OA21125A

OA21125A - Crystalline form of L-glufosinate ammonium salt and process for production thereof.

Info

Publication number: OA21125A
Application number: OA1202300038
Authority: OA
Inventors: Prashant Vasant KINI; Ashishkumar Ravindra MISHRA; Santosh Ganpat SHELKE; Chandrasekhar Dayal Mudaliar
Original assignee: Upl Limited
Priority date: 2020-07-31
Filing date: 2021-07-30
Publication date: 2023-11-13

Abstract

The present disclosure relates to a novel crystalline form of L-glufosinate ammonium salt and a process for preparation thereof. The present disclosure also provides compositions comprising said form and a method for the control of undesired plant growth using said compositions.

Description

CRYSTALLINE FORM OF L-GLUFOSINATE AMMONIUM SALT AND PROCESS FOR PRODUCTION THEREOF

Field of the invention

The present invention relates to a novel solid form of L-glufosinate ammonium sait 5 and a process for préparation thereof. The present invention also provides compositions comprising said form and a method for the control of undesired plant growth using said compositions.

Background of the invention

DL-homoalanin-4-yl(methyl)phosphinic acid (glufosinate) and salts are amino acid 10 dérivatives with herbicidal activity. The amino acid dérivatives are active in the Lform. Several processes hâve been developed to préparé L-homoalanin-4yl(methyl)phosphinic acid (L-glufosinate) and particularly the ammonium sait in order to use the pure active ingrédient.

Many synthetic processes end up with an acid addition sait of L-glufosinate from 15 which the corresponding free acid(L-Glufosinate) or the ammonium sait needs to be produced. Salts are preferred commercially due to high solubility in water.

US4226941 discloses the préparation of L-glufosinate or a sait by enzymatic préparation.

US5869668 and CN 111072718A disclose the préparation of L-glufosinate or a sait 20 by résolution via précipitation of one of the diastereomeric sait using a chiral base followed by the isolation process.

US7795464 discloses the préparation of L-glufosinate by an asymmetric synthesis reaction.

CN 105541906A discloses a two-step process for the préparation of L-glufosinate 25 ammonium sait starting from L-glufosinate hydrochloride sait using an aqueous alcohol solvent System and ammonia.

In most cases, the addition sait of L-glufosinate is obtained at the end of reaction, which needs to be converted to ammonium sait or alkali meta! sait of L-glufosinate. This can be done in two ways, either by converting the acid addition sait to the free acid followed by conversion to the desired sait; or by converting the acid addition sait to the desired sait.

By following any of the method as described above, the isolation process will require post treatment process involving complex procedures using ion exchange column or treatment of acid addition sait of L-glufosinate with hazardous Chemicals such as ethylene oxide and propylene oxide. The préparation and purification of Lglufosinate ammonium sait often requires multistep process which includes hydrolysis and crystal lisatîon procedures affecting the yield and purity of the product.

Therefore, there is a need for novel solid form of L-glufosinate ammonium sait and to develop a production method for preparing high purity L-glufosinate ammonium sait that is free of acid addition sait of L-glufosinate and/or L-glufosinate starting from acid addition sait of L-glufosinate.

It is surprisingly found by the present inventors that L-glufosinate ammonium sait having high purity and high yield can be prepared in a single step from acid addition sait of L-glufosinate. The present disclosure also provides a crystalline form of Lglufosinate ammonium sait advantageous for production and use in formulation products.

Object of the invention

It is an object to provide a novel solid form of L-glufosinate ammonium sait.

It îs another object to provide a simple and convenient production of L-giufosinate ammonium sait.

It îs another object to provides a single step process for producing ammonium sait of L-glufosinate.

Yet another object is to provide a production method for L-glufosinate ammonium sait that is substantially free from acid addition sait of L-glufosinate and/or Lglufosinate and any other reaction by-products.

It is another object to provide L-glufosinate ammonium sait in high purity and yield.

Summary of the invention

In an aspect the présent disclosure provides a novel solid form of L-glufosinate ammonium sait.

In another aspect the présent disclosure provides a crystalline form of L-glufosinate ammonium sait, substantially free from acid addition sait of L-glufosinate and/or 10 L-glufosinate and any other reaction by-products.

In another aspect the présent disclosure provides a process for preparîng a compound expressed by the following Formula (I)

Formula (I) said process comprising:

a) suspending an acid addition sait compound expressed by the following Formula (II), wherein A is an anion, in a solvent to form a suspension;

Formula (II)

b) contacting the suspension with gaseous ammonia until complété dissolution ofcompound expressed by Formula (II) to form a solution; and

c) precipitating the compound expressed by Fonnula (Γ)

In another aspect the present disclosure provides a process for producing a 5 compound expressed by Formula (I) said process comprising:

a) suspending an acid addition sait compound expressed by Formula (II) in an alcohol solvent, in a ratio of compound expressed by Formula (II) to alcohol, from about 1:5 to about 1:15 by weight to form a suspension;

b) contacting the suspension with gaseous ammonia in nonaqueous conditions 10 until complété dissolution of compound expressed by Formula (II) to fonn a soluiton; and

c) subjecting the solution to conditions sufficient to precipitate the compound expressed by Formula (I).

In another aspect the present disclosure provides L-glufosinate ammonium sait 15 having a volume average particle size distribution D50 less than or equal to about 250 microns, specifically about 1 micron to about 200 microns, and most specifically about 10 microns to about 175 microns.

The present disclosure also provides the uses of crystalline form I of L-glufosinate ammonium sait for preparing other forms of L-glufosinate or other salts thereof.

The present disclosure also encompasses the use of crystalline form I of Lglufosinate ammonium sait of the present disclosure for the préparation of agrochemical compositions and/or formulations.

In another aspect, the present disclosure provides agrochemical compositions 25 comprising crystalline form I of L-glufosinate ammonium sait according to the present disclosure.

In yet another embodiment, the present disclosure agrochemical formulations comprising crystalline form I of L-glufosinate ammonium sait and at least one agrochemically acceptable additive/excipient.

