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium cation and the 3,6-dichloro-2-methoxybenzoic acid anion. The cation of the organic salt shows surface active activity, due to which the contact angle of the weed leaf is increased. The active substance in the form of the Dicamba acid anion penetrates the plant more easily, causing it to die faster. An additional advantage of the compounds is their high activity, which enables more economical use of the product by reducing the dose of the agent, additionally protecting the natural environment against excessive pesticide load.

PL 231 526 B1

The invention relates to ionic liquids of general formula I, wherein R is a straight-chain alkyl substituent containing from four to sixteen carbon atoms.

Examples of these types of compounds are:

• butyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate • hexyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate • 3,6-dichloro -2-methoxybenzoate [2- (2-hydroxyethoxy) ethyl] dimethyloctyl ammonium • 3,6-dichloro-2-methoxybenzoate decyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium • 3,6-dichloro-2-methoxybenzoate dodecyl [2 - (2-hydroxyethoxy) ethyl] dimethylammonium • 3,6-dichloro-2-methoxybenzoate [2- (2-hydroxyethoxy) ethyl] dimethyltetradecylammonium • hexadecyl [2- (2-hydroxyethoxy) ethyl 3,6-dichloro-2-methoxybenzoate ] dimethylammonium.

The invention relates to alkyl [2- (2-hydroxyethoxy) ethyl] dimethyl ammonium 3,6-dichloro-2-methoxybenzoates of the general formula I, wherein R is an alkyl substituent with a carbon chain length of four to sixteen carbon atoms.

The method of their preparation consists in reacting the quaternary alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium bromide of the general formula 2, in which R is a straight-chain alkyl substituent containing from four to sixteen carbon atoms, is subjected to an anion exchange reaction with a potassium salt or lithium or sodium or ammonium of 3,6-dichloro-2-methoxybenzoic acid in molar ratio of quaternary ammonium salt to acid salt from 1: 0.9 to 1: 1.1, preferably 1: 1, at 20-45 ° C , in an organic solvent from the group: methanol, isopropanol, butanol, and then the formed inorganic by-product is filtered off from the organic solvent, the solvent is evaporated from the filtrate, and the reaction product is dried under reduced pressure at 50 ° C.

It is advantageous if the obtained butyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate compound after the bromide anion exchange reaction is additionally cooled to -20 ° C.

It is also preferable that the obtained [2- (2-hydroxyethoxy) ethyl] dimethyloctyl ammonium compound 3,6-dichloro-2-methoxybenzoate after the bromide anion exchange reaction is further purified by dissolving it in a 1: 1 acetone: methanol solvent mixture.

The second method of preparation is that the quaternary alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium bromide of the general formula II, in which R is a straight-chain alkyl substituent containing from four to sixteen carbon atoms, is dissolved in water, mixed with an aqueous solution of sodium, potassium or lithium salt of 3,6-dichloro-2-methoxybenzoic acid in the molar ratio of quaternary ammonium salt to 3,6-dichloro-2-methoxybenzoic acid salt from 1: 0.9 to 1: 1.1 , preferably 1: 1 at a temperature of 20-45 ° C, for at least 1 minute, then the reaction mixture is subjected to two-phase extraction with a non-polar solvent from the group: chloroform, or dichloromethane, or toluene, and after phase separation, the organic phase is washed with water and then the solvent is evaporated off and the obtained product is dried in vacuo at 50 ° C.

Use of the new alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoates of the general formula I, wherein R is a straight chain alkyl substituent containing four to sixteen carbon atoms as herbicide.

It is preferred that the ionic liquids are used in the form of an aqueous solution with a concentration of at least 0.05% or in the form of a 1: 1 water-ethanol solution.

Thanks to the solution according to the invention, the following technical and economic effects were obtained:

• a method of synthesizing new herbicidal ionic liquids with the alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium cation and the 3,6-dichloro-2-methoxybenzoate anion was developed, • the obtained organic salts exhibit a low non-volatile and non-flammable parsia under ambient conditions • the compounds retain the herbicidal activity of the anion derived from 3,6-dichloro-2-methoxybenzoic acid, • the obtained salts are characterized by high chemical and thermal stability, • the synthesized ammonium ionic liquids dissolve perfectly in water, methanol and DMSO,

Due to their properties, ammonium ionic liquids are used as herbicides.

