A method for the continuous production of furanones by a dynamic tubular reactor

Abstract

This invention provides a method for the continuous preparation of furanones using a dynamic tubular reactor. The method includes: using a dynamic tubular reactor, with rhamnose as a raw material, inorganic salts as a catalyst, adding amino acids and polymerization inhibitors, and water as a solvent, to react and obtain furanones. This method provides a continuous synthesis of furanones, with a simple process flow and significantly improved product yield.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for the continuous preparation of furanones using a dynamic tubular reactor. Background Technology

[0002] Furanones, also known as pineapple furanones or strawberry furanones, are naturally found in strawberries, pineapples, grapes, oranges, mangoes, roasted almonds, heated beef broth in coffee, and wine and brandy. They possess a strong strawberry and caramel aroma and have wide applications in the food industry, earning them the title of "King of Flavors." Furthermore, furanones are important raw materials for sweet flavorings and excellent flavor enhancers, recognized as safe food flavorings by both the American Flavor Manufacturers Association and the Council of Europe. Their structure is as follows:

[0003]

[0004] Currently, there are three main routes for the production of furanone: The first is the acetone aldehyde route, which uses acetone aldehyde as a raw material. Under the action of zinc powder, it generates 3,4-dihydroxy-2,5-hexanedione, and then removes one molecule of water to obtain furanone. This process has drawbacks such as involving high-temperature oxidation (300-500℃) and the use of zinc powder producing a large amount of basic zinc carbonate as a byproduct. The second is the ethyl lactate route, which uses ethyl lactate and ethyl α-bromopropionate under strongly alkaline conditions for alkoxylation, followed by a condensation reaction under the action of metallic sodium. The resulting aliquot is then oxidized to obtain furanone. This process has drawbacks such as a long process flow, low yield, and a dark product color. The third is the rhamnose route, which uses naturally derived rhamnose as a raw material. The resulting furanone is a fully bio-based fragrance with very good market prospects.

[0005] In 1963, Hodge et al. reacted rhamnose with organic secondary amines (such as dibutylamine and hexahydropyridine), acetic acid, and ethanol in a heating medium, achieving a furanone yield of 70-80%. However, this method suffered from complex reactions and the need for large amounts of additives. Decnop et al. reported that L-rhamnose under L-lysine and L-hydroxyproline conditions under sodium dihydrogen phosphate and sodium hydroxide conditions under these conditions achieved furanone yields of 38% and 63%, respectively. Meguro et al. used glucose as a starting material to obtain 6-deoxy-D-pyranose glucose through multiple steps, which was then refluxed with piperidine acetic acid to obtain furanone. Wong et al. reacted D-fructose-1,6-diphosphate with α-hydroxyaldehyde under enzymatic action to obtain 6-deoxyfructose-1-phosphate, which was further hydrolyzed to 6-deoxyfructose, and then reacted with piperidine acetic acid to obtain furanone. The Maillard reaction has received widespread attention in recent years due to its mild conditions and extensive applications in the food industry. However, because the Maillard reaction process is complex and furanone is only a product of an intermediate stage, controlling the reaction process and improving the reaction yield is very difficult.

[0006] In summary, the current industrial routes for synthesizing furanones have many drawbacks, so developing a new method to synthesize furanones in high yield is of great significance. Summary of the Invention

[0007] This invention provides a method for the continuous preparation of furanones using a dynamic tubular reactor. This method has a simple process flow and significantly improves product yield.

[0008] To achieve the above-mentioned objectives and technical effects, the technical solution adopted by the present invention is as follows:

[0009] A method for the continuous preparation of furanone via a dynamic tubular reactor, the method comprising the following steps:

[0010] Using a dynamic tubular reactor, rhamnose was used as the raw material, inorganic salts as the catalyst, amino acids and polymerization inhibitors were added, and water was used as the solvent to produce furanone.

[0011] In this invention, the inorganic salt is one or more of sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium borate, sodium tetraborate, sodium bisulfate, sodium sulfite, and sodium bisulfite, preferably sodium sulfite and sodium dihydrogen phosphate.

[0012] Preferably, the molar ratio of the inorganic salt to rhamnose is 0.01-0.3:1, more preferably 0.025-0.15:1.

[0013] In this invention, the amino acid is one or more selected from glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine, preferably cysteine.

[0014] Preferably, the molar ratio of the amino acid to rhamnose is 0.005-0.15:1, more preferably 0.01-0.1:1.

[0015] In this invention, the polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, 2,5-di-tert-butylhydroquinone, 2-tert-butylhydroquinone, ferulic acid, epicatechin, and epigallocatechin gallate, preferably ferulic acid and epicatechin.

[0016] Preferably, the molar ratio of the polymerization inhibitor to rhamnose is 0.005-0.1:1, more preferably 0.01-0.03:1.