The présent disclosure comprises processes for preparing the above mentioned agrochemical formulations of L-glufosinate ammonium sait comprising crystalline form I of L-glufosinate ammonium sait and at least one agrochemically acceptable additive/excipient.

In another aspect the present disclosure provides a method for the control of undesired plant growth, comprising subjecting the plants or their locus to the action of a crystalline form I of L-glufosinate ammonium sait.

Brief description of Figures:

Figure 1: X-ray powder diffractogram recorded using Cu—Ka radiation for crystalline form 1 of L-glufosinate ammonium sait.

Figure 2: Differential Scanning Calorimetry thermogram for crystalline form I of L-glufosinate ammonium sait.

Figure 3; HPLC chromatogram of L-glufosinate ammonium sait prepared according 20 to the present disclosure.

Figure 4: Chiral HPLC chromatogram of L-glufosinate ammonium sait prepared according to the present disclosure.

Figure 5: Particle size distribution of L-glufosinate ammonium sait.

Detailed Description of the invention

En any aspect or embodiment described hereinbelow, the phrase comprising may be replaced by the phrases “consisting of’ or “consisting essentially of’ or “consisting substantially of’. Additionally, the terms “including,” “having,” “învolving,” “containing,” “characterized by,” variants thereof (e.g., “includes,” “has,” and “involves,” “contains,” etc.), and similar terms as used herein, including the claims.

shall be inclusive and/or open-ended, shall hâve the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”), and do not exclude additional, un-recited éléments or method steps, illustratively. As used herein in this context, the expression “substantially free” will be understood to mean that the crystalline form contains 20% or less, 10% or less, 5% or less, 2% or less, or l% or less of any other form or sait of the subject compound as measured, for example, by PXRD. As used herein, the term about refers to a measurable value such as a parameter, an amount, a temporal duration, and the like and is meant to include variations of +/-15% or less, specifically variations of +/-10% or less, more specifically variations of +/-5% or less, even more specifically variations of +/-!% or less, and still more specifically variations of +/-0.1% or less of and from the particularly recited value, in so far as such variations are appropriate to perform in the disclosure described herein. Furthermore, it is also to be understood that the value to which the modifier about refers is itself specifically disclosed herein.

In an aspect the present disclosure provides a novel solid form of L-glufosinate ammonium sait.

With respect to the present disclosure L-glufosinate ammonium sait is a crystalline form of L-glufosinate ammonium sait referred herein as Form I. “L-glufosînate ammonium sait”, “L-glufosinate ammonium” and crystalline form of L-glufosinate ammonium sait interchangeably used throughout the spécification refers to crystalline Form I.

Accordingly, the present disclosure provides a crystalline fonn I of L-glufosinate ammonium sait.

The present disclosure provides crystalline form 1 of L-glufosinate ammonium sait which at least 80% by weight, in particular at least 90% by weight, consists of form I of L-glufosinate ammonium sait.

The crystalline form I of L-glufosinate ammonium sait can be identified by X-ray powder diffractonietry on the basis of its diffractogram.

Typically, the crystalline form of L-glufosinate ammonium sait is characterized by X-ray powder diffractogram pattern substantially as depicted in Figure L

In an embodiment the present disclosure provides a crystalline form 1 of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka 5 radiation display s at least three of the following reflections, quoted as 2Θ (±0.2°) values of about 9.0, 11.6, 13.1, 14.1, 17.6, 18.2, 1 8.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3 and 36.3.

In an embodiment the present invention provides a crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka 10 radiation displays at least a reflection, quoted as 20 (±0.2°) value of about 9.0, 13.1,

14.1 and 18.9.

In an embodiment the present invention provides a crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one peak selected from the group 17.6, 18.2, 18.9 and 15 23.4 degree 20 ±0.2 degree 2Θ.

In an embodiment the present disclosure provides a crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 20 (±0.2°) selected from 17.6, 18.2, 18.9 and 23.4 degree 20 ±0.2 degree 20 having at least 30% relative intensîty 20 compared to the highest intensîty peak at 18.9.

In an embodiment the present disclosure provides a crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 20 (±0.2°) selected from 17.6, 18.2, 18.9 and 23.4 having at least 30% relative intensîty compared to the highest 25 intensîty peak at 1 8.9.

In another embodiment the present disclosure provides a crystalline fonn I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 2Θ (±0.2°)s selected from

17.6, 18.2, 18.9 and 23.4 having at least 50% relative intensity compared to the highest intensity peak at 18.9.

In an embodiment a crystalline form I of L-glufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the 5 values quoted as 20 (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having % intensity of the peak as follows:

Peak Value (20 (±0.2°)	Intensity (%)
17.6	88.3
18.2	80.6
18.9	100.0
23.5	54.3

In another embodiment a crystalline form I of L-glufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 20 (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having % intensity of the peak as follows:

Peak Value (20 (±0.2°)	Intensity (%)
17.5	79.8
18.1	49.3
18.9	100.0
23.4	53.2

In another embodiment a crystalline form I of L-glufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 20 (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having % 15 intensity of the peak as follows:

Peak Value (20 (±0.2°)	Intensity (%)
17.6	79.1
18.2	53.0
19.0	100.0
23.5	54.6

In another embodiment a crystalline form I of L-glufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 2Θ (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having % intensity of the peak as follows:

Peak Value (20 (±0.2°)	Intensity (%)
17.6	82.3
18.2	55.6
19.0	100.0
23.5	59.3

In another embodiment a crystalline form I of L-glufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 2Θ (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having % 10 intensity of the peak as follows:

Peak Value (20 (±0.2°)	Intensity (%)
17.6	88.5
18.2	61.6
18.9	100.0
23.5	61.8

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least six of the following reflections, quoted as 2Θ (±0.2°) 15 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 embodiment the present disclosure provides a crystalline form of Lglufosinate ammonium sait characterized by one or more data selected from an X-ray powder diffractogram 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 degree 20 ±0.2 degree 20;

an X-ray powder diffractogram pattern having at least three peaks selected from the group 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 degree 20 ±0.2 degree 20;

an X-ray powder diffractogram pattern substantially as depicted in Figure 1;

a dîftèrential Scanning Calorimetry thermogram having at least two characteristic thermal events in the range of 65-115°C, 185-210°C and 210235°C;

a differential Scanning Calorimetry thermogram substantially as depicted in Figure 2;

and combinations thereof.

