A method for preparing propionate

Abstract

This invention provides a method for preparing propionate, the method comprising: reacting propionate and metal hydroxide in the presence of water and an organic solvent at a temperature of 50-130°C; wherein the weight ratio of the organic solvent to water is 1:1.2-10; the method of this invention is not only simple in procedure and convenient in operation, but also has high conversion rate and reaction selectivity of propionate, and the obtained propionate has high purity.

Description

Technical Field

[0001] This invention relates to the field of propionate preparation technology, and in particular to a method for preparing propionate. Background Technology

[0002] Propionates, including sodium propionate, calcium propionate, and ammonium propionate, are safe and reliable food and feed preservatives approved by the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO). They are widely used in agriculture, food, medicine, and textile industries. Propionates have advantages such as high temperature resistance, non-volatility, unaffected by other components in feed, low corrosivity, low irritation, and suitability for long-term feed storage. They overcome many shortcomings of propionic acid as a direct preservative, such as: 1) propionic acid has a low boiling point (79℃) and is easily volatile; 2) propionic acid is rapidly lost during feed storage, resulting in a short duration of efficacy, which is not conducive to long-term feed preservation; 3) propionic acid is easily neutralized by proteins in feed, thus reducing or eliminating its activity. Therefore, in the application of edible preservatives, propionates are recognized as the most economical, safe, and effective edible preservatives, and are widely used as preservatives and anti-mold agents in pastries, soy products, canned goods processing, and beer production. In addition, propionates such as sodium propionate, calcium propionate, and ammonium propionate can be used as silage preservatives and are widely used in cattle, sheep, and poultry feed. In the textile industry, propionates are used as masking agents in leather making to improve the alkali resistance and tanning uniformity of leather.

[0003] Currently, propionate is mainly produced through a neutralization reaction of propionic acid with sodium hydroxide, sodium carbonate, or calcium hydroxide. However, the production process of propionic acid is relatively complex. First, propionaldehyde is produced by hydroformylation of ethylene under the catalysis of rhodium and cobalt metal complexes at 70-150℃ and 2-100 atm pressure. The resulting propionaldehyde is then oxidized to propionic acid under the catalysis of manganese, cobalt, vanadium, etc., at 40-45℃ and 3-7 atm pressure. The overall process is lengthy and requires high equipment investment.

[0004] CN108191637A discloses a method for synthesizing sodium propionate, specifically a method for producing sodium propionate under slurry conditions using solid sodium carbonate and liquid propionic acid. Sodium carbonate and propionic acid are added to a reaction vessel and mixed, then stirred at high speed to form a slurry for direct reaction, yielding a sodium propionate product with quality and properties comparable to those produced by conventional processes.

[0005] US10239813B2 discloses a method for producing calcium dipropionate in a batch process within a single pressure-resistant reaction vessel. Calcium oxide, calcium hydroxide, calcium carbonate, or a mixture thereof are added to the reaction vessel. Then, pure, high-concentration propionic acid is added to the solid feedstock, and the mixture is heated to a maximum temperature of 160°C. After a reaction time of 3–6 hours, pure calcium dipropionate with a water content of less than 1% is obtained. However, this method involves a relatively long reaction temperature and time. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a method for preparing propionate. The method for preparing propionate provided by this invention has a simple process flow, is easy to operate, and has low production costs. Moreover, the method of this invention can achieve high yield and purity of propionate. At the same time, the method of this invention has high propionate conversion rate and propionate selectivity.

[0007] The objective of this invention is mainly achieved through the following technical solutions.

[0008] In a first aspect, the present invention provides a method for preparing propionate, the method comprising: reacting propionate and metal hydroxide in the presence of water and an organic solvent at a temperature of 50-130°C.

[0009] The weight ratio of the organic solvent to water is 1:1.2-10.

[0010] The organic solvent is selected from at least one of alcohols, ketones, nitriles and ethers.

[0011] Preferably, the temperature is 50-110℃, more preferably 50-70℃.