The following examples illustrate the invention:

P r z k ł a d 1

Method for the preparation of butyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate

2.7 g (0.01 mol) of butyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium chloride in a flask and dissolved in 15 cm ³ of methanol. While stirring continuously, a stoichiometric amount of 2.36 g (0.01 mol) of 3,6-dichloro-2-methoxybenzoic acid ammonium salt was added. The reaction was carried out for 2 hours at 40 ° C. At this time, the product was placed at -20 ° C for 30 minutes. The precipitated inorganic salt was then filtered off, and the solvent was evaporated on a rotary vacuum evaporator. The finished product was vacuum dried at 50 ° C.

The product structure was confirmed by performing proton and carbon nuclear magnetic resonance spectra:

¹ H NMR (CDCl 3) δ [ppm] = 0.91 (t, J = 7.3 Hz, 3H), 1.27 (q, J = 7.3 Hz, 2H), 1.64 (m, 2H ), 3.09 (s, 6H), 3.35 (m, 2H), 3.49 (m, 4H), 3.55 (m, 2H), 3.80 (s, 5H), 7.07 (d, J = 8.4 Hz, 1H), 7.21 (d, J = 8.6 Hz, 1H); ¹³ C NMR (CDCb) δ [ppm] = 165.5; 151.2; 140.3; 127.5; 126.8; 125.2; 72.1; 63.9; 62.1; 61.0; 59.9; 50.7; 23.8; 19.1; 13.5.

Elemental analysis of CHN for C18H29Cl2NO5 (Mmol = 410.33 g / mol): calculated values (%): C = 52.69; H = 7.12; N = 3.41; measured values: C = 52.49; H = 7.21; N = 3.28.

P r z k ł a d 2

Method for the preparation of hexyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate

3.28 g (0.011 mol) of hexyl [2- (2-hydroxyethoxy) ethyl] dimethyl ammonium bromide dissolved in 15 cm ³ of distilled water were added to the reaction vessel, then 2.67 g (0.011 mol) of 3,6-dichloro-2 were added. sodium methoxybenzoate dissolved in 15 cm ³ of distilled water. The product was extracted from the solution with dichloromethane. The organic phase was washed 3 times with distilled water and then the solvent was evaporated using a rotary vacuum evaporator. The finished product, hexyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate, was dried in a vacuum oven at 50 ° C.

The structure of the compound was confirmed by spectral analysis by ¹ H NMR and ¹³ C

NMR:

¹ H NMR (CDCl 3) δ [ppm] = 0.90 (t, J = 7.4 Hz, 3H), 1.31 (q, J = 7.4 Hz, 6H), 1.61 (m, 2H ), 3.11 (s, 6H), 3.39 (m, 2H), 3.41 (m, 4H), 3.59 (m, 2H), 3.81 (s, 5H), 7.11 (d, J = 8.4 Hz, 1H), 7.22 (d, J = 8.6 Hz, 1H); ¹³ C NMR (CDCl 3) δ [ppm] = 165.1; 150.8; 140.1 127.9; 127.0; 125.9; 72.7; 63.5; 62.6; 61.2; 59.7; 50.5; 23.6; 19.3; 13.6.

Elemental analysis of CHN for C20H33Cl2NO5 (Mmol = 438.39 g / mol): calculated values (%): C = 54.80; H = 7.59; N = 3.20; measured values: C = 54.99; H = 7.68; N = 3.56.

P r z k ł a d 3

Method for the preparation of [2- (2-hydroxyethoxy) ethyl] dimethyloctyl ammonium 3,6-dichloro-2-methoxybenzoate

2.94 g (0.009 mol) of [2- (2-hydroxyethoxy) ethyl] dimethyloctylammonium bromide dissolved in 10 cm ^{3 of} butanol were introduced into a flask equipped with a magnetic stirrer, a stoichiometric amount (0.009 mol) of 3,6-dichloro-2-methoxybenzoate was added. lithium dissolved in 10 cm ^{3 of} butanol. The reaction was carried out for 1 hour at 45 ° C. Then the precipitated inorganic salt was filtered off and the solvent was evaporated. To purify the compound, it was dissolved in 20 cm ^{3 of} an acetone: methanol mixture (1: 1 vol.), The precipitated solid was filtered off, and the solvent mixture was evaporated using a rotary vacuum evaporator. The finished product was vacuum dried at 50 ° C.

