WO2008138088A2

WO2008138088A2 - Solid and water-soluble gluphosinate for herbicide formulation, production process therefor, and process for controlling weeds

Info

Publication number: WO2008138088A2
Application number: PCT/BR2008/000141
Authority: WO
Inventors: Ricardo Amaral Remer
Original assignee: Ricardo Amaral Remer
Priority date: 2007-05-16
Filing date: 2008-05-15
Publication date: 2008-11-20
Also published as: WO2008138088A3; BRPI0702341B1; BRPI0702341A2

Abstract

The present invention provides active ingredients for agrochemical formulations, as well as the production processes therefor. The active ingredient of the invention is a dry, solid ammonium salt of gluphosinate, having high purity (95 to 100%) and low humidity (<1.0% m/m), and is useful as 'technical salt' for the preparation of dry, solid, and water-soluble herbicide formulations. The production process of said active ingredient comprises a solid/liquid/solid reaction between a solid ammonium salt and solid gluphosinate acid, both solids being dispersed in an organic liquid medium. The products of the invention are highly water-soluble and are useful for controlling crop weeds.

Description

Descriptive Report

Solid and water-soluble gluphosinate for herbicide formulation, Production process therefor, and Process for controlling weeds

Field of the Invention

The present invention is related to agrochemicals and production processes therefor. More specifically, the present invention discloses a process for the production of a solid ammonium salt of gluphosinate, generally known as ammonium salt of gluphosinate, in high purity (95 to 100%) and low humidity (<1 ,0% m/m), as an active ingredient of solid and water-soluble herbicide formulations. The production process of said active ingredient comprises a solid/liquid/solid reaction between a solid ammonium salt and solid gluphosinate acid, both solids being dispersed in an organic liquid medium. The thus obtained ammonium salt of gluphosinate has low or zero solubility in the liquid medium, therefore precipitating in said liquid medium and thus allowing its separation in the form of a highly pure and concentrated solid. The product of such reaction scheme is highly water-soluble and can be used directly for controlling crop weeds and/or as active ingredient for the preparation of agrochemical formulations containing the ammonium salt of gluphosinate.

Related Prior Art

Patent prior art relating to the subject-matter of the invention is available. However, neither one of the documents found in the art anticipates or indisputably suggests the teachings of the invention, nor the skilled person in the art would reach the invention or would be motivated to combine any of such documents so as achieve the teachings herein provided.

Gluphosinate (4-hydroxy(methyl)phosphinoyl]-DL-homoalanine acid or DL-homoalanin-4-yl(methyl) phosphinic acid) is known in the art as an effective herbicide. Gluphosinate is a weak organic acid only partially water-soluble, typically being commercialized in its ammonium salt form, which is water- soluble. Therefore, most of patent literature is directed to processes and formulations aiming to circumvent the poor solubility problem.

Patent US 5,308,827 of Fumakilla Ltd. and entitled "Herbicidal Foam Composition", was filed on February 24, 1996. Said document reveals an herbicide composition comprising, based on the total weight: (a) an herbicide comprising gluphosinate or a mixture thereof with other herbicides; (b) an anionic and/or non-ionic surfactant; (c) a solvent; (d) an antifoaming agent; (e) water as diluent; and (f) liquified petrόil gas as propellent. The pH of said composition is adjusted to 3-11. Patent US 5,491 ,125 of Hoechst AG and entitled "Liquid herbicidal formulations of gluphosinate", was filed on December 1st, 1992. Said document reveals the use of gluphosinate in liquid herbicides which are adequate to low temperatures, also presenting better herbicide action and low requirement of organic solvents. Patent US 4,830,658 of Hoechst AG and entitled "Herbicidal

Compositions", was filed on October 30, 1986. Said document reveals herbicide compositions comprising effective amounts of phosphinotricyns of general a formula which includes gluphosinate, said compositions being combined with SIMAZIM. The proportion in weight of phosphinotricyn and SIMAZIM is of about 1 : 1.5 to 1 :4, thus improving the herbicide activity.

