Method for continuously preparing furanone through dynamic tubular reactor

Abstract

The invention provides a method for continuously preparing furanone through a dynamic tubular reactor, which comprises the following steps: by using the dynamic tubular reactor, taking rhamnose as a raw material, taking inorganic salt as a catalyst, adding amino acid and a polymerization inhibitor, and taking water as a solvent, and reacting to obtain furanone. The method for continuously synthesizing furanone is simple in technological process, and the product yield is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical industry, and particularly relates to a method for continuously preparing furanone through a dynamic tubular reactor. Background Art

[0002] Furanone, also known as pineapple furanone or strawberry furanone, is naturally present in strawberries, pineapples, grapes, oranges, mangoes, roasted almonds, coffee-heated beef soup, wine, and brandy. It has a strong strawberry aroma and caramel aroma, and is widely used in the food industry. It is called the "king of spices". In addition, furanone is also an important raw material for sweet spices and an excellent flavor enhancer. It is a safe edible spice recognized by the American Flavor Manufacturers Association and the European Council. The structure is as follows:

[0003]

[0004] At present, there are three main routes for furanone production: the first is the acetone aldehyde route, which uses acetone aldehyde as a raw material, generates 3,4-dihydroxy-2,5-hexanedione under the action of zinc powder, and then removes a molecule of water to obtain furanone; this process has the disadvantages of involving high-temperature oxidation (300-500℃), and the use of zinc powder will produce a large amount of basic zinc carbonate by-products. The second is the ethyl lactate route, which uses ethyl lactate and ethyl α-bromopropionate to undergo alkoxylation under strong alkaline conditions, and then undergoes a condensation reaction under the action of metallic sodium. The final acyloin is oxidized to obtain furanone; this process has the disadvantages of long process, low yield, and heavy product color. The third is the rhamnose route, which uses rhamnose from natural sources as a raw material, and the obtained furanone is a fully bio-based fragrance with very good market prospects.

[0005] In 1963, Hodge et al. heated rhamnose in organic secondary amines (such as dibutylamine, hexahydropyridine), acetic acid and ethanol to react, and the yield of furanone was 70-80%. This scheme has the problems of complex reaction and large amount of additives. Decnop et al. reported that L-rhamnose under L-lysine and L-hydroxyproline conditions under the Maillard reaction in sodium dihydrogen phosphate and sodium hydroxide, and the yield of furanone can reach 38% and 63%, respectively. Meguro et al. used glucose as raw material, obtained 6-deoxy-D-pyranose glucose through multi-step reactions, and finally refluxed with piperidine acetic acid to obtain furanone. Wong et al. reacted D-fructose-1,6-diphosphate with α-hydroxyaldehyde under the action of enzyme 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 wide application in the food field. However, due to the complexity of the Maillard reaction process and the fact that furanone is only a product of the intermediate stage, it is very difficult to control the reaction process and improve the reaction yield.

[0006] In summary, there are many shortcomings in the current industrial route for synthesizing furanone, so it is of great significance to develop a new method to synthesize furanone with high yield. Summary of the invention

[0007] The invention provides a method for continuously preparing furanone by using a dynamic tubular reactor. The method has a simple process flow and significantly improves the product yield.

[0008] In order to achieve the above-mentioned purpose and technical effect, the technical solution adopted by the present invention is as follows:

[0009] A method for continuously preparing furanone by a dynamic tubular reactor, the method comprising the following steps:

[0010] A dynamic tubular reactor is used, rhamnose is used as a raw material, an inorganic salt is used as a catalyst, amino acids and inhibitors are added, and water is used as a solvent to react and obtain furanone.

[0011] In the present 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 hydrogen sulfate, sodium sulfite, 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, preferably 0.025-0.15:1.

[0013] In the present invention, the amino acid is one or more of 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, preferably 0.01-0.1:1.

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

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

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

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

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

[0020] A furanone is prepared by adopting the above-mentioned method for synthesizing furanone.

