Crystalline form of l-glufosinate ammonium salt and process for production thereof

Abstract

To provide a novel solid form of L-glufosinate ammonium salt for preparing high purity L-glufosinate ammonium salt and / or L-glufosinate.SOLUTION: The present invention provides a crystalline form of L-glufosinate ammonium salt characterized by one or more data selected from an X-ray powder diffractogram pattern having peaks at least three peaks selected from a specific group of 2θ values, 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, and a combination of them.SELECTED DRAWING: Figure 1

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 compositions containing said forms and methods for using said compositions to control undesirable plant growth. [Background technology]

[0002] Dl-Homoalanin-4-yl(methyl)phosphinic acid (Glufosinate) and salts are amino acid derivatives with herbicidal activity. The amino acid derivatives are active in the L-form. In order to use the pure active ingredient, several processes have been developed for the preparation of L-Homoalanin-4-yl(methyl)phosphinic acid (L-Glufosinate), especially the ammonium salt.

[0003] Many synthetic processes end with an acid addition salt of L-glufosinate, which requires the production of the corresponding free acid (L-glufosinate) or the ammonium salt, which is commercially preferred due to its high solubility in water.

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

[0005] US Patent No. 5,869,668 and Chinese Patent Publication No. 111,072,718 disclose the preparation of L-glufosinate or a salt by precipitation of one of the diastereomeric salts using a chiral base followed by resolution through an isolation process.

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

[0007] CN105541906 discloses a two-step process for the preparation of L-glufosinate ammonium salt starting from L-glufosinate hydrochloride using an aqueous alcoholic solvent system and ammonia.

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

[0009] According to any of the above methods, the isolation process requires complicated procedures using ion exchange columns or post-processing processes involving treatment of the acid addition salt of L-glufosinate with harmful chemicals such as ethylene oxide and propylene oxide. Preparation and purification of L-glufosinate ammonium salt often requires multi-step processes including hydrolysis and crystallization procedures that affect the yield and purity of the product.

[0010] Therefore, there is a need for the development of new solid forms of L-glufosinate ammonium salt and production methods for preparing high-purity L-glufosinate ammonium salt and / or L-glufosinate free of acid addition salts of L-glufosinate starting from acid addition salts of L-glufosinate.

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

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

[0013] It is also an object to provide a simple and convenient production of L-glufosinate ammonium salt.

[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 yet 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 an ammonium salt of L-glufosinate in a crystalline form that is substantially free of L-glufosinate and any other reaction by-products.

[0019] In another aspect, the 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; and c) precipitating the compound represented by formula (I).

[0022] In another aspect, the disclosure provides a process for producing a compound represented by formula (I), the process comprising: a) suspending the acid addition salt compound of formula (II) in an alcohol solvent in a weight ratio of the compound of 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; and c) subjecting the solution to conditions sufficient to precipitate the compound represented by formula (I).

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

[0024] The present disclosure also provides the use of crystalline Form I of L-glufosinate ammonium salt to prepare other forms of L-glufosinate or other salts.

[0025] The present disclosure also encompasses the use of the crystalline Form I of the L-glufosinate ammonium salt of the present disclosure for the preparation of an agrochemical composition and / or formulation.

[0026] In another aspect, the present disclosure provides an agrochemical composition comprising the crystalline Form I of L-glufosinate ammonium salt according to the present disclosure.

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

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

[0029] In another aspect, the present disclosure provides a method for controlling undesirable plant growth comprising subjecting a plant or its locus to a crystalline form of L-glufosinate ammonium salt. [Brief description of the drawings]