¹ H NMR (CDCl 3) δ [ppm] = 0.90 (t, J = 7.5 Hz, 3H), 1.26 (q, J = 7.4 Hz, 10H), 1.61 (m, 2H ), 3.12 (s, 6H), 3.29 (m, 2H), 3.51 (m, 4H), 3.54 (m, 2H), 3.81 (s, 5H), 7.08 (d, J = 8.5 Hz, 1H), 7.20 (d, J = 8.64 Hz, 1H); ¹³ C NMR (CDCb) δ [ppm] = 165.1; 151.3; 140.0; 127.9; 126.2; 125.0; 72.4; 63.8; 62.2; 61.0; 60.2; 50.6; 23.7; 19.2; 13.7.

The analysis of proton and carbon nuclear magnetic resonance spectra confirms the structure of the obtained ionic liquid.

Elemental analysis of CHN for C22H37Cl2NO5 (Mmol = 466.44 g / mol): calculated values (%): C = 56.65; H = 8.00; N = 3.00; measured values: C = 56.87; H = 7.89; N = 3.20.

PL 231 526 B1

P r z k ł a d 4

Method for the preparation of decyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate

3.9 g (0.011 mol) of decyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium bromide dissolved in 20 cm ^{3 of} isopropanol were placed in the flask, a stoichiometric amount of sodium 3,6-dichloro-2-methoxybenzoate dissolved in 10 cm ^{3 of} isopropanol was added. . The reaction was carried out for 1 hour at 45 ° C. Then the precipitated inorganic salt was filtered off and the solvent was evaporated. For purification, the compound was dissolved in 20 cm ³ of acetone, the precipitate was filtered off and the solvent evaporated on a rotary vacuum evaporator. The finished product was vacuum dried at 50 ° C.

The decyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate was obtained, the structure of which was confirmed by proton spectra and nuclear carbon resonance analysis:

¹ H NMR (CDCl 3) δ [ppm] = 0.93 (t, J = 7.2 Hz, 3H), 1.29 (q, J = 7.3 Hz, 14H), 1.69 (m, 2H ), 3.10 (s, 6H), 3.33 (m, 2H), 3.51 (m, 4H), 3.54 (m, 2H), 3.81 (s, 5H), 7.05 (d, J = 8.3 Hz, 1H), 7.20 (d, J = 8.6 Hz, 1H); ¹³ C NMR (CDCl 3) δ [ppm] = 165.4; 151.3; 140.1; 127.8; 126.9; 125.2; 72.1; 63.7; 62.2; 61.0; 60.3; 50.3; 23.9; 19.2; 13.4.

Elemental analysis of CHN for C24H41Cl2NO5 (Mmol = 494.49 g / mol): calculated values (%): C = 58.29; H = 8.36; N = 2.83; measured values: C = 58.09; H = 8.55; N = 2.59.

P r z k ł a d 5

Method for the preparation of dodecyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate

3.44 g (0.009 mol) of dodecyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium bromide dissolved in 20 cm ³ of distilled water were added to the reactor, then 2.04 g (0.009 mol) were added.

Lithium 3.6-dichloro-2-methoxybenzoate dissolved in 20 cm ³ of distilled water. The product was extracted from the solution with ethyl acetate. The organic phase was washed 3 times with distilled water and then the solvent was evaporated using a rotary vacuum evaporator. The finished product dodecyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3.6-dichloro-2-methoxybenzoate was dried in a vacuum oven at 50 ° C.

The product structure was confirmed by performing proton and carbon nuclear magnetic resonance spectra:

¹ H NMR (CDCl) δ [ppm] = 0.90 (t, J = 7.3 Hz, 3H), 1.26 (q, J = 7.4 Hz, 18H), 1.65 (m, 2H ), 3.09 (s, 6H), 3.34 (m, 2H), 3.49 (m, 4H), 3.53 (m, 2H), 3.81 (s, 5H), 7.08 (d, J = 8.6 Hz, 1H), 7.20 (d, J = 8.7 Hz, 1H); ¹³ C NMR (CDCl 3) δ [ppm] = 165.4; 151.2; 140.2; 127.7; 126.8; 125.4; 72.3; 63.7; 62.2; 61.3; 59.7; 50.4; 23.7; 18.9; 13.4.

