Process for preparation of 5-chloro-2-((ethoxycarbonyl) amino)-3-methylbenzoic acid

Abstract

Described herein are methods of synthesizing 5-chloro-2-((ethoxycarbonyl) amino)-3-methylbenzoic acid and derivatives thereof.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 330,813, filed on April 14, 2022. Technical Field

[0003] The present disclosure relates to methods for synthesizing 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and its derivatives. The compounds prepared by the methods disclosed herein are particularly useful for preparing certain anthranilamide compounds of interest as insecticides, such as, for example, the insecticides chlorantraniliprole and cyantraniliprole. Background Art

[0004] The present disclosure provides novel methods that can be used to prepare 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and its derivatives. Methods for preparing 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid are known in the art, such as those described in U.S. Patent Application No. 8,153,844. However, these known methods are expensive and wasteful.

[0005] In this known process, chlorine is produced on site from 30% hydrogen peroxide and 37% hydrochloric acid. The reaction rate is controlled by the dosage rate of hydrogen peroxide. Typically, the reaction is carried out in acetic acid solution at 30°C-35°C for 3-5 hours. After the reaction, the product is obtained by diluting the reaction mixture with a large amount of water, thus generating a large amount of waste water. Acetic acid remains in the waste water and is difficult to recover.

[0006] The benefits of the disclosed processes are numerous and include improved waste reduction, recovery and / or recycling of solvents, and cost reduction compared to conventional processes. Summary of the invention

[0007] In one aspect, there is provided a method for preparing a compound having formula (II)

[0008]

[0009] Where R 3 It is CH3 or Cl;

[0010] R 4 is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and

[0011] X is Cl or Br, the method comprising:

[0012] (I) forming a mixture comprising:

[0013] A) Compounds having formula (I)

[0014]

[0015] Where R 1 is CH3 or Cl; and

[0016] R 2 is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and

[0017] B) an aqueous solvent, wherein the aqueous solvent is present at a concentration of less than or equal to about 90% v / v;

[0018] (II) introducing a halogenating agent into the mixture;

[0019] (III) optionally removing the halogenating agent from the mixture; and

[0020] (IV) Optionally cooling the mixture to a temperature in the range of from about 0°C to about 5°C. DETAILED DESCRIPTION

[0021] Described herein is a method for the synthesis of 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and its derivatives.

[0022] Embodiments of the present disclosure include:

[0023] Example 1. A method for preparing a compound having formula (II)

[0024]

[0025] Where R 3 is CH3 or Cl;

[0026] R 4 is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and

[0027] X is Cl or Br, the method comprising:

[0028] (I) forming a mixture comprising:

[0029] A) Compounds having formula (I)

[0030]

[0031] Where R 1 is CH3 or Cl; and

[0032] R 2is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and

[0033] B) an aqueous solvent, wherein the aqueous solvent is present at a concentration of less than or equal to about 90% v / v;

[0034] (II) introducing a halogenating agent into the mixture;

[0035] (III) optionally removing the halogenating agent from the mixture; and

[0036] (IV) optionally cooling the mixture to a temperature in the range of from about 0°C to about 5°C.

[0037] Embodiment 2. The method of embodiment 1, wherein R3 and X are each Cl.

[0038] Embodiment 3. The method as described in any one of embodiments 1-2, wherein R 3 is CH3 and X is Cl.

[0039] Embodiment 4. The method as described in any one of embodiments 1-3, wherein R 4 It is a C1-C2 alkyl group.

[0040] Embodiment 5. The method of any one of embodiments 1-4, wherein R 1 It is CH3.

[0041] Embodiment 6. The method of any one of embodiments 1-5, wherein R 2 It is a C1-C2 alkyl group.

[0042] Embodiment 7. The method of any one of embodiments 1-6, wherein R 3 is CH3, X is Cl, and R 4 It is ethyl.

