Preparation method of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one

Abstract

The invention provides a preparation method of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-ketone, which comprises the following steps: S1) mixing furfuryl propanol with a solution of an inorganic alkaline compound to carry out first reaction to obtain a first solution; s2) carrying out a second reaction on the first solution and chlorine to obtain a second solution; and S3) performing separation and purification on the second solution to obtain the 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. The invention also discloses a preparation method of the 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. The synthesis method can be used for solving the problem of low purity of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-ketone synthesized by a synthesis method in the prior art, and is suitable for the field of synthesis of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-ketone.

Description

Technical Field

[0001] This invention relates to the field of synthesis of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, and more specifically, to a method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. Background Technology

[0002] Ethyl maltol is a broad-spectrum flavor enhancer, generally used as an aroma synergist, sweetener, and masking agent for unpleasant tastes. It is widely used in the formulation of various flavorings or directly applied in the preparation of food, beverages, feed, cigarettes, pharmaceuticals, toothpaste, and cosmetics. It is versatile, requires small amounts, and has significant effects. 6-Hydroxy-4-chloro-2-ethyl-6H-pyran-3-one is one of the main intermediates in the chemical synthesis of ethyl maltol, and its purity directly affects the quality of ethyl maltol.

[0003] The current conventional industrial production method for synthesizing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one uses furfurylpropanol and chlorine as raw materials. The process involves a chlorination reaction, followed by solvent recovery to obtain 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. However, the chlorination reaction is complex, involving both oxidation and chlorination processes. In the traditional synthetic route, furfurylpropanol undergoes a violent polymerization reaction with chlorine under strong acid and high temperature. Besides producing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, this also generates a resin-like black tar byproduct, which severely reduces the purity of the target product.

[0004] Therefore, there is a lack of existing technologies for preparing high-purity 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, in order to solve the problem of low purity of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one synthesized in the prior art.

[0006] To achieve the above objective, according to a first aspect of the present invention, a method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one is provided, the method comprising: S1) mixing furfuryl propanol with a solution of an inorganic basic compound to undergo a first reaction to obtain a first solution; S2) reacting the first solution with chlorine gas to obtain a second solution; and S3) separating and purifying 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one from the second solution.

[0007] Further, S1) includes: mixing furfuryl propanol with a solution of an inorganic alkaline compound, causing a first reaction to produce a precipitate, and then mixing water with the reaction system of the first reaction to obtain a first solution; preferably, the total concentration of furfuryl propanol, the inorganic alkaline compound and the precipitate in the first solution is 15-25 wt%.

[0008] Furthermore, the inorganic alkaline compound includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, potassium bicarbonate, sodium bicarbonate, or sodium carbonate; preferably, the inorganic alkaline compound is sodium carbonate.

[0009] Furthermore, the concentration of the inorganic alkaline compound solution is 10-20 wt%.

[0010] Furthermore, the molar ratio of furfuryl propanol to the inorganic basic compound is 1:(1-1.1).

[0011] Furthermore, the temperature of the first reaction is 10-25℃.

[0012] Further, S2) includes: adjusting the temperature of the first solution to -30℃ to -10℃, and then introducing chlorine gas into the first solution to cause a second reaction; preferably, adjusting the temperature of the first solution to -15℃ to -10℃, and then introducing chlorine gas into the first solution to cause a second reaction.

[0013] Furthermore, in S2), the temperature of the second reaction is controlled to be -5 to -10℃.

[0014] Further, in S2), when the total mass of furfuryl propanol and the intermediate product of the second reaction is 1-2% of the mass of the reaction system of the second reaction, the chlorine gas is stopped; preferably, the intermediate product includes: 2,5-dichloro-α-dihydrofuranpropanol and / or 2-ethyl-6-hydroxy-6-pyran-3-one.

[0015] Furthermore, in S3), separation and purification include one or more of the following: extraction, washing, filtration, drying, or distillation.

[0016] By applying the technical solution of this invention, a first solution is obtained by mixing furfuryl propanol with a solution of an inorganic alkaline compound to undergo a first reaction. The obtained first solution is then reacted with chlorine gas under mild conditions to avoid the generation of byproducts. After the second reaction, the obtained second solution is separated and purified to obtain high-purity 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. This preparation method reduces the generation of byproducts, decreases the workload of separation and purification, lowers production costs, and improves the quality of products further prepared using 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one during the preparation of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0018] As mentioned in the background section, existing preparation methods for synthesizing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one often produce resin-like black tar byproducts due to the vigorous and difficult-to-control chlorination reaction, thus affecting the purity of the product. Therefore, in this application, the inventors attempted to regulate the chlorination reaction by reacting furfuryl propanol with an inorganic basic compound, reducing the generation of byproducts and obtaining high-purity 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, thus proposing a series of protection schemes in this application.