In an aspect the present disclosure provides crystalline form I of L-glufosinate ammonium sait which is further characterised by the w/w ratio of L-glufosinate to ammonium.

According to an embodiment, the present invention provides a crystalline form of L-glufosinate ammonium wherein the ratio of L-glufosînate and ammonium is in the range of 9.5-1 LL

Crystalline form I of L-glufosinate ammonium sait is further characterised by the ratio of L-glufosinate to ammonium that is équivalent to the theoretical ratio of 10.06:1.

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait which contains L-glufosinate and ammonium în a w/w ratio in the range of 9.5-11:1.

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait which contains L-glufosinate and ammonium în a w/w ratio in the range of 9.9-10.5: 1,

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu— Ka radiation display s at least three of the following reflections, quoted 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 w/w ratio in the range of 9.5-11:1.

In an embodiment the present disclosure provides a crystalline form 1 of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu-—Ka radiation displays at least one of the values quoted as 20 (±0.2°)s selected from 17.6, 18.2, 18.9 and 23.4 having at least 50% relative intensity compared to the highest intensity peak and containing L-glufosinate and ammonium in a w/w ratio in the range of 9.5-11:1.

In an embodiment the present disclosure provides a crystalline fonn I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 20 (±0.2°) of about 11.6, 17.6,

18.2, 23.4, 26.0 and 33.3 and containing L-glufosinate and ammonium in a w/w ratio in the range of 9.5-11:1.

In an embodiment the present disclosure provides a crystalline form I of Lglufosinate ammonium sait which displays a Differentîal Scanning Calorimetry (DSC) thermogram with at least two characteristic thermal events in the range of 65-115°C, 185-210°C and 210-235°C.

In an embodiment characteristic thermal events were recorded as endotherm.

In an embodiment the present invention provides a crystalline form I of Lglufosinate ammonium sait which displays a Differentîal Scanning Calorimetry (DSC) thermogram having at least two characteristic endotherm in the range of 65115°C, 185-210°C and 210-235°C.

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait which displays a DSC thermogram with reference to Figure 2.

With respect to the present disclosure compound expressed by Formula (I) refers to L-glufosinate ammonium, L-glufosinate ammonium sait or crystalline form I of Lglufosinate ammonium sait.

With respect to the present disclosure compound expressed by Formula (II) refers to an acid addition sait of L-glufosinate, the sait being formed with an acid selected from an inorganic acid or an organic acid, for example hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid etc.

In an embodiment the present disclosure provides crystalline form I of Lglufosinate ammonium sait characterised by data selected from at least one of the following:

an X-ray powder diffractogram using Cu—Ka radiation displays at least three of the following reflections, quoted 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 a Differential Scanning Calorimetry (DSC) thermogram with at least two characteristic thermal events in the range of 65-115°C, 185-210°C and 210235°C.

In an embodiment the present disclosure provides crystalline form 1 of Lglufosinate ammonium sait characterised by at least one property selected from an X-ray powder diffractogram using Cu—Ka radiation displays at least three of the following reflections, quoted as 20 (±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 9.511: 1 or a Differential Scanning Calorimetry (DSC) thermogram with at least two characteristic thermal events in the range of 65-115°C, 185-210°C and 210235°C.

In an embodiment the present disclosure provides a crystalline form I of Lglufosinate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one of the values quoted as 2Θ (±0.2°)s selected from 17,6, 1 8.2, 18.9 and 23.4 having % intensity of the peak at least 50 and containing L-glufosinate and ammonium in a w/w ratio în the range of 9,5-11: 1 and exhibiting a Differential Scanning Calorimetry (DSC) thermogram with at least two characteristic thermal events in the range of 65-] 15°C, 185-210°C and 210-235°C.

In an embodiment the present disclosure provides a crystalline form I of Lglufosînate ammonium sait which in an X-ray powder diffractogram using Cu—Ka radiation displays at least one ofthe values quoted as 2Θ (±0.2°) of about 11.6, 17.6, 18,2, 23.4, 26.0 and 33.3 and containing L-glufosinate and ammonium in a w/w ratio in the range of 9.5-11: 1 and exhibiting a Differential Scanning Calorimetry (DSC) thermogram with at least two characteristic thermal events in the range of 65-1 15°C, 185-210°C and 210-235°C,

In another aspect the present disclosure provides a single step conversion of an acid addition sait of L-glufosinate to ammonium sait of L-glufosinate in high yield and purity.

In an aspect the present disclosure provides a process for the préparation of solidform of L-glufosinate ammonium sait.

In an embodiment the present disclosure provides a process for preparing crystalline form of L-glufosinate ammonium sait,

The present process can produce the solid from of L-glufosinate ammonium sait in substantially pure form.

The term “substantially pure solid form of L-glufosinate ammonium sait” refers to the solid form having a purity of greater than about 95 wt %, specifically greater than about 98 wt %. The substantially pure fonn of L-glufosinate ammonium sait is substantially free from acid addition sait of L-glufosinate and/or L-glufosinate and any other reaction by-products.

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

In another aspect the present disclosure provides substantially pure crystalline fonn of L-glufosinate ammonium sait.

In an embodiment the present disclosure provides a process for producing a compound expressed by the foilowing Formula (I)

Formula (I) said process comprising:

a) suspending an acid addition sait compound expressed by the foilowing Formula (II), wherein A' is an anîon, in an alcohol solvent to form a suspension;

Formula (II)

b) contacting the suspension with gaseous ammonia until complété dissolution of compound expressed by Formula (11) to form a solution; and

The process according to the present disclosure is schematically represented as follows:

wherein A is an anion.

in an embodiment the anion A' is selected from halides, phosphates, sulphates or acétates.

In an embodiment the acid addition sait of compound expressed by the following Formula (II) is being formed with L-glufosinate and an acid selected from hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid.

