Direct conversion of esters to carboxylate salts

Abstract

Calcium carboxylate is prepared by reacting water, calcium oxide, and a compound of formula (I), wherein R is C1-C3 alkyl and R1 is C1 alkyl or C2 alkyl. The reaction solution is heated to remove a quantity of by-product from the reaction solution. The calcium carboxylate can be recovered from the reaction solution in solid form.

Description

Technical Field

[0001] This invention relates to a method for producing calcium carboxylate directly from esters or acid anhydrides. Background Technology

[0002] Calcium carboxylate can be used to produce the corresponding carboxylic acids. Calcium carboxylate also has other beneficial uses. For example, calcium acetate is used as a thickener, such as in cake batters, puddings, and pie fillings; as a buffer to control the pH of food at multiple stages of processing; as a preservative to prevent microbial growth in finished products; and as a calcium supplement in pet products. Furthermore, calcium propionate is widely used as a preservative in the food industry, particularly in baked goods, and as a preservative and nutritional supplement in animal feed.

[0003] Short-chain fatty acids have recently attracted attention due to their beneficial effects on the gut microbiota. Furthermore, acetates, propionates, butyrates, and lactates, for example, have shown commercially useful antimicrobial properties.

[0004] Calcium carboxylate is typically prepared using conventional methods for synthesizing carboxylate salts, such as by reacting concentrated or dilute carboxylic acids with carbonates, hydroxides, or oxides. For example, calcium propionate is usually produced from propionic acid and calcium.

[0005] Given the wide range of applications for calcium carboxylate, there is a need for improved production methods. In particular, there is a need for improved methods that are rapid, have high yields, consume less energy, and / or generate minimal waste. Summary of the Invention

[0006] This invention relates to a method for converting esters into calcium carboxylate.

[0007] Therefore, one implementation method is to react water, calcium oxide, and a compound of formula (I) to obtain a reaction solution.

[0008]

[0009] Wherein R is a C1-C3 alkyl group and R1 is a C1 alkyl or C2 alkyl group, and the reaction solution is heated to remove a certain amount of byproducts from the reaction solution. Furthermore, calcium carboxylate can be recovered from the reaction solution in solid form.

[0010] Another embodiment is a method for producing calcium propionate, comprising reacting water and calcium oxide to obtain a slurry; reacting the slurry with methyl propionate to obtain a reaction solution, wherein calcium oxide reacts in a molar excess relative to methyl propionate; heating the reaction solution to remove a certain amount of methanol from the reaction solution; neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding sufficient propionic acid; and filtering the reaction solution. Furthermore, calcium propionate can be recovered in solid form from the filtered reaction solution.

[0011] The present invention also relates to a method for converting acid anhydrides into calcium carboxylate.

[0012] Other objects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims.

[0013] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the scope of the claimed invention. Attached Figure Description

[0014] Figure 1 This is an apparatus for converting methyl propionate to calcium propionate. The corresponding reference numerals in the diagram are: methanol tank 8; integrated steam coil 12; condenser 14; three-way valve 16; agitator 18; reactor vessel 20; slurry pump 22; and reflux tower 30. Detailed Implementation

[0015] Although it was expected to contain Ca +2 The insolubility of cationic carboxylates presents a problem, but the inventors have discovered a method to directly convert the ester of formula (I) into calcium carboxylate according to the following reaction:

[0016]

[0017] R and R1 are independently selected from H, Ph, Ar, and substituted C1-C. 60 Alkyl and unsubstituted C1-C 60 alkyl.

[0018] The inventors have also discovered a method for directly converting the anhydride of formula (II) into calcium carboxylate according to the following reaction:

[0019]

[0020] R and R1 are independently selected from H, Ph, Ar, and substituted C1-C. 60 Alkyl and unsubstituted C1-C 60 alkyl.

[0021] C1-C 60 The alkyl group may be substituted with at least one of the following substituents: F, Cl, Br, I, At, O, S, S(O), SO2, N, P, P(O), Si, Si(O), B, Al, and combinations thereof. Suitably, Ar is an optionally substituted C6 or C6 group. 12Aryl or heteroaryl, wherein the heteroatom can be O or N, and the substituents can be selected from H, F, Cl, Br, I, At, SO2, NH2, NHR, NR2, and combinations thereof, wherein R is as defined herein. In C1-C 60 The number of such substituents on the alkyl group can be 1, 2, 3 or 4.

