Direct conversion of esters to carboxylic acids

Abstract

The calcium carboxylate is prepared by reacting water, calcium oxide and a compound of formula (I). [Formula 1] JPEG2023541962000008.jpg17153 where R is a C1-C3 alkyl and R1 is a C1 or C2 alkyl. The reaction solution is heated to remove a certain amount of by-products from the reaction solution. The calcium carboxylate may be recovered in a solid state from the reaction solution.

Description

[Technical Field]

[0001] The present invention relates to a process for producing calcium carboxylates directly from their esters or anhydrides. [Background technology]

[0002] Calcium carboxylates are useful in the production of the corresponding carboxylic acids. They also have other beneficial uses. For example, calcium acetate is used as a thickener in cake batters, puddings, pie fillings, etc.; as a buffer to control the pH of foods at various stages of processing, as well as in the finished product; as a preservative to prevent microbial growth; and as a calcium supplement in pet products. Furthermore, calcium propionate is used extensively in the food industry, especially as a preservative in baked goods, and as a preservative and dietary supplement in animal feed.

[0003] Short-chain fatty acids have recently been attracting attention for their beneficial effects on the intestinal microflora, and acetate, propionate, butyrate, and lactate salts have shown commercially useful antibacterial properties.

[0004] Calcium carboxylates are typically prepared by conventional methods for synthesizing carboxylates, such as by reacting a carbonate, hydroxide, or oxide with concentrated or diluted carboxylic acid. For example, calcium propionate is commonly made from propionic acid and calcium.

[0005] Because calcium carboxylates have many diverse uses, there is a need for improved processes for their production, particularly improved processes that can be carried out quickly, provide high yields, consume little energy, and / or minimize waste. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is directed to a method for converting an ester into a calcium carboxylate. [Means for solving the problem]

[0007] Thus, one aspect of the present invention is a method of reacting water, calcium oxide and a compound of formula (I). [ka] wherein R is a C1-C3 alkyl, R1 is a C1 or C2 alkyl, a reaction solution is obtained, and the reaction solution is heated to remove a certain amount of by-products from the reaction solution. Alternatively, calcium carboxylate may be recovered in a solid form from the reaction solution.

[0008] Another aspect of the present invention is a method for producing calcium propionate, comprising reacting water with calcium oxide to obtain a slurry, reacting the slurry with methyl propionate to obtain a reaction solution, 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 a sufficient amount of propionic acid, and filtering the reaction solution, wherein the calcium oxide is reacted in a molar excess amount relative to the methyl propionate. Alternatively, the calcium propionate may be recovered in solid form from the filtered reaction solution.

[0009] Additionally, the present invention is directed to a method for converting an anhydride to a calcium carboxylate.

[0010] Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

[0011] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. [Brief explanation of the drawings]

[0012] [Figure 1] This is an apparatus for converting methyl propionate into calcium propionate. DETAILED DESCRIPTION OF THE INVENTION

[0013] Ca +2 Although the insolubility of cation-containing carboxylates was expected to be a problem, the inventors have discovered a process for directly converting the esters of formula (I) to calcium carboxylates according to the following reaction: [ka] where R and R are independently H, Ph, Ar, substituted C1-C 60 Alkyl and unsubstituted C1-C 60 alkyl.

[0014] The present inventors have also discovered a process for directly converting the anhydride of formula (II) into calcium carboxylate according to the following reaction: [ka] where R and R are independently H, Ph, Ar, substituted C1-C 60 Alkyl and unsubstituted C1-C 60 alkyl.

[0015] C1~C 60 The alkyl may be substituted with at least one substituent selected from the group consisting of F, Cl, Br, I, At, O, S, S(O), SO, N, P, P(O), Si, Si(O), B, Al, and combinations thereof. Preferably, Ar is C or C 12 C1-C are aryl or optionally substituted heteroaryl groups, where the heteroatom is O or N, and the substituents may be selected from the group consisting of H, F, Cl, Br, I, At, SO2, NH2, NHR, NR2, and combinations thereof, where R is as defined herein.60 The number of such substituents substituted on the alkyl may be one, two, three or four.

[0016] In another embodiment of the present invention, C1 to C 60 The alkyl is substituted with at least one Cl substituent. 60 The alkyl is substituted with two Cl substituents.

