Production process for crystalline form of l-glufosinate ammonium salt

Abstract

To provide a novel crystalline form of L-glufosinate ammonium salt and a preparation process therefor.SOLUTION: A method comprises: suspending L-glufosinate hydrochloride in an alcohol solvent to form a suspension; contacting the suspension with gaseous ammonia in nonaqueous conditions until complete dissolution of the L-glufosinate hydrochloride to form a solution; and subjecting the solution to conditions sufficient to precipitate L-glufosinate ammonium.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel solid form of L-glufosinate ammonium salt and a process for its preparation. The present invention also provides a composition comprising said form and a method for controlling unwanted plant growth using said composition.

Background Art

[0002] Dl-homoalanine-4-yl(methyl)phosphinic acid (glufosinate) and salts are amino acid derivatives having herbicidal activity. The amino acid derivatives are active in the L-form. To use the pure active ingredient, several processes for preparing L-homoalanine-4-yl(methyl)phosphinic acid (L-glufosinate), particularly the ammonium salt, have been developed.

[0003] Many synthetic processes end with an acid addition salt of L-glufosinate that is required to produce the corresponding free acid (L-glufosinate) or ammonium salt. The salts are commercially preferred because of their high solubility in water.

[0004] U.S. Patent No. 4,226,941 discloses the preparation of L-glufosinate or salts by enzymatic preparation.

[0005] U.S. Patent No. 5,869,668 and Chinese Patent Application Publication No. 111072718 disclose the preparation of L-glufosinate or salts by the precipitation of one of the diastereomeric salts using a chiral base followed by isolation and resolution.

[0006] U.S. Patent No. 7,795,464 discloses the preparation of L-glufosinate by an asymmetric synthesis reaction.

[0007] Chinese Patent Application Publication No. 105541906 discloses a two-step process for the preparation of L-glufosinate ammonium salt starting from L-glufosinate hydrochloride using an aqueous alcohol solvent system and ammonia.

[0008] In most cases, the addition salts of L-glufosinate are obtained at the end of the reaction and need to be converted to the ammonium or alkali metal salts of L-glufosinate. This can be done in either of two ways: by converting the acid addition salt to the free acid and then to the desired salt, or by converting the acid addition salt directly to the desired salt.

[0009] Following any of the above methods, the isolation process requires complex procedures using ion exchange columns or post-treatment processes involving the treatment of acid addition salts of L-glufosinate with harmful chemicals such as ethylene oxide and propylene oxide. The preparation and purification of ammonium L-glufosinate often require multi-step processes involving hydrolysis and crystallization procedures that affect the yield and purity of the product.

[0010] Therefore, there is a need to develop novel solid forms of ammonium L-glufosinate and methods for producing high-purity ammonium L-glufosinate and / or L-glufosinate free of acid addition salts of L-glufosinate starting from acid addition salts of L-glufosinate.

[0011] Surprisingly, the inventors have found that ammonium L-glufosinate with high purity and high yield can be prepared in a single step from acid addition salts of L-glufosinate. The present disclosure also provides crystalline forms of ammonium L-glufosinate that are advantageous for production and use in pharmaceutical products.

[0012] Object of the Invention It is an object of the present invention to provide a novel solid form of ammonium L-glufosinate.

[0013] It is also another object of the present invention to provide a simple and convenient process for producing ammonium L-glufosinate.

[0014] A single-step process for producing the ammonium salt of L-glufosinate is also another object.

[0015] Yet another object is to provide a production method for acid addition salts of L-glufosinate and / or L-glufosinate ammonium salt that is substantially free of L-glufosinate and any other reaction by-products.

[0016] It is another object to provide L-glufosinate ammonium salt in high purity and high yield. Summary of the Invention

[0017] In one aspect, the present disclosure provides a novel solid form of L-glufosinate ammonium salt.

[0018] In another aspect, the present disclosure provides an acid addition salt of L-glufosinate and / or L-glufosinate ammonium salt in a crystalline form that is substantially free of L-glufosinate and any other reaction by-products.

[0019] In another aspect, the present disclosure provides a process for preparing a compound represented by formula (I): [ka]

[0020] The process is a) suspending an acid addition salt compound represented by the following formula (II): - is an anion in a solvent to form a suspension;

[0021] [ka] b) contacting the suspension with gaseous ammonia until the compound represented by formula (II) is completely dissolved to form a solution; c) precipitating the compound represented by formula (I).

[0022] In another aspect, the present disclosure provides a process for producing a compound represented by formula (I), the process comprising: a) suspending an acid addition salt compound represented by formula (II) in an alcohol solvent at a weight ratio of the compound represented by formula (II) to alcohol of about 1:5 to about 1:15 to form a suspension; b) contacting the suspension with gaseous ammonia under non-aqueous conditions until the compound represented by formula (II) is completely dissolved to form a solution; c) subjecting the solution to conditions sufficient to precipitate the compound represented by formula (I).

[0023] In another aspect, the present disclosure provides an ammonium L-glufosinate having a volume average particle size distribution D50 of about 250 microns or less, specifically about 1 micron to about 200 microns, and most specifically about 10 microns to about 175 microns.

[0024] The present disclosure also provides the use of crystalline form I ammonium L-glufosinate for preparing other forms of L-glufosinate or other salts.

[0025] The present disclosure also encompasses the use of crystalline form I ammonium L-glufosinate of the present disclosure for the preparation of pesticidal compositions and / or formulations.

[0026] In another aspect, the present disclosure provides a pesticidal composition comprising crystalline form I ammonium L-glufosinate according to the present disclosure.

[0027] In yet another embodiment, the pesticidal formulation of the present disclosure comprises crystalline form I ammonium L-glufosinate and at least one pesticidally acceptable additive / excipient.