[0012] Preferably, the contact reaction time is 1-10 hours, more preferably 1-3 hours.

[0013] Preferably, the contact reaction is carried out under stirring, and the stirring speed is preferably 300-1000 rpm, more preferably 500-1000 rpm, and even more preferably 500-700 rpm.

[0014] Preferably, the weight ratio of the organic solvent to the propionate ester is 1:0.1-2, more preferably 1:0.5-1.

[0015] Preferably, the weight ratio of the organic solvent to water is 1:1.2-5, more preferably 1:1.5-2.5.

[0016] Preferably, the molar ratio of the propionate ester to the metal hydroxide is 1:1-10, more preferably 1:1.2-5, and even more preferably 1:1.7-2.

[0017] Preferably, the alcohol is a monohydric alcohol with 1-16 carbon atoms, more preferably a monohydric alcohol with 1-8 carbon atoms.

[0018] Preferably, the organic solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isooctyl alcohol, acetone, and acetonitrile.

[0019] Preferably, the metal hydroxide is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and zinc hydroxide.

[0020] Preferably, the propionate is selected from one of methyl propionate, ethyl propionate, butyl propionate and isooctyl propionate.

[0021] Preferably, the pH value at the endpoint of the contact reaction is >7, and more preferably, the pH value at the endpoint of the reaction is 7-12.

[0022] Preferably, the method further includes: concentrating, crystallizing and filtering the reaction solution obtained after the contact reaction, and drying the filtered product to obtain crude propionate.

[0023] Preferably, the reaction solution is concentrated to less than 1 / 3 of its original volume.

[0024] Preferably, the pore size of the filter membrane used for filtration is 1-10 μm, and more preferably 3-5 μm.

[0025] Preferably, the drying method is selected from at least one of vacuum drying, spray drying, freeze drying, and infrared drying.

[0026] The method for preparing propionate according to the present invention has the following advantages:

[0027] (1) The propionate can be prepared by direct hydrolysis at a lower temperature using the method of the present invention. The process is simple and convenient.

[0028] (2) It has a high propionate yield and purity;

[0029] (3) Using the preparation method of the present invention, a high propionate conversion rate and propionate selectivity were obtained. Detailed Implementation

[0030] The present invention provides a method for preparing propionate, the method comprising: reacting propionate and metal hydroxide in contact at a temperature of 50-130°C in the presence of water and an organic solvent;

[0031] The weight ratio of the organic solvent to water is 1:1.2-10;

[0032] The organic solvent is selected from at least one of alcohols, ketones, nitriles and ethers.

[0033] In this invention, the reaction of propionate ester and metal hydroxide to produce propionate in a system containing both water and an organic solvent at 50-130°C exhibits higher propionate conversion and selectivity. Analysis suggests that the different polarities of propionate and metal hydroxide solutions, coupled with their varying solubilities in a single-solvent reaction system, make it difficult to mix propionate and sodium hydroxide uniformly, resulting in poor contact reaction and low yield. Typically, higher reaction temperatures are required to drive the reaction, leading to increased energy consumption and, more importantly, increased byproducts, further reducing selectivity and product purity. The method of this invention uses water and an organic solvent to form a homogeneous reaction system, significantly improving the conversion rate and product yield of propionate ester and metal hydroxide at a lower reaction temperature. Furthermore, the controlled low reaction temperature greatly reduces byproduct formation, improving reaction selectivity and product purity.

[0034] In this invention, the conversion rate of propionate refers to the proportion of the amount of propionate that participated in the reaction after the reaction to the total amount of propionate before the reaction; that is, conversion rate = (weight of propionate before reaction - weight of propionate after reaction) ÷ weight of propionate before reaction × 100%.

[0035] In this invention, selectivity refers to the ratio of the amount of propionate that generates propionate to the amount of propionate that participates in the reaction; that is, selectivity = amount of propionate that generates propionate ÷ amount of propionate that participates in the reaction × 100%.

[0036] In this invention, the purity of propionate refers to the proportion of the mass of the generated propionate to the total mass of the generated product.