In an embodiment the acid addition sait of L-glufosinate is L-glufosinate hydrochloride sait.

L-glufosinate hydrochloride sait can be prepared by processes known in the art.

In an embodiment the present disclosure provides a process for producing Lglufosinate ammonium sait said process comprising:

a) suspending L-glufosinate hydrochloride sait in an alcohol solvent to form a suspension;

b) contacting the suspension with gaseous ammonia in nonaqueous conditions until complété dissolution of L-glufosinate hydrochloride sait to form a solution; and

c) subjecting the solution to conditions sufficient to precipitate L-glufosinate ammonium sait.

In an embodiment the the process for producing L-glufosinate ammonium sait comprising:

a) contacting a suspension comprising L-glufosinate hydrochloride sait in an alcohol solvent with gaseous ammonia in nonaqueous conditions to form a solution and

b) subjecting the solution to conditions sufficient to obtain L-glufosinate 5 ammonium sait.

The présent disclosure further provides a process for producing a compound expressed by Formula (I) said process comprising;

a) suspending an acid addition sait compound expressed by Formula (II) in an alcohol solvent, in a ratio of compound expressed by Formula (II) to 10 alcohol, from about 1:5 to about 1:15 by weight, to form a suspension;

b) contacting the suspension with gaseous ammonia in nonaqueous conditions until complété dissolution of compound expressed by Formula (II) to form a solution; and

c) subjecting the solution to conditions sufficient to precipitate the compound 15 expressed by Formula (1).

In an embodiment the présent disclosure provides a process for producing Lglufosinate ammonium sait said process comprising:

a) suspending L-glufosinate hydrochloride sait in an alcohol solvent, in a ratio of L-glufosinate hydrochloride sait to alcohol, from about 1:5 to about 1:10 by weight, to form a suspension;

c) subjecting the solution to conditions sufficient to precipitate L-glufosinate 25 ammonium sait.

In an embodiment the process îs carried out în nonaqueous conditions.

In an embodiment the alcohol solvent is selected from but not limited to methanol, éthanol, propyl alcohol, isopropyl alcohol, glycol, glycérol or mixtures thereof.

In an embodiment the alcohol solvent is methanol.

In an embodiment the ratio of acid addition sait compound expressed by Formula (II) to alcohol, is from about 1:5 to about 1:10 by weight.

In an embodiment the ratio of acid addition sait compound expressed by Formula (II) to alcohol, is from about 1:5 to about 1:8 by weight.

In an embodiment the ratio of L-glufosinate hydrochloride sait to alcohol, from about 1:5 to about 1:8 by weight.

In an embodiment the alcohol solvent is selected from mixture of an alcohol solvent with ketonic solvent such as acetone.

In an embodiment step b) is performed by contacting step a) suspension with gaseous ammonia until complété dissolution of L-glufosinate hydrochloride.

In an embodiment step b) is performed by purging gaseous ammonia.

In an embodiment the ratio of acid addition sait compound expressed by Formula (II) to gaseous ammonia is from about 1:1 to about 1:5.

In an embodiment the ratio of acid addition sait compound expressed by Formula (II) to gaseous ammonia is from about 1:2 to about 1:5.

In an embodiment the mole ratio of L-glufosinate hydrochloride sait to gaseous ammonia is from about 1:2 to about 1: 5.

In an embodiment step b) provides a solution, wherein the solution has a pH of 7 to 12.

In an embodiment step b) provides a solution, wherein the solution has a pH of 7.5 to 10.

In an embodiment step c) is performed at a temperature between 30°-90°C to allow L-glufosinate ammonium sait to precipitate out.

In an embodiment step c) is performed at a température between 40°-80°C to allow L-glufosinate ammonium sait to precipitate out.

In an embodiment L-glufosinate ammonium sait is filtered out.

In an embodiment, the impurities and side products from the previous steps and 5 ammonium chloride formed in the reaction remained in the filtrate.

In an embodiment the Chemical purity of L-glufosinate ammonium sait is at least 95% by weight.

In an embodiment the Chemical purity of L-glufosinate ammonium sait is more than 96% by weight.

In an embodiment the chiral purity of L-glufosinate ammonium sait is absolute.

In an embodiment the L: D ratio of L-glufosinate ammonium sait is from about 95:5 to about 99.9:0.1.

In an embodiment the L: D ratio of L-glufosinate ammonium sait is from about 96:4 to about 99:1.

The present disclosure further provides L-glufosinate ammonium sait that is substantially free from acid addition sait of L-glufosinate and/or L-glufosinate.

in an embodiment the present disclosure provides L-glufosinate ammonium sait that is substantially free from acid addition sait of L-glufosinate.

In an embodiment the present disclosure provides L-glufosinate ammonium sait 20 that is substantially free from L-glufosinate hydrochloride sait.

In an embodiment the present disclosure provides L-glufosinate ammonium sait that contains less than 0.5% by weight of L-glufosinate hydrochloride sait.

In an embodiment the present disclosure provides L-glufosinate ammonium sait that is substantially free from L-glufosinate.

In an embodiment the present disclosure provides L-glufosinate ammonium sait that contains less than 0.5% by weight of L-glufosinate.

L- glufosinate ammonium sait prepared according to the present disclosure is having a volume average particle size distribution D50 less than or equal to about 250 microns, specifically about I micron to about 200 microns, and most specifically about 10 microns to about 175 microns.

In an embodiment, the particîes of L- glufosinate ammonium sait prepared according to the present disclosure hâve a D50 (the médian for a volume distribution, has been defined as the diameter where half of the population lies below this value) less than or equal to about 250 microns.

In an embodiment the present disclosure provides a process for preparing crystalline form I of L-glufosinate ammonium sait characterised by data selected from one or more of the foilowing:

an X-ray powder diffractogram using Cu—Ka radiation displays at least three of the foilowing reflections, quoted as 20 (±0.2°) values of about 9.0, 1 1.6, 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 sait containing L-glufosinate and ammonium in a ratio in the range of 9.5-11: 1 ;

a Differential Scanning Calorimetry (DSC) thermogram with at least two characteristic thennal events in the range of 65-115°C, 185-210°C and 210235°C;

said process comprising:

a) suspending L-glufosinate hydrochloride sait in an alcohol solvent to fonn a suspension;

c) subjecting the solution to conditions sufficient to precipitate crystalline form I of L-glufosinate ammonium sait.