[0022] In another implementation, C1-C 60 Alkyl groups are formed by at least one C l Substituent substitution. In yet another embodiment, C1-C 60 Alkyl groups are formed by two Cs l Substituent substitution.

[0023] In one implementation, R and R1 are independently selected from H and unsubstituted C1-C. 10 Alkyl group. In another embodiment, R and R1 are independently selected from unsubstituted C1-C8 alkyl groups. In yet another embodiment, R and R1 are independently selected from unsubstituted C1-C6 alkyl groups. In yet another embodiment, R and R1 are independently selected from unsubstituted C1-C4 alkyl groups.

[0024] R and R1 can each be an unsubstituted C1 alkyl group. R and R1 can each be an unsubstituted C2 alkyl group. In another embodiment, R is an unsubstituted C2 alkyl group and R1 is an unsubstituted C1 alkyl group. In yet another embodiment, R is an unsubstituted C3 alkyl group and R1 is an unsubstituted C1 alkyl group.

[0025] The compounds of formula (I) and formula (II) may include fewer than ten, eight, six, five, or four carbon atoms. In one embodiment, the compounds of formula (I) and formula (II) include fewer than six carbon atoms.

[0026] Unless otherwise stated, the term "alkyl" refers to a straight-chain or branched, acyclic or cyclic hydrocarbon group or a combination thereof, which may be fully saturated, monounsaturated or polyunsaturated, and may include divalent and polyvalent groups, having a specified number of carbon atoms (e.g., C60, C10, C2 ... 1-10A saturated alkyl group (representing 1 to 10 carbons) can be substituted or unsubstituted. Examples of saturated alkyl groups include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, and homologues and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, n-octyl, etc. Unsaturated alkyl groups are unsaturated alkyl groups having one or more double or triple bonds. Examples of unsaturated alkyl groups include vinyl, 2-propenyl, crotonyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1-propynyl and 3-propynyl, 3-butynyl, and more advanced homologues and isomers.

[0027] The compound of formula (I) can be methyl acetate, ethyl propionate, methyl propionate, or methyl butyrate. In one embodiment, the compound of formula (I) is methyl propionate.

[0028] The compound of formula (II) can be acetic anhydride, propionic anhydride, butyric anhydride, or acetopropionic anhydride. In one embodiment, the compound of formula (II) is acetic anhydride.

[0029] The amount of calcium oxide used in the transformation of the compound of formula (I) can be expressed as the molar ratio of calcium oxide to the compound of formula (I). Generally speaking, calcium oxide in molar excess relative to the compound of formula (I) can be used. The molar ratio of calcium oxide to the compound of formula (I) can be from 0.5:1 to 0.75:1. A stoichiometric excess of calcium oxide relative to the compound of formula (I), i.e., a molar ratio greater than 0.5:1, will result in calcium oxide excess. For example, a molar ratio of 0.75:1 corresponds to a 50% molar excess. The molar ratio of calcium oxide to the compound of formula (I) can be from 0.5:1 to 0.6:1 (calcium oxide excess reaching 20% ​​molar excess). The molar ratio of calcium oxide to the compound of formula (I) can be from about 0.505:1 to about 0.55:1 (molar excess 1% to 10%).

[0030] The amount of calcium oxide used in the conversion of the compound of formula (II) can be expressed as the molar ratio of calcium oxide to the compound of formula (II). More broadly, calcium oxide in molar excess relative to the compound of formula (II) can be used. The molar ratio of calcium oxide to the compound of formula (II) can be from 1:1 to 1.5:1. A stoichiometric excess of calcium oxide relative to the compound of formula (II), i.e., a molar ratio greater than 1:1, will result in calcium oxide excess. For example, a molar ratio of 1.5:1 corresponds to a 50% molar excess. The molar ratio of calcium oxide to the compound of formula (II) can be from 1:1 to 1.2:1 (calcium oxide excess reaching 20% ​​molar excess). The molar ratio of calcium oxide to the compound of formula (II) can be from about 1.01:1 to about 1.1:1 (molar excess 1% to 10%).