[0028] The present disclosure includes a process for preparing the above-mentioned pesticidal formulation of the L-glufosinate ammonium salt, which comprises the crystalline form I of the L-glufosinate ammonium salt and at least one agriculturally acceptable additive / excipient.

[0029] In another aspect, the present disclosure provides a method for controlling unwanted plant growth, which comprises applying the crystalline form of the L-glufosinate ammonium salt to a plant or its growth site.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0031] In any aspect or embodiment described below, the phrase "comprising" may be replaced by the phrases "consisting of", "consisting essentially of", or "consisting substantially of". Further, "including", "having", "involving", "containing", "characterized by", its variations (e.g., "includes", "has", "involves", "contains", etc.), and terms used herein in the same manner as used in the claims, including the claims, are to be inclusive and / or not limiting, and have the same meaning as the word "comprising" and its variations (e.g., "comprise" and "comprises"), and by way of example, do not exclude additional, unrecited elements or method steps. As used herein, the expression "substantially free of" is understood to mean containing, for example, 20% or less, 10% or less, 5% or less, 2% or less, or 1% or less of any other form or salt of the target compound, as measured by PXRD. As used herein, the term "about" refers to a measurable value such as a parameter, quantity, time, etc., and includes variations of + / - 15% or less, specifically + / - 10% or less, more specifically + / - 5% or less, even more specifically + / - 1% or less, and still more specifically + / - 0.1% or less from a particular recited value, as long as such variations are appropriate in the practice of the disclosure described herein. Further, it is to be understood that the value to which the modifier "about" refers is itself specifically disclosed herein.

[0032] In one aspect, the present disclosure provides a novel solid form of ammonium L - glufosinate.

[0033] With respect to the present disclosure, the L-glufosinate ammonium salt is the crystalline form of the L-glufosinate ammonium salt referred to herein as Form I. "L-glufosinate ammonium salt", "L-glufosinate ammonium", and the crystalline form of the L-glufosinate ammonium salt used interchangeably throughout this specification refer to Form I.

[0034] Accordingly, the present disclosure provides the L-glufosinate ammonium salt in crystalline Form I.

[0035] The present disclosure provides the L-glufosinate ammonium salt in crystalline Form I, consisting of at least 80% by weight, particularly at least 90% by weight, of the L-glufosinate ammonium salt of Form I.

[0036] The L-glufosinate ammonium salt in crystalline Form I can be identified by X-ray powder diffraction based on its diffraction pattern.

[0037] Typically, the L-glufosinate ammonium salt in crystalline form is characterized by an X-ray powder diffraction pattern substantially as shown in Figure 1.

[0038] In one embodiment, the present disclosure provides the L-glufosinate ammonium salt in crystalline Form I, showing at least three of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0039] In one embodiment, the present invention provides the L-glufosinate ammonium salt in crystalline Form I, showing the reflections cited as 2θ (±0.2°) values of at least about 9.0, 13.1, 14.1, and 18.9 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0040] In one embodiment, the present invention provides an L-glufosinate ammonium salt in crystalline form I that exhibits at least one peak selected from the group of 17.6, 18.2, 18.9, and 23.4 degrees 2θ ± 0.2 degrees 2θ in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0041] In one embodiment, the present disclosure provides an L-glufosinate ammonium salt in crystalline form I that exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees 2θ ± 0.2 degrees 2θ having a relative intensity of at least 30% compared to the highest intensity peak at 18.9 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0042] In one embodiment, the present disclosure provides an L-glufosinate ammonium salt in crystalline form I that exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees having a relative intensity of at least 30% compared to the highest intensity peak at 18.9 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0043] In another embodiment, the present disclosure provides an L-glufosinate ammonium salt in crystalline form I that exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees having a relative intensity of at least 50% compared to the highest intensity peak at 18.9 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0044] In one embodiment, the L-glufosinate ammonium salt in crystalline form I exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees having the following peak intensity % in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0045] [Table 1]

[0046] In another embodiment, the L-glufosinate ammonium salt of crystalline form I exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, with peak intensity % as follows, in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0047] [Table 2]

[0048] In another embodiment, the L-glufosinate ammonium salt of crystalline form I exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, with peak intensity % as follows, in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0049] [Table 3]

[0050] In another embodiment, the L-glufosinate ammonium salt of crystalline form I exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, with peak intensity % as follows, in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0051] [Table 4]

[0052] In another embodiment, the L-glufosinate ammonium salt of crystalline form I exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having peak intensity % as follows in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0053]

Table 5

[0054] In one embodiment, the present disclosure provides an L-glufosinate ammonium salt of crystalline form I that exhibits at least six of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 in an X-ray powder diffraction pattern using Cu-Kα radiation.

[0055] In one embodiment, the present disclosure An X-ray powder diffraction pattern having peaks at 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 degrees 2θ ± 0.2 degrees 2θ, An X-ray powder diffraction pattern having at least three peaks selected from the group of 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 degrees 2θ ± 0.2 degrees 2θ, An X-ray powder diffraction pattern substantially as shown in FIG. 1, A differential scanning calorimetry thermogram having at least two characteristic thermal events in the ranges of 65-115°C, 185-210°C, and 210-235°C, A differential scanning calorimetry thermogram substantially as shown in FIG. 2, And provides an L-glufosinate ammonium salt of a crystalline form characterized by one or more data selected from combinations thereof.

[0056] In one aspect, the present disclosure provides an ammonium L - glufosinate in crystalline form I, which is further characterized by the w / w ratio of L - glufosinate to ammonium.

[0057] According to one embodiment, the present invention provides an ammonium L - glufosinate in crystalline form, wherein the ratio of L - glufosinate to ammonium is in the range of 9.5 to 11:1.