[0019] In a first typical embodiment of this application, a method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one is provided. The method includes: S1) mixing furfuryl propanol with a solution of an inorganic basic compound to undergo a first reaction to obtain a first solution; S2) reacting the first solution with chlorine gas to obtain a second solution; and S3) separating and purifying 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one from the second solution.

[0020] In the existing technology for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, the chlorination reaction is violent and difficult to control, easily generating a large amount of resin-like black tar byproducts. The resulting product has low purity, and these byproducts also pose a significant environmental hazard. The method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one described in this application reduces byproduct generation, improves product purity, and increases yield, laying the foundation for further preparation of high-quality ethyl maltol. Furthermore, the method described in this application is simple to operate, with mild reaction conditions; the reaction can be initiated with a single chlorine gas introduction, avoiding the process hazards associated with multiple chlorine gas introductions to control the reaction.

[0021] In a preferred embodiment, S1) includes: mixing furfuryl propanol with a solution of an inorganic alkaline compound, causing a first reaction to produce a precipitate, and then mixing water with the reaction system of the first reaction to obtain a first solution; preferably, the total concentration of furfuryl propanol, the inorganic alkaline compound, and the precipitate in the first solution is 15-25 wt%, including but not limited to 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 21.28 wt%, 21.4 wt%, 22 wt%, 22.4 wt%, 23 wt%, 23.2 wt%, 23.6 wt%, 24 wt%, or 25 wt%.

[0022] The process involves a first reaction between furfuryl propanol and an inorganic basic compound, resulting in a salt precipitate. Water is then added to the first reaction system to dissolve the precipitate, yielding a first solution of a certain mass concentration. This first solution can be used in subsequent chlorination reactions to prevent violent reactions and avoid the generation of byproducts.

[0023] In a preferred embodiment, the inorganic alkaline compound includes, but is not limited to, one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, potassium bicarbonate, sodium bicarbonate, or sodium carbonate; preferably, the inorganic alkaline compound is sodium carbonate.

[0024] This application utilizes an inorganic basic compound to provide a weakly alkaline environment while also maintaining the stability of the system to a greater extent, thereby improving the chlorination reaction effect and reducing the generation of side reactions. The preferred inorganic basic compound is sodium carbonate. Sodium carbonate has moderate alkalinity, providing a milder reaction environment that maintains system stability. This allows furfurylpropanol to fully undergo the chlorination reaction with chlorine gas without triggering other side reactions due to the introduction of a new reaction system. Furthermore, sodium carbonate has higher solubility than other inorganic basic reagents, which is more conducive to the stability of the reaction system in this application.

[0025] In a preferred embodiment, in S1), the concentration of the inorganic alkaline compound solution is 10-20 wt%, including but not limited to 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%.

[0026] In a preferred embodiment, in S1), the molar ratio of furfuryl propanol to the inorganic basic compound is 1:(1-1.1), including but not limited to 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, or 1:1.1; preferably, the temperature of the first reaction is 10-25°C, including but not limited to 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, or 25°C.

[0027] In this application, the molar ratio of furfuryl propanol to the inorganic basic compound is between 1:(1-1.1). Compared to existing technologies, this involves a smaller amount of inorganic basic compound. Adding the inorganic basic compound at this molar ratio provides a suitable weakly alkaline environment, maintains system stability, facilitates the reaction of furfuryl propanol with chlorine, and avoids side reactions caused by excessive alkali. This application improves the reaction efficiency by controlling the temperature of the first reaction and avoids the problem of excessively high temperatures in the first reaction system due to the exothermic reaction caused by the dropwise addition of furfuryl propanol, which could lead to impurities. By controlling the temperature variation of the first reaction within the range of 10-25℃, the first reaction system becomes more stable and efficient.

[0028] In a preferred embodiment, S2) includes: adjusting the temperature of the first solution to -30°C to -10°C, including but not limited to -10°C, -11°C, -12°C, -13°C, -14°C, -15°C, -16°C, -17°C, -18°C, -19°C, -20°C, -21°C, -22°C, -23°C, -24°C, -25°C, -26°C, -27°C, -28°C, -29°C, or -30°C, and then introducing chlorine gas into the first solution to cause a second reaction; preferably, adjusting the temperature of the first solution to -15°C to -10°C, and then introducing chlorine gas into the first solution to cause a second reaction; more preferably, adjusting the temperature of the first solution to -10°C.