[0031] The amount of water used in this method is the amount necessary to form the slurry; those skilled in the art can adjust the amount of water so that it is neither too much to impede the volumetric throughput of the reaction vessel, nor too little to make the slurry immobile, i.e., unable to be mixed and / or pumped. In one embodiment, the amount of calcium hydroxide formed by the reaction of water and calcium oxide is 8% to 10% (w / w). In another embodiment, the amount of calcium hydroxide formed by the reaction of water and calcium oxide is 10% to 30% (w / w). In yet another embodiment, the amount of calcium hydroxide formed by the reaction of water and calcium oxide is 30% to 60% (w / w).

[0032] Calcium oxide, water, and a compound of formula (I) or (II) can react in one or more reaction vessels in any order. For example, calcium oxide and water can react in a first reaction vessel, and then react with a compound of formula (I) or (II) in a second reaction vessel. In another embodiment, the reaction can be carried out in a single reaction vessel. For example, water can be added to a reaction vessel, followed by calcium oxide, and then a compound of formula (I) or (II). Alternatively, calcium oxide can be added to a reaction vessel, followed by water, and then a compound of formula (I) or (II).

[0033] Calcium oxide, water, and one or more of the compounds of formula (I) or (II) may be added over a period of time, rather than in a single large dose. For example, the compound of formula (I) or (II) may be added to the reaction vessel over a period of up to three hours. In one embodiment, the compound of formula (I) or (II) is added to the reaction vessel over a period of 30 to 120 minutes. In yet another embodiment, the compound of formula (I) or (II) is added to the reaction vessel over a period of 30, 45, 60, 90, or 120 minutes.

[0034] The method of the present invention can generally be carried out at a temperature sufficient to allow the reaction to proceed. For example, the reaction temperature can be from 50°C to 100°C. If necessary, the reaction temperature can be maintained by conventional techniques, such as by using heating coils or heating jackets. The reaction time will be the time required to convert the compound of formula (I) or (II) into calcium carboxylate. Typically, the reaction time will vary depending on process parameters, including the reaction temperature and the compound of formula (I) or (II) used. For example, after the reactants have been added, the reaction may be allowed to proceed for 2 to 4 hours, or 2 to 8 hours, or 2 to 12 hours. Depending on the scale of the process and the required capital investment, the process of the present invention can be carried out as a batch, semi-batch, or continuous process.

[0035] After the reaction is complete, a reaction solution comprising calcium carboxylate is obtained. The method also includes the removal of one or more byproducts. For example, the byproducts may be methanol or ethanol. The byproducts may also be propanol or butanol.

[0036] In one embodiment, a certain amount of byproduct can be removed by heating the reaction solution to distill the byproduct topsoil. The temperature at which the reaction solution is heated is any suitable temperature at which the desired amount of byproduct is effectively removed, and such temperature will be apparent to those skilled in the art. For example, the temperature can be from 70°C to 100°C, or it can be from 70°C to 150°C.

[0037] The distillation time period can be set according to the distillation conditions and the desired level of byproducts remaining in the calcium carboxylate product, and this will be apparent to those skilled in the art. In one embodiment, nitrogen gas can be introduced below the surface of the reaction solution to facilitate the distillation process. The distilled byproducts can be pure enough for recovery and reuse. It should be understood that it is impossible to remove all byproducts from the reaction solution, and therefore trace amounts of byproducts will remain as impurities in the reaction solution. In one embodiment, substantially all byproducts are removed from the reaction solution. In some embodiments, the amount of byproducts (e.g., methanol) relative to the calcium carboxylate in the distilled reaction solution is less than 1%, or 0.1%, or 0.01%, or 0.001%, or even undetectable.

[0038] After distillation, it may be necessary to adjust the concentration of calcium carboxylate in the reaction solution based on the amount of water removed during the distillation process. For example, it may be necessary to adjust the concentration to ensure that all calcium carboxylate is in solution, and / or if the final product is a solution. Concentration adjustment can be achieved, for example, by adding additional water or other diluent to the reaction solution. In one embodiment, the concentration of calcium carboxylate is adjusted to 23% to 28% (w / w) by adding water. For example, the concentration of calcium carboxylate can be adjusted to 25% or 26% (w / w) by adding water.