[0058] The ammonium L - glufosinate in crystalline form I is further characterized by a ratio of L - glufosinate to ammonium equal to the theoretical ratio of 10.06:1.

[0059] In one embodiment, the present disclosure provides an ammonium L - glufosinate in crystalline form I, which contains L - glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1.

[0060] In one embodiment, the present disclosure provides an ammonium L - glufosinate in crystalline form I, which contains L - glufosinate and ammonium in a w / w ratio in the range of 9.9 to 10.5:1.

[0061] In one embodiment, the present disclosure provides an ammonium L - glufosinate in crystalline form I, which shows at least three of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 in an X - ray powder diffraction pattern using Cu - Kα radiation, and contains L - glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1.

[0062] In one embodiment, the present disclosure provides crystalline Form I of L-glufosinate ammonium salt, which exhibits at least one of the values quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees in an X-ray powder diffractogram using Cu-Kα radiation, having a relative intensity of at least 50% compared to the most intense peak, and contains L-glufosinate and ammonium in a w / w ratio ranging from 9.5 to 11:1.

[0063] In one embodiment, the present disclosure provides crystalline Form I of L-glufosinate ammonium salt, which exhibits at least one of the values quoted as 2θ (±0.2°) values of about 11.6, 17.6, 18.2, 23.4, 26.0, and 33.3 in an X-ray powder diffractogram using Cu-Kα radiation, and contains L-glufosinate and ammonium in a w / w ratio ranging from 9.5 to 11:1.

[0064] In one embodiment, the present disclosure provides crystalline Form I of L-glufosinate ammonium salt, which exhibits a differential scanning calorimetry (DSC) thermogram with at least two characteristic thermal events in the ranges of 65-115°C, 185-210°C, and 210-235°C.

[0065] In one embodiment, the characteristic thermal event was recorded as an endotherm.

[0066] In one embodiment, the present invention provides crystalline Form I of L-glufosinate ammonium salt, which exhibits a differential scanning calorimetry (DSC) thermogram with at least two characteristic endotherms in the ranges of 65-115°C, 185-210°C, and 210-235°C.

[0067] In one embodiment, the present disclosure provides crystalline Form I of L-glufosinate ammonium salt, exhibiting a DSC thermogram with reference to FIG. 2.

[0068] With respect to the present disclosure, the compound represented by formula (I) refers to ammonium L - glufosinate, an ammonium L - glufosinate salt, or an ammonium L - glufosinate salt in crystalline form I.

[0069] With respect to the present disclosure, the compound represented by formula (II) refers to an acid addition salt of L - glufosinate, and the salt is formed with an acid selected from inorganic acids or organic acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, etc.

[0070] In one embodiment, the present disclosure provides an ammonium L - glufosinate salt in crystalline form I, characterized by X - ray powder diffraction patterns using Cu - Kα radiation showing at least three of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3, and at least one selected from data of differential scanning calorimetry thermograms (DSC) having at least two characteristic thermal events in the ranges of 65 - 115 °C, 185 - 210 °C, and 210 - 235 °C.

[0071] In one embodiment, the present disclosure provides an ammonium L - glufosinate salt in crystalline form I, characterized by an X - ray powder diffraction pattern using Cu - Kα radiation showing at least three of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 and containing L - glufosinate and ammonium in a ratio in the range of 9.5 - 11:1, or at least one characteristic selected from differential scanning calorimetry thermograms (DSC) having at least two characteristic thermal events in the ranges of 65 - 115 °C, 185 - 210 °C, and 210 - 235 °C.

[0072] In one embodiment, the present disclosure provides an L-glufosinate ammonium salt in crystalline form I, which exhibits at least one of the values cited as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having a peak intensity % of at least 50 in an X-ray powder diffraction pattern using Cu-Kα radiation, contains L-glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1, and exhibits a differential scanning calorimetry (DSC) thermogram having at least two characteristic thermal events in the ranges of 65 to 115 °C, 185 to 210 °C, and 210 to 235 °C.

[0073] In one embodiment, the present disclosure provides an L-glufosinate ammonium salt in crystalline form I, which exhibits at least one of the values cited as 2θ (±0.2°) values of about 11.6, 17.6, 18.2, 23.4, 26.0, and 33.3 in an X-ray powder diffraction pattern using Cu-Kα radiation, contains L-glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1, and exhibits a differential scanning calorimetry (DSC) thermogram having at least two characteristic thermal events in the ranges of 65 to 115 °C, 185 to 210 °C, and 210 to 235 °C.

[0074] In another aspect, the present disclosure provides a single-step conversion from an acid addition salt of L-glufosinate to an ammonium salt of L-glufosinate in high yield and purity.

[0075] In one aspect, the present disclosure provides a process for preparing a solid form of an L-glufosinate ammonium salt.

[0076] In one embodiment, the present disclosure provides a process for preparing a crystalline form of an L-glufosinate ammonium salt.

[0077] The process of the present invention can produce a solid from substantially pure form of an L-glufosinate ammonium salt.

[0078] The term "substantially pure solid form of L-glufosinate ammonium salt" refers to a solid form having a purity of greater than about 95% by weight, and more particularly greater than about 98% by weight. The substantially pure form of the L-glufosinate ammonium salt is substantially free of acid addition salts of L-glufosinate and / or L-glufosinate and any other reaction by-products.

[0079] Typically, the purity can be measured by High Performance Liquid Chromatography (HPLC).

[0080] In another aspect, the present disclosure provides a substantially pure crystalline form of the L-glufosinate ammonium salt.

[0081] In one embodiment, the present disclosure provides a process for producing a compound represented by the following formula (I).