[0029] In a preferred embodiment, in S2), the temperature of the second reaction is controlled to be -5 to -10°C, including but not limited to -5°C, -6°C, -7°C, -8°C, -9°C, or -10°C.

[0030] The method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one disclosed in this application involves reacting a certain mass proportion of an inorganic basic compound with the raw material furfurylpropanol, followed by dissolving the precipitate to obtain a first solution. The second reaction requires reaction with chlorine gas. As chlorine gas is introduced, the temperature of the reaction system increases. By controlling the temperature of the first solution before introducing chlorine gas and by controlling the temperature of the system during the second reaction, the temperature change of the second reaction is controlled within the range of -5 to -10°C. This ensures reaction efficiency while preventing the solute in the first solution from polymerizing and affecting the chlorination reaction (second reaction), and also controls the vigorous reactions that occur during the chlorination process.

[0031] In a preferred embodiment, chlorine gas is stopped when the total mass of furfuryl propanol and the intermediate product of the second reaction is 1-2% of the mass of the reaction system of the second reaction, including but not limited to 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. Preferably, the intermediate product includes 2,5-dichloro-α-dihydrofuranpropanol and / or 2-ethyl-6-hydroxy-6-pyran-3-one.

[0032] By monitoring the remaining amounts of the raw material (furfuryl propanol) and intermediate products (including but not limited to compounds generated during the transition from the first reaction to the end of the second reaction: 2,5-dichloro-α-dihydrofuranpropanol and / or 2-ethyl-6-hydroxy-6-pyran-3-one) using liquid chromatography, chlorine gas is stopped when the reaction system turns pale yellow and the total content of the raw material (first solution) and intermediate products is 1-2 wt%. This avoids over-reaction and the generation of other byproducts, ensuring the complete formation of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. In existing technologies, improving product purity often sacrifices some product yield. However, the product obtained by the preparation method of this application achieves improved purity while avoiding a decrease in yield. Moreover, compared with existing preparation methods, the operation is simpler, the reaction conditions are milder, and the product purity is higher.

[0033] In a preferred embodiment, in S3), the separation and purification includes one or more of the following: extraction, washing, filtration, drying, or distillation.

[0034] In S3 above, the purification may include conventional post-processing operations in the art, including but not limited to one or more purification post-processing methods such as extraction layering, water washing, filtration, drying, distillation, solvent recovery or rectification, which should not be construed as limiting the present invention by those skilled in the art.

[0035] The beneficial effects of this application will be explained in further detail below with reference to specific embodiments. Unless otherwise specified, all embodiments of this application use conventional commercially available products.

[0036] Example 1

[0037] 1. Stir and cool 347g of a 20wt% Na2CO3 aqueous solution (69.4g of sodium carbonate solid and 277.62g of water) to below 10℃, then slowly add 75g of furfurylpropanol. The reaction is slightly exothermic, and the temperature of the first reaction is controlled between 10-25℃. A solid sodium salt precipitate is formed. After the furfurylpropanol is added, stir and keep warm for 30min. Then add 250g of water to dissolve the precipitate, obtaining a first solution with a total concentration of 21.4wt% for furfurylpropanol, inorganic basic compounds, and precipitate.

[0038] 2. Cool the first solution to -10℃ and then slowly introduce chlorine gas, controlling the second reaction temperature between -5℃ and -10℃. When the reaction solution finally turns pale yellow, and the liquid phase monitoring shows that the total content of the raw material (furfuryl propanol) and intermediate product is about 1-2%, stop the chlorination and obtain the second solution.

[0039] 3. Transfer the second solution into a separatory funnel, add dichloromethane and let it stand to separate into layers. The lower organic phase is 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one.

[0040] The solvent was recovered from the lower organic layer, and after distillation, 99.73 g of the purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained. The purity was 98.6% and the molar yield was 93.6% as determined by liquid chromatography.

[0041] Example 2

[0042] The only difference between this embodiment and Example 1 is that in step 1 of this embodiment, the first reaction temperature is controlled at 25-40℃; all other steps are the same as in Example 1. 98.97g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained, with a purity of 98.4% and a molar yield of 92.7%.

[0043] Example 3

[0044] The only difference between this embodiment and Example 1 is that in step 1 of this embodiment, the first reaction temperature is controlled between -5 and 10°C; all other steps are the same as in Example 1. 98.89 g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained, with a purity of 98.3% and a molar yield of 92.53%.