Patent US 5,391 ,539 of lshihara Sangyo Kaisha and entitled "Herbicidal composition comprising glufosinate and a heterocyclic sulfonylurea herbicide", was filed on December 3, 1986. Said document reveals compositions comprising as active ingredients: 1-(4,6-dimethoxypyrimidin-2-yl)-3-(3- trifluoromethyl-2-pyridylsulfonyl)urea; and an ammonium salt of homoalanin-4- yl(methyl)phosphinic acid (known as ammonium salt of gluphosinate), said composition being more effective than those having these ingredients separately.

Patent US 5,420,329 of Hoechst AG and entitled "Process for the preparation of L-phosphinothricin and its derivatives", was published on 1995. Said document reveals a process for the enantioselective preparation of L- phosphinotricyn or its derivatives of formula:

by means of a reacion of a L-vynilglycine derivative with a methanophosphonic monoesther acid of formula:

in the presence of a catalytic amount of a free radical initiator selected from the group consisting of: t-butyl perbenzoate, t-butyl perpivalate, t-butyl perethylhexanoate, t-butyl perneodecanoate, or azobisisobutyronitryl, and combinations thereof, at temperatures of 70° C to 115° C. Alternatively, the process may include the conversion of the compound obtained in the first step, by hydrolysis or aminolysis, into a structurally different compound, optionally converted into its salt.

Patent US 6,274,156 of Rhone-Poulenc Agrochimie and entitled "Agrochemical compositions in the form of dispersible granules", was published/granted on August 14, 2001. Said document describes an homogeneous agrochemical composition which is formed by admixing two compositions in the form of water-dispersible granules. The solid composition consists of an homogeneous mixture of: (1) at least one concentrated composition A in the form of dispersible granules comprising the active ingredient and without any effervescent agent, having a pore volume of 0,17 to 0.35 rnL/g and an apparent density of 0.35 to 0.8 g/cm³; and (2) a concentrated composition B in the form of dispersible granules, containing an effervescent agent and not the active ingredient, the effervescent agent containing:

(a) an alkaline carbonate or hydrogen carbonate; and

(b) an acid, in which the weight ratio acid/carbonate is 0.3 to 30, and the granules of composition B have pore size of 0.020 to 0.13 mL/g and an apparent density of 0,8 to 1.5 g/cm³.

Brazilian Patent Application Pl 0312663, filed by Chinese inventors, is entitled "Preparacao de Glifosato de Amόnio Sόlido Usando Solvente Organico em Extracao". Such document discloses a process for the preparation of the ammonium salt of glyphosate (and not for gluphosinate) by means of organic solvent extraction in a gas/liquid/solid reaction scheme. Such process consists in adding acid glyphosate and water in a reactor having homogenizing means; introducing gaseous ammonia to the reactor so as acid glyphosate reacts therewith and a solution of the ammonium salt of glyphosate is formed by the end of the reaction; adding a water-soluble organic solvent such as methanol or ethanol or formaldehyde so as to decrease the solubility of the ammonium salt of glyphosate in the system, thereby crystallizing it; and suction-filtering it, optionally drying it so as to obtain a solid.

The Brazilian Patent Application Pl 9205234-7 (equivalent to US 5,324,708), was filed by Alkaloida Vegyeszeti Gyar and is entitled "Novos Sais de Mono-amδnio Nao-higroscόpicos". This application was rejected and discloses monoisopropylamine salts of gluphosinate or glyphosate, as well as processes for the production thereof. Herbicides and methods for controlling weeds are described and claimed, but no process is claimed. Said processes consist in the reaction of the corresponding phosphinic or phosphonic acid, in solid form, in a reactor containing liquid monoisopropylamine salt, also known as MIPA. The reaction is therefore a solid/liquid/liquid reaction scheme. Several disadvantages of said processes and of the corresponding products occur, and include: the products are gluphosinate or glyphosate MIPA salts, whose dissolutions in water are highly exotermic, posing risks and difficulties to the final user. Also, the use of MIPA in an industrial plant is highly dangerous: beyond being highly toxic (MIPA is considered as IDLH immediately dangerous to Life and Health), MIPA is also flammable. The reaction between MIPA the phosphinic or phosphonic acid is also exotermic, thus requiring sophisticated reaction controls in the industrial processing and the corresponding costs. The present invention provides, between other advantages, a new solid dry and water-soluble active ingredient and agrochemical formulations containing the ammonium salt of gluphosinate. The active ingredient of the invention is heretofore referred to as "technical monoammonium salt of gluphosinate", or simply "technical salt", which has a purity of at least 95%, preferably 95,5%. The solid dry formulation provides several advantages such as transportation economy and, most importantly, substantial reduction in the capital and operating costs of the corresponding industrial plant, as compared to other known technologies for producing water-dispersible granules containing gluphosinate. These and other advantages of the invention will be appreciated by the skilled persons.