[0017] In one embodiment, R and R are independently selected from H and unsubstituted C-C 10 In other embodiments, R and R1 are independently selected from the group consisting of unsubstituted C1-C8 alkyl. In yet other embodiments, R and R1 are independently selected from the group consisting of unsubstituted C1-C6 alkyl. In yet other embodiments, R and R1 are independently selected from the group consisting of unsubstituted C1-C4 alkyl.

[0018] R and R1 may each be an unsubstituted C1 alkyl. R and R1 may each be an unsubstituted C2 alkyl. In other embodiments, R is an unsubstituted C2 alkyl and R1 is an unsubstituted C1 alkyl. In yet other embodiments, R is an unsubstituted C3 alkyl and R1 is an unsubstituted C1 alkyl.

[0019] The compound of formula (I) and the compound of formula (II) may contain less than 10, 8, 6, 5, or 4 carbon atoms. In one embodiment, the compound of formula (I) and the compound of formula (II) contain less than 6 carbon atoms.

[0020] The term "alkyl," unless otherwise specified, means straight- or branched-chain, acyclic or cyclic hydrocarbon groups, or combinations thereof, which may be fully saturated, mono- or polyunsaturated, and which can include divalent and polyvalent radicals, and which have a specified number of carbon atoms (e.g., C 1-10means 1 to 10 carbon atoms), and may be substituted or unsubstituted. Examples of saturated hydrocarbon groups include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, and homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, and n-octyl. Unsaturated alkyl groups are those containing one or more double or triple bonds. Examples of unsaturated alkyl groups include vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl, 3-butynyl, and the higher homologs and isomers.

[0021] The compound of formula (I) may be methyl acetate, ethyl propionate, methyl propionate, or methyl butanoate. In one embodiment, the compound of formula (I) is methyl propionate.

[0022] The compound of formula (II) can be acetic anhydride, propionic anhydride, butanoic anhydride, or propionic acetic anhydride. In one embodiment, the compound of formula (II) is acetic anhydride.

[0023] The amount of calcium oxide used in the conversion of the compound of formula (I) can be expressed as a molar ratio of calcium oxide to the compound of formula (I). Generally, a molar excess of calcium oxide can be used relative to the compound of formula (I). 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, results in excess calcium oxide. 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 (up to a 20% molar excess of calcium oxide). The molar ratio of calcium oxide to the compound of formula (I) can be from about 0.505:1 to about 0.55:1 (1% to 10% molar excess).

[0024] 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). Broadly speaking, a molar excess of calcium oxide relative to the compound of formula (II) can be used. The molar ratio of calcium oxide to the compound of formula (II) can be 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 excess calcium oxide. 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 1:1 to 1.2:1 (up to a 20% molar excess of calcium oxide). The molar ratio of calcium oxide to the compound of formula (II) can be about 1.01:1 to about 1.1:1 (1% to 10% molar excess).

[0025] The amount of water used in this method is the amount necessary to form a slurry. One skilled in the art can adjust the amount of water so that it is not too much and would destroy the volumetric throughput of the reaction vessel, and so that it is not too little and the slurry becomes immobile, i.e., unable to be mixed, and / or unable to be pumped. In one embodiment, the amount of calcium hydroxide formed from the reaction of water with calcium oxide is 8% to 10% (w / w: weight percent concentration). In another embodiment, the amount of calcium hydroxide formed from the reaction of water with calcium oxide is 10% to 30% (w / w: weight percent concentration). In yet another embodiment, the amount of calcium hydroxide formed from the reaction of water with calcium oxide is 30% to 60% (w / w: weight percent concentration).

[0026] The calcium oxide, water, and compound of Formula (I) or (II) can be reacted in any order in one or more reaction vessels. For example, calcium oxide and water can be reacted in a first reaction vessel, followed by reaction with a compound of Formula (I) or (II) in a second reaction vessel. In another embodiment, the reaction can occur in a single reaction vessel. For example, water can be added to a single reaction vessel, followed by calcium oxide, followed by the compound of Formula (I) or (II). Alternatively, calcium oxide, followed by water, followed by the compound of Formula (I) or (II) can be added to a single reaction vessel.

[0027] The 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 addition. For example, the compound of Formula (I) or (II) may be added to the reaction vessel over a period of up to 3 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.

[0028] The process of the present invention is generally carried out at a temperature sufficient to allow the reaction to proceed. For example, the reaction temperature may be between 50°C and 100°C. The reaction temperature may be maintained, if necessary, by conventional techniques, such as the use of a heating coil or mantle. The reaction time is a time suitable to obtain the desired conversion of the compound of Formula (I) or (II) to calcium carboxylate. Generally, 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 addition of the reactants is complete, 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 capital investment required, the process of the present invention can be carried out as a batch, semi-batch, or continuous process.