[0030] [Figure 1] X-ray powder diffraction pattern recorded using Cu-Kα radiation of crystalline form I of L-glufosinate ammonium salt. [Diagram 2] Differential scanning calorimetry thermogram of crystalline form I of L-glufosinate ammonium salt. [Diagram 3] HPLC chromatogram of L-glufosinate ammonium salt prepared according to the present disclosure. [Figure 4] Chiral HPLC chromatogram of L-glufosinate ammonium salt prepared according to the present disclosure. [Diagram 5] Particle size distribution of L-glufosinate ammonium salt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In any aspect or embodiment described below, the term "comprising" may be replaced with the terms "consisting of," "consisting essentially of," or "consisting substantially of." Additionally, terms such as "including," "having," "involving," "containing," "characterized by," variations thereof (e.g., "includes," "has," "involves," "contains," etc.), and similar terms used herein, including the claims, are intended to be inclusive and / or open-ended, have the same meaning as the word "comprising" and variations thereof (e.g., "comprise" and "comprises"), and illustratively do not exclude additional, unrecited elements or method steps. As used herein, the expression "substantially free" will be understood to mean containing 20% ​​or less, 10% or less, 5% or less, 2% or less, or 1% or less of any other form or salt of the subject compound, for example, as measured by PXRD. As used herein, the term "about" refers to a measurable value of a parameter, amount, time, etc., and means to include a variation of + / -15% or less from a particular recited value, particularly a variation of + / -10% or less, more particularly a variation of + / -5% or less, even more particularly a variation of + / -1% or less, and even more particularly a variation of + / -0.1% or less, so long as such variation is appropriate in the practice of the present disclosure described herein. It will also 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 L-glufosinate ammonium salt.

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

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

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

[0036] Crystalline Form I of L-glufosinate ammonium salt can be identified by X-ray powder diffraction methods based on its diffractogram.

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

[0038] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting at least three of the following reflections quoted as 2θ (±0.2°) values ​​in an X-ray powder diffractogram using Cu-Kα radiation:

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

[0040] In one embodiment, the present invention provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting 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 diffractogram using Cu-Kα radiation.

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

[0042] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting at least one of the values ​​quoted 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 most intense peak at 18.9 in an X-ray powder diffractogram using Cu-Kα radiation.

[0043] In another embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting at least one of the values ​​quoted 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 most intense peak at 18.9 in an X-ray powder diffractogram using Cu-Kα radiation.

[0044] In one embodiment, the crystalline form I of L-glufosinate ammonium salt exhibits in an X-ray powder diffraction diagram using Cu-Kα radiation at least one of the values ​​quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, with the % intensities of the peaks as follows:

[0045] [Table 1]

[0046] In another embodiment, the crystalline form I of L-glufosinate ammonium salt exhibits in an X-ray powder diffractogram using Cu-Kα radiation at least one of the values ​​quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having the following % intensities of peaks:

[0047] [Table 2]

[0048] In another embodiment, the crystalline form I of L-glufosinate ammonium salt exhibits in an X-ray powder diffractogram using Cu-Kα radiation at least one of the values ​​quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having the following % intensities of peaks:

[0049] [Table 3]

[0050] In another embodiment, the crystalline form I of L-glufosinate ammonium salt exhibits in an X-ray powder diffractogram using Cu-Kα radiation at least one of the values ​​quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having the following % intensities of peaks:

[0051] [Table 4]

[0052] In another embodiment, the crystalline form I of L-glufosinate ammonium salt exhibits in an X-ray powder diffractogram using Cu-Kα radiation at least one of the values ​​quoted as 2θ (±0.2°) selected from 17.6, 18.2, 18.9, and 23.4 degrees, having the following % intensities of peaks:

[0053] [Table 5]

[0054] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt exhibiting at least six of the following reflections quoted as 2θ (±0.2°) values ​​in an X-ray powder diffractogram using Cu-Kα radiation:

[0055] In one embodiment, the present disclosure provides: 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. 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. and combinations thereof.

[0056] In one aspect, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, further characterized by the w / w ratio of L-glufosinate to ammonium.

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

[0058] Crystalline Form I of L-glufosinate ammonium salt 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 a crystalline Form I of L-glufosinate ammonium salt containing L-glufosinate and ammonium in a w / w ratio ranging from 9.5 to 11:1.

[0060] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt containing L-glufosinate and ammonium in a w / w ratio ranging from 9.9 to 10.5:1.

[0061] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting 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 diffractogram using Cu-Kα radiation, and containing L-glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1.

[0062] In an embodiment, the present disclosure provides a 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 having a relative intensity of at least 50% compared to the most intense peak in an X-ray powder diffractogram using Cu-Kα radiation, and contains L-glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1.

[0063] In one embodiment, the present disclosure provides a crystalline Form I of L-glufosinate ammonium salt, exhibiting 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 containing L-glufosinate and ammonium in a w / w ratio in the range of 9.5 to 11:1.

[0064] In one embodiment, the present disclosure provides a 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 a crystalline Form I of L-glufosinate ammonium salt, which exhibits a differential scanning calorimetry (DSC) thermogram having 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 a crystalline Form I of L-glufosinate ammonium salt, exhibiting a DSC thermogram with reference to FIG.