[0043] Embodiment 8. The method of any one of embodiments 1-7, wherein the aqueous solvent is present at a concentration of less than or equal to about 85% v / v.

[0044] Embodiment 9. The method of any one of embodiments 1-8, wherein the aqueous solvent is present at a concentration of less than or equal to about 80% v / v.

[0045] Embodiment 10. The method of any one of embodiments 1-9, wherein the aqueous solvent is an aqueous solution of acetic acid.

[0046] Embodiment 11. The method of any one of embodiments 1-10, wherein the aqueous solvent does not contain hydrogen peroxide.

[0047] Embodiment 12. The method of any one of embodiments 1-11, wherein the aqueous solvent comprises recovered and / or recycled aqueous solvent.

[0048] Embodiment 13. The method of any one of embodiments 1-12, wherein the halogenating agent is a chlorinating agent or a brominating agent.

[0049] Embodiment 14. The method of any one of embodiments 1-13, wherein the halogenating agent is selected from the group consisting of Cl2, Br2, and combinations thereof.

[0050] Embodiment 15. The method of any one of embodiments 1-14, wherein the method step of introducing a halogenating agent into the mixture comprises introducing the halogenating agent into the mixture at a temperature in the range of about 0°C to about 35°C.

[0051] Embodiment 16. The method of any one of embodiments 1-15, wherein the method step of removing the halogenating agent from the mixture comprises bubbling N2 through the mixture.

[0052] Embodiment 17. The method of any one of embodiments 1-16, wherein the method produces a solid product, and wherein the method further comprises the steps of filtering and / or washing the solid product.

[0053] Embodiment 18. The method of any one of embodiments 1-18, wherein the method further comprises a method step of recovering and / or recycling the aqueous solvent.

[0054] Embodiment 19. The method of embodiment 19, wherein the method step of recovering and / or recycling the aqueous solvent recovers and / or recycles at least 50% v / v of the aqueous solvent.

[0055] Embodiment 20. The method of embodiment 18, wherein the method step of recovering and / or recycling the aqueous solvent recovers and / or recycles at least 75% v / v of the aqueous solvent.

[0056] Embodiment 21. The method of any one of embodiments 1-20, wherein the method further comprises a step of recovering and / or recycling the mother liquor.

[0057] Embodiment 22. A method as described in Embodiment 21, wherein the method step of recovering and / or recycling the mother liquor recovers and / or recycles at least 50% v / v of the mother liquor.

[0058] Embodiment 23. A method as described in Embodiment 21, wherein the method step of recovering and / or recycling the mother liquor recovers and / or recycles at least 80% v / v of the mother liquor.

[0059] In one aspect, 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid is prepared according to the method represented by Scheme 1.

[0060] Solution 1.

[0061]

[0062] In one aspect, compounds having Formula II are prepared according to the method represented by Scheme 2. The R groups and X are as defined anywhere in the disclosure.

[0063] Solution 2.

[0064]

[0065] This aspect includes forming a mixture comprising a compound having Formula I and an aqueous solvent, introducing a halogenating agent to the mixture, optionally removing the halogenating agent from the mixture, and optionally cooling the mixture to a temperature in the range of from about 0°C to about 5°C.

[0066] In some embodiments, the reaction of the mixture is complete after the reaction time has expired.

[0067] In some embodiments, the aqueous solvent is an aqueous solution of acetic acid. In some embodiments, the aqueous solvent does not contain hydrogen peroxide. In some embodiments, the aqueous solvent comprises a recovered and / or recycled aqueous solvent.

[0068] Generally, any suitable amount of acetic acid can be used in the solvent. In many embodiments, the amount and / or concentration of acetic acid is relatively low to reduce acetic acid usage and waste.

