# US 12,760,044 B2 · Method for obtaining L-glufosinate

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,760,044 B2
- Document ID: US12760044B2
- Status: Granted
- Kind: B2
- Application number: 18/566,477
- Filed: 2022-06-10
- Published: 2024-08-15
- Granted: 2026-10-13
- Earliest claimed: 2021-06-11
- Assignees: Upl Ltd
- Applicants: Upl Limited
- Inventors: Chandrasekhar Dayal Mudaliar; Ashishkumar Ravindra Mishra; Mukesh Deshmukh; Prashant Kini
- Web page: https://patentgrep.com/patent/US12760044B2

## CPC

- C07F 9/301: {Acyclic saturated acids which can have further substituents on alkyl}
- A01N 57/20: containing acyclic or cycloaliphatic radicals
- A01P 13/00: Herbicides; Algicides
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01P: BIOCIDAL, PEST REPELLANT, PEST ATTRACTANT OR PLANT GROWTH REGULATORY ACTIVITY OF CHEMICAL COMPOUNDS OR PREPARATIONS

## Abstract

The present invention relates to a safer, easier and cost-effective method for preparing L-glufosinate or salts thereof. The present invention further relates to a novel L-glufosinate quinine tetrahydrate salt and its use in a method for obtaining L-glufosinate or salts thereof.

## Claims

### Claim 1

A method for obtaining L-glufosinate or salts thereof, said method comprising:
a) reacting glufosinate or its salt with a chiral base to obtain a salt of L-glufosinate and the chiral base;
b) dissolving said salt of L-glufosinate and chiral base in water and adjusting pH to 6 to 9 with a base to precipitate the chiral base; and
c) removing said precipitated chiral base to obtain the L-glufosinate or salts thereof.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein said chiral base is substantially water insoluble.

### Claim 3 (depends on 2)

The method as claimed in claim 2, wherein said chiral base is selected from group comprising of brucine, quinine, cinchonine, cinchonidine and strychnine and isomers thereof.

### Claim 4 (depends on 3)

The method as claimed in claim 3, wherein said chiral base is quinine.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein the step a) is carried out in presence of a catalyst and a solvent.

### Claim 6 (depends on 5)

The method as claimed in claim 5, wherein said catalyst is selected from group comprising of fomaldehyde, propionaldehyde, butyraldehyde, heptanal, acrylaldehyde, benzaldehyde, salicyladehyde, p-hydroxybenzaldehyde, o-nitrobenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 2-hydroxy-3,5-dinitrobenzaldehyde, 5-nitrosalicylaldehyde and furfural.

### Claim 7 (depends on 5)

The method as claimed in claim 5, wherein said solvent comprises an alcohol, a ketone, water or a mixture thereof.

### Claim 8 (depends on 7)

The method as claimed in claim 7, wherein said solvent is mixture of tert-butanol and water.

### Claim 9 (depends on 8)

The method as claimed in claim 8, wherein a ratio of water and tert-butanol is in a range from 10:90 to 15:85 volumes.

### Claim 10 (depends on 1)

The method as claimed in claim 1 wherein step a) is carried out at a temperature from about 20 to about 100° C. and step b) is carried out at temperature from about 20 to about 80° C.

### Claim 11 (depends on 1)

The method as claimed in claim 1, wherein in the step b) the base comprises an alkali or alkaline earth metal hydroxide, an alkali metal or alkaline earth metal carbonate, an alkaline earth metal oxide, ammonia, or an amine.

### Claim 12 (depends on 1)

The method as claimed in claim 1, wherein said L-glufosinate is obtained as a concentrated aqueous L-glufosinate salt solution.

### Claim 13 (depends on 11)

The method as claimed in claim 11, wherein
a) reacting the glufosinate or its salt the chiral base is with quinine in presence of a catalyst and a solvent to obtain a L-glufosinate quinine tetrahydrate salt;
b) dissolving said L-glufosinate quinine tetrahydrate salt in water and adjusting the pH to 6 to 9 is with ammonia to precipitate the quinine; and
c) removing said precipitated quinine to obtain a L-glufosinate ammonium solution.

### Claim 14 (depends on 1)

The method of claim 1, further comprising adding an agrochemically acceptable excipient to provide a composition.

### Claim 15

A method for obtaining L-glufosinate or salts thereof, said method comprising:
a) reacting glufosinate or its salt with quinine to obtain L-glufosinate quinine tetrahydrate salt;
b) dissolving said L-glufosinate quinine tetrahydrate salt in water and adjusting pH to 6 to 9 with a base to precipitate quinine; and
c) removing said precipitated quinine to obtain L-glufosinate or salts thereof.

### Claim 16 (depends on 15)

The method as claimed in claim 15, wherein a ratio of water:tert-butanol is in the range of 10:90 to 15:85 volumes.