[0039] The reaction solution may optionally be neutralized or optionally filtered. In other words, the reaction solution may be neutralized only, filtered only, both neutralized and filtered, or neither neutralized nor filtered. If neutralization (pH adjustment) and filtration are performed simultaneously, they may be performed in any order.

[0040] For example, after distillation, the reaction solution can be filtered using conventional equipment and techniques to remove excess insoluble calcium oxide, any other impurities that may be adsorbed onto the particle surface, and any other insoluble materials present in the reactants used, such as sand, gravel, pebbles, carbonaceous materials, polymers formed during the reaction, etc. After filtration, the pH can be adjusted with a carboxylic acid corresponding to calcium carboxylate to neutralize the soluble calcium compounds (forming additional calcium carboxylate) and achieve the pH required for the product. For example, the pH can be adjusted to 7.0 to 9.5, 7.0 to 8.0, or 7.5, or 10.0.

[0041] In another embodiment, excess calcium compound is neutralized with a carboxylic acid corresponding to calcium carboxylate. The neutralized reaction solution is then filtered to remove any remaining insoluble matter.

[0042] In yet another embodiment, filtration is not performed. The reaction solution obtained by distillation and optional concentration adjustment is neutralized with a carboxylic acid corresponding to calcium carboxylate to neutralize any excess calcium oxide present.

[0043] Once any filtration and neutralization have been performed, the reaction solution can be further processed, depending on the desired form of the final product, such as a solution product or a solid product. For solution products, the calcium carboxylate product optionally has a concentration adjusted by, for example, adding water or calcium carboxylate, and can be subjected to one or more additional filtrations using, for example, a zeolite filter or an equivalent separation device.

[0044] For solid products, the calcium carboxylate product can be recovered and dried. Recovery and drying can be carried out using any conventional methods known to those skilled in the art. For example, the solution can be dried directly into a powder using a spray dryer or by spraying it onto dry particles in a fluidized bed dryer. In another embodiment, the calcium carboxylate product can be crystallized by water evaporation, collection on a filter or centrifuge, and final drying in any conventional solid dryer used for drying wet solids. In yet another embodiment, the calcium carboxylate solution can be processed by a granulator to produce a granular product.

[0045] The purity of solid calcium carboxylate can be determined according to the standard Ca-EDTA titration method specified in FCC 11 (“Calcium Propionate”, Food Chemicals Codex 11, page 221, US Pharmacopeia, 2018). For example, the purity of solid calcium carboxylate can be greater than 95.0%, greater than 98.0%, greater than 98.5%, greater than 99.0%, greater than 99.5%, or greater than 99.9%.

[0046] Example

[0047] The following examples are not intended to limit the scope of the invention, but rather represent certain implementations of the invention.

[0048] Example 1

[0049] Convert methyl acetate to calcium acetate

[0050] 15.2 g (0.26 mol) of lime (95%; Specialty Minerals, Inc.) was added to a three-necked round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-balanced dropping funnel. A miscible slurry was then prepared by adding sufficient tap water (159.9 g). The temperature of the slurry did not exceed 45°C. Over 1.5 hours, 40.7 g (0.55 mol) of methyl acetate (96.4%; Sekisui) was added dropwise to the stirred slurry. After the addition was complete, the reaction solution was maintained at 60°C for 2 hours, and then the temperature was raised to 70°C to distill the volatile components into a receiver. A total of 26.5 g of distillate was collected over 2 hours. Analysis of the distillate by Karl Fischer titration yielded 11.8 g of water. Gas chromatography analysis of the distillate yielded 11.6 g of methanol (70% recovery) and 3.1 g of unreacted methyl acetate. The remaining contents of the round-bottom flask had a pH of 6.7. Upon cooling, the solid precipitated, was removed by filtration, and dried in an oven to give 37.9 g of calcium acetate (98.3% yield based on 92% conversion), a white solid. The purity was 99.8% as determined by standard Ca-EDTA titration.