[0069] In certain embodiments, the aqueous solvent is a mother liquor. In certain embodiments, the aqueous solvent is a mother liquor recovered and / or recycled. In these embodiments, the mother liquor is an aqueous solvent, an optional residual product from an earlier reaction, and an optional mixture of impurities from an earlier reaction. In many embodiments, recovery from the mother liquor of an earlier reaction and in subsequent reactions, it is recycled as an aqueous solvent to allow reduction in waste and to improve productivity.

[0070] In some embodiments, the aqueous solvent is present at a concentration less than or equal to about 90% v / v, about 85% v / v, or about 80% v / v. In some embodiments, the aqueous solvent is present at a concentration ranging from about 80% v / v to about 85% v / v.

[0071] In some embodiments, the aqueous solvent is present in the mother liquor at a concentration of less than or equal to about 90% v / v, about 85% v / v, or about 80% v / v. In some embodiments, the aqueous solvent is present in the mother liquor at a concentration ranging from about 80% v / v to about 85% v / v.

[0072] In certain embodiments, halogenating agent is chlorinating agent or brominating agent. In certain embodiments, halogenating agent is gaseous halogenating agent. In certain embodiments, halogenating agent is gaseous chlorinating agent or gaseous brominating agent. In certain embodiments, halogenating agent is selected from the group consisting of gaseous Cl2, gaseous Br2, liquid Br2 and combinations thereof. In certain embodiments, gaseous halogenating agent is blasted into mixture. In certain embodiments, gaseous halogenating agent is blasted into mixture in the time period of about 1,2,3,4,5 or 6 hours. In certain embodiments, gaseous halogenating agent is blasted into mixture in the time period of about 1-6,2-5 or 2-4 hours. In certain embodiments, halogenating agent is selected from the group consisting of gaseous Cl2, gaseous Br2 and combinations thereof, and blasted into mixture. In certain embodiments, gaseous halogenating agent is blasted into mixture in the time period of about 2 hours.

[0073] In some embodiments, when the halogenating agent is a liquid halogenating agent, the liquid halogenating agent is added to the mixture by dropwise addition.

[0074] In some embodiments, the halogenating agent does not comprise hydrochloric acid. In some embodiments, the halogenating agent does not comprise concentrated hydrochloric acid.

[0075] In some embodiments, the method step of introducing a halogenating agent to the mixture comprises introducing the halogenating agent to the mixture at a temperature in the range of about 0°C to about 35°C.

[0076] In some embodiments, the method step of removing the halogenating agent from the mixture comprises bubbling an inert gas through the mixture. In some embodiments, the method step of removing the halogenating agent from the mixture comprises bubbling N2 through the mixture.

[0077] In some embodiments, the method produces a solid product, and the method further comprises a method step of filtering and / or washing the solid product. In some embodiments, the method step of filtering and / or washing the solid product comprises washing the solid product with a solution comprising acetic acid and / or water.

[0078] In some embodiments, the method further comprises a method step of recovering and / or recycling the aqueous solvent. In some embodiments, the method step of recovering and / or recycling the aqueous solvent recovers and / or recycles at least about 50% v / v, at least about 55% v / v, at least about 60% v / v, at least about 65% v / v, at least about 70% v / v, at least about 75% v / v, at least about 80% v / v, at least about 85% v / v, at least about 90% v / v, at least about 95% v / v, or about 100% v / v of the aqueous solvent.

[0079] In some embodiments, the method further comprises a method of recovering and / or recycling the step of mother liquor. In some embodiments, the method step of recovering and / or recycling mother liquor recovers and / or recycles at least about 50% v / v, at least about 55% v / v, at least about 60% v / v, at least about 65% v / v, at least about 70% v / v, at least about 75% v / v, at least about 80% v / v, at least about 85% v / v, at least about 90% v / v, at least about 95% v / v, or about 100% v / v of mother liquor.