[0021] In the present invention, unless otherwise specified, the pressures mentioned are absolute pressures.

[0022] The beneficial effects of the present invention are:

[0023] 1) By using amino acids and inhibitors to control the Maillard reaction process, more intermediate furanone is generated in the reaction, and the progressive reaction is avoided, thereby synthesizing furanone with a high yield.

[0024] 2) Using a dynamic tubular reactor instead of the traditional intermittent reaction, the residence time can be better controlled, the process is simpler, and the reaction yield is higher. DETAILED DESCRIPTION

[0025] The method of the present invention is further described below by means of specific examples, but the present invention is not limited to the listed examples, and should also include any other known changes 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) Liquid chromatograph: Agilent 1200 series, equipped with C18 liquid chromatograph column, column temperature set at 40°C, acetonitrile and 0.1wt% phosphoric acid aqueous solution as mobile phase, flow rate of 1.0mL / min, UV detector at 285nm wavelength, external standard method for quantification. Samples were appropriately diluted with acetonitrile before injection and analyzed.

[0029] 3) Gas chromatograph: Agilent 7890, DB-5 separation column, vaporization chamber temperature 240°C, detector temperature 240°C, temperature ramp program, starting temperature 80°C, constant temperature for 1 min, then increasing the temperature from 80°C to 220°C at 10°C / min, and finally constant temperature at 220°C 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, manufacturer: Shandong Weijing Chemical Technology Co., Ltd.

[0034] Example 1

[0035] In the raw material mixing kettle, rhamnose, sodium sulfite, lysine, 2,6-di-tert-butyl-p-cresol are added into the raw material mixing kettle in a molar ratio of 1:0.025:0.01:0.01 and a water concentration of 80wt%. After stirring evenly, the raw material mixture preheated by a heat exchanger (preheated to 20°C) is pumped into the dynamic tubular reactor, wherein the effective volume of the dynamic tubular reactor is 1200mL, the raw material mixture feed rate is 10mL / min, and the volume space velocity is 0.5h -1 , maintaining the system reaction temperature at 110°C, pressure at 0.7MPa, stirring speed at 300rpm, the dynamic tubular reactor discharge was cooled to 20°C by a cooler. After the reaction system was stabilized, the discharge reaction liquid was analyzed by external standard method, and the rhamnose conversion rate was 95% and the furanone yield was 83%. After the discharge was cooled, the reaction aqueous solution was extracted three times at room temperature with 2 times the mass of butyl acetate. The extracted butyl acetate solution was concentrated by vacuum rotary evaporation at 200hPa and 50°C. The furanone crude product was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.85% and a final total yield of 76%.

[0036] Example 2

[0037] In the raw material mixing kettle, rhamnose, sodium dihydrogen phosphate, asparagine and ferulic acid were added in a molar ratio of 1:0.1:0.1:0.1 and a water concentration of 70wt%. After stirring evenly, the raw material mixture preheated by a heat exchanger (preheated to 20°C) was pumped into the dynamic tubular reactor, wherein the effective volume of the dynamic tubular reactor was 1200mL, the raw material mixture feed rate was 20mL / min, and the volume space velocity was 1.0h -1 , maintaining the system reaction temperature at 130°C, pressure at 1MPa, stirring speed at 200rpm, the dynamic tubular reactor discharge was cooled to 20°C by a cooler. After the reaction system was stabilized, the discharge reaction liquid was analyzed by external standard method, and the rhamnose conversion rate was 99% and the furanone yield was 86%. After the discharge was cooled, the reaction aqueous solution was extracted three times at room temperature with 2 times the mass of butyl acetate. The extracted butyl acetate solution was concentrated by vacuum rotary evaporation at 200hPa and 50°C. The furanone crude product was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.86% and a final total yield of 79%.