[0029] After completion of the reaction to obtain a reaction solution containing calcium carboxylate, the process further includes removing an amount of one or more by-products. The by-products may be, for example, methanol or ethanol. The by-products may also be propanol or butanol.

[0030] In one embodiment, a certain amount of by-products can be removed by heating the reaction solution to distill off the indirect by-products. The reaction solution can be heated to a suitable temperature effective to remove the desired amount of by-products, which would be readily apparent to one skilled in the art. The temperature can be, for example, 70°C to 100°C, or 70°C to 150°C.

[0031] The time cycle for distillation can be set depending on the distillation conditions and the desired level of residual by-products in the calcium carboxylate product, and will be readily apparent to one skilled in the art. In one embodiment, nitrogen gas may be introduced below the liquid level of the reaction solution to aid in the distillation process. The distilled by-product may be sufficiently pure to be recovered and reused. It should be understood that it is not possible to remove all amounts of co-products from the reaction solution, and trace amounts of by-products may still be present in the reaction solution as impurities. In one embodiment, substantially all by-products are removed from the reaction solution. In some embodiments, the amount of co-products, such as methanol, is less than 1%, or less than 0.1%, or less than 0.01%, or less than 0.001%, or even undetectable, relative to the calcium carboxylate in the reaction solution after distillation.

[0032] After distillation is complete, it may be necessary to adjust the concentration of the calcium carbonate in the reaction solution depending on the amount of water removed during distillation. For example, concentration adjustment may be necessary to ensure that all of the calcium carbonate is in solution and / or to adjust the concentration of the calcium carbonate if the final product is a solution. Concentration adjustment may be performed, for example, by adding additional water or other diluent to the reaction solution. In one embodiment, the calcium carbonate concentration is adjusted to 23% to 28% (w / w: weight percent concentration) by adding water. The calcium carbonate concentration can be adjusted to, for example, 25% or 26% (w / w: weight percent concentration) by adding water.

[0033] The reaction solution may be neutralized as needed and may be filtered as needed. In other words, the reaction solution may be neutralized only, filtered only, neutralized and filtered, or may not be neutralized or filtered. When neutralization (pH adjustment) and filtration are performed, they may be performed in either order.

[0034] As an example, the reaction solution may be filtered using conventional equipment and techniques after distillation to remove excess insoluble calcium oxide, other impurities that may be adsorbed onto particle surfaces, other insoluble materials present in the reactants used, sand, gravel, pebbles, carbonaceous materials, polymers, etc. formed during the reaction. After filtration, the pH may be adjusted with a carboxylic acid corresponding to the calcium carbonate to neutralize soluble calcium compounds (forming additional calcium carboxylate) and reach the desired pH of the product. The pH may be adjusted to, for example, 7.0 to 9.5, 7.0 to 8.0, or 7.5, or 10.0.

[0035] In another embodiment, the excess calcium compound is neutralized with a carboxylic acid corresponding to the calcium carboxylate, and the neutralized reaction solution is then filtered to remove any remaining insoluble matter.

[0036] In yet another embodiment, no filtration is performed. The reaction solution resulting from distillation and any concentration adjustment is neutralized with a carboxylic acid corresponding to the calcium carboxylate in order to neutralize any excess calcium oxide present.

[0037] Once the filtration and neutralization operations have been carried out, the reaction solution may be further processed depending on the form of the desired final product, e.g., a solution product or a solid product. In the case of a solution product, the calcium carboxylate product may optionally have its concentration adjusted, e.g., by adding water or calcium carboxylate, and may be subjected to one or more additional filtrations, e.g., using a polishing filter or equivalent separation device.

[0038] For solid products, the calcium carboxylate product may be recovered and dried. The recovery and drying may be carried out using any conventional process known to those skilled in the art. For example, the solution may be dried directly to a powder using a spray dryer or by spraying onto dry particles in a fluidized bed dryer. In another embodiment, the calcium carboxylate product may be crystallized by evaporation of the water, collection in a filter or centrifuge, and final drying in any conventional solids dryer used to dry wet solids.