[0080] In some embodiments, the method includes forming a mixture comprising a compound having formula I and an optionally recycled aqueous solvent, wherein the aqueous solvent is present at a concentration of less than or equal to about 90% v / v; introducing a gaseous halogenating agent into the mixture; reacting the mixture at a temperature ranging from about 20°C to about 35°C; cooling the mixture to a temperature ranging from about 0°C to about 5°C; filtering and washing the mixture; and recovering a compound having formula II in the form of a wet cake. After the filtering and washing steps, a small portion of the mother liquor is optionally subjected to a stripping step to recover acetic acid. The recovered acetic acid is optionally recycled in a further reaction. Also after the filtering and washing steps, a large portion of the mother liquor is optionally recycled in a further reaction.

[0081] In some embodiments, the method includes forming a mixture comprising a compound having formula I and an optionally recycled aqueous solvent, wherein the aqueous solvent is present at a concentration of less than or equal to about 90% v / v; introducing a gaseous halogenating agent into the mixture; reacting the mixture at a temperature ranging from about 20°C to about 35°C; removing the gaseous halogenating agent from the mixture by bubbling N2 through the mixture; cooling the mixture to a temperature ranging from about 0°C to about 5°C; filtering and washing the mixture; and recovering a compound having formula II in the form of a wet cake. After the filtering and washing steps, the cake is optionally slurried with water to produce a first portion of wet cake. Also after the filtering and washing steps, the mother liquor is optionally subjected to a stripping step at -20°C to 60°C to recover acetic acid, and subsequent cooling and filtering and washing steps to further recover acetic acid and produce a second portion of wet cake. The recovered acetic acid is optionally recycled in a further reaction. The first portion of wet cake and the second portion of wet cake are optionally combined.

[0082] Examples

[0083] Without further elaboration, it is believed that those skilled in the art can make the most of the present invention using the previous description. Therefore, the following examples should be interpreted as being illustrative only and not limiting the present disclosure in any way. The starting materials of the following examples may not necessarily be prepared by specific preparation runs, and their procedures are described in other examples. It should also be understood that any numerical ranges listed herein include all values ​​from the lower limit to the upper limit. For example, if the range is specified as 10-50, it is expected that values ​​such as 12-30, 20-40 or 30-50 are explicitly listed in this specification. These are only examples of specific intent, and all possible combinations of numerical values ​​between the lowest and highest values ​​listed (and including their lowest and highest values) will be considered to be clearly stated in the present application.

[0084] Comparative Example 1. Chlorination with hydrochloric acid.

[0085] 120g of anhydrous 2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and 420g of acetic acid were added to a 1L flask equipped with a condenser, a thermometer and a dropping funnel. The mixture was stirred and heated to 35°C-40°C until all solids dissolved. The mixture was then cooled to about 30°C. Next, 124g of 37% hydrochloric acid was added to the mixture and 77g of 30% hydrogen peroxide solution was added over a period of 3 hours. After addition, the mixture was stirred for another 2 hours until the reaction was complete. 1000g of water was added dropwise to the mixture over a period of 2 hours at 30°C-35°C, and the product appeared as white crystals during the water addition process. The mixture was cooled to 20°C-25°C and the product was obtained by filtration and subsequent water washing. About 124g of 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid product was obtained with a yield of about 90%.

[0086] Example 1. Chlorination with chlorine gas.

[0087] 120 g of 2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and 465 g of about 83% acetic acid were added to a 1 L flask equipped with a condenser, a thermometer and a gas inlet tube. Chlorine was gradually bubbled into the mixture at 0°C-35°C over a period of 2 hours, and solids disappeared as the temperature increased during the bubbling process. At the end of the gas bubbling stage, some product appeared as white crystals. After the reaction was complete, the reaction mixture was bubbled with nitrogen to remove excess chlorine. The reaction mixture was cooled to 0°C-5°C and stirred for another 2 hours. The first portion of the product was obtained by filtration and subsequent 80% acetic acid washing and water washing. The filtrate was concentrated to about 20% volume at 40°C-50°C under reduced pressure. The residual solution was cooled to 0°C-5°C again, and then the second portion of the product was obtained by filtration and subsequent 80% acetic acid washing and water washing. The combined yield of 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid product was about 92%.