The present disclosure also provides use of crystalline form of L-glufosinate ammonium sait for preparing other forms of L-glufosinate or its sait.

The present disclosure also encompasses the uses of above described crystalline form of L-glufosinate ammonium sait of the present disclosure for the préparation of agrochemical compositions and/or formulations.

The present disclosure comprises processes for preparing the above mentioned agrochemical formulations of L-glufosinate ammonium sait comprising above described crystalline form of L-glufosinate ammonium sait and one or more agrochemically acceptable additives/excipients.

in an aspect, the present disclosure provides an agrochemical composition comprising crystalline form I of L-glufosinate ammonium sait.

Thus, in an embodiment the present disclosure provides a herbicide composition comprising:

i) a crystalline form I of L-glufosinate ammonium sait; and ii) at least one agrochemically acceptable additives/excipients.

In an embodiment the compositions according to the present disclosure comprises crystalline form I of L-glufosinate ammonium sait in an amount from about l% to about 99% by weight of the composition.

In an embodiment the compositions according to the present disclosure comprises crystalline fonn I of L-glufosinate ammonium sait having a volume average particle size distribution D50 less than or equal to about 250 microns, specifically about l micron to about 200 microns, and most specifically about I0 microns to about 175 microns.

In an embodiment the agrochemically acceptable excipient /additives can be selected from adjuvants or surfactants including but not limited to wetting agents, emulsifiers, dispersants, viscosity-modifying agents, antifoaming agents, antifreeze agents, pH adjusting agents, stabilizers, anticaking agents, biocides and the like.

The L-glufosinate ammonium composition according to the present disclosure may comprise additives such as surfactants, solvent, fertilizer, pH modifiées, 5 crystall ization inhibitors, viscosity modifiers, suspending agents, spray droplet modifiers, pigments, antioxidants, foaming agents, light-blocking agents, compatibilizing agents, antifoam agents, sequestering agents, neutral izing agents, corrosion inhibitors, dyes, odorants, spreading agents, pénétration aids, micronutrients, émollients, lubricants, sticking agents, dispersing agents, 10 thickening agents, freezing point depressants, antimicrobial agents, and the like.

In an embodiment the compositions according to the present disclosure can be in the form of soluble liquid concentrâtes, émulsion concentrâtes, microemulsions, suspension concentrâtes, water-dispersible powders or granules.

In an embodiment the compositions according to the present disclosure can be in the form of water-dispersible powders or granules.

In an embodiment the compositions according to the present disclosure further comprises one or more other active ingrédients.

In an embodiment the active ingrédients that can be present in the compositions according to the present disclosure îs selected from but not limited to herbicides, fungicides, insecticides, défoliants, desiccants and plant growth regulators.

In an embodiment the active ingrédient that can be present in the compositions according to the present disclosure is an herbicide.

The actives may 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; Pyrîmidinyloxybenzoic analogue herbicides such as pyrithiobac sodium, bispyribac sodium; Organophosphrous based herbicides such as glyphosate and its salts, bilanafos and its salts, bialaphos and its salts; Bipyridinium herbicides such as paraquat and diquat and salts thereof; aryloxyalkanoic acid herbicides such as 2, 4-D and its salts and esters, MCPA, MCPB and their salts; aryloxyphenoxyprop ionic herbicides such as haloxyfop, isomers and esters, clodinafop and its esters; Pyridîne herbicides such as triclopyr, picloram, aminopyralîd and salts thereof; Aromatic herbicides such as dicamba, 2,3,6-TBA, trîcamba and their salts; Pyridinecarboxylic acid herbicides such as clopyralid; Imidazolinones selected from imazameth, imazamethabenz, imazamox, îmazapic, imazapyr, imazaquin, imazethapyr; herbicides such as sulfonyl urea herbicides such as flazasulfuron, rimsulfuron, bensulfuron, ethoxysulfuron, mesosulfuron, oxasulf uron, pyrazosurfuron-ethyl and their salts; cyclohexanedione oxime herbicides such as clethodim and its salts, chloroacetamide herbicide such as metolachlor and its salts and isomers, phenyl phthalimide herbicides such as ilumioxazin and its salts, mesotrione, dinitroanilîne herbicides such as oryzalin, pendimethalin, profluralin, trifluralin and its salts, bicyclic dicarboxyiic acid herbicides such as endothal and its salts or mixtures of such herbicides.

In an embodiment suitabie herbicides may be selected from acetochlor, acifluorfen, aclonifen, alachlor, ametryn, amidosulfuron, aminopyralîd, amitrole, anilofos, asulam, atrazine, azafenidin, azimsulfuron, benazolin, benfluralin, bensulfuronmethyi, bentazone, bîfenox, binalafos, bispyribac-sodium, bromacil, bromoxynil, butachlor, butroxidim, cafenstrole, carbetamide, carfentrazone-ethyl, chloridazon, Chlorimuron-ethyl, chlorobromuron, chlorotoluron, chlorsulfuron, cinidon-ethyl, cinosulfuron, clethodim, Clomazone, Clopyralid, Cloransulam-methyl, Clorsulfuron, Cyanazine, Cycloate, Cyclosulfamuron, Cycloxydim, Dalapon, Desmedipham, Dicamba, Dichlobenil, Dichlormid, Diclosulam, Diflufenican, Dimefuron, Dimepipeate, Dimethachlor, Dimethenamîd, Diquat, Diuron, Esprocarb, Ethalfiuralin, Ethametsulfuron-methyi, Ethofumesate, Ethoxysulfuron, Fentrazamide, Flazasulfuron, Florasulam, Fluchloralin, Flufenacet, Flumetsulam,