[0039] The purity of the solid calcium carboxylate can be determined according to the standard Ca-EDTA titration method described in FCC 11 ("Calcium Propionate", Food Chemicals Codex 11, p. 221, US Pharmacopeia, 2018). The purity of the solid calcium carboxylate may be, for example, greater than 95.0%, greater than 98.0%, greater than 98.5%, greater than 99.0%, or greater than 99.5%, or greater than 99.9%. [Example]

[0040] The present invention is not limited to the following examples, which represent specific embodiments of the invention. Example 1 <Conversion of methyl acetate to calcium acetate>

[0041] To a three-neck round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-equalizing dropping funnel, 15.2 g (0.26 mol) of lime (95%; Specialty Minerals) was added, followed by sufficient tap water (159.9 g) to form a mixable slurry. The temperature of the slurry did not exceed 45°C. To this stirred slurry, 40.7 g (0.55 mol) of methyl acetate (96.4%; Sekisui) was added dropwise over 1.5 hours. After the addition was complete, the reaction solution was held at 60°C for 2 hours, then the temperature was raised to 70°C and the volatiles were distilled into a receiver. A total of 26.5 g of distillate was collected over 2 hours. Analysis of this distillate by Karl Fischer titration gave 11.8 g of water. Gas chromatography of the volatile organic components of the distillate gave 11.6 g of methanol (70% recovery) and 3.1 g of unreacted methyl acetate. The pH of the remaining contents of the round-bottom flask was 6.7. Upon cooling, a solid precipitated, which was removed by filtration and dried in an oven to give 37.9 g of calcium acetate as a white solid (98.3% yield based on 92% conversion). Analysis by standard Ca-EDTA titration gave a purity of 99.8%. Example 2 <Conversion of methyl propionate to calcium propionate>

[0042] A three-neck round-bottom flask, placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-equalizing dropping funnel, was charged with 1600 g of tap water, followed by 127.7 g (2.28 mol) of lime (95%; Specialty Minerals) added over 6 minutes. To this stirred slurry, 399 g (4.53 mol) of methyl propionate (99.95%; Lucite thermoplastic acrylic resin) was added dropwise over 0.75 hours. After the addition was complete, the resulting reaction solution was maintained at 60°C for 2 hours, with a pH of 12.2. 38.8 g of propionic acid was added to adjust the pH to 7.2. The temperature of the reaction solution was raised to 95°C, and volatiles were distilled into a receiver. A total of 575.9 g of distillate was collected over 6 hours. Analysis of this distillate by Karl Fischer titration gave 426.4 g of water. Analysis of the distillate for volatile organic components by gas chromatography yielded 149.5 g of methanol (103% recovery). The removal of water by distillation was calculated to confirm that the remaining contents of the round-bottom flask were a 26% aqueous solution of calcium propionate. The solution was filtered through diatomaceous earth. Upon cooling, a solid precipitated, which was removed by filtration and oven-dried to give 404.3 g of calcium propionate (95.9% yield) as a white solid. Analysis by standard Ca-EDTA titration gave a purity of 99.8%. Example 3 <Conversion of ethyl propionate to calcium propionate>

[0043] To a three-neck round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-equalizing dropping funnel, 12.8 g (0.2 mol) of lime (95%; Specialty Minerals) was added, followed by sufficient tap water (160.1 g) to form a mixable slurry. The temperature of the slurry did not exceed 45°C. To this stirred slurry, 39.7 g (0.39 mol) of ethyl propionate (99%; Aldrich) was added dropwise over 2 hours. After the addition was complete, the reaction solution was held at 85°C for 2 hours, after which the temperature was raised to 95°C and the volatiles were distilled into the receiver. A total of 52.3 g of distillate was collected over 4 hours. Analysis of this distillate gave 35.3 g of water by Karl Fischer titration. Gas chromatography of the volatile organic components of the distillate 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 (84% yield) as a white solid. Example 4 <Conversion of methyl butanoate to calcium butanoate>

[0044] To a three-neck round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-equalizing dropping funnel, 12.7 g (0.2 mol) of lime (95%; Specialty Minerals) was added, followed by sufficient tap water (160.1 g) to form a mixable slurry. The temperature of the slurry did not exceed 45°C. To this stirred slurry, 40 g (0.39 mol) of methyl butanoate (99%; Aldrich) was added dropwise over 2 hours. After the addition was complete, the reaction solution was held at 85°C for 2 hours, after which the temperature was raised to 100°C and the volatiles were distilled into the receiver. A total of 36.8 g of distillate was collected over 5 hours. Analysis of this distillate by Karl Fischer titration revealed 23.5 g of water. Gas chromatography of the volatile organic components of the distillate yielded 13.3 g of methanol (105% recovery). No unreacted methylbutanoic acid 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 butanoate (94% yield) as a white solid. Example 5 Large-scale conversion of methyl propionate to calcium propionate