[0051] Example 2

[0052] Convert methyl propionate to calcium propionate

[0053] 1600 g of tap water was added to a three-necked round-bottom flask equipped with a heating mantle, a mechanical stirrer, a thermocouple, and a pressure-balanced dropping funnel. Then, 127.7 g (2.28 mol) of lime (95%; SpecialtyMinerals, Inc.) was added dropwise over 6 minutes. Over 0.75 hours, 399 g (4.53 mol) of methyl propionate (99.95%; Lucite) was added dropwise to the stirred slurry. After the addition was complete, the resulting reaction solution was maintained at 60°C for 2 hours and had a pH of 12.2. The pH was adjusted to 7.2 by adding 38.8 g of propionic acid. The temperature of the reaction solution was raised to 95°C to distill the volatile components into a receiver. A total of 575.9 g of distillate was collected over 6 hours. Analysis of the distillate by Karl Fischer titration yielded 426.4 g of water. Gas chromatography analysis of the volatile organic components of the distillate yielded 149.5 g of methanol (103% recovery). The amount of water removed by distillation was calculated to ensure that the remaining contents in the round-bottom flask were a 26% aqueous solution of calcium propionate. This solution was filtered through diatomaceous earth. Upon cooling, the solid precipitated, was removed by filtration, and dried in an oven to give 404.3 g of calcium propionate (95.9% yield) as a white solid. The purity was determined to be 99.8% by standard Ca-EDTA titration.

[0054] Example 3

[0055] Convert methyl acetate to calcium acetate

[0056] 12.8 g (0.2 mol) of lime (95%; Specialty Minerals, Inc.) was added to a three-necked round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-balanced dropping funnel. A miscible slurry was then prepared by adding sufficient tap water (160.1 g). The temperature of the slurry did not exceed 45°C. Over 2 hours, 39.7 g (0.39 mol) of ethyl propionate (99%; Aldrich) was added dropwise to the stirred slurry. After the addition was complete, the reaction solution was maintained at 85°C for 2 hours, and then the temperature was raised to 95°C to distill the volatile components into a receiver. A total of 52.3 g of distillate was collected over 4 hours. Analysis of the distillate by Karl Fischer titration yielded 35.3 g of water. Analysis of the volatile organic components of the distillate by gas chromatography yielded 17 g of ethanol (95% recovery). No unreacted ethyl propionate was detected. The solid was removed from the round-bottom flask by filtration and dried in an oven to give 30.4 g of essentially pure calcium propionate (yield 84%) as a white solid.

[0057] Example 4

[0058] Convert methyl butyrate to calcium butyrate.

[0059] 12.7 g (0.2 mol) of lime (95%; Specialty Minerals, Inc.) was added to a three-necked round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-balanced dropping funnel. A miscible slurry was then prepared by adding sufficient tap water (160.1 g). The temperature of the slurry did not exceed 45 °C. Over 2 hours, 40 g (0.39 mol) of methyl butyrate (99%; Aldrich) was added dropwise to the stirred slurry. After the addition was complete, the reaction solution was maintained at 85 °C for 2 hours, and then the temperature was raised to 100 °C to distill the volatile components into a receiver. A total of 36.8 g of distillate was collected over 5 hours. Analysis of the distillate by Karl Fischer titration yielded 23.5 g of water. Analysis of the volatile organic components of the distillate by gas chromatography yielded 13.3 g of methanol (105% recovery). No unreacted methyl butyrate was detected. The solid was removed from the round-bottom flask by filtration and dried in an oven to give 34.3 g of essentially pure calcium butyrate (yield 94%) as a white solid.

[0060] Example 5

[0061] Large-scale conversion of methyl propionate to calcium propionate

[0062] A lime slurry was prepared in a 55-gallon polypropylene tank equipped with a stirrer by adding 12.8 kg of lime (95%; Specialty Minerals, Inc.) to 131.9 kg of tap water. This slurry mixture was pumped into a jacketed 50-gallon fiberglass reactor equipped with a stirrer and a condenser. Then, over 0.75 hours, 36.9 kg of methyl propionate (99.95%; Lucite) was added to the reactor. After the addition was complete, the reaction solution was maintained at 65°C for 1 hour. The temperature of the reaction solution was kept below 65°C, and the final pH was adjusted from 11.3 to 7.8 by adding 0.9 kg of propionic acid. When the temperature reached 100°C, nitrogen gas was introduced below the liquid surface at a rate of 50 SCFH to distill off volatile components via a condenser and into a receiving vessel. After 6 hours of distillation, a total of 111.5 kg of distillate was collected, which, upon analysis, consisted of 96.4 kg of water, 13.4 kg of methanol (100% recovery), and 1.7 kg of unreacted methyl propionate. The volatiles removed by distillation were calculated to ensure that the remaining contents of the reactor were a 25% aqueous solution of calcium propionate. This solution was filtered through diatomaceous earth. The solution was found to contain 38.8 kg of calcium propionate (99.5% yield), and its purity was determined to be 99.8% by standard Ca-EDTA titration.