Elemental analysis of CHN for C26H45Cl2NO5 (Mmol = 522.55 g / mol): calculated values (%): C = 59.76; H = 8.68; N = 2.68; measured values: C = 59.87; H = 8.45; N = 2.47.

P r z k ł a d 6

Method for the preparation of [2- (2-hydroxyethoxy) ethyl] dimethyltetradecylammonium 3,6-dichloro-2-methoxybenzoate

The flask was charged with 4.93 g (0.012) of the bromide [2- (2-hydroxyethoxy) ethyl] dimetylotetradecyloamoniowego dissolved in 25 cm ^{3 of} propanol was added a stoichiometric amount of 3,6-dichloro-2-methoxybenzoate sodium dissolved in 15 cm ^{3 of} isopropanol. The reaction was carried out for 1 hour at 45 ° C. Then the precipitated inorganic salt was filtered off and the solvent was evaporated. The finished product was dried under reduced pressure at 50 ° C.

The obtained [2- (2-hydroxyethoxy) ethyl] dimethyltetradecylammonium 3,6-dichloro-2-methoxybenzoate, the structure of which is confirmed by the following analysis:

¹ H NMR (CDCl 3) δ [ppm] = 0.90 (t, J = 7.2 Hz, 3H), 1.26 (q, J = 7.2 Hz, 22H), 1.66 (m, 2H ), 3.09 (s, 6H), 3.35 (m, 2H), 3.49 (m, 4H), 3.54 (m, 2H), 3.81 (s, 5H), 7.10 (d, J = 8.5 Hz, 1H), 7.22 (d, J = 8.6 Hz, 1H); ¹³ C NMR (CDCl 3) δ [ppm] = 165.5; 151.2; 140.2; 127.3; 126.7; 125.1; 72.2; 63.8; 62.3; 61.1; 59.9; 50.6; 23.7; 19.2; 13.4.

Elemental analysis of CHN for C28H49Cl2NO5 (Mmol = 550.60 g / mol): calculated values (%): C = 61.08; H = 8.97; N = 2.54; measured values: C = 61.24; H = 9.15; N = 2.35.

P r z k ł a d 7

Method for the preparation of hexadecyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate

PL 231 526 B1

5.26 g (0.012 mol) of hexadecyl [2- (2-hydroxyethoxy) ethyl] dimethyl ammonium bromide dissolved in 20 cm ³ of distilled water were added to the flask, then 3.10 g (0.012 mol) were added.

Potassium 3.6-dichloro-2-methoxybenzoate dissolved in 20 cm ³ of distilled water. The product was extracted from the solution with chloroform. The organic phase was washed 3 times with distilled water and then the solvent was evaporated using a rotary vacuum evaporator. The finished product hexadecyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3.6-dichloro-2-methoxybenzoate was dried in a vacuum oven at 50 ° C.

The structure of the product was confirmed by proton nuclear magnetic resonance and carbon nuclear magnetic resonance spectroscopy:

¹ H NMR (CDCl 3) δ [ppm] = 0.90 (t, J = 7.5 Hz, 3H), 1.26 (q, J = 7.4 Hz, 26H), 1.64 (m, 2H ), 3.09 (s, 6H), 3.34 (m, 2H), 3.48 (m, 4H), 3.54 (m, 2H), 3.81 (s, 5H), 7.07 (d, J = 8.4 Hz, 1H), 7.22 (d, J = 8.6 Hz, 1H); ¹³ C NMR (CDCl 3) δ [ppm] = 165.4; 151.3; 140.2; 127.5; 126.8; 125.0; 72.1; 63.8; 62.2; 61.1; 59.9; 50.5; 23.7; 19.1; 13.5.

Elemental analysis of CHN for C30H53Cl2NO5 (Mmol = 578.65 g / mol): calculated values (%): C = 62.27; H = 9.23; N = 2.42; measured values: C = 62.02; H = 9.42; N = 2.23.