[0045] A lime slurry was prepared in a 55-gallon (1 gallon = 3.785 liters) polypropylene tank equipped with an agitator by adding 12.8 kg of lime (95%; Specialty Minerals) to 131.9 kg of tap water. This mixed slurry was pumped to a 50-gallon, jacketed, glass-lined steel reactor equipped with an agitator and a condenser. 36.9 kg of methyl propionate (99.95%; Lucite thermoplastic acrylic resin) was then added to the reactor over 0.75 hours. After the addition was complete, the reaction solution was held at 65°C for 1 hour. The temperature of the reaction solution did not exceed 65°C, and the final pH was adjusted from 11.3 to 7.8 by adding 0.9 kg of propionic acid. As the temperature increased to 100°C, nitrogen gas was introduced below the liquid surface at a rate of 50 SCFH (Standard Cubic Foot per Hour), distilling volatile components through the condenser into a receiving vessel. After 6 hours of distillation, a total of 111.5 kg of distillate was collected and analyzed, revealing 96.4 kg of water, 13.4 kg of methanol (100% recovery), and 1.7 kg of unreacted methyl propionate. The distillation volatile removal was calculated to confirm that the remaining reactor contents were a 25% aqueous solution of calcium propionate. The solution was filtered through diatomaceous earth. The solution was found to contain 38.8 kg of calcium propionate (99.5% yield) of 99.8% purity as determined by standard Ca-EDTA titration. Example 6 <Conversion of acetic anhydride to calcium acetate>

[0046] To a three-neck round-bottom flask placed in a heating mantle and equipped with a mechanical stirrer, a thermocouple, and a pressure-equalizing dropping funnel, 15 g (0.25 mol) of lime (95%; Specialty Minerals) was added, followed by sufficient tap water (159.9 g) to create a mixable slurry. The temperature of the slurry did not exceed 65°C. To this stirred slurry, 24.9 g (0.24 mol) of acetic anhydride (99%; Fisher) was added dropwise over 2 hours. After this addition was complete, the reaction solution was maintained at 70°C for 4 hours. After this time, the final reaction solution had a pH of 12, and sufficient acetic acid was added to lower the pH to 7.0. Analysis of the reaction solution by high-performance liquid chromatography (HPLC) indicated an essentially pure aqueous solution of calcium acetate. The water was removed by evaporation to yield 38.1 g of dry calcium acetate (98.8% yield) as an essentially pure white solid. Example 7 <Conversion System>

[0047] The reactor system for this example is shown in Figure 1. The system includes a 50-gallon reactor vessel 20. Water and calcium oxide are reacted in a separate vessel (not shown) and the resulting slurry is added to the reactor vessel 20. A slurry pump 22 and a three-way valve 16 allow the slurry to be recirculated to and back into the reactor vessel 20 to ensure complete slurry formation. Methyl propionate (MEP) is fed to the reactor vessel 20. The contents of the reactor vessel 20 are mixed using an agitator 18. Propionic acid is added to the reactor 20 to neutralize any residual calcium hydroxide.

[0048] The reactor contents are heated using integral steam coil 12. Water and methanol vapors produced as the contents of reactor vessel 20 are heated are condensed at the top of reflux column 30 and returned to methanol tank 8 via condenser 14. The methanol and water may be recycled to the next successive batch. Once the methanol is removed, the calcium propionate solution is transferred to a drum filter by slurry pump 22. Three-way valve 16 can be turned to pump the reactor contents from reactor vessel 20 to the plant instead of being recycled to reactor vessel 20.