In short, no document was found in the art specifically disclosing a process for producing the ammonium salt of gluphosinate in a solid/liquid/solid reaction scheme between a solid ammonium salt and solid acid gluphosinate, these solids being dispersed in an organic liquid medium. The present invention enables the obtainment of the ammonium salt of gluphosinate, which is insoluble in the reaction medium and thus allows its direct isolation in the form a highly pure and concentrated salt. Further, the equipments required for the process of the present invention are much more simple and cheaper than those of similar processes known in the art. The process of the invention also avoids using gaseous or liquid anhydrous ammonia as ammonium cation source, therefore eliminating the corresponding concerns regarding safety and environmental issues. These and other disadvantages of the processes known in the art are overcome by the process and products of the present invention. Summary of the Invention

One of the objects of the present invention is to provide an improved process for producing the ammonium salt of gluphosinate in solid form. The product of such process is another object of the invention, and is useful as herbicide active ingredient of agrochemical formulations, which in turn can be available in several forms such as combinations with other herbicides, insecticides, fungicides and other pest control formulations.

It is another object of the invention to provide a production process which requires less capital and operational costs for producing the solid ammonium salt of gluphosinate.

It is another object of the invention to provide a safer production process, since the process of the invention does not require the use of toxic or dangerous consumables such as those of the processes known in the art.

It is another object of the invention to provide a more environmental- friendly production process, since the process of the invention does not require the use of toxic or dangerous consumables such as those of the known process in the art, and most of the reagents are reused and/or recycled during the process without producing large amount of industrial waste.

In another feature of the invention, being therefore another of its objects, the conditions of the process for obtaining the ammonium salt of gluphosinate circumvent the technical problem of heat generation, as occurs with the processes known in the art.

In another feature of the invention, being therefore another of its objects, the active ingredient which is a product of the invention is a highly pure and concentrated ammonium salt of gluphosinate in the solid form, which is in contrast to the processes known in the art.

In another feature of the invention, being therefore another of its objects, the active ingredient which is a product of the invention has low water content, thus substantially reducing the technical problems and costs for manipulation and transport, which is in contrast to the processes known in the art. Another object of the present invention is to provide an improved process for preparing dry, solid and water-soluble herbicide formulations comprising the ammonium salt of gluphosinate.

Another object of the present invention is to provide highly pure and improved herbicide formulations in the form of a water-soluble powder, which is in contrast to the related products known in the art.

These and other objects of the invention will be readily appreciated by the skilled persons and by the industries in this technical field. Further details are heretofore provided so as such skilled persons can reproduce the invention.

Brief Description of the Figures

Figure 1 shows a schematic diagram of a preferred embodiment an industrial scale process for producing the solid, dry and water-soluble ammonium salt of gluphosinate (the "technical salt"), where: an agitated stainless steel tank (A); an agitated stainless steel reactor (B) comprising a dryer and filter; a condenser (C); a recovery column (D); and the materials flow lines (1), (2), (3), (4), (5), (6), (7), (8), (9), (10) and (11).

Detailed Description of the Invention The inventor, searching for alternative technical solutions for the problems of the products and processes known in the art, developed an improved process for producing the ammonium salt of gluphosinate in the form of a highly pure and concentrated solid.