[0037] In this invention, yield refers to the ratio of the actual amount of product generated to the theoretical amount of product generated, i.e., yield = actual amount of product generated ÷ theoretical amount of product generated × 100%.

[0038] In a preferred embodiment of the present invention, the temperature is 50-110℃, preferably 50-70℃. Using this preferred temperature ensures higher conversion rate and selectivity while further reducing energy consumption.

[0039] In this invention, the degree of reaction increases with the extension of time. However, when the conversion rate of propionate reaches a certain level, it is difficult to achieve a significant improvement even if the time is extended further. Instead, it leads to an increase in by-products and increases production costs.

[0040] In a preferred embodiment of the present invention, the contact reaction time is 1-10 hours, preferably 1-3 hours; using this preferred reaction time not only ensures a high conversion rate and selectivity, but also saves reaction time and reduces the amount of by-products.

[0041] In a preferred embodiment of the present invention, the contact reaction is carried out under stirring, and the stirring speed is 300-1000 rpm, preferably 500-1000 rpm, and more preferably 500-700 rpm.

[0042] In a preferred embodiment of the present invention, the weight ratio of the organic solvent to the propionate ester is 1:0.1-2, preferably 1:0.5-1. Using this preferred weight ratio of organic solvent to propionate ester effectively improves the solubility of propionate ester in the reaction system formed by water and organic solvent, while ensuring that the metal hydroxide maintains good solubility as the reaction proceeds, thereby improving the conversion rate and reaction selectivity of propionate ester.

[0043] In a preferred embodiment of the present invention, the weight ratio of the organic solvent to water is 1:1.2-5, more preferably 1:1.5-2.5. Using this preferred weight ratio of organic solvent to water can effectively improve the solubility of the metal hydroxide and propionate in the water and organic solvent system, enabling the metal hydroxide and propionate to have better contact reaction effects, and further improving the conversion rate and reaction selectivity of the propionate.

[0044] In this invention, the molar amount of metal hydroxide is in excess relative to the molar amount of propionate, which ensures that the reaction system is alkaline and promotes the hydrolysis reaction of propionate. To further promote the hydrolysis reaction of propionate, and in a preferred embodiment, the molar ratio of propionate to metal hydroxide is 1:1-10, preferably 1:1.2-5, and more preferably 1.7-2.

[0045] In a preferred embodiment of the present invention, the weight ratio of the metal hydroxide to water is 1:1-15, preferably 1:2-5. This preferred weight ratio of metal hydroxide to water effectively maintains the good solubility of the metal hydroxide in the reaction system formed by water and organic solvent, allowing for better contact reaction between the metal hydroxide and propionate ester, further improving the conversion rate and reaction selectivity of the propionate ester.

[0046] In a more preferred embodiment of the present invention, the alcohol is a monohydric alcohol having 1-16 carbon atoms, more preferably a monohydric alcohol having 1-8 carbon atoms.

[0047] In this invention, propionate ester is hydrolyzed to form the corresponding alcohol. In a preferred embodiment, the organic solvent is the same as the alcohol obtained after hydrolysis of propionate ester. This preferred embodiment can further improve the conversion rate and reaction selectivity of propionate ester.

[0048] In a more preferred embodiment of the present invention, the organic solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isooctanol, acetone, and acetonitrile, more preferably methanol and / or ethanol. Using methanol and / or ethanol can achieve higher propionate conversion and reaction selectivity. The inventors' analysis shows that the combined action of methanol and / or ethanol with water is more conducive to improving the solubility of metal hydroxide and propionate in the water and organic solvent reaction system, thereby promoting the contact reaction effect between the two. Further research revealed that when the organic solvent and the alcohol produced after hydrolysis of propionate are the same, the conversion rate and reaction selectivity of propionate are further improved.

[0049] In a preferred embodiment of the present invention, the metal hydroxide is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and zinc hydroxide; preferably, it is selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide, and more preferably, it is sodium hydroxide and / or potassium hydroxide.