[0082] [Chemical formula] The process comprises a) suspending an acid addition salt compound represented by the following formula (II), wherein A - is an anion in an alcohol solvent for forming a suspension, the suspending step;

[0083] [Chemical formula] b) contacting the suspension with gaseous ammonia until the compound represented by formula (II) is completely dissolved to form a solution; and c) subjecting the solution to conditions sufficient to precipitate the compound represented by formula (I).

[0084] The process according to the present disclosure is schematically represented as follows.

[0085] [Chemical formula] In the formula, A - is an anion.

[0086] In one embodiment, the anion A - is selected from halides, phosphates, sulfates, or acetates.

[0087] In one embodiment, the acid addition salts of the compounds represented by the following formula (II) are formed with an acid selected from L-glufosinate and hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid.

[0088] In one embodiment, the acid addition salt of L-glufosinate is L-glufosinate hydrochloride.

[0089] L-glufosinate hydrochloride can be prepared by a process known in the art.

[0090] In one embodiment, the present disclosure provides a process for producing an L-glufosinate ammonium salt, the process comprising a) suspending L-glufosinate hydrochloride in an alcohol solvent to form a suspension; and b) contacting the suspension with gaseous ammonia under non-aqueous conditions until the L-glufosinate hydrochloride is completely dissolved to form a solution; and c) subjecting the solution to conditions sufficient to precipitate the L-glufosinate ammonium salt.

[0091] In one embodiment, the process for producing an L-glufosinate ammonium salt comprises a) contacting a suspension containing L-glufosinate hydrochloride in an alcohol solvent with gaseous ammonia under non-aqueous conditions to form a solution; and b) subjecting the solution to conditions sufficient to obtain the L-glufosinate ammonium salt.

[0092] The present disclosure further provides a process for producing a compound represented by formula (I), the process comprising: a) suspending an acid addition salt compound represented by formula (II) in an alcohol solvent at a weight ratio of the compound represented by formula (II) to alcohol of about 1:5 to about 1:15 to form a suspension; b) contacting the suspension with gaseous ammonia under non-aqueous conditions until the compound represented by formula (II) is completely dissolved to form a solution; c) subjecting the solution to conditions sufficient to precipitate the compound represented by formula (I).

[0093] In one embodiment, the present disclosure provides a process for producing L-glufosinate ammonium salt, the process comprising: a) suspending L-glufosinate hydrochloride in an alcohol solvent at a weight ratio of L-glufosinate hydrochloride to alcohol of about 1:5 to about 1:10 to form a suspension; b) contacting the suspension with gaseous ammonia under non-aqueous conditions until L-glufosinate hydrochloride is completely dissolved to form a solution; c) subjecting the solution to conditions sufficient to precipitate L-glufosinate ammonium salt.

[0094] In one embodiment, the process is carried out under non-aqueous conditions.

[0095] In one embodiment, the alcohol solvent is selected from, but not limited to, methanol, ethanol, propyl alcohol, isopropyl alcohol, glycol, glycerol, or mixtures thereof.

[0096] In one embodiment, the alcohol solvent is methanol.

[0097] In one embodiment, the ratio of the acid addition salt compound represented by formula (II) to alcohol is a weight ratio of about 1:5 to about 1:10.

[0098] In one embodiment, the ratio of the acid addition salt compound represented by formula (II) to the alcohol is a weight ratio of about 1:5 to about 1:8.

[0099] In one embodiment, the ratio of L-glufosinate hydrochloride to the alcohol is a weight ratio of about 1:5 to about 1:8.

[0100] In one embodiment, the alcohol solvent is selected from a mixture of an alcohol solvent and a ketone solvent such as acetone.

[0101] In one embodiment, step b) is carried out by contacting the suspension of step a) with gaseous ammonia until the L-glufosinate hydrochloride is completely dissolved.

[0102] In one embodiment, step b) is carried out by purging with gaseous ammonia.

[0103] In one embodiment, the ratio of the acid addition salt compound represented by formula (II) to gaseous ammonia is about 1:1 to about 1:5.

[0104] In one embodiment, the ratio of the acid addition salt compound represented by formula (II) to gaseous ammonia is about 1:2 to about 1:5.

[0105] In one embodiment, the molar ratio of L-glufosinate hydrochloride to gaseous ammonia is about 1:2 to about 1:5.

[0106] In one embodiment, step b) provides a solution, and the solution has a pH of 7 to 12.

[0107] In one embodiment, step b) provides a solution, and the solution has a pH of 7.5 to 10.

[0108] In one embodiment, step c) is carried out at a temperature of 30°C to 90°C, enabling the precipitation of the L-glufosinate ammonium salt.

[0109] In one embodiment, step c) is carried out at a temperature of 40°C to 80°C, enabling the precipitation of ammonium L-glufosinate.

[0110] In one embodiment, the ammonium L-glufosinate is filtered.

[0111] In one embodiment, impurities from the previous steps, as well as by-products and ammonium chloride formed during the reaction, remained in the filtrate.

[0112] In one embodiment, the chemical purity of the ammonium L-glufosinate is at least 95% by weight.

[0113] In one embodiment, the chemical purity of the ammonium L-glufosinate is greater than 96% by weight.

[0114] In one embodiment, the chiral purity of the ammonium L-glufosinate is the absolute configuration.

[0115] In one embodiment, the L:D ratio of the ammonium L-glufosinate is from about 95:5 to about 99.9:0.1.

[0116] In one embodiment, the L:D ratio of the ammonium L-glufosinate is from about 96:4 to about 99:1.

[0117] The present disclosure further provides an ammonium L-glufosinate substantially free of L-glufosinate and / or acid addition salts of L-glufosinate.

[0118] In one embodiment, the present disclosure provides an ammonium L-glufosinate substantially free of acid addition salts of L-glufosinate.