[0049] The invention is also described in the following numbered clauses: 1. Step (a) of reacting water with calcium oxide to obtain a slurry; (b) reacting the slurry with methyl propionate, the calcium oxide being in molar excess relative to the methyl propionate to obtain a reaction solution; (c) heating the reaction solution to remove methanol from the reaction solution; (d) neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding a sufficient amount of propionic acid; Step (e) of filtering the reaction solution; A method for producing calcium propionate comprising the steps of: 2. In clause 1 above: The method for producing calcium propionate further comprises adding nitrogen gas to the reaction solution while heating the reaction solution. 3. In clause 1 above: The method for producing calcium propionate further comprises recovering the calcium propionate in solid form from the filtered reaction solution. 4. In clause 3 above: A method for producing calcium propionate, wherein the solid calcium propionate has a purity level of 98.5% or more as measured by Ca-EDTA titration. 5. In clause 1 above: A method for producing calcium propionate, wherein the pH in the step (d) is 7.0 to 8.0. 6. In clause 1 above: A method for producing calcium propionate, wherein the filtered reaction solution in step (e) contains 23% to 28% (w / w: weight percent concentration) of calcium propionate. 7. Step (a) of reacting water, calcium oxide and a compound of formula (I) to obtain a reaction solution; [ka] (b) heating the reaction solution to remove a quantity of by-products from the reaction solution; Step (c) of filtering the reaction solution. and R in the formula (I) is C1-C3 alkyl, A method for producing calcium carboxylate wherein R1 in formula (I) is C1 or C2 alkyl. 8. In clause 7 above: A method for producing a calcium carboxylate, comprising reacting said calcium oxide in a molar excess relative to said compound of formula (I). 9. In clause 7 above: A method for producing calcium carboxylate, wherein the compound of formula (I) is methyl propionate. 10. In clause 7 above: A method for producing calcium carboxylate, wherein the compound of formula (I) is any one of ethyl propionate, methyl butyrate, and methyl acetate. 11. In clause 7 above: The method for producing calcium carboxylate further comprises adding nitrogen gas to the reaction solution while heating the reaction solution. 12. In clause 7 above: The method for producing calcium carboxylate, further comprising recovering solid calcium carboxylate from the filtered reaction solution. 13. In clause 12 above: A method for producing calcium carboxylate, wherein the solid calcium carboxylate has a purity level of 98.5% or more as measured by Ca-EDTA titration. 14. In clause 7 above: The method for producing calcium carboxylate further comprises neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding a sufficient amount of acid. 15. In clause 14 above: The method for producing calcium carboxylate, wherein the pH is 7.0 to 8.0. 16. In clause 7 above: The filtered reaction solution contains 23% to 28% (w / w: weight percent concentration) of calcium carboxylate. 17. In clause 7 above: A method for producing a calcium carboxylate, wherein the compound of formula (I) has less than 6 carbon atoms. 18. Step (a) of reacting water, calcium oxide and a compound of formula (I) to obtain a reaction solution; [ka] (b) heating the reaction solution to remove a quantity of by-products from the reaction solution; and R in the formula (I) is C1-C3 alkyl, A method for producing calcium carboxylate wherein R1 in formula (I) is C1 or C2 alkyl. 19. In clause 18 above: A method for producing calcium carboxylate, wherein the compound of formula (I) is methyl propionate. 20. In clause 18 above: The method for producing a calcium carboxylate further comprises recovering solid calcium carboxylate from the reaction solution after heating. [Explanation of symbols]

[0050] 8 Methanol Tank 12 Integrated steam coil 14 Condenser 16 Three-way valve 18 Stirrer 20 reaction vessel 22 Slurry pump 30 Reflux tower

Claims

1. Step (a) of reacting water with calcium oxide to obtain a slurry; (b) reacting the slurry with methyl propionate, the calcium oxide being in molar excess relative to the methyl propionate to obtain a reaction solution; (c) heating the reaction solution to remove methanol from the reaction solution; (d) neutralizing the reaction solution to a pH of 7.0 to 9.5 by adding propionic acid; Step (e) of filtering the reaction solution; a step (f) of recovering calcium propionate from the reaction solution filtered in the step (e); Calcium propionate production method comprising the steps of:

2. In claim 1, 1. A method for producing calcium propionate, further comprising adding nitrogen gas to the reaction solution while heating the reaction solution.

3. In claim 1 or 2, The method for producing calcium propionate, wherein the step (f) is a step of recovering the calcium propionate in a solid state from the filtered reaction solution.

4. In claim 3, A method for producing calcium propionate, wherein the solid calcium propionate has a purity level of 98.5% or more.

5. In claim 1 or 2, A method for producing calcium propionate, wherein the pH in the step (d) is 7.0 to 8.

0.

6. In claim 1 or 2, 2. A method for producing calcium propionate, wherein the filtered reaction solution in step (e) contains 23% to 28% (w / w: weight percent concentration) of calcium propionate.

7. In claim 1 or 2, Calcium propionate is produced by the method of claim 1, wherein the step (b) is carried out at a temperature of 50°C to 100°C.

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