[0068] For purposes of this disclosure, the compound represented by formula (I) refers to L-glufosinate ammonium, L-glufosinate ammonium salt, or crystalline Form I of L-glufosinate ammonium salt.

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

[0070] In one embodiment, the present disclosure provides: an X-ray powder diffractogram 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 The present invention provides a crystalline Form I of L-glufosinate ammonium salt characterized by data selected from at least one of a differential scanning calorimetry thermogram (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 X-ray powder diffractogram 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 ranging from 9.5 to 11:1; or The present invention provides a crystalline form I of L-glufosinate ammonium salt characterized by at least one property selected from a differential scanning calorimetry thermogram (DSC) having at least two characteristic thermal events in the ranges of 65-115°C, 185-210°C, and 210-235°C.

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

[0073] In one embodiment, the present disclosure provides a 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, contains L-glufosinate and ammonium in a w / w ratio in the range of 9.5-11:1, and exhibits a differential scanning calorimetry thermogram (DSC) having at least two characteristic thermal events in the ranges of 65-115° C., 185-210° C., and 210-235° C.

[0074] In another aspect, the present disclosure provides a single step conversion of 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 L-glufosinate ammonium salt in solid form.

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

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

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

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

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

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

[0082] [ka] The process is a) suspending an acid addition salt compound represented by the following formula (II): - is an anion in an alcohol solvent to form a suspension;

[0083] [ka] 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 generally represented as follows:

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

[0086] In one embodiment, the anion A - is selected from a halide, a phosphate, a sulfate, or an acetate.

[0087] In one embodiment, the acid addition salt of the compound represented by the following formula (II) is formed with L-glufosinate and an acid selected from 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 processes known in the art.

[0090] 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 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; and c) subjecting the solution to conditions sufficient to precipitate the L-glufosinate ammonium salt.

[0091] In one embodiment, the process for producing L-glufosinate ammonium salt comprises: a) contacting a suspension comprising L-glufosinate hydrochloride in an alcoholic solvent with gaseous ammonia under non-aqueous conditions to form a solution; b) subjecting the solution to conditions sufficient to obtain 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 the acid addition salt compound of formula (II) in an alcohol solvent in a weight ratio of the compound of 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; and 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 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.

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

[0095] In one embodiment, the alcohol solvent is selected from, but is 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 the alcohol is in 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 in a weight ratio of about 1:5 to about 1:8.

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

[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 gaseous ammonia.

[0103] In one embodiment, the ratio of the acid addition salt compound represented by Formula (II) to gaseous ammonia is from 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 from about 1:2 to about 1:5.

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

[0106] In one embodiment, step b) provides a solution, the solution having a pH of 7-12.

[0107] In one embodiment, step b) provides a solution, the solution having a pH of 7.5-10.

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

[0109] In one embodiment, step c) is carried out at a temperature between 40° C. and 80° C. to allow the L-glufosinate ammonium salt to precipitate.

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

[0111] In one embodiment, impurities from the previous step 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 L-glufosinate ammonium salt is at least 95% by weight.

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

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

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

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

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

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

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

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

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

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

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

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

[0125] In one embodiment, the present disclosure provides: an X-ray powder diffractogram using Cu-Kα radiation showing at least three of the reflections cited as having 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; L-glufosinate ammonium salt, containing L-glufosinate and ammonium in a ratio ranging from 9.5 to 11:1; The present invention provides a process for preparing a crystalline Form I of L-glufosinate ammonium salt, characterized by data selected from at least one of a differential scanning calorimetry thermogram (DSC) having at least two characteristic thermal events in the ranges of 65-115°C, 185-210°C, and 210-235°C; The process in question is: 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; and c) subjecting the solution to conditions sufficient to precipitate crystalline Form I of L-glufosinate ammonium salt.

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

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

[0128] The present disclosure includes processes for preparing the above-mentioned pesticide formulations of L-glufosinate ammonium salt, comprising the above-mentioned crystalline forms of L-glufosinate ammonium salt and one or more pesticide-acceptable additives / excipients.

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

[0130] Thus, in one embodiment, the present disclosure provides a method for producing a method for treating a cancer cell comprising: i) L-glufosinate ammonium salt in crystalline form I; ii) at least one pesticidally acceptable additive / excipient.