Flumioxazin, Fluometuron, Flupyrsulfuron-methyl, Fluorochloridone, Fluoroxypyr, Fîurtamone, Fomesafen, Foramsulfuron, Hexazinone, Imazamethabenz-m, Imazamox, mazapic, Imazapyr, Imazaquin, Imazethapyr, Imazosulfuron, lodosulfuron, loxynil, Isoproturon, Isoxaben, Isoxaflutole, 5 Lactofen, Lenacil, Linuron, Mefenacet, Mesosulfuron-Methyl, Mesotrîone, tembotrione, topramezone, Metamîtron, Metazachlor, Methabenzthiazuron, Metobromuron, Metolachlor, S-metolachlor Metosulam, Metoxuron, Metribuzin, Metsulfuron-methyl, Moiinate, MSMA, Napropamide, Nicosulfuron, Norflurazon, Oryzalin, Oxadiargyl, Oxadiazon, Oxasulfuron, Oxyfluorfen, Paraquat, 10 Pendimethalin, Phenmedipham, Picloram, Pretilachlor, Profoxydim, Prometryn, Propanil, Propisochlor, Propoxycarbazone, Propyzamide, Prosulfocarb,

Prosu Ifuron, Pyraflufen-ethyl, Pyrazosulfuron, Pyroxasulfone, Py ri date, Pyrithiobac, Quinclorac, Quinmerac, Quinotrione, Rimsulfuron, Sethoxydim, Simazine, Sulcotrione, Sulfentrazone, Sulfosulfuron, Tebuthiuron, Tepraloxydim, 15 Terbuthylazine, Terbutryn, Thifensulfuron-methyl, Thîobencarb, Tralkoxydim, Triallate, Triasulfuron, Tribenuron-methyl, Triclopyr, Trifloxysulfuron, Trifluralin, Triflusulfuron-methyl, Tritosulfuron, and mixtures and combinations thereof.

In an embodiment the compositions ofthe present disclosure can be used on tolérant 20 crops which are tolérant to glufosinate.

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

In an embodiment the compositions according to the present disclosure can be used in combination with herbicides that are sélective for the crop being treated and which complément the spectrum of weeds controlled by these compositions at the application rate employed. When used in conjunction with the other active 30 ingrédients, the presently claimed L-glufosinate ammonium sait can be formulated with the other active ingrédients as premix concentrâtes, tank mixed with the other active ingrédients for spray application or applied sequentially with the other active ingrédients in separate spray applications. The compositions may be diluted from 1 to 2000 foid in a pesticide spray mixture at the point of use depending on the local agriculturai practices and used in pesticide spray applications to control weeds in crop and non-crop environments.

In an embodiment the disclosure provides a method for the control of undesired plant growth, comprising subjectîng the plants or their locus to the action of a composition comprising:

i) a crystalline form I of L-glufosinate ammonium sait; and ii) one or more agrochemically acceptable additives.

In an aspect the present disclosure provides a method for the control of undesired plant growth, comprising subjectîng the plants or their locus to the action of a crystalline form I of L-glufosinate ammonium sait.

In an embodiment the present disclosure provides a method for the control of undesired plant growth, comprising subjectîng the plants or their locus to the action of agronomically effective amount of a crystalline form I of L-glufosinate ammonium sait.

In an embodiment the agronomically effective amount comprises from about 10 grams of a crystalline form 1 of L-glufosinate ammonium sait per hectare to about 1500 grams of a crystalline form 1 of L-glufosinate ammonium sait per hectare.

In an embodiment the agronomically effective amount comprises from about 100 grams of a crystalline form I of L-glufosinate ammonium sait per hectare to about 1000 grams of a crystalline form I of L-glufosinate ammonium sait per hectare.

In an embodiment the température range during the application period of the compositions according to the present invention may be critical and would vary based on the crops and geographical région.

ANALYTICAL METHODS

Powder X-Rav Diffraction (XRD) Method:

X-ray powder diffractogram crystalline form I of L-glufosinate ammonium sait recorded using Cu—Ka radiation. The detailed parameters are given below

Instrument; Bruker make 2^nd génération D2 Phaser Powder X-Ray diffractometer;

Operated at: 30.0kV, 10mA;

Radiation: Cu Ka;

Mode: Reflection

Wavelength: 1.54060 °A,

Scan Range: 2-40 20,

Step size: 0.02°

Differential Scanning Calorîmeter (DSC):

Differential Scanning Calorimetry thermogram for crystalline form I of L15 glufosinate ammonium sait were recorded as follows:

Instrument :Differential Scanning Calorîmeter Mettler Toledo DSC-3

Heating rate: l0°C/min

Temperature range: 30 °C to 350 °C, under N2 flow of 20 ml/min

Particle size:

Particle size distribution of L-glufosînate ammonium sait was recorded using Malvern Mastersizer 2000 Particle Size Analyzer with Hydro 2000SM (A) accessory using 1% suspension of L-glufosinate ammonium sait in dry isopropyl alcohol.

The instant invention is more specifically explained by below examples. However, it should be understood that the scope of the present invention is not limited by the examples in any manner. In some instances, some features of the disclosed embodiments may be employed without a corresponding use of the other features.

Accordingly, it is appropriate that the claims be construed broadly and in a manner consistent with the scope of the invention, It will be appreciated by any person skilled in this art that the present invention includes below examples and further can be modified and altered within the technical scope of the present invention,

EXAMPLES:

Préparation of crystalline fonn of L-glufosinate ammonium sait

Example l : Préparation of L-glufosinate ammonium sait

366 g (L35 mole) of L-glufosinate hydrochloride sait was suspended in 2820 g of methanol (1:7.7 w/w) at 30°C. The suspension was purged with dry ammonia gas (57.1g, 3.36 moles) until the pH of the solution reaches between 7.9-8.5 and complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated Lglufosînate ammonium sait was filtered and washed with 300 g of methanol to give 225 g ofthe L-glufosinate ammonium sait. Yield 78.4%; Purity by HPLC 96.63%; L-glufosinate; 0.25%; L-glufosinate hydrochloride sait <0.05%, Figure 1 and 2. Lglufosinate to ammonium ratio (w/w)- 9.88: 1.