[0038] Example 3

[0039] In the raw material mixing kettle, rhamnose, potassium dihydrogen phosphate, cysteine, epicatechin are added in a molar ratio of 1:0.02:0.05:0.03 and a water concentration of 60wt%. After stirring evenly, the raw material mixture preheated by a heat exchanger (preheated to 20°C) is pumped into the dynamic tubular reactor, wherein the effective volume of the dynamic tubular reactor is 1200mL, the raw material mixture feed rate is 40mL / min, and the volume space velocity is 2h -1 , maintaining the system reaction temperature at 150°C, pressure at 1.5MPa, stirring speed at 400rpm, the dynamic tubular reactor discharge was cooled to 20°C by a cooler. After the reaction system was stabilized, the discharge reaction liquid was analyzed by external standard method, and the rhamnose conversion rate was 99% and the furanone yield was 88%. After the discharge was cooled, the reaction aqueous solution was extracted three times at room temperature with 2 times the mass of butyl acetate. The extracted butyl acetate solution was concentrated by vacuum rotary evaporation at 200hPa and 50°C. The furanone crude product was further crystallized with butyl acetate to obtain the furanone product with a purity of 99.88% and a final total yield of 83%.

[0040] Example 4

[0041] In the raw material mixing kettle, rhamnose, disodium hydrogen phosphate, glutamine, and epigallocatechin gallate are added in a molar ratio of 1:0.15:0.15:0.02 and a water concentration of 90wt%. After stirring evenly, the raw material mixture preheated by a heat exchanger (preheated to 20°C) is pumped into the dynamic tubular reactor with a pump. The effective volume of the dynamic tubular reactor is 1200mL, the raw material mixture feed rate is 60mL / min, and the volume space velocity is 3h -1 , maintaining the system reaction temperature at 180°C, pressure at 2MPa, stirring speed at 600rpm, the dynamic tubular reactor discharge is cooled to 20°C by a cooler. After the reaction system is stable, the discharge reaction liquid is analyzed by external standard method, and the rhamnose conversion rate is 100% and the furanone yield is 80%. After the discharge is cooled, the reaction aqueous solution is extracted three times at room temperature with 2 times the mass of butyl acetate. The extracted butyl acetate solution is concentrated by vacuum rotary evaporation at 200hPa and 50°C. The furanone crude product obtained is further crystallized with butyl acetate to obtain the furanone product with a purity of 99.83% and a final total yield of 75%.

[0042] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for continuously preparing furanone, characterized in that: A dynamic tubular reactor is used, rhamnose is used as a raw material, an inorganic salt is used as a catalyst, amino acids and inhibitors are added, and water is used as a solvent to react and obtain furanone.

2. The method according to claim 1, characterized in that 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 hydrogen sulfate, sodium sulfite, and sodium bisulfite, preferably sodium sulfite and sodium dihydrogen phosphate.

3. The method according to claim 1 or 2, characterized in that: The molar ratio of the inorganic salt to rhamnose is 0.01-0.3:1, preferably 0.025-0.15:

1.

4. The method according to claim 1, characterized in that: The amino acid is one or more of 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.

5. The method according to claim 1 or 4, characterized in that: The molar ratio of the amino acid to rhamnose is 0.005-0.15:1, preferably 0.01-0.1:

1.

6. The method according to claim 1, characterized in that The polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, 2,5-di-tert-butyl-hydroquinone, 2-tert-butyl-hydroquinone, ferulic acid, epicatechin, and epigallocatechin gallate, preferably ferulic acid and epicatechin.

7. The method according to claim 1 or 6, characterized in that: The molar ratio of the inhibitor to rhamnose is 0.005-0.1:1, preferably 0.01-0.03:

1.

8. The method according to any one of claims 1 to 7, characterized in that: The concentration of water in the raw material mixture is 10-95 wt %, preferably 60-80 wt %.

9. The method according to any one of claims 1 to 8, characterized in that: The reaction temperature is 50-200°C, preferably 90-130°C; the system pressure is 0.1-3MPa, preferably 0.3-1.5MPa; the feed volume space velocity of the raw material mixture is 0.5-3h -1 , preferably 1-2h -1 ; Stirring speed 50-600rpm, preferably 100-300rpm.

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