[0050] In a preferred embodiment of the present invention, the alcohol providing the hydroxyl group in the propionate contains a substituted or unsubstituted C1-C. 10 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C 6- C 30 One of the aryl groups. The C1-C 10 This refers to C3-C having 1-10 carbon atoms. 12 and C6-C 30 Similarly.

[0051] In a preferred embodiment of the present invention, the propionate is selected from one of methyl propionate, ethyl propionate, butyl propionate and isooctyl propionate, preferably methyl propionate or ethyl propionate.

[0052] In this invention, the propionate ester generally has a high purity, such as 99% or higher. However, the technical solution of this invention is also applicable to propionate esters with lower purity. In a preferred embodiment, the propionate ester has a purity of ≥95%, preferably ≥99%.

[0053] In this invention, the propionate ester can be derived from the product of propionate esterification or prepared by ethylene carbonylation. The propionate esterification method refers to the esterification of propionic acid to produce propionate ester.

[0054] In this invention, the contact reaction is carried out under alkaline conditions. In order to further improve the conversion rate and reaction selectivity of propionate, it is necessary to maintain the alkaline conditions of the reaction system throughout the reaction process. In a preferred embodiment, the pH value of the reaction endpoint of the contact reaction is >7, and preferably the pH value of the reaction endpoint is 7-12.

[0055] In this invention, it is necessary to separate the propionate obtained from the reaction solution to obtain the propionate product. The separation method is not particularly limited; filtration and / or centrifugation can be selected, with filtration being preferred. In a preferred embodiment, the method further includes: concentrating, crystallizing, and filtering the reaction solution obtained after the contact reaction, and drying the filtered product to obtain crude propionate. In this invention, the reaction solution is concentrated to less than 1 / 3 of its original volume; the concentration temperature is controlled at 50-130℃, preferably 50-90℃, during the concentration process. Any known method in the art can be used to concentrate and crystallize the propionate reaction solution to separate the crude propionate product. The volume of the concentrated reaction solution can be controlled experimentally or theoretically to ensure complete precipitation of propionate while minimizing or eliminating the precipitation of impurities.

[0056] In this invention, the filtration method is not particularly limited, and suction filtration, pressure filtration or centrifugal filtration can be selected.

[0057] In a preferred embodiment of the present invention, the pore size of the filter membrane used for filtration is 1-10 μm, preferably 3-5 μm.

[0058] In a preferred embodiment of the present invention, the drying method is selected from at least one of vacuum drying, spray drying, freeze drying and infrared drying, preferably spray drying.

[0059] In this invention, the propionate ester can also be prepared by the manufacturer, and the preparation method of the propionate ester includes:

[0060] Step (1): Mix the palladium catalyst, ligand, acid and ethylene evenly in the solvent system;

[0061] Step (2): Introduce carbon monoxide to carry out the reaction;

[0062] The ligand is ROH, and R is selected from substituted or unsubstituted C1-C. 10 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C6-C 30 One of the aryl groups.

[0063] In a preferred embodiment of the present invention, the acid is selected from at least one of methanesulfonic acid, sulfuric acid, benzenesulfonic acid and hydrochloric acid, preferably methanesulfonic acid and / or sulfuric acid; using this preferred acid helps to improve the catalytic performance of the catalyst.

[0064] In a preferred embodiment of the present invention, the weight ratio of the ligand, acid, ethylene and carbon monoxide is (1-10):(2-200):(10000-10000000):(10000-10000000).

[0065] In a preferred embodiment of the present invention, the preparation method of the propionate ester includes the following reaction conditions: reaction temperature of 50-120℃; and reaction time of 3-13h.

[0066] In a preferred embodiment of the present invention, the propionate ester is prepared under stirring conditions.

[0067] In a preferred embodiment of the present invention, the solvent system in step (1) includes an alcohol and an auxiliary solvent miscible with the alcohol; more preferably, the solvent system includes an alcohol having 1-16 carbon atoms, and even more preferably an alcohol having 1-8 carbon atoms;

[0068] In a preferred embodiment of the present invention, the auxiliary solvent is selected from at least one of tetrahydrofuran, toluene, acetone and acetonitrile, more preferably tetrahydrofuran.