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

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

[0133] In one embodiment, the pesticide acceptable excipients / additives may be selected from adjuvants or surfactants including, but not limited to, wetting agents, emulsifiers, emulsifiers, dispersing agents, viscosity modifiers, antifoam agents, antifreeze agents, pH adjusters, stabilizers, anti-caking agents, biocides, and the like. L-glufosinate ammonium compositions according to the present disclosure may include additives such as surfactants, solvents, fertilizers, pH adjusters, crystallization inhibitors, viscosity adjusters, suspending agents, spray droplet modifiers, pigments, antioxidants, foaming agents, light blocking agents, compatibilizers, defoamers, sequestering agents, neutralizing agents, corrosion inhibitors, dyes, odorants, diffusing agents, penetration aids, micronutrients, emollients, lubricants, adhesives, dispersants, thickeners, freezing point depressants, antibacterial agents, and the like.

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

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

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

[0137] In one embodiment, an active ingredient that may be present in a composition according to the present disclosure is a herbicide. Active substances include diphenyl ether herbicides, such as oxyfluorfen, acifluorfen and its salts, lactofen and its salts, fomesafen and its salts; pyrimidinyloxybenzoic acid herbicides, such as pyrithiobac-sodium, bispyribac-sodium; organophosphorus herbicides, such as glyphosate and its salts, bialaphos and its salts, bialaphos 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; pyridine carbo herbicides, such as clopyralid; imidazolinones selected from imazamet, imazamethabenz, imazamox, imazapic, imazapyr, imazaquin, imazethapyr; herbicides, such as sulfonylurea herbicides, such as flazasulfuron, rimsulfuron, bensulfuron, ethoxysulfuron, mesosulfuron, oxasulfuron, pyrazosulfuron-ethyl and salts thereof; cyclohexanedione oxime herbicides, such as cletosulfuron, The herbicide may be a water soluble or water insoluble herbicide selected from dim 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, profluralin, trifluralin and its salts, bicyclic dicarboxylic acid herbicides such as endothal and its salts, or a mixture of such herbicides.

[0138] In one embodiment, suitable herbicides are acetochlor, acifluorfen, aclonifen, alachlor, ametryn, amitosulfuron, aminopyralid, amitrole, anilofos, asulam, atrazine, azafenidine, azimsulfuron, benazolin, benfluralin, bensulfuron-methyl, bentazon, bifenox, binaraphos, bispyribac-sodium, bromacil, bromoxynil, butachlor, butroxydim, caffentrol, carbetamide, carfentrazone-ethyl, chloridazon, chlorimuron-ethyl , chlorbromuron, chlorotoluron, chlorsulfuron, cinidon-ethyl, cinosulfuron, clethodim, clomazone, clopyralid, chloransulam-methyl, chlorsulfuron, cyanazine, cycloate, cyclosulfamuron, cycloxydim, dalapon, desmedipham, dicamba, dichlobenil, dichlormid, diclosulam, diflufenican, dimefuron, dimepipate, dimethachlor, dimethenamid, diquat, diuron, esprocarb, ethalfluralin, ethametsurufuron-methyl, ethofumesate, ethoxysulfuron , fentrazamide, flazasulfuron, florasulam, fluchloralin, flufenacet, flumetsulam, flumioxazin, fluometuron, flupyrsulfuron-methyl, fluorochloridone, fluroxypyr, flurtamone, fomesafen, foramsulfuron, hexazinone, imazamethabenz-m, imazamox, mazapic, imazapyr, imazaquin, imazethapyr, imazosulfuron, iodosulfuron, loxinil, isoproturon, isoxaben, isoxaflutole, lactofen, lenacil, linuron, mefenacet, Mesosulfuron-methyl, mesotrione, tembotrione, topramezone, metamitron, metazachlor, methabenzthiazuron, metobromuron, metolachlor, S-metolachlormethoslam, methoxuron, metribuzin, metsulfuron-methyl, molinate, MSMA, napropamide, nicosulfuron, norflurazon, oryzalin, oxadiargyl, oxadiazon, oxasulfuron, oxyfluorfen, paraquat, pendimethalin, phenmedipham, picloram, pretilachlor, profoxydim, prometryn, propanil,The active ingredient may be selected from propisochlor, propoxycarbazone, propyzamide, prosulfocarb, prosulfuron, pyraflufen-ethyl, pyrazosulfuron, pyroxasulfone, pyridate, pyrithiobac, quinclorac, quinmerac, quinotrion, rimsulfuron, sethoxydim, simazine, sulcotrione, sulfentrazone, sulfosulfuron, tebuthiuron, tebularoxydim, terbuthylazine, terbutryn, thifensulfuron-methyl, thiobencarb, tralkoxydim, triallert, 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 further be 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, compositions according to the present disclosure can be used in combination with herbicides that are selective to the crops being treated and that complement the spectrum of weeds controlled by these compositions at the application rates utilized. When used in conjunction with other active ingredients, the presently claimed L-glufosinate ammonium salt can be combined with the other active ingredients as a premixed concentrate, tank mixed with the other active ingredients for spray application, or applied sequentially with the other active ingredients in separate spray applications. The compositions can be used in pesticide spray applications to control weeds in crop and non-crop environments, diluting the pesticide spray mixture 1-2000 times at the time of use, depending on local agricultural practices.