[0119] In one embodiment, the present disclosure provides an ammonium L-glufosinate substantially free of L-glufosinate hydrochloride.

[0120] In one embodiment, the present disclosure provides an ammonium L - glufosinate salt containing less than 0.5 wt% of L - glufosinate hydrochloride.

[0121] In one embodiment, the present disclosure provides an ammonium L - glufosinate salt substantially free of L - glufosinate.

[0122] In one embodiment, the present disclosure provides an ammonium L - glufosinate salt containing less than 0.5 wt% of L - glufosinate.

[0123] The ammonium L - glufosinate salt prepared according to the present disclosure has a volume - average particle size distribution D50 of about 250 microns or less, specifically, about 1 micron to about 200 microns, and most specifically, about 10 microns to about 175 microns.

[0124] In one embodiment, the particles of the ammonium L - glufosinate salt prepared according to the present disclosure have a D50 (the median of the volume distribution is defined as the diameter below which half of the population lies) of about 250 microns or less.

[0125] In one embodiment, the present disclosure An X - ray powder diffraction pattern using Cu - Kα radiation showing at least three of the reflections cited as 2θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3, and 36.3 An ammonium L - glufosinate salt containing L - glufosinate and ammonium in a ratio in the range of 9.5 to 11:1 A process for preparing a crystalline form I ammonium L - glufosinate salt characterized by data selected from at least one of differential scanning calorimetry thermograms (DSC) having at least two characteristic thermal events in the ranges of 65 - 115°C, 185 - 210°C, and 210 - 235°C is provided, wherein the process a) Suspending L-glufosinate hydrochloride in an alcohol solvent to form a suspension; b) Contacting the suspension with gaseous ammonia under non-aqueous conditions until the L-glufosinate hydrochloride is completely dissolved to form a solution; c) Subjecting the solution to conditions sufficient to precipitate the L-glufosinate ammonium salt in crystalline form I.

[0126] The present disclosure also provides the use of the crystalline form of L-glufosinate ammonium salt for preparing other forms of L-glufosinate or salts thereof.

[0127] The present disclosure also encompasses the use of the above-described crystalline form of L-glufosinate ammonium salt of the present disclosure for the preparation of agrochemical compositions and / or formulations.

[0128] The present disclosure includes a process for preparing the above-described agrochemical formulation of L-glufosinate ammonium salt, comprising the above-described crystalline form of L-glufosinate ammonium salt and one or more agriculturally acceptable additives / excipients.

[0129] In one aspect, the present disclosure provides an agrochemical composition comprising the L-glufosinate ammonium salt in crystalline form I.

[0130] Accordingly, in one embodiment, the present disclosure provides i) the L-glufosinate ammonium salt in crystalline form I, and ii) at least one agriculturally acceptable additive / excipient, an herbicidal composition.

[0131] In one embodiment, the composition according to the present disclosure comprises the L-glufosinate ammonium salt in crystalline form in an amount of about 1% to about 99% by weight of the composition.

[0132] In one embodiment, the composition according to the present disclosure contains ammonium L - glufosinate having a volume - average particle size distribution D50 of about 250 microns or less, specifically, about 1 micron to about 200 microns, and most specifically, about 10 microns to about 175 microns.

[0133] In one embodiment, acceptable excipients / additives in pesticides can be selected from adjuvants or surfactants including, but not limited to, wetting agents, emulsifiers, emulsifying agents, dispersants, viscosity modifiers, defoaming agents, antifreezing agents, pH adjusters, stabilizers, anti - caking agents, biocides, etc. The ammonium L - glufosinate composition according to the present disclosure may contain additives such as surfactants, solvents, fertilizers, pH adjusters, crystallization inhibitors, viscosity modifiers, suspending agents, spray droplet adjusters, pigments, antioxidants, foaming agents, light - shielding agents, compatibilizers, defoaming agents, blocking agents, neutralizing agents, corrosion inhibitors, dyes, odorants, dispersants, penetration aids, micronutrients, skin softeners, lubricants, adhesives, dispersing agents, thickeners, freezing - point depressants, antibacterial agents, etc.

[0134] In one embodiment, the composition according to the present disclosure can be in the form of a soluble liquid concentrate, an emulsion concentrate, a micro - emulsion, a suspension concentrate, a water - dispersible powder, or granules.

[0135] In one embodiment, the composition according to the present disclosure can be in the form of a water - dispersible powder or granules. In one embodiment, the composition according to the present invention further contains one or more other active ingredients.

[0136] In one embodiment, the active ingredients that can be present in the composition according to the present disclosure are selected from, but not limited to, herbicides, fungicides, insecticides, defoliants, desiccants, and plant growth regulators.

[0137] In one embodiment, the active ingredient that can be present in the composition according to the present disclosure is a herbicide. The active substance can be a water-soluble or water-insoluble herbicide selected from diphenyl ether herbicides such as oxyfluorfen, acifluorfen and its salts, lactofen and its salts, fomesafen and its salts; pyrimidinyl oxybenzoic acid herbicides such as pyrithiobac sodium, bispyribac sodium; organophosphorus herbicides such as glyphosate and its salts, bilanafos and its salts, bilanafos and its salts; bipyridinium herbicides such as paraquat and diquat and its salts; aryloxyalkanoic acid herbicides such as 2,4-D and its salts and esters, MCPA, MCPB and its salts; aryloxyphenoxypropionic herbicides such as haloxyfop, isomers and esters, clodinafop and its esters; pyridine herbicides such as triclopyr, picloram, aminopyralid and its salts; aromatic herbicides such as dicamba, 2,3,6-TBA, tricamba and its salts; pyridinecarboxylic acid herbicides such as clopyralid; imidazolinones selected from imazameth, imazamethabenz, imazamox, imazapic, imazapyr, imazakine, imazethapyr; herbicides such as sulfonylurea herbicides such as flazasulfuron, rimsulfuron, bensulfuron, ethoxysulfuron, mesosulfuron, oxasulfuron, pyrazosulfuron-ethyl and its salts; cyclohexanedione oxime herbicides such as clethodim and its salts, chloroacetamide herbicides such as metolachlor, and its salts and isomers, phenylphthalimide herbicides such as flumioxazin and its salts, mesotrione, dinitroaniline herbicides such as oryzalin, pendimethalin, prodiamine, trifluralin and its salts, bicyclic dicarboxylic acid herbicides such as endothal and its salts, or mixtures of such herbicides.