[0045] Example 4

[0046] 1. Stir and cool 247g of a 20wt% NaHCO3 aqueous solution to below 10℃, slowly add 75g of furfuryl propanol, slightly exothermicly, and control the first reaction temperature at 10-25℃. The reaction precipitates solid sodium salt. After the furfuryl propanol is added, stir and keep warm for 30min, then add 210g of water to dissolve the precipitate, obtaining a first solution with a total concentration of 23.2wt% for furfuryl propanol, inorganic basic compounds and precipitate.

[0047] 2. After cooling the first solution to -10℃, slowly introduce chlorine gas and control the second reaction temperature between -5℃ and -10℃. When the reaction solution turns pale yellow and the liquid phase monitoring shows that the raw material (furfuryl propanol) and intermediate product together are about 1-2% remaining, stop the chlorination and obtain the second solution.

[0048] 3. Transfer the second solution into a separatory funnel, add dichloromethane and let it stand to separate into layers. The lower organic phase is 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one.

[0049] The solvent was recovered from the lower organic layer, and after distillation, 98.96 g of the purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained. The purity was 98.2% and the molar yield was 92.5% as determined by liquid chromatography.

[0050] Example 5

[0051] 1. Stir and cool 175g of a 15wt% NaOH aqueous solution to below 10℃, then slowly add 75g of furfuryl propanol. The reaction is slightly exothermic, and the temperature of the first reaction is controlled between 10-25℃. A solid sodium salt precipitate is formed. After the furfuryl propanol is added, stir and keep warm for 30 minutes. Then add 180g of water to dissolve the precipitate, obtaining a first solution with a total concentration of 23.6wt% for furfuryl propanol, inorganic alkaline compounds, and precipitate.

[0052] 2. After cooling the first solution to -10℃, slowly introduce chlorine gas and control the second reaction temperature between -5℃ and -10℃. When the reaction solution turns pale yellow and the liquid phase monitoring shows that the raw material (furfuryl propanol) and intermediate product together are about 1-2% remaining, stop the chlorination and obtain the second solution.

[0053] 3. Transfer the second solution into a separatory funnel, add dichloromethane and let it stand to separate into layers. The lower organic phase is 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one.

[0054] The solvent was recovered from the lower organic layer, and after distillation, 98.73 g of the purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained. The purity was 98% and the molar yield was 92.1% as determined by liquid chromatography.

[0055] Example 6

[0056] 1. Stir and cool 175g of 15wt% KOH aqueous solution to below 10℃, slowly add 75g of furfurylpropanol, slightly exothermicly, and control the temperature of the first reaction at 10-25℃. Solid potassium salt precipitate will be formed. After the addition of furfurylpropanol is completed, stir and keep warm for 30min, then add 180g of water to dissolve the precipitate, and obtain a first solution with a total concentration of 22.4wt% for furfurylpropanol, inorganic basic compounds and precipitate.

[0057] 2. After cooling the first solution to -10℃, slowly introduce chlorine gas and control the second reaction temperature between -5℃ and -10℃. When the reaction solution turns pale yellow and the liquid phase monitoring shows that the raw material (furfuryl propanol) and intermediate product together are about 1-2% remaining, stop the chlorination and obtain the second solution.

[0058] 3. Transfer the second solution into a separatory funnel, add dichloromethane and let it stand to separate into layers. The lower organic phase is 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one.

[0059] The solvent was recovered from the lower organic layer, and after distillation, 98.61 g of the purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained. The purity was 97.8% and the molar yield was 91.8% as determined by liquid chromatography.

[0060] Example 7

[0061] The only difference between this embodiment and Example 1 is that the Na₂CO₃ solution concentration in this embodiment is 5 wt%, and the amount used is 1388 g (69.4 g Na₂CO₃ + 1318 g water). After the first reaction, a first solution with a total concentration of 8.4 wt% of furfurylpropanol, inorganic basic compounds, and precipitate is obtained. The remaining steps are the same as in Example 1. 93.5 g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one is obtained with a purity of 98.3% and a molar yield of 90.1%.

[0062] Example 8

[0063] The only difference between this embodiment and Example 1 is that the Na₂CO₃ solution concentration in this embodiment is 30 wt%, and the amount used is 232 g. After the first reaction, a first solution with a total concentration of 26 wt% of furfurylpropanol, inorganic basic compounds, and precipitate is obtained. The remaining steps are the same as in Example 1. 90.51 g of the purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained with a purity of 97.9% and a molar yield of 88%.

[0064] Example 9

[0065] The difference between this embodiment and Example 1 is that in step 1, 361g of water, 90g of K2CO3 (concentration of 19.96wt%), and 75g of furfurylpropanol are mixed evenly, and then 250g of water is added to dissolve the precipitate, obtaining a first solution with a total concentration of 21.28wt% for furfurylpropanol, inorganic basic compounds, and the precipitate. The remaining steps are the same as in Example 1. 95.22g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained, with a purity of 96.1% and a molar yield of 87.1%.