Example 2: Préparation of L-glufosinate ammonium sait

530 g (1.95 mole) of L-glufosinate hydrochloride sait 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) till complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at 65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1 -2 hours for complété précipitation of the product. The precipitated L-glufosinate ammonium sait was filtered and washed with 400 g of methanol to give 342 g of the L-glufosinate ammonium sait. Yield 85%; Purity by HPLC 96.47%, Fig.3; L-glufosinate: 0.19%; L-glufosinate hydrochloride sait <0.05%. L-glufosinate to ammonium ratio- 9.79: 1.

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

Example 3: Préparation of L-glufosinate ammonium sait g (0.283 mole) of L-glufosinate hydrochloride sait was suspended in 490g of methanol (1:7.0 w/w) at 30°C. The suspension was purged with dry ammonia gas (12 g, 0.70 moles) until complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was heated to and maintained at 70-75 °C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated L-glufosinate ammonium sait was filtered and washed with 50g of methanol to give 45 g of the L-glufosinate ammonium sait. Yield: 80%; Purity by HPLC: 98.13%; Chiral purity: 97.05:2.95; Fig 4.

Example 4: Préparation of L-glufosinate ammonium sait (ratio of L-glufosinate hydrochloride sait to alcohol is 1:6) g (0.283 mole) of L-glufosinate hydrochloride sait was suspended in 420g 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 pH ofthe solution reaches between 7.9-8.5 and complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at 65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated Lglufosinate ammonium sait was filtered and washed with 42g of methanol to give 48 g ofthe L-glufosinate ammonium sait. Yield: 82.7%; Purity by HPLC: 96.5%.

Example 5: Préparation of L-glufosinate ammonium sait (ratio of L-glufosinate hydrochloride sait to alcohol is 1:10) g (0.283 mole) of L-glufosinate Hydrochloride sait was suspended in 700g of methanol (t : 10.0 w/w) at 30°C. The suspension was purged with dry ammonia gas (12 g, 0.70 moles) until the pH ofthe solution reaches between 7.9-8.5 and complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at 65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated Lglufosinate ammonium sait was filtered and washed with 70g of methanol to give 40 g of the L-Glufosinate ammonium sait. Yieîd:70.6 %; Purity by HPLC: 98.9%.

Example 6: Préparation of L-glufosinate ammonium sait

350g (1.29 mole) of L-glufosinate hydrochloride sait 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 pH of the solution reaches between 7.9-8.5 and complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at 65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated Lglufosinate ammonium sait was filtered and washed with 290 g of methanol to give 209 g ofthe L-glufosinate ammonium sait. Yieid 80%; Purity by HPLC 97.4%; Lgiufosinate: 0.1%; L-glufosinate hydrochloride sait <0.05%, Figure 2. Lglufosinate to ammonium ratio (w/w)- 9.90: 1.

Example 7: Préparation of L-glufosinate ammonium sait

350g (1.29 mole) of L-glufosinate hydrochloride sait 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 equ.) until the pH of the solution reaches between 7.9-8.5 and complété dissolution of L-glufosinate hydrochloride sait. The reaction mass was then heated to and maintained at 65-70°C until L-glufosinate ammonium sait started precipitating out (4-6 hours). The reaction mass was then cooled to 30°C and left for 1-2 hours for complété précipitation of the product. The precipitated Lglufosinate ammonium sait was filtered and washed with 290 g of methanol to give 262 g of the L-glufosinate ammonium sait. Yieid 92.5%; Chiral ratio 98.7 : 1.3; Lglufosinate to ammonium ratio (w/w/) - 9.60: 1.

The sample was tested after a period of 50 days and L-glufosinate to ammonium ratio (w/w) was found to be 9.61 : L

Formulations:

Example 8: A soluble liquid concentrate formulation comprising crystalline form I of L-glufosinate ammonium sait prepared according to the present disclosure is given below:

Ingrédients	Quantity (% w/w)
L-Glufosinate ammonium sait	13.5
Alkyl glucamîde	5
Sodium lauryl ether sulfate	20
Glycol ether (solvent)	3
Potassium chloride	5
Water	Q.S
Total	100

Example 9: A water dispersible granular formulation comprising crystalline form I of L-glufosinate ammonium sait is given below:

Ingrédients	Quantity (% w/w)
L-Glufosinate ammonium sait	50
Alcohol ethoxylate	7
Methyl palmitate/oleate	7
Polyvinylpyrrolidone	0.5
Potassium chloride	3
Sodium alkyl sulfate	6
Hexamethy i enetetram i ne	5
Ammonium sulfate	Q.S
Total	100

Example 10: A water dispersible granular formulation comprising crystalline form I of L-glufosinate ammonium sait is given below:

Ingrédients	Quantity (% w/w)
L-Glufosinate ammonium sait	50
Alcohol ethoxylate	6
Methyl palmitate/oleate	2.5
Potassium chloride	5
Sodium alkyl sulfate	8
Hexamethylenetetramine	l
Ammonium sulfate	Q.S
Total	100

Example 11 : A water dispersible granular formulation comprising crystalline form I of L-glufosînate ammonium sait is given below:

Ingrédients	Quantity (% w/w)
L-Glufosinate ammonium sait	26
methyl palmitate/oleate methyl ester blend	2.5
silica	3
Hexamethy lenetetram i ne	1
Alcohol ethoxylate	6
Sodium alkyl sulfate	8
Potassium chloride	5
Ammonium sulfate	48
Polydimety! siloxane	0.5

Example 12: A water dispersible granular formulation comprising crystalline form I of L-glufosinate ammonium sait is given below:

Ingrédients	Quantîty (% w/w)
L-Glufosinate ammonium sait	26
methyl palmitate/oleate methyl ester blend	2.5
Magnésium chloride	20
silica	3
Hexamethylenetetramine	1
Alcohol ethoxylate	6
Sodium alkyi sulfate	8
Potassium chloride	5
Polydimethyl siloxane	0.5
Ammonium sulfate	28
Total	100

Example 13: A water dispersible granular formulation comprising crystalline form I of L-glufosinate ammonium sait is given below