Application example:

White quinoa (Chenopodium album L.) and cornflower (Centaurea cyanus L.) were the test plants. Weed seeds were sown into pots filled with soil to an equal depth of 1 cm. After producing the cotyledons, an interruption was made, leaving 5 plants in each pot. After the production of 4 true leaves (BBCH 14), the plants were sprayed with the application liquid containing the tested compounds using a cabin sprayer equipped with a Tee Jet 11002 sprayer, moving over the plants at a constant speed of 3.7 m / s. The liquid pressure in the sprayer was 0.2 MPa, and the liquid output per 1 ha was 200 dm ³ . The investigated herbicidal ionic liquids were dissolved in a 1: 1 volume ratio of water: ethanol in an amount corresponding to a dose of 400 g of herbicide (anion) per 1 ha. The herbicide Dikamba 700 SG was used as a comparative agent. After the treatment, the plants were returned to the greenhouse at 20 ° C and 60% air humidity. After 2 weeks, the plants were cut and their weight was determined with an accuracy of 0.01 g. The test was performed in 4 replications in a completely randomized design. On the basis of the obtained results, the reduction of the fresh weight of plants was calculated in comparison to the control object (plants not sprayed with the tested compounds).

Table 1. Biological activity of the new herbicidal ionic liquids containing dichloroprop-p against cornflower and white quinoa plants.

T a b e l a 1

Object Reduction of fresh weight [%] cornflower cornflower white quinoa [C4-N] [Dik] 79 60 [C6-N] [Dik] 79 71 [C8-N] [Dik] 86 73 [C10-N] [Dik] 88 81 [C12-N] [Dik] 88 69 [C14-N] [Dik] 89 73 [C16-N] [Dik] 91 66 Comparative measure 71 0.6

PL 231 526 B1

Claims (8)

Patent claims 1. Alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-Dichloro-2-methoxybenzoates of general formula I wherein R is an alkyl substituent with a carbon chain length of four to sixteen carbon atoms. 2. A process for the preparation of alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoates as defined in Claims The process of claim 1, wherein the quaternary alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium bromide of general formula II, wherein R is a straight chain alkyl substituent containing four to sixteen carbon atoms, is subjected to an anion exchange reaction with a potassium or lithium salt or sodium or ammonium of 3,6-dichloro-2-methoxybenzoic acid in a molar ratio of quaternary ammonium salt to acid salt of 1: 0.9 to 1: 1.1, preferably 1: 1, at 20-45 ° C, in an organic solvent from the group: methanol, isopropanol, butanol, and then the formed inorganic by-product is filtered off from the organic solvent, the solvent is evaporated from the filtrate, and the reaction product is dried under reduced pressure at 50 ° C. 3. The method according to p. The process according to claim 2, characterized in that the obtained butyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoate compound is cooled further to -20 ° C after the bromide anion exchange reaction. 4. The method according to p. 2. The process according to claim 2, characterized in that the obtained [2- (2-hydroxyethoxy) ethyl] dimethyloctyl ammonium compound 3,6-dichloro-2-methoxybenzoate after the bromide anion exchange reaction is additionally purified by dissolving it in a 1: 1 mixture of acetone: methanol solvents . 5. A process for the preparation of alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoates of the general formula 1 as defined in claim 1, characterized in that the quaternary alkyl [2- (2-hydroxyethoxy) ethyl bromide ] dimethylammonium of general formula 2, in which R is a straight-chain alkyl substituent containing from four to sixteen carbon atoms, is dissolved in water, mixed with an aqueous solution of a sodium, potassium or lithium salt of 3,6-dichloro-2-methoxybenzoic acid in the molar ratio of quaternary ammonium salt to 3,6-dichloro-2-methoxybenzoic acid salt of from 1: 0.9 to 1: 1.1, preferably 1: 1 at 20-45 ° C for at least 1 minute, then the reaction mixture is subjected to two-phase extraction with a non-polar solvent from the group: chloroform or dichloromethane or toluene, and after phase separation, the organic phase is washed with water and then the solvent is evaporated, and the obtained product is dried under reduced pressure at 50 ° C. 6. Use of the new alkyl [2- (2-hydroxyethoxy) ethyl] dimethylammonium 3,6-dichloro-2-methoxybenzoates of the general formula I, wherein R is a straight chain alkyl substituent containing from four to sixteen carbon atoms as herbicide. 7. Use according to claim 1 6. The method according to claim 6, characterized in that the ionic liquids are used in the form of an aqueous solution with a concentration of at least 0.05%. 8. Use according to claim 1 6. A method according to claim 6, characterized in that the ionic liquids are used in the form of a 1: 1 water-ethanol solution.