[0069] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0070] The yield of sodium propionate powder product = actual weight of propionate powder product ÷ theoretical weight of propionate to propionate × 100%.

[0071] Example 1

[0072] 1) Add 100g water, 50g methanol, 30g NaOH and 35g methyl propionate to the reaction vessel, and stir at 600rpm for 20min until the mixture is homogeneous;

[0073] 2) Heat to 70℃, stir at 600 rpm for 2 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 10.7.

[0074] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0075] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0076] Example 2

[0077] 1) Add 100g water, 67g methanol, 54g NaOH and 67g methyl propionate to the reaction vessel, and stir at 600rpm for 20min until the mixture is homogeneous;

[0078] 2) Heat to 70℃, stir at 600 rpm for 2 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 11.3.

[0079] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0080] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0081] Example 3

[0082] 1) Add 100g water, 40g methanol, 16g NaOH and 20g methyl propionate to the reaction vessel, and stir at 600rpm for 20min until the mixture is homogeneous;

[0083] 2) Heat to 90℃, stir at 600 rpm for 2 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 11.9.

[0084] 3) At 75°C, the volume of the reaction mixture is concentrated to 1 / 4 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5 μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0085] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0086] Example 4

[0087] 1) Add 100g water, 50g acetone, 30g NaOH and 35g methyl propionate to the reaction vessel, and stir for 30 minutes until the mixture is homogeneous;

[0088] 2) Heat to 70℃, stir at 400 rpm for 4 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.

[0089] 3) At 85℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0090] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0091] Example 5

[0092] 1) Add 100g water, 50g acetonitrile, 30g NaOH and 35g methyl propionate to the reaction vessel, and stir for 30 minutes until the mixture is homogeneous;

[0093] 2) Heat to 70℃, stir at 500 rpm for 4 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.3.

[0094] 3) At 75°C, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5 μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0095] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0096] Example 6

[0097] 1) Add 100g water, 50g methanol, 30g Ca(OH)2 and 35g methyl propionate to the reaction vessel, and stir for 30 minutes until the mixture is homogeneous;

[0098] 2) Heat to 90℃, stir at 350 rpm for 5 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.0.

[0099] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 5 of the original volume. Then, the concentrated liquid is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain calcium propionate powder product (crude calcium propionate).

[0100] The conversion rate and reaction selectivity of propionate, the yield and purity of calcium propionate powder were determined, and the results are shown in Table 1.

[0101] Example 7

[0102] 1) Add 100g water, 50g methanol, 30g KOH and 35g methyl propionate to the reaction vessel and stir for 10 minutes until the mixture is homogeneous;

[0103] 2) Heat to 80℃, stir at 300 rpm for 2 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 11.2.

[0104] 3) At 70℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 10μm. The filter residue obtained by filtration is spray-dried to obtain potassium propionate powder product (crude potassium propionate).

[0105] The conversion rate and reaction selectivity of propionate, the yield and purity of potassium propionate powder were determined, and the results are shown in Table 1.

[0106] Example 8

[0107] 1) Add 100g water, 50g ethanol, 30g NaOH and 35g ethyl propionate to the reaction vessel and stir for 10 minutes until the mixture is homogeneous;

[0108] 2) Heat to 90℃, stir at 500 rpm for 3 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.0.

[0109] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 4 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0110] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0111] Example 9

[0112] 1) Add 100g water, 50g butanol, 30g Ca(OH)2 and 35g butyl propionate to the reaction vessel, and stir for 30 minutes until the mixture is homogeneous;

[0113] 2) Heat to 100℃, stir at 500 rpm for 3 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 10.5.

[0114] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated liquid is filtered using a filter membrane with a pore size of 10μm. The filter residue obtained by filtration is spray-dried to obtain calcium propionate powder product (crude calcium propionate).