In the present invention, all concentrations are indicated in % weight/weight, except when specified on the contrary. The ammonium salt of gluphosinate is obtained in the present invention by the reaction between a solid acid gluphosinate (for example, in the form of humid or dry cake, the latter being preferred) and solid, water-insoluble ammonium salts, said solids reacting in a liquid organic medium under room temperature (the reaction is not exotermic) and with constant agitation until the reaction is complete. The reaction therefore occurs in a solid/liquid/solid system. The thus obtained ammonium salt of gluphosinate is not soluble in the organic liquid medium and therefore precipitates, thus allowing its easy isolation with high purity and concentration. The product of the reaction, although being insoluble in the organic liquid medium, is sufficiently water soluble so as to be directly used as agrochemical and/or used as active ingredient for the preparation of herbicide formulations containing the ammonium salt of gluphosinate. The thus obtained product (the ammonium salt of gluphosinate) is then isolated and optionally dryed by classical methods. The remaining liquid can be recycled for the next batch without any previous treatment, preferably up to about five cycles and then recovered by simple distillation. The ammonium salts used in the process of the present invention are, preferably, ammonium hydrogen carbonate, ammonium carbonate and/or ammonium carbamate (NH₂COONH4, CAS Number 1111-78-0). The organic liquid medium is a solvent in which the final product has low or no solubility, being preferred in the invention alcohols of up to four carbon atoms. The most preferred solvent is ethanol, for its low cost, low toxicity and high availability. The following examples illustrate, but are not intended to limit, some forms of reducing the invention to practice.

Example 1 In a mechanically agitated reactor, 810.Og of commercial ethanol (96%) and 372, 8g of solid acid gluphosinate 95.5% (2.00 moles) were fed. Subsequently, 100.8g of ammonium carbonate (1.05 moles) were fed and the mixture was agitated under room temperature for about 30 minutes, so as the reaction completes. The reaction can be simplified as follows:

2 + (NH₄J₂CO₃ ^

The contents of the reactor were filtered and the solids dryed until constant weight. The remaining liquid (licquor) was reused for the next batch. The process yielded 370 g of the ammonium salt of gluphosinate, having <1.0% w/w humidity and >95.5% purity.

Example 2

In a mechanically agitated reactor, 810.Og of commercial ethanol (96%) and 416,4g of humid cake acid gluphosinate 85.5% (2.00 moles) were fed. Subsequently, 100.8g of ammonium carbonate (1.05 moles) were fed and the mixture was agitated under room temperature for about 30 minutes, so as the reaction completes. The contents of the reactor were filtered and the solids dryed until constant weight. The remaining liquid (licquor) was reused for the next batch. The process yielded 368g of the ammonium salt of gluphosinate, having <1.0% w/w humidity and >95.5% purity.

Example 3

The conditions of example 1 were repeated now using 810.Og of methanol 98%. The process yielded 368g of the ammonium salt of gluphosinate, having <1.0% w/w humidity and >95.5% purity..

Example 4

The conditions of example 1 were repeated now using 162.Og of ammonium hydrogen carbonate (2.05 moles). The process yielded 366g of the ammonium salt of gluphosinate, having <1.0% w/w humidity and >95.5% purity. The results are similar to those using ammonium carbonate, but in this case a higher specific consumption occurred because of the altered stechiometric relation.

Example 5

The conditions of example 3 were repeated now using 162.Og of ammonium hydrogen carbonate (2.05 moles). The process yielded 319g of the ammonium salt of gluphosinate, having <1.0% w/w humidity and >95.5% purity. The results are similar to those using ammonium carbonate.

Example 6

The process of the present invention was also tested in industrial scale. Making reference to figure 1: the line (1) feeds tank (A) with commercial ethanol (96%), while line (2) feeds solid acid gluphosinate 95.5% to tank (A), which is kept agitated for homogeneity. Subsequently, line (3) feeds the contents of tank (A) to reactor (B), which is also fed by line (4) with ammonium carbonate. The mixture is homogenized under room temperature for about 30 minutes until the reaction is complete. The reaction occurring in reactor (B) can be described as follows:

The content of reactor (B) is then filtered, and the resulting liquid (licquor) containing alcohol is directly reused for the next batch or optionally fed by line (7) to a recovery column (D). The final product, the solid ammonium salt of gluphosinate, is obtained in line (9) and, after drying until constant weight, has <1.0% w/w humidity and >95.5% purity. The yield of this preferred embodiment of the invention is >98%. It is worth noting, making reference to figure 1, that the production plant is quite simple and does not require utilities such as vapor, cold water etc. The use of N₂ for the control of the atmosphere within the tank and reactor is recommended in some cases (compliance to Brazilian rules). The gases formed in reactor (B) are preferably treated in a condenser (C). The solvent recovery for reuse is quite simple for any plant having heat sources such as vapor.