[0066] Example 10

[0067] The only difference between this embodiment and Example 9 is that in step 2 of this embodiment, the system is cooled to -10°C and then chlorine gas is slowly introduced to control the temperature of the second reaction solution between 0°C and -5°C. All other steps are the same as in Example 9. 93.22 g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained, with a purity of 95.5% and a molar yield of 84.7%.

[0068] Example 11

[0069] The only difference between this embodiment and Example 9 is that in step 2 of this embodiment, the system is cooled to -10°C and then chlorine gas is slowly introduced to control the temperature of the second reaction solution between -15°C and -20°C. All other steps are the same as in Example 9. 91.22 g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained, with a purity of 96% and a molar yield of 83.4%.

[0070] Comparative Example 1

[0071] 75g of furfuryl propanol was stirred and cooled to below -10℃. Chlorine gas was slowly introduced, and the temperature of the reaction solution was controlled between -5℃ and -10℃. The liquid phase was monitored until the total amount of raw material (furfuryl propanol) and intermediate product was about 1-2%. The chlorination was stopped, nitrogen was used to replace the liquid, and the mixture was transferred to a separatory funnel with dichloromethane and allowed to stand for separation. The lower organic phase was 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one. The solvent was recovered from the lower organic layer, and after distillation, 93.66g of purified product 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained with a purity of 93.1% and a molar yield of 83.1%.

[0072] The purity and molar yield of the products from Examples 1-11 and Comparative Example 1 are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: Using the preparation method of 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one of this application, the chlorination reaction during the preparation process is controllable, and the obtained product, 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, has a purity of up to 95.5%–98.6%, and the molar yield is not reduced in order to improve the purity; the molar yield can reach 83.4%–93.6%. Compared with the synthetic routes of the prior art, the synthesized product has fewer byproducts, fewer preparation steps, a simpler method, milder reaction conditions, lower preparation cost, and is more environmentally friendly. The purity and yield of the product are both improved, making it suitable for industrial-scale production.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one, characterized in that, The preparation method includes: S1) Mix furfuryl propanol with a solution of an inorganic basic compound to undergo a first reaction, thereby obtaining a first solution; S2) The first solution is reacted with chlorine gas in a second reaction to obtain a second solution; S3) The 6-hydroxy-4-chloro-2-ethyl-6H-pyran-3-one was obtained by separation and purification from the second solution.

2. The preparation method according to claim 1, characterized in that, S1) includes: mixing the furfuryl propanol with a solution of the inorganic alkaline compound to produce the first reaction, generating a precipitate, and then mixing water with the reaction system of the first reaction to obtain the first solution; Preferably, the total concentration of furfuryl propanol, the inorganic alkaline compound, and the precipitate in the first solution is 15-25 wt%.

3. The preparation method according to claim 2, characterized in that, The inorganic alkaline compound includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, potassium bicarbonate, sodium bicarbonate, or sodium carbonate. Preferably, the inorganic alkaline compound is sodium carbonate.

4. The preparation method according to claim 2, characterized in that, The concentration of the inorganic alkaline compound solution is 10-20 wt%.

5. The preparation method according to claim 2, characterized in that, The molar ratio of furfuryl propanol to the inorganic basic compound is 1:(1-1.1).

6. The preparation method according to claim 2, characterized in that, The temperature of the first reaction is 10-25℃.

7. The preparation method according to claim 1, characterized in that, S2) includes: adjusting the temperature of the first solution to -30℃ to -10℃, and then introducing chlorine gas into the first solution to cause the second reaction; Preferably, the temperature of the first solution is adjusted to -15 to -10°C, and then chlorine gas is introduced into the first solution to cause the second reaction.

8. The preparation method according to claim 1, characterized in that, In step S2), the temperature of the second reaction is controlled to be -5 to -10°C.

9. The preparation method according to claim 1, characterized in that, In step S2), when the total mass of furfuryl propanol and the intermediate product of the second reaction is 1-2% of the mass of the reaction system of the second reaction, the chlorine gas supply is stopped. Preferably, the intermediate product comprises: 2,5-dichloro-α-dihydrofuranpropanol and / or 2-ethyl-6-hydroxy-6-pyran-3-one.

10. The preparation method according to claim 1, characterized in that, In S3), the separation and purification includes one or more of the following: extraction, washing, filtration, drying, or distillation.

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