[0115] The conversion rate and reaction selectivity of propionate, the yield and purity of calcium propionate powder were determined, and the results are shown in Table 1.

[0116] Example 10

[0117] 1) Add 100g water, 50g isooctyl alcohol, 30g Ca(OH)2 and 35g isooctyl propionate to the reaction vessel, and stir for 30 minutes until the mixture is homogeneous;

[0118] 2) Heat to 110℃, stir at 500 rpm for 5 hours and then stop stirring to obtain a reaction mixture. The pH at the reaction endpoint was measured to be 10.8.

[0119] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 4 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 10μm. The filter residue obtained by filtration is spray-dried to obtain calcium propionate powder product (crude calcium propionate).

[0120] The conversion rate and reaction selectivity of propionate, the yield and purity of calcium propionate powder were determined, and the results are shown in Table 1.

[0121] Example 11

[0122] 1) Add 100g water, 50g isooctyl alcohol, 30g NaOH and 35g isooctyl propionate to the reaction vessel, and stir for 10 minutes until the mixture is homogeneous;

[0123] 2) Heat to 80℃, stir at 300 rpm for 5 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.0.

[0124] 3) At 80℃, the volume of the reaction mixture is concentrated to 1 / 5 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0125] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0126] Example 12

[0127] Sodium propionate was prepared according to the method of Example 1, except that methanol was replaced with an equal amount of ethanol.

[0128] Sodium propionate powder product (crude sodium propionate) was obtained.

[0129] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0130] Example 13

[0131] Sodium propionate was prepared according to the method in Example 1, except that 25g of methanol was used.

[0132] Sodium propionate powder product (crude sodium propionate) was obtained.

[0133] The conversion rate and reaction selectivity of propionate, as well as the yield and purity of sodium propionate powder, were determined, and the results are shown in Table 1.

[0134] Example 14

[0135] Sodium propionate was prepared according to the method in Example 1, except that the amount of sodium hydroxide used was 48g.

[0136] Sodium propionate powder product (crude sodium propionate) was obtained.

[0137] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0138] Example 15

[0139] Sodium propionate was prepared according to the method in Example 1, except that the reaction time in step 2) was 8 hours.

[0140] Sodium propionate powder product (crude sodium propionate) was obtained.

[0141] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0142] Comparative Example 1

[0143] 1) Add 100g water, 30g NaOH and 35g methyl propionate to the reaction vessel and stir for 30 minutes until the mixture is homogeneous;

[0144] 2) Heat to 90℃, stir at 600 rpm for 5 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.5.

[0145] 3) At 100℃, the volume of the reaction mixture is concentrated to 1 / 3 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0146] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0147] Comparative Example 2

[0148] 1) Add 100g water, 30g NaOH and 35g isooctyl propionate to the reaction vessel and stir for 10 minutes until the mixture is homogeneous;

[0149] 2) Heat to 80℃, stir at 750 rpm for 5 hours and then stop stirring to obtain a reaction mixture. The pH value at the reaction endpoint was 12.8.

[0150] 3) At 90℃, the volume of the reaction mixture is concentrated to 1 / 4 of the original volume. Then, the concentrated solution is filtered using a filter membrane with a pore size of 5μm. The filter residue obtained by filtration is spray-dried to obtain sodium propionate powder product (crude sodium propionate).

[0151] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0152] Comparative Example 3

[0153] Sodium propionate was prepared according to the method of Example 1, except that the temperature was raised to 135°C in step 2).

[0154] Sodium propionate powder product (crude sodium propionate) was obtained.

[0155] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0156] Comparative Example 4

[0157] Sodium propionate was prepared according to the method of Example 1, except that water was replaced with an equal amount of methanol.

[0158] Sodium propionate powder product (crude sodium propionate) was obtained.

[0159] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0160] Comparative Example 5

[0161] Sodium propionate was prepared according to the method in Example 1, except that 100g of methanol was used.

[0162] Sodium propionate powder product (crude sodium propionate) was obtained.