[0138] In one embodiment, suitable herbicides are acetochlor, asiflufen, acifluorfen, acrolein, ametryn, amidosulfuron, aminopyralid, amitrole, anilofos, asulam, atrazine, azafenidin, azimsulfuron, benazolin, benfluralin, bensulfuron-methyl, bentazone, biphenox, binapacryl, bispyribac-sodium, bromacil, bromoxynil, butachlor, butroxydim, cafentrole, carbetamide, carfentrazone-ethyl, chloridazon, chlormuron-ethyl, chlorobromuron, chlorotoluron, chlorsulfuron, cinidon-ethyl, cinosulfuron, clethodim, chromazone, clopyralid, chloransulam-methyl, chlorsulfuron, cyanazine, cycloate, cyclosulfamuron, cycloxydim, dalapon, desmedipham, dicamba, diclobenil, dichlormid, dichlorsulam, diflufenican, dimefuron, dimepiperate, dimethachlor, dimethenamid, diquat, diuron, esprocarb, ethalfluralin, ethametsulfuron-methyl, ethofumesate, ethoxysulfuron, fentrazamide, flazasulfuron, florasulam, fluchloralin, flufenacet, flumetsulam, flumioxazin, fluometuron, flupyrsulfuron-methyl, flurochloridone, fluroxypyr, flurtamon, fomesafen, foramsulfuron, hexazinone, imazamethabenz-m, imazamox, mazapic, imazapyr, imazakine, imazethapyr, imazosulfuron, iodosulfuron, ioxynil, isoproturon, isoxaben, isoxaflutole, lactofen, lenacil, linuron, mefenacet, mesosulfuron-methyl, mesotrione, tembotrione, topramezone, metazachlor, metobenzthiazuron, metobromuron, metolachlor, S-metolachlor metosulam, metoxuron, metribuzin, metsulfuron-methyl, molinate, MSMA, napropamide,nicosulfuron, norflurazon, oryzalin, oxadiargyl, oxadiazone, oxasulfuron, oxyfluorfen, paraquat, pendimethalin, phenmedipham, picloram, pretilachlor, profoxydim, prometryn, propanil,It may be selected from propisochlor, propoxycarbazone, propyzamide, prosulfocarb, prosulfuron, pyraflufen-ethyl, pyrazosulfuron, pyroxasulfone, pyridate, pyrithiobac, cinchlorac, cinmethylac, quinotoluron, rimsulfuron, Sethoxydim, simazine, sulcotrione, sulfentrazone, sulfosulfuron, tebuthiuron, tebuconazole, terbuthylazine, terbutryn, thifensulfuron-methyl, thiobencarb, tralkoxydim, triallate, triasulfuron, tribenuron-methyl, triclopyr, trifloxysulfuron, trifluralin, triflusulfuron-methyl, tritosulfuron, and mixtures and combinations thereof.

[0139] In one embodiment, the compositions of the present disclosure can be used on tolerant crops that are tolerant to glufosinate.

[0140] The herbicidal compositions of the present disclosure can be further used in combination with glyphosate, dicamba, or 2,4-D on glyphosate-tolerant, dicamba-tolerant, or 2,4-D-tolerant crops.

[0141] In one embodiment, the compositions according to the present disclosure are selective for the crops to be treated and can be used in combination with herbicides that complement the spectrum of weeds controlled by these compositions at the application rates utilized. When used in combination with other active ingredients, the presently claimed L-glufosinate ammonium salt can be formulated with other active ingredients as a pre-mixed concentrate, tank-mixed with other active ingredients for spray application, or applied sequentially with other active ingredients in separate spray applications. The compositions can be used in pesticide spray applications for controlling weeds in crop and non-crop environments by diluting the pesticide spray mixture 1 to 2000 times at the time of use, depending on local agricultural practices.

[0142] In one embodiment, the present disclosure provides to a plant or its growth site i) the L-glufosinate ammonium salt in crystalline form I, and ii) applying a composition comprising one or more agriculturally acceptable additives and an agrochemical, to control unwanted plant growth.

[0143] In one aspect, the present disclosure provides a method for controlling unwanted plant growth, comprising applying to a plant or its growth medium a crystalline form of the L-glufosinate ammonium salt. In one embodiment, the present disclosure provides a method for controlling unwanted plant growth, comprising applying to a plant or its growth medium an agriculturally effective amount of a crystalline form of the L-glufosinate ammonium salt.

[0144] In one embodiment, the agriculturally effective amount consists of from about 10 grams per hectare to about 1500 grams per hectare of the crystalline Form I of the L-glufosinate ammonium salt. In one embodiment, the agriculturally effective amount consists of from about 100 grams per hectare to about 1000 grams per hectare of the crystalline Form I of the L-glufosinate ammonium salt. In one embodiment, the temperature range during the application period of the composition according to the invention may be important and will vary depending on the crop and the geographical area.