Ingrédients	Quantîty (% w/w)
L Glufosinate ammonium sait	26
Magnésium Chloride	20
Silica	3
Hexamethy lenetetram i ne	1
Phosphate ester	8
Sodium alkyi sulfate	8
Potassium chloride	5
Polydimethyl siloxane	0.5
Ammonium sulfate	28.5

Example 14: A water dispersible granular formulation comprising racemic glufosinate ammonium sait is given below (comparative example)

Ingrédients	Quantity (% w/w)
Glufosinate ammonium sait	52,1
methyl palmitate/oleate	2,5
Silica	3
Hexamethylenetetramine	1
Alcohol ethoxylate	6
Sodium alkyl sulfate	8
Potassium chloride	5
Polydimethyl siloxane	0.5
Ammonium sulfate	21.9

Example 15: A water dispersible granular formulation comprising racemic glufosinate ammonium sait îs given below (comparative example)

Ingrédients	Quantity (% w/w)
Glufosinate ammonium sait	52.1
Silica	3
Magnésium Chloride	20
Hexamethylenetetramine	1
Phosphate ester	8
Sodium alkyl sulfate	8
Potassium chloride	5
Polydimethyl siloxane	0.5
Ammonium sulfate	2.4

Field trial efficacy data:

Field trials were carried out using water dispersible granular formulation comprising crystalline form I of L-glufosinate ammonium sait prepared according to the present disclosure as the broad spectrum herbicide,

The compositions were dispersed with water and optionally with other tank mix auxiliaries and applied at a water application rate of 300-600 l/ha to crop and noncrop land containing many broad leave weeds, grasses and sedges.

Inventors of the present disclosure carried out field trials using samples prepared according to Examples l i (Sample 1), Example 12 (Sample 2) and Example 13 10 (Sample 3) at a dose of 250 g a.i per hectare, After treatment using said compositions, chlorosis followed by necrosis of the weeds were observed demonstrating the bio-efficacy of the new formulations. The observations at 4 days and 14 days after application were summarized in below tables. Comparative samples were prepared according Example 14 (Sample 4) and 15 Example 15(Sample 5) and trials were conducted at a dose of 500 g a.i/ha, The details of the trials are presented below.

Table 1 :

Crop:	Grapes

Target weeds:	Amaranthus Viridis, Parthenium hysterophorus, Euphorbia Hirta, Euphorbia Hyperceifolia and Echinocloa Colonum
Water Volume:	600 l/ha
Nozzle:	Fiat Fan Nozzle

Table 2: % weed control at 4 days after application

Sample	Amaranthus viridis	Parthenium hysterophorus	Euphorbia hirla	Euphorbia hyperceifoïia	Echinocloa coionum
Sample 1	42.5	42.5	32.5	30.0	25.0
Sample 2	40.0	42.5	27.5	27.5	-
Sample 3	40.0	42.5	27.5	27.5	30.0
Sample 4	40.0	35.0	30.0	25.0	25.0
Sample 5	40.0	40.0	30.0	30.0	25.0

Table 3: % weed control at 14 days after application

Treatments	Amaranthus viridis	Parthenium hysterophorus	Euphorbia hirta	Euphorbia hyperceifoïia	Echinocloa
Sample 1	72.5	72.5	50.0	47.5	40.0
Sample 2	67.5	70.0	50.0	47.5	-
Sample 3	65.0	72.5	47.5	47.5	40.0
Sample 4	65.0	72.5	47.5	45.0	40.0
Sample 5	67.5	70.0	47.5	47.5	40.0

It has been évident from the above table the compositions according to the present disclosure exhibited acceptable weed control against various persistent weeds. It has been further noted that performance of the inventive compositions at half dosage are at least equal and, in many cases, surpasses the weed control measures compared to racemic glufosinate ammonium compositions. Thus, it has been established that the inventive compositions are highly efficacîous and éliminâtes employing inactive D isomer of glufosinate thereby making such compositions environmentally friendly and easily biodégradable.

Claims

l. A crystalline form of L-glufosinate ammonium sait which is a compound of Formula (I)

Formula (I) characterized by one or more of an X-ray powder diffractogram pattern having peaks at 9.0, 11.6, I3.l, 14.1, 17.6, 18.2, 18.9, 19.5, 22.4, 23.4, 26.0, 31.1, 33.3 and 36.3 degree 20 ±0.2 degree 20;

an X-ray powder diffractogram pattern having at least three peaks selected from the group consisting 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 degree 20 ±0.2 degree 20;

an X-ray powder diffractogram pattern substantially as depicted in Figure 1;

a differential Scanning Calorimetry thermogram having at least two characteristic thermal events in the range of65-l 15°C, 185-210°C and 210-235°C;

a differential Scanning Calorimetry thermogram substantially as depicted in Figure 2; and combinations thereof.
2. The crystalline form of L-glufosinate ammonium of claim 1, wherein the ratio of L-glufosinate to ammonium is in the range of 9.5-11:1.
3. The crystalline form of L-glufosinate ammonium of claim 1, that is substantially free from an acid addition sait of L-glufosinate, and/or L-glufosinate.
4. The crystalline form of L-glufosinate ammonium of claim l, having a volume average particle size distribution D50 less than or equal to about 250 microns.
5. The L-glufosinate ammonium sait according to claim 4, having a volume average particle size distribution D50 from about 10 microns to about 175 microns.
6. An agrochemical composition comprising:

i) the crystalline form of L-glufosinate ammonium sait of claim 1 ; and ii) one or more agrochemically acceptable additive.
7. The agrochemical composition according to claim 6, wherein said composition comprises the crystalline form of L-glufosinate ammonium sait in an amount from about 1% to about 99% by weight of the composition.
8. The agrochemical composition according to claim 6, wherein said composition is in the form of a solid formulation.
9. The agrochemical composition according to claim 6, wherein said composition further comprises one or more active ingrédients.
10. The agrochemical composition according to claim 9, wherein said one or more active ingrédients is an herbicide.
11. A method for control of undesired plant growth, comprising applying to the plants or their locus the crystalline form of L-glufosinate ammonium sait according to claim I.
12. A method for control of undesired plant growth, comprising applying to the plants or their locus the agrochemical composition of claim 6.