[0163] The conversion rate and reaction selectivity of propionate, the yield and purity of sodium propionate powder were determined, and the results are shown in Table 1.

[0164] Table 1

[0165]

[0166]

[0167] As can be seen from Examples 1-15 and Comparative Examples 1-5, the propionate prepared in Examples 1-3 using the preferred technical solution of the present invention achieved a propionate conversion rate, propionate selectivity, and propionate yield of 99%, and the purity of the prepared propionate reached 93%. Furthermore, the reaction temperature was low, the reaction time was short, and the efficiency was high.

[0168] Compared to ethanol as the organic solvent in Example 12, methanol was chosen as the organic solvent in Example 1, and it is the same as the alcohol produced after the hydrolysis of methyl propionate. Using this preferred organic solvent, the propionate was prepared with a higher conversion rate and yield, and the prepared propionate had higher purity.

[0169] Compared to Example 14, where the molar ratio of propionate to metal oxide was 1:3, Example 1, using a molar ratio of 1:1.89 (within the preferred range of 1:1.7-2), prepared propionate with higher purity.

[0170] Compared to Comparative Example 3, which used a reaction temperature of 135°C, the propionate prepared in Example 1 at a reaction temperature of 70°C exhibited higher purity. Analysis suggests that excessively high reaction temperatures promote the formation of more byproducts.

[0171] Compared to Comparative Example 4, which prepared propionate only in the presence of an organic solvent, Example 1 prepared propionate in the presence of both water and an organic solvent, resulting in higher propionate conversion and yield, and the obtained propionate had higher purity.

[0172] Compared to Comparative Example 5, where the weight ratio of organic solvent to water was 1:1, the propionate was prepared in Example 1 with a preferred weight ratio of 1:2, resulting in a significantly higher conversion rate and yield of propionate compared to Comparative Example 5.

[0173] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing propionate, characterized in that, The method includes: reacting propionate with metal hydroxide in the presence of water and an organic solvent at a temperature of 50-130°C; The weight ratio of the organic solvent to water is 1:1.2-10; The organic solvent is selected from at least one of alcohols, ketones, nitriles and ethers.

2. The method according to claim 1, characterized in that, The temperature is 50-110℃, preferably 50-70℃; And / or, the contact reaction time is 1-10 hours, preferably 1-3 hours.

3. The method according to claim 1 or 2, characterized in that, The contact reaction is carried out under stirring, and the stirring speed is preferably 300-1000 rpm, more preferably 500-1000 rpm, and even more preferably 500-700 rpm.

4. The method according to any one of claims 1-3, characterized in that, The weight ratio of the organic solvent to the propionate ester is 1:0.1-2, preferably 1:0.5-1; And / or, the weight ratio of the organic solvent to water is 1:1.2-5, preferably 1:1.5-2.

5.

5. The method according to any one of claims 1-4, characterized in that, The molar ratio of the propionate ester to the metal hydroxide is 1:1-10, preferably 1:1.2-5, and more preferably 1:1.7-2.

6. The method according to any one of claims 1-5, characterized in that, The alcohol is a monohydric alcohol with 1-16 carbon atoms, more preferably a monohydric alcohol with 1-8 carbon atoms; Preferably, the organic solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isooctyl alcohol, acetone, and acetonitrile.

7. The method according to any one of claims 1-6, characterized in that, The metal hydroxide is selected from one of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and zinc hydroxide; And / or, the propionate ester is selected from one of methyl propionate, ethyl propionate, butyl propionate and isooctyl propionate.

8. The method according to any one of claims 1-7, characterized in that, The method further includes: concentrating, crystallizing and filtering the reaction solution obtained after the contact reaction, and drying the filtered product to obtain crude propionate.

9. The method according to claim 8, characterized in that, The reaction solution is concentrated to less than 1 / 3 of its original volume.

10. The method according to claim 8 or 9, characterized in that, The filter membrane used for filtration has a pore size of 1-10 μm, preferably 3-5 μm; And / or, the drying method is selected from at least one of vacuum drying, spray drying, freeze drying and infrared drying.

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