[0145] Analytical methods Powder X-ray diffraction (XRD) method: The X-ray powder diffraction pattern of the crystalline Form I of the L-glufosinate ammonium salt was recorded using Cu-Kα radiation. The detailed parameters are shown below. Instrument: A second-generation D2 Phaser X-ray powder diffractometer manufactured by Bruker Operation: 30.0 kV, 10 mA Radiation: Cu Kα Mode: Reflection Wavelength: 1.54060 Å Scan range: 2-40 2θ Step size: 0.02° Differential Scanning Calorimeter (DSC): The differential scanning calorimetry thermogram of the ammonium L - glufosinate in crystalline form I was recorded as follows: Equipment: Differential Scanning Calorimeter METTLER TOLEDO DSC - 3 Heating rate: 10 °C / min Temperature range: 30 °C to 350 °C, under a N2 flow rate of 20 ml / min

[0146] Particle size: The particle size distribution of ammonium L - glufosinate was recorded using a Malvern Mastersizer 2000 particle size analyzer equipped with a Hydro 2000SM(A) accessory, using a 1% suspension of ammonium L - glufosinate in dry isopropyl alcohol.

[0147] The present invention is described in more detail by the following examples. However, it should be understood that the scope of the present invention is not limited by the examples in any way. In some cases, some features of the disclosed embodiments may be utilized without the corresponding use of other features. Therefore, it is appropriate that the claims be construed broadly in a manner consistent with the scope of the present invention. It will be understood by those skilled in the art that the present invention includes the following examples and can be modified and changed within the technical scope of the present invention.

Examples

[0148] Preparation of the Crystalline Form of Ammonium L - Glufosinate Example 1: Preparation of Ammonium L - Glufosinate 366 g (1.35 mol) of L-glufosinate hydrochloride was suspended in 2820 g of methanol (1:7.7 w / w) at 30 °C. The suspension was purged with dry ammonia gas (57.1 g, 3.36 mol) until the pH reached 7.9 - 8.5 and the L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65 - 70 °C until the L-glufosinate ammonium salt began to precipitate (4 - 6 hours). The reaction mass was then cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 300 g of methanol to obtain 225 g of L-glufosinate ammonium salt. Yield 78.4%; purity by HPLC 96.63%; L-glufosinate: 0.25%; L-glufosinate hydrochloride <0.05%, Figures 1 and 2. The L-glufosinate to ammonium ratio (w / w) was 9.88:1.

[0149] Example 2: Preparation of L-glufosinate ammonium salt 530 g (1.95 mol) of L-glufosinate hydrochloride was suspended in 3700 g of methanol (1:7.0 w / w) at 30 °C. The suspension was purged with dry ammonia gas (83 g, 4.87 mol) until the L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65 - 70 °C until the L-glufosinate ammonium salt began to precipitate (4 - 6 hours). The reaction mass was then cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 400 g of methanol to obtain 342 g of L-glufosinate ammonium salt. Yield 85%; purity by HPLC 96.47%, Figure 3; L-glufosinate: 0.19%; L-glufosinate hydrochloride <0.05%. The L-glufosinate to ammonium ratio - 9.79:1.

[0150] After a period of 360 days, the sample was retested and found that the L-glufosinate to ammonium ratio (w / w) was 9.82:1.

[0151] Example 3: Preparation of L-glufosinate ammonium salt 70 g (0.283 mol) of L-glufosinate hydrochloride was suspended in 490 g of methanol (1:7.0 w / w) at 30 °C. The suspension was purged with dry ammonia gas (12 g, 0.70 mol) until the L-glufosinate hydrochloride was completely dissolved. The reaction mass was heated and maintained at 70 - 75 °C until the precipitation of L-glufosinate ammonium salt began (4 - 6 hours). Then, the reaction mass was cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 50 g of methanol to obtain 45 g of L-glufosinate ammonium salt. Yield: 80%; Purity by HPLC: 98.13%; Chiral purity: 97.05:2.95; Figure 4.

[0152] Example 4: Preparation of L-glufosinate ammonium salt (the ratio of L-glufosinate hydrochloride to alcohol is 1:6) 70 g (0.283 mol) of L-glufosinate hydrochloride was suspended in 420 g of methanol (1:6.0 w / w) at 30 °C. The suspension was purged with dry ammonia gas (12 g, 0.70 mol) until the pH reached 7.9 - 8.5 and the L-glufosinate hydrochloride was completely dissolved. Then, the reaction mass was heated and maintained at 65 - 70 °C until the precipitation of L-glufosinate ammonium salt began (4 - 6 hours). Then, the reaction mass was cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 42 g of methanol to obtain 48 g of L-glufosinate ammonium salt. Yield: 82.7%; Purity by HPLC: 96.5%.

[0153] Example 5: Preparation of L-glufosinate ammonium salt (the ratio of L-glufosinate hydrochloride to alcohol is 1:10) 70 g (0.283 mol) of L-glufosinate hydrochloride was suspended in 700 g of methanol (1:10.0 w / w) at 30 °C. The suspension was purged with dry ammonia gas (12 g, 0.70 mol) until the pH reached 7.9 - 8.5 and the L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65 - 70 °C until the L-glufosinate ammonium salt began to precipitate (4 - 6 hours). The reaction mass was then cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 70 g of methanol to obtain 40 g of L-glufosinate ammonium salt. Yield: 70.6%; Purity by HPLC: 98.9%.

[0154] Example 6: Preparation of L-glufosinate ammonium salt 350 g (1.29 mol) of L-glufosinate hydrochloride was suspended in 2700 g of methanol (1:7.7 w / w) at 30 °C. The suspension was purged with dry ammonia gas (54.6 g, 3.19 mol) until the pH reached 7.9 - 8.5 and the L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65 - 70 °C until the L-glufosinate ammonium salt began to precipitate (4 - 6 hours). The reaction mass was then cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 290 g of methanol to obtain 209 g of L-glufosinate ammonium salt. Yield 80%; Purity by HPLC 97.4%; L-glufosinate: 0.1%; L-glufosinate hydrochloride <0.05%, Figure 2. The L-glufosinate to ammonium ratio (w / w) was 9.90:1.