[0063] Example 6

[0064] Conversion of acetic anhydride to calcium acetate

[0065] 15 g (0.25 mol) of lime (95%; Specialty Minerals, Inc.) was added to a three-necked round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-balanced dropping funnel. A miscible slurry was then prepared by adding sufficient tap water (159.9 g). The temperature of the slurry did not exceed 65°C. Over 2 hours, 24.9 g (0.24 mol) of acetic anhydride (99%; Fisher) was added dropwise to the stirred slurry. After the addition was complete, the reaction solution was maintained at 70°C for 4 hours. Subsequently, the final pH of the reaction solution was 12, and sufficient acetic acid was added to lower the pH to 7.0. HPLC analysis of the reaction solution showed that it was a substantially pure aqueous solution of calcium acetate. Water was removed by evaporation to give 38.1 g of dried calcium acetate (98.8% yield), a substantially pure white solid.

[0066] Example 7

[0067] Transformation System

[0068] The reactor system in this embodiment is Figure 1 As shown in the diagram. The system comprises a 50-gallon reaction vessel 20. Water and calcium oxide react in a separate vessel (not shown), and a slurry is added to reaction vessel 20. A slurry pump 22 and a three-way valve 16 allow the slurry to be recirculated through and back to reaction vessel 20 to ensure complete slurry formation. Methyl propionate (MEP) is fed into reaction vessel 20. The contents of reaction vessel 20 are mixed using a stirrer 18. Propionic acid is added to reaction vessel 20 to neutralize any remaining calcium hydroxide.

[0069] The reactor contents are heated using an integrated steam coil 12. Water and methanol vapors generated during the heating of the contents in reaction vessel 20 can be condensed at the top of reflux tower 30 and returned from condenser 14 to methanol tank 8. Methanol and water can be recycled to the next consecutive batch. Once the methanol is removed, the calcium propionate solution is transferred to a drum filter via slurry pump 22. A three-way valve 16 can be turned to pump the reactor contents from reaction vessel 20 to the plant, instead of recirculating them back into reaction vessel 20.

[0070] This invention may also be described in the following terms numbered:

[0071] 1. A method for producing calcium propionate, comprising:

[0072] a. React water and calcium oxide to obtain a slurry;

[0073] b. React the slurry with methyl propionate to obtain a reaction solution, wherein the calcium oxide reacts in an amount that is molar excess relative to the methyl propionate;

[0074] c. Heating the reaction solution to remove a certain amount of methanol from the reaction solution;

[0075] d. Neutralize the reaction solution to a pH of 7.0 to 9.5 by adding sufficient propionic acid; and

[0076] e. Filter the reaction solution.

[0077] 2. The method according to Clause 1 further includes adding nitrogen gas to the reaction solution during heating.

[0078] 3. The method according to Clause 1 further includes recovering the calcium propionate in solid form from the filtered reaction solution.

[0079] 4. The method according to Clause 3, wherein the purity level of the solid calcium propionate is 98.5% or higher, as measured by Ca-EDTA titration.

[0080] 5. The method according to Clause 1, wherein the pH is 7.0 to 8.0.

[0081] 6. The method according to Clause 1, wherein the filtered reaction solution contains 23% to 28% (w / w) calcium propionate.

[0082] 7. A method for producing calcium carboxylate, comprising:

[0083] a. React water, calcium oxide, and the compound of formula (Ⅰ) to obtain a reaction solution.

[0084]

[0085] in

[0086] R is a C1-C3 alkyl group, and

[0087] R1 is a C1 alkyl or a C2 alkyl;

[0088] b. Heating the reaction solution to remove a certain amount of byproducts from the reaction solution; and

[0089] c. Filter the reaction solution.