[0142] In one embodiment, the present disclosure provides a method for treating a plant or its habitat by administering: i) L-glufosinate ammonium salt in crystalline form I; ii) one or more pesticide-acceptable additives.

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

[0144] In one embodiment, the agriculturally effective amount consists of about 10 grams of crystalline Form I of L-glufosinate ammonium salt per hectare to about 1500 grams of crystalline Form I of L-glufosinate ammonium salt per hectare. In one embodiment, the agriculturally effective amount consists of about 100 grams of crystalline Form I of L-glufosinate ammonium salt per hectare to about 1000 grams of crystalline Form I of L-glufosinate ammonium salt per hectare. In one embodiment, the temperature range during application of the compositions according to the present invention can be important and will vary based on crop and geographic region.

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

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

[0147] The present invention will be 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 can be utilized without the corresponding use of other features. Therefore, it is appropriate that the claims be broadly interpreted 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 further modified and altered within the technical scope of the present invention. EXAMPLES

[0148] Preparation of crystalline form of L-glufosinate ammonium salt Example 1: Preparation of L-glufosinate ammonium salt 366 g (1.35 moles) 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 moles) until the solution reached pH 7.9-8.5 and L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started precipitating (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 moles) 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 moles) until L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started 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 96.47% by HPLC, Figure 3; L-glufosinate: 0.19%; L-glufosinate hydrochloride <0.05%. L-glufosinate to ammonium ratio-9.79:1.

[0150] The sample was tested again after a period of 360 days and the L-glufosinate to ammonium ratio (w / w) was found to be 9.82:1.

[0151] Example 3: Preparation of L-glufosinate ammonium salt 70 g (0.283 moles) 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 moles) until L-glufosinate hydrochloride was completely dissolved. The reaction mass was heated and maintained at 70-75 °C until L-glufosinate ammonium salt started 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 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 (ratio of L-glufosinate hydrochloride to alcohol is 1:6) 70 g (0.283 moles) 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 moles) until the solution reached pH 7.9-8.5 and L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started precipitating (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 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 (ratio of L-glufosinate hydrochloride to alcohol is 1:10) 70 g (0.283 moles) 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 moles) until the solution reached pH 7.9-8.5 and L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started precipitating (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 moles) 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 moles) until the solution reached pH 7.9-8.5 and L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started precipitating (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 97.4% by HPLC; L-glufosinate: 0.1%; L-glufosinate hydrochloride <0.05%, Figure 2. The L-glufosinate to ammonium ratio (w / w) is 9.90:1.

[0155] Example 7: Preparation of L-glufosinate ammonium salt 350 g (1.29 moles) 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 equiv.) until the solution reached pH 7.9-8.5 and L-glufosinate hydrochloride was completely dissolved. The reaction mass was then heated and maintained at 65-70°C until L-glufosinate ammonium salt started to precipitate (4-6 h). The reaction mass was then cooled to 30°C and left for 1-2 h 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] The samples were tested after a period of 50 days and the L-glufosinate to ammonium ratio (w / w) was found to be 9.61:1.

[0157] formulation: Example 8: A soluble liquid concentrate formulation containing 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 crystalline Form I of L-glufosinate ammonium salt is shown below.