[0155] Example 7: Preparation of L-glufosinate ammonium salt 350 g (1.29 mol) of L-glufosinate hydrochloride was suspended in 2450 g of methanol (1:7 w / w) at 30 °C. The suspension was purged with dry ammonia gas (68 g, 2.5 equivalents) until the pH reached 7.9 - 8.5 and the L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65 - 70 °C until the L-glufosinate ammonium salt began to precipitate (4 - 6 hours). The reaction mass was then cooled to 30 °C and left for 1 - 2 hours for complete precipitation of the product. The precipitated L-glufosinate ammonium salt was filtered and washed with 290 g of methanol to obtain 262 g of L-glufosinate ammonium salt. Yield 92.5%, chiral ratio 98.7:1.3; L-glufosinate to ammonium ratio (w / w) was 9.60:1.

[0156] After a 50-day period, the sample was tested and found that the L-glufosinate to ammonium ratio (w / w) was 9.61:1.

[0157] Formulation: Example 8: A soluble liquid concentrate formulation containing the crystalline form I of L-glufosinate ammonium salt prepared according to the present disclosure is shown below.

[0158] [Table 6]

[0159] Example 9: A water-dispersible granular formulation containing the crystalline form I of L-glufosinate ammonium salt is shown below.

[0160] [Table 7]

[0161] Example 10: A water-dispersible granular formulation containing the crystalline form I of L-glufosinate ammonium salt is shown below.

[0162] [Table 8]

[0163] Example 11: A water-dispersible granular formulation containing the ammonium L-glufosinate of crystalline form I is shown below.

[0164] [Table 9]

[0165] Example 12: A water-dispersible granular formulation containing the ammonium L-glufosinate of crystalline form I is shown below.

[0166] [Table 10]

[0167] Example 13: A water-dispersible granular formulation containing the ammonium L-glufosinate of crystalline form I is shown below.

[0168] [Table 11]

[0169] Example 14: A water-dispersible granular formulation containing the racemic ammonium glufosinate is shown below (comparative example).

[0170] [Table 12]

[0171] Example 15: A water-dispersible granular formulation containing the racemic ammonium glufosinate is shown below (comparative example).

[0172] [Table 13]

[0173] Field test efficacy data: Field trials were conducted using a water-dispersible granule formulation containing the crystalline form I L-glufosinate ammonium salt prepared according to the present disclosure as a broad-spectrum herbicide. The composition was dispersed in water, optionally with other tank mix adjuvants, and applied to crop and non-crop land containing many broadleaf weeds, grasses, and sedges at a water application rate of 300 - 600 l / ha.

[0174] The inventors of the present disclosure conducted field trials using samples prepared according to Example 11 (Sample 1), Example 12 (Sample 2), and Example 13 (Sample 3) at a dose of 250 g a.i. per hectare. After treatment with the composition, bleaching of the weeds followed by necrosis was observed, indicating the biological effectiveness of the new formulation. Observations at 4 and 14 days after application are summarized in the following table. Comparative samples were prepared according to Example 14 (Sample 4) and Example 15 (Sample 5), and the tests were conducted at a dose of 500 g a.i. / ha. The details of the tests are shown below.

[0175]

Table 14

[0176]

Table 15

[0177]

Table 16

[0178] As is apparent from the above tables, the compositions according to the present disclosure showed acceptable weed control against various persistent weeds. Furthermore, it should be noted that the performance of the composition of the present invention at half the dose was at least equivalent to that of the racemic glufosinate ammonium composition and, in many cases, exceeded the degree of weed control. Thus, the compositions of the present invention are very effective and have established that by eliminating the use of the inactive D-isomer of glufosinate, such compositions are environmentally friendly and readily biodegradable.

Claims

1. A process for producing a compound of formula (I), 【Chemical 1】 wherein the process comprises a) A step of suspending an acid addition salt compound of the following formula (II), wherein A － is an anion in an alcohol solvent for forming a suspension, and the step; 【Chemical 2】 b) contacting the suspension with gaseous ammonia until the compound of formula (II) is completely dissolved to form a solution; c) subjecting the solution to conditions sufficient to precipitate the compound of formula (I).

2. A process for preparing a compound of formula (I), a) forming a suspension comprising an acid addition salt compound of formula (II) in an alcohol solvent and contacting the suspension with gaseous ammonia under non-aqueous conditions to form a solution; b) subjecting the solution to conditions sufficient to precipitate the compound of formula (I).

3. a) suspending an acid addition salt compound of formula (II) in an alcohol solvent at a weight ratio of the compound of formula (II) to alcohol of about 1:5 to about 1:15 to form the suspension; b) contacting the suspension with gaseous ammonia under non-aqueous conditions until the compound of formula (II) is completely dissolved to form the solution; c) subjecting the solution to conditions sufficient to precipitate the compound of formula (I). A process for producing a compound of formula (I) according to claim 1.

4. The process for producing a compound of formula (I) according to claim 1, wherein the alcohol solvent is methanol, ethanol, propyl alcohol, isopropyl alcohol, glycol, glycerol, or a mixture thereof.

5. The process for producing a compound of formula (I) according to claim 1, wherein the weight ratio of the acid addition salt compound of formula (II) to alcohol is 1:5 to 1:

15.

6. The process for producing a compound of formula (I) according to claim 4, wherein the weight ratio of the acid addition salt compound of formula (II) to gaseous ammonia is 1:1 to 1:

5.

7. The process for producing a compound of formula (I) according to claim 1, wherein the compound is the crystalline form of L-glufosinate ammonium salt.

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