[0090] 8. The method according to Clause 7, wherein the calcium oxide is reacted in an excess amount relative to the molar excess of the compound of Formula (I).

[0091] 9. The method according to Clause 7, wherein the compound of formula (I) is methyl propionate.

[0092] 10. The method according to Clause 7, wherein the compound of formula (I) is ethyl propionate, methyl butyrate or methyl acetate.

[0093] 11. The method according to Clause 7 further includes adding nitrogen gas to the reaction solution during heating.

[0094] 12. The method according to Clause 7 further includes recovering the calcium carboxylate in solid form from the filtered reaction solution.

[0095] 13. The method according to Clause 12, wherein the purity level of the solid calcium carboxylate is 98.5% or higher, as measured by Ca-EDTA titration.

[0096] 14. The method according to Clause 7 further comprises neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding sufficient acid.

[0097] 15. The method according to Clause 14, wherein the pH is 7.0 to 8.0.

[0098] 16. The method according to Clause 7, wherein the filtered reaction solution contains 23% to 28% (w / w) calcium carboxylate.

[0099] 17. The method according to Clause 7, wherein the compound of formula (I) has fewer than 6 carbon atoms.

[0100] 18. A method for producing calcium carboxylate, comprising:

[0101] a. React water, calcium oxide, and the compound of formula (Ⅰ) to obtain a reaction solution.

[0102]

[0103] in

[0104] R is a C1-C3 alkyl group, and

[0105] R1 is a C1 or C2 alkyl group; and

[0106] b. Heating the reaction solution to remove a certain amount of byproducts from the reaction solution.

[0107] 19. The method according to Clause 18, wherein the compound of formula (I) is methyl propionate.

[0108] 20. The method according to Clause 18 further includes recovering the calcium carboxylate in solid form from the reaction solution by heating.

Claims

1. A method of producing calcium propionate, the method comprising: a. reacting water and calcium oxide to obtain a slurry; b. reacting the slurry with methyl propionate to obtain a reaction solution, wherein the calcium oxide is reacted in a molar excess relative to methyl propionate; c. heating the reaction solution to remove an amount of methanol from the reaction solution; d. neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding propionic acid; e. filtering the reaction solution; and f. recovering the calcium propionate in solid form from the filtered reaction solution; wherein the purity level of the solid calcium propionate is greater than 95.0%.

2. The method of claim 1, further comprising adding nitrogen gas to the reaction solution during heating of the reaction solution.

3. The method of claim 1, wherein the purity level of the solid calcium propionate is 98.5% or greater.

4. The method of any one of claims 1 to 3, wherein the pH is 7.0 to 8.

0.

5. The method of any one of claims 1 to 3, wherein the filtered reaction solution comprises 23% to 28% (w / w) calcium propionate.

6. The method of any one of claims 1 to 3, wherein step b. is performed at a temperature of 50 °C to 100 °C.

7. A method of producing a calcium carboxylate, comprising: a. reacting water, calcium oxide, and a compound of formula (I) to obtain a reaction solution, wherein R is C1-C3 alkyl, and R1is C1 alkyl or C2 alkyl; b. heating the reaction solution to remove an amount of a byproduct from the reaction solution; c. filtering the reaction solution; and d. recovering the calcium carboxylate in solid form from the filtered reaction solution; wherein the purity level of the solid calcium carboxylate is greater than 95.0%.

8. The method of claim 7, wherein the compound of formula (I) has fewer than 6 carbon atoms.

9. The method of claim 7 or 8, wherein the compound of formula (I) is methyl propionate.

10. The method of claim 7 or 8, wherein the compound of formula (I) is ethyl propionate, methyl butyrate, or methyl acetate.

11. The method of claim 7 or 8, further comprising adding nitrogen gas to the reaction solution during heating of the reaction solution.

12. The method of claim 7, wherein the purity level of the solid calcium carboxylate is 98.5% or greater.

13. The method of claim 7 or 8, further comprising neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding an acid.

14. The method of claim 13, wherein the pH is 7.0 to 8.

0.

15. The method of claim 7 or 8, wherein the filtered reaction solution comprises 23% to 28% (w / w) calcium carboxylate.

16. The method of claim 7 or 8, wherein step a. is performed at a temperature of 50 °C to 100 °C.

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