[0017] In this invention, the content of solvent water in the raw material mixture (rhamnose, inorganic salt, amino acid, polymerization inhibitor, water) is 10-95 wt%, preferably 60-80 wt%.

[0018] In this invention, the reaction uses a dynamic tubular reactor; the reaction temperature is 50-200℃, preferably 90-130℃; the system pressure is 0.1-3MPa, preferably 0.3-1.5MPa; and the feed volume hourly space velocity of the raw material mixture is 0.5-3h⁻¹. -1 1-2 hours is preferred -1 Stirring speed: 50-600 rpm, preferably 100-300 rpm.

[0019] Another object of the present invention is to provide a furanone.

[0020] A furanone, prepared using the above-described method for synthesizing furanone.

[0021] In this invention, unless otherwise specified, all pressures are absolute pressures.

[0022] The beneficial effects of this invention are as follows:

[0023] 1) By using amino acids and polymerization inhibitors to control the Maillard reaction process, the reaction generates more intermediate furanone, avoiding further reaction and thus achieving high-yield synthesis of furanone.

[0024] 2) Using a dynamic tubular reactor instead of a traditional batch reaction allows for better control of residence time, simplifies the process, and increases reaction yield. Detailed Implementation

[0025] The method of the present invention will be further illustrated below through specific embodiments, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0026] Analytical instruments:

[0027] 1) Nuclear magnetic resonance spectrometer model: BRUKER ADVANCEⅢ400, 400MHz, CDCl3 as solvent;

[0028] 2) High-performance liquid chromatography (HPLC): Agilent Technologies 1200 series, equipped with a C18 HPLC column, column temperature set at 40℃, using acetonitrile and 0.1 wt% phosphoric acid aqueous solution as the mobile phase, flow rate at 1.0 mL / min, detection at 285 nm wavelength using a UV detector, and quantification using the external standard method. Samples were appropriately diluted with acetonitrile before injection for analysis.

[0029] 3) Gas chromatograph: Agilent 7890, DB-5 separation column, vaporization chamber temperature 240℃, detector temperature 240℃, temperature ramping program: initial temperature 80℃, hold temperature for 1 min, then ramp from 80℃ to 220℃ at 10℃ / min, and finally hold temperature at 220℃ for 10 min.

[0030] Main raw material information:

[0031] Rhamnose, sodium sulfite, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, lysine, cysteine, asparagine, glutamine, 2,6-di-tert-butyl-p-cresol, ferulic acid, epicatechin, epigallocatechin gallate, chemical purity ≥98%, Aladdin Reagent Co., Ltd.

[0032] Butyl acetate, chemical purity ≥99%, Aladdin Reagent Co., Ltd.

[0033] Main synthesis equipment: dynamic tubular reactor, manufactured by Shandong Weijing Chemical Technology Co., Ltd.

[0034] Example 1

[0035] In a raw material mixing vessel, rhamnose, sodium sulfite, lysine, and 2,6-di-tert-butyl-p-cresol were added in a molar ratio of 1:0.025:0.01:0.01, with a water concentration of 80 wt%. After thorough mixing, the raw material mixture, preheated (to 20°C) by a heat exchanger, was pumped into a dynamic tubular reactor. The effective volume of the dynamic tubular reactor was 1200 mL, the feed rate of the raw material mixture was 10 mL / min, and the volumetric hourly space velocity (VHSV) was 0.5 h⁻¹. -1 The reaction system was maintained at a temperature of 110℃, a pressure of 0.7MPa, and a stirring speed of 300rpm. The effluent from the dynamic tubular reactor was cooled to 20℃ via a cooler. After the reaction system stabilized, the effluent reaction solution was analyzed by external standard method, showing a rhamnose conversion rate of 95% and a furanone yield of 83%. The cooled effluent reaction solution was extracted three times at room temperature with twice its mass of butyl acetate. The extracted butyl acetate solution was concentrated by rotary evaporation under reduced pressure at 200hPa and 50℃. The crude furanone obtained was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.85%, resulting in a final overall yield of 76%.

[0036] Example 2

[0037] In a raw material mixing vessel, rhamnose, sodium dihydrogen phosphate, asparagine, and ferulic acid were added in a molar ratio of 1:0.1:0.1:0.1, with a water concentration of 70 wt%. After thorough mixing, the raw material mixture, preheated (to 20°C) by a heat exchanger, was pumped into a dynamic tubular reactor. The effective volume of the dynamic tubular reactor was 1200 mL, the feed rate of the raw material mixture was 20 mL / min, and the volumetric hourly space velocity (VHSV) was 1.0 h⁻¹. -1 The reaction system was maintained at a temperature of 130℃, a pressure of 1MPa, and a stirring speed of 200rpm. The effluent from the dynamic tubular reactor was cooled to 20℃ via a cooler. After the reaction system stabilized, the effluent reaction solution was analyzed by external standard method, showing a rhamnose conversion rate of 99% and a furanone yield of 86%. The cooled effluent reaction solution was extracted three times at room temperature with twice its mass of butyl acetate. The extracted butyl acetate solution was concentrated by rotary evaporation under reduced pressure at 200hPa and 50℃. The resulting crude furanone product was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.86%, and the final overall yield was 79%.