[0088] Example 2. Chlorination with chlorine gas and recycle.

[0089] At room temperature, 120 g of 2-((ethoxycarbonyl)amino)-3-methylbenzoic acid and 465 g of about 83% acetic acid were added to a 1 L flask equipped with a condenser, a thermometer and a gas inlet tube. Chlorine was bubbled into the mixture over a period of 2 hours at 0°C-35°C, and solids disappeared as the temperature increased during the bubbling process. At the end of the gas bubbling stage, some products appeared as white crystals. After the reaction was complete, the reaction mixture was bubbled with nitrogen to remove excess chlorine. The reaction mixture was cooled to 0°C-5°C and stirred for another 2 hours. The first portion of the product was obtained by filtering and subsequent 80% acetic acid washing and water washing. The productive rate of 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid product in the first batch of product was about 80%.

[0090] The filtrate was used as solvent for the next batch, and after the same reaction on the same scale and the above recrystallization process, the second batch gave more product. The yield of 5-chloro-2-((ethoxycarbonyl)amino)-3-methylbenzoic acid product in the second batch was about 95%.

[0091] The filtrate of the second batch can also be recycled in the third, fourth and fifth batches. The average yield of the first to fifth batches is about 90%-91%.

[0092] The disclosed method reduces the amount of wastewater by about 80%. The disclosed method also reduces the use of acetic acid by about 80%-85%. Therefore, the disclosed method is particularly beneficial for reducing costs and waste.

[0093] This written description uses examples to illustrate the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[0094] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," "characterized by," or any other variation thereof, are intended to cover a non-exclusive inclusion, subject to any limitation expressly stated. For example, a composition, mixture, process, or method that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, mixture, process, or method.

[0095] The transitional phrase "consisting of" excludes any unrecited element, step, or ingredient. If in a claim, this phrase will make the claim closed, excluding materials other than those recited, except for impurities normally associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the preamble, the phrase limits only the elements recited in that clause; the claim as a whole does not exclude other elements.

[0096] The conjunction "consisting essentially of" is used to define compositions or methods that include materials, steps, features, components or elements other than those literally disclosed, provided that these additional materials, steps, features, components or elements do not materially affect the basic and novel characteristics of the claimed invention. The term "consisting essentially of" is intermediate between "comprising" and "consisting of."

[0097] When an invention or a portion thereof is defined by an open-ended term such as "comprising," it should be readily understood that (unless otherwise indicated) the description should be interpreted as also using the term "consisting essentially of" or "consisting of" to describe such an invention.

[0098] In addition, unless expressly stated to the contrary, "or" refers to an inclusive or rather than an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0099] In addition, the indefinite article "a and an" before an element or component of the present invention is intended to be non-restrictive with respect to the number of instances (i.e., occurrences) of the element or component. Therefore, "a or an" should be understood to include one or at least one, and the singular word form of an element or component also includes the plural, unless the number obviously means the singular.

[0100] As used herein, the term "about" means plus or minus 10% of the value.

[0101] The term "alkyl", used alone or in compound words such as "alkylthio" or "haloalkyl", includes straight or branched chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, or the different butyl, pentyl, or hexyl isomers.

[0102] The term "alkenyl" may include straight or branched olefins such as 1 propenyl, 2 propenyl, and the different butenyl, pentenyl and hexenyl isomers. "Alkenyl" also includes polyenes such as 1,2 propadienyl and 2,4 hexadienyl.

[0103] The term "halogen", alone or in compound words such as "haloalkyl", includes fluorine, chlorine, bromine or iodine.

[0104] The total number of carbon atoms in a substituent is represented by "C i -C j " prefix represents, wherein i and j are numbers from 1 to 8. For example, C1-C3 alkylsulfonyl represents methylsulfonyl to propylsulfonyl.