The solid gluphosinate salt or "technical salt" obtained in the present invention is an active ingredient that can be used in several ways and formulations, including those combining this active with other actives such as other herbicides, fungicides etc. Those skilled in the art will readily appreciate from the teachings of the present invention that modifications on the preferred embodiments herein provided can be envisaged by combining other dry, solid adjuvants. Such alternative embodiments are to be deemed within the spirit of the invention and of the scope of the appended claims.

Claims

ClaimsSolid and water-soluble gluphosinate for herbicide formulation, Production process therefor, and Process for controlling weeds

1. Process for the preparation of solid salt of ammonium gluphosinate characterized by comprising a solid/liquid/solid reaction, wherein a solid ammonium salt and a solid acid gluphosinate are dispersed in an organic liquid and thereby react to form the solid salt of ammonium gluphosinate.

2. Process, according to claim 1 , characterized by the fact that said solid ammonium salt is selected from group consisting of ammonium carbonate, ammonium hydrogen carbonate, ammonium carbamate, or combinations thereof.

3. Process, according to claims 1-2, characterized by the fact that said organic liquid comprise at least one alcohol having up to four carbon atoms, optionally combined with other alcohols and/or other organic solvents.

4. Process, according to claims 1-3, characterized by the fact that, after the reaction is completed the product is separated from the organic liquid and is obtained as solid, water-soluble product having purity equal to or greater than 95% w/w.

5. Process, according to claim 4, characterized by the fact that said product is obtained as a solid, water-soluble product having humidity equal to or lower than 1 % w/w.

6. Process, according to claims 1-5, characterized by being conducted at room temperature without substantial heat formation.

7. Process, according to claims 1-6, characterized by the fact that said organic liquid is directly reused in another batch or optionally recycled.

8. Solid and water-soluble active ingredient, characterized by comprising an ammonium salt of gluphosinate having purity equal to or greater than 95% w/w.

9. Active ingredient, according to claim 8, characterized by having humidity equal to or lower than 1%.

10. Active ingredient, according to claims 8-9, characterized by the fact that said ammonium salt is selected from group consisting of ammonium carbonate, ammonium carbamate, ammonium hydrogen carbonate, or combinations thereof.

11. Active ingredient, according to claims 8-10, characterized by being obtained by the reaction of a solid ammonium salt and a solid acid gluphosinate in a solid/liquid/solid reaction in an organic liquid medium.

12. Agrochemical composition characterized by comprising: - an ammonium salt of gluphosinate having purity equal to or greater than 95% w/w; and

- at least one dry, solid adjuvant.

13 Process for the preparation of solid, water-soluble herbicide formulation, characterized by comprising the mixture of:

- at least one ammonium salt of gluphosinate having purity equal to or greater than 95% w/w; and

- at least one dry, solid adjuvant.

14. Process, according claim 13, characterized by the fact that said solid ammonium salt is the monoammonium salt of gluphosinate.

15. Process, according to claims 13-14, characterized by the fact that said product is obtained as a water-soluble solid having humidity equal to or lower than 1 % w/w.

16. Process, according to claims 13-15, characterized by the fact that said ammonium salt of gluphosinate is obtained by the reaction of a solid ammonium salt and a solid acid gluphosinate in a solid/liquid/solid reaction in an organic liquid medium.

17. Process for controlling agricultural weeds characterized by comprising the application, to the plant culture to be protected, of an agrochemical composition comprising as active ingredient the ammonium salt of gluphosinate having purity equal to or greater than 95% w/w.

18. Process, according to claim 17, characterized by the fact that said agrochemical further comprises at least one dry, solid adjuvant.

19. Use, in the preparation of an agrochemical for controlling weeds, of an active ingredient characterized by comprising the ammonium salt of gluphosinate having purity equal to or greater than 95% w/w.

20. Use, in the preparation of an agrochemical for controlling weeds, of an active ingredient characterized by being obtained by a solid/liquid/solid reaction, wherein a solid ammonium salt and a solid acid gluphosinate are dispersed in an organic liquid and thereby react to form the solid salt of ammonium gluphosinate.