[0160] [Table 7]

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

[0162] [Table 8]

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

[0164] [Table 9]

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

[0166] [Table 10]

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

[0168] [Table 11]

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

[0170] [Table 12]

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

[0172] [Table 13]

[0173] Field Testing Efficacy Data: Field trials were conducted using water-dispersible granular formulations containing crystalline Form I of L-glufosinate ammonium salt prepared according to the present disclosure as broad-spectrum herbicides. The compositions were dispersed with water, and optionally with other tank-mix adjuvants, and applied to crop and non-crop land, including many broadleaf weeds, grasses, and sedges, at water application rates 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 ai per hectare. After treatment with the composition, bleaching of the weeds followed by necrosis was observed, indicating the biological effectiveness of the novel formulation. The observations at 4 and 14 days after application are summarized in the table below. Comparative samples were prepared according to Example 14 (sample 4) and Example 15 (sample 5) and trials were conducted at a dose of 500 g ai / ha. The details of the trials are given below.

[0175] [Table 14]

[0176] [Table 15]

[0177] [Table 16]

[0178] As is evident from the above table, the compositions according to the present disclosure demonstrated acceptable weed control for a variety of persistent weeds. Furthermore, it is noted that the performance of the half-dose compositions of the present invention was at least equivalent, and in many cases even superior, to the weed control of the racemic glufosinate ammonium compositions. Thus, it has been established that the compositions of the present invention are highly effective and, by eliminating the utilization of the inactive D-isomer of glufosinate, make such compositions environmentally friendly and readily biodegradable.

Claims

1. 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. 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. and combinations thereof.

2. The crystalline form of L-glufosinate ammonium described in claim 1, further characterized by an X-ray powder diffraction pattern having at least one peak selected from the group of 17.6, 18.2, 18.9, and 23.4 degrees 2θ±0.2 degrees 2θ.

3. L-glufosinate ammonium in a crystalline form, wherein the ratio of L-glufosinate to ammonium is within the range of 9.5 to 11:

1.

4. A process for producing a compound of formula (I), comprising: 【Chemistry 1】 The process comprising: a) suspending an acid addition salt compound of formula (II) below, wherein A − is an anion in an alcohol solvent to form a suspension; 【Chemistry 2】 b) contacting said suspension with gaseous ammonia until the compound of formula (II) is completely dissolved to form a solution; and c) subjecting said solution to conditions sufficient to precipitate said compound of formula (I).

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

6. A method for producing a suspension comprising the steps of: a) suspending an acid addition salt compound of formula (II) in an alcohol solvent in 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 said suspension with gaseous ammonia under non-aqueous conditions until the compound of formula (II) is completely dissolved to form said solution; and c) subjecting said solution to conditions sufficient to precipitate said compound of formula (I).

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

8. 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 the alcohol is from about 1:5 to about 1:

10.

9. A 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 from about 1:1 to about 1:

5.

10. A process for producing a compound of formula (I) as described in claim 4, wherein the compound is L-glufosinate ammonium salt in a crystalline form as described in claim 1.

11. L-glufosinate ammonium salt, substantially free of L-glufosinate and / or acid addition salts of L-glufosinate.

12. L-glufosinate ammonium salt, having a volume average particle size distribution D50 of approximately 250 microns or less.

13. The L-glufosinate ammonium salt of claim 12, having a volume average particle size distribution D50 of about 10 microns to about 175 microns.

14. Use of the crystalline form of L-glufosinate ammonium salt according to claim 1 for preparing another form of L-glufosinate or its salt.

15. Use of L-glufosinate ammonium salt in a crystalline form according to any one of claims 1 to 3 for the preparation of an agrochemical composition and / or formulation.

16. i) L-glufosinate ammonium salt in crystalline form; and ii) one or more agriculturally acceptable additives; and 13. A pesticide composition comprising:

17. The pesticide composition of claim 16, wherein the composition comprises a crystalline form of L-glufosinate ammonium salt in an amount of from about 1% to about 99% by weight of the composition.

18. The pesticide composition of claim 16, wherein the composition is in the form of a solid formulation.

19. The pesticide composition of claim 16, wherein the composition further comprises one or more active ingredients.

20. The pesticide composition of claim 16, wherein the active ingredient is a herbicide.

21. A method for controlling undesirable plant growth comprising applying to a plant or its habitat a crystalline form of L-glufosinate ammonium salt.

22. The method comprises the step of: i) L-glufosinate ammonium salt in crystalline form; ii) one or more pesticide-acceptable additives; 22. A method for controlling undesirable plant growth according to claim 21, comprising administering to said plant agrochemical composition comprising:

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