[0105] When a group contains a substituent which may be hydrogen, for example R 4 When the substituent is regarded as hydrogen, this is considered to be equivalent to the group being unsubstituted.

[0106] Certain compounds of the present invention may exist as one or more stereoisomers. Various stereoisomers include enantiomers, diastereomers, atropisomers and geometric isomers. It will be appreciated by those skilled in the art that a stereoisomer may be more active and / or may exhibit beneficial effects when enriched relative to one or more other stereoisomers, or when separated from one or more other stereoisomers. In addition, those skilled in the art know how to separate, enrich and / or selectively prepare the stereoisomers.

Claims

1. A method for preparing a compound having formula (II) Where R 3 It is CH3 or Cl; R 4 is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and X is Cl or Br, the method comprising: (I) forming a mixture comprising: A) Compounds having formula (I) Where R 1 is CH3 or Cl; and R 2 is C1-C6 alkyl or C3-C6 alkenyl, each optionally substituted with up to 3 halogens and up to 1 phenyl; and B) an aqueous solvent, wherein the aqueous solvent is present at a concentration of less than or equal to about 90% v / v; (II) introducing a halogenating agent into the mixture; (III) optionally removing the halogenating agent from the mixture; and (IV) optionally cooling the mixture to a temperature in the range of from about 0°C to about 5°C.

2. The method of claim 1, wherein: R 3 and X are each Cl.

3. The method according to any one of claims 1 to 2, wherein: R 3 is CH3 and X is Cl.

4. The method according to any one of claims 1 to 3, wherein: R 4 It is a C1-C2 alkyl group.

5. The method according to any one of claims 1 to 4, wherein: R 1 It is CH3.

6. The method according to any one of claims 1 to 5, wherein: R 2 It is a C1-C2 alkyl group.

7. The method according to any one of claims 1 to 6, wherein: R 3 is CH3, X is Cl, and R 4 It is ethyl.

8. The method according to any one of claims 1 to 7, wherein: The aqueous solvent is present at a concentration of less than or equal to about 85% v / v.

9. The method according to any one of claims 1 to 8, wherein: The aqueous solvent is present at a concentration of less than or equal to about 80% v / v.

10. The method according to any one of claims 1 to 9, wherein: The aqueous solvent is an aqueous solution of acetic acid.

11. The method according to any one of claims 1 to 10, wherein: The aqueous solvent does not contain hydrogen peroxide.

12. The method according to any one of claims 1 to 11, wherein: The aqueous solvent comprises recovered and / or recycled aqueous solvent.

13. The method according to any one of claims 1 to 12, wherein: The halogenating agent is a chlorinating agent or a brominating agent.

14. The method according to any one of claims 1 to 13, wherein: The halogenating agent is selected from Cl2, Br2, and combinations thereof.

15. The method according to any one of claims 1 to 14, wherein: The method step of introducing the halogenating agent to the mixture comprises introducing the halogenating agent to the mixture at a temperature in the range of about 0°C to about 35°C.

16. The method according to any one of claims 1 to 15, wherein: This process step of introducing the halogenating agent comprises bubbling gaseous Cl2 or Br2.

17. The method of claim 16, wherein: This process step of introducing the halogenating agent comprises bubbling gaseous Cl2 or Br2 over a period of about 1, 2, 3, 4, 5 or 6 hours.

18. The method according to any one of claims 1 to 17, wherein: The process step of removing the halogenating agent from the mixture comprises bubbling N2 through the mixture.

19. The method according to any one of claims 1 to 18, wherein: The process produces a solid product, and wherein the process further comprises the process steps of filtering and / or washing the solid product.

20. The method of any one of claims 1 to 19, wherein: The method further comprises a method step of recovering and / or recycling the aqueous solvent.

21. The method of any one of claims 1 to 20, wherein: The method further comprises the step of recovering and / or recycling the mother liquor.

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