[0038] Example 3

[0039] In a raw material mixing vessel, rhamnose, potassium dihydrogen phosphate, cysteine, and epicatechin were added in a molar ratio of 1:0.02:0.05:0.03, with a water concentration of 60 wt%. After thorough mixing, the raw material mixture, preheated (to 20°C) by a heat exchanger, was pumped into a dynamic tubular reactor. The effective volume of the dynamic tubular reactor was 1200 mL, the feed rate of the raw material mixture was 40 mL / min, and the volumetric hourly space velocity (VHSV) was 2 h⁻¹. -1 The reaction system was maintained at a temperature of 150℃, a pressure of 1.5MPa, and a stirring speed of 400rpm. The effluent from the dynamic tubular reactor was cooled to 20℃ via a cooler. After the reaction system stabilized, the effluent reaction solution was analyzed by external standard method, showing a rhamnose conversion rate of 99% and a furanone yield of 88%. The cooled effluent reaction solution was extracted three times at room temperature with twice its mass of butyl acetate. The extracted butyl acetate solution was concentrated by rotary evaporation under reduced pressure at 200hPa and 50℃. The resulting crude furanone product was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.88%, and the final overall yield was 83%.

[0040] Example 4

[0041] In a raw material mixing vessel, rhamnose, disodium hydrogen phosphate, glutamine, and epigallocatechin gallate were added in a molar ratio of 1:0.15:0.15:0.02, with a water concentration of 90 wt%. After thorough mixing, the raw material mixture, preheated (to 20°C) by a heat exchanger, was pumped into a dynamic tubular reactor. The effective volume of the dynamic tubular reactor was 1200 mL, the feed rate of the raw material mixture was 60 mL / min, and the volumetric hourly space velocity (VHSV) was 3 h⁻¹. -1 The reaction system was maintained at a temperature of 180℃, a pressure of 2MPa, and a stirring speed of 600rpm. The effluent from the dynamic tubular reactor was cooled to 20℃ via a cooler. After the reaction system stabilized, the effluent reaction solution was analyzed by external standard method, showing a 100% conversion of rhamnose and an 80% yield of furanone. The cooled effluent reaction solution was extracted three times at room temperature with twice its mass of butyl acetate. The extracted butyl acetate solution was concentrated by rotary evaporation under reduced pressure at 200hPa and 50℃. The crude furanone obtained was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.83%, resulting in a final overall yield of 75%.

[0042] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for the continuous preparation of furanone, characterized in that, Using a dynamic tubular reactor, with rhamnose as raw material, inorganic salts as catalysts, amino acids and polymerization inhibitors added, and water as solvent, furanone was obtained by reaction. The amino acid is one or more selected from glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine, and the molar ratio of the amino acid to rhamnose is 0.005-0.15:

1. The inorganic salt is one or more of sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium bisulfate, sodium sulfite, and sodium bisulfite, and the molar ratio of the inorganic salt to rhamnose is 0.01-0.3:1; The polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, 2,5-di-tert-butyl-p-hydroxyanisole, 2-tert-butyl-p-hydroxyanisole, ferulic acid, epicatechin, and epigallocatechin gallate, and the molar ratio of the polymerization inhibitor to rhamnose is 0.005-0.1:

1.

2. The method according to claim 1, characterized in that, The inorganic salt is selected from sodium sulfite and sodium dihydrogen phosphate.

3. The method according to claim 1, characterized in that, The molar ratio of the inorganic salt to rhamnose is 0.025-0.15:

1.

4. The method according to claim 1, characterized in that, The molar ratio of the amino acid to rhamnose is 0.01-0.1:

1.

5. The method according to claim 1, characterized in that, The polymerization inhibitor is selected from ferulic acid and epicatechin.

6. The method according to claim 1, characterized in that, The molar ratio of the polymerization inhibitor to rhamnose is 0.01-0.03:

1.

7. The method according to claim 1, characterized in that, The water concentration in the raw material mixture is 10-95 wt%.

8. The method according to claim 1, characterized in that, The water concentration in the raw material mixture is 60-80 wt%.

9. The method according to claim 1, characterized in that, The reaction temperature is 50-200℃; the system pressure is 0.1-3MPa; the feed volume hourly space velocity of the raw material mixture is 0.5-3h-1; and the stirring speed is 50-600rpm.

10. The method according to claim 1, characterized in that, The reaction temperature is 90-130℃; the system pressure is 0.3-1.5MPa; the feed volume hourly space velocity of the raw material mixture is 1-2h-1; and the stirring speed is 100-300rpm.

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