阅读说明：本技术 一种乙酰丙酸酯的制备方法 (Preparation method of levulinate ) 是由 傅尧 李兴龙 朱瑞 刘煦旸 于 2021-10-21 设计创作，主要内容包括：本发明公开了一种乙酰丙酸酯的制备方法,包括：将六碳糖类化合物和催化剂加入三烷氧基甲烷中,在第一预设温度、第一预设压力、第一预设长下,六碳糖类化合物在三烷氧基甲烷及催化剂的催化作用下,生成乙酰丙酸酯。(The invention discloses a preparation method of levulinate, which comprises the following steps: adding a hexose compound and a catalyst into trialkoxymethane, and generating levulinic acid ester by the hexose compound under the catalysis of the trialkoxymethane and the catalyst at a first preset temperature, a first preset pressure and a first preset length.)

1. A method for preparing a levulinate ester, comprising:

adding a hexose compound and a catalyst into trialkoxymethane, and generating levulinic acid ester by the hexose compound under the catalytic action of the trialkoxymethane and the catalyst at a first preset temperature, a first preset pressure and a first preset length.

2. A method of preparing levulinic acid esters according to claim 1, wherein the six-carbon sugar-based compounds comprise at least one of: fructose, glucose, maltose, sucrose, microcrystalline cellulose.

3. A method of preparing levulinic acid esters according to claim 1, wherein the catalyst comprises any one of: a catalyst loaded with phosphotungstic acid, a catalyst loaded with phosphomolybdic acid, a catalyst loaded with silicotungstic acid and a catalyst loaded with silicomolybdic acid.

4. The production process of levulinic acid esters according to claim 3, wherein the support of the phosphotungstic acid-supported catalyst, the support of the phosphomolybdic acid-supported catalyst, the support of the silicotungstic acid-supported catalyst, and the support of the silicomolybdic acid-supported catalyst each comprise any one of: silicon dioxide, zirconium dioxide, titanium oxide and active carbon.

5. A method of preparing levulinic acid esters according to claim 1, wherein the trialkoxymethane comprises at least one of: trimethyl orthoformate, triethyl orthoformate.

6. A method of producing levulinic acid esters according to claim 1, wherein the mass ratio of the hexose compound to trialkoxymethane is 1:5 to 1: 100.

7. The method for producing a levulinic acid ester according to claim 1, wherein the mass ratio of the catalyst to the hexose compound is 0.1 to 10.

8. A method of preparing a levulinate ester according to claim 1, wherein the first predetermined temperature comprises 50-100 ℃.

9. A method of preparing levulinic acid esters according to claim 1, wherein the first predetermined pressure comprises from 0.1 to 5 Mpa.

10. A method of preparing levulinic acid esters according to claim 1, wherein the first predetermined period of time comprises from 1 to 48 hours.

Technical Field

The invention relates to a preparation method of chemicals, and particularly relates to a preparation method of levulinate.

Background

The increasing decrease in petroleum resources and global warming requires the search for a green, environmentally sustainable energy source to reduce the dependence on fossil fuels. The levulinate is one of important platform molecules of biomass base, can perform various reactions such as oxidation, reduction, substitution, polymerization, addition and the like, and is an important platform molecule with wide application prospect in the industries such as coating, spice, food, medicine and the like. The short-chain fatty acid ester of levulinic acid is very similar to biodiesel in properties, and therefore can be used as a potential biofuel or fuel additive.

Currently, there are four main routes for levulinate production: direct esterification of levulinic acid, acid hydrolysis of furfuryl alcohol, 5-chloromethyl furfural alcoholysis, and direct alcoholysis of carbohydrates. The direct esterification method of levulinic acid has mild reaction conditions and high yield, but the method has high cost for producing levulinic acid ester due to the fact that the levulinic acid as the raw material is expensive and difficult to purify. The acid hydrolysis method of furfuryl alcohol is to obtain furfuryl alcohol by furfural hydrogenation first, and ethyl levulinate is obtained by furfuryl alcohol alcoholysis under an acidic condition, the method is designed with multi-step reaction, and furfuryl alcohol is difficult to purify, high pressure hydrogenation is involved, the process is complex, the equipment requirement is high, and the development of the path is limited; the preparation process of the raw material 5-chloromethyl furfural by the 5-chloromethyl furfural alcoholysis method needs the participation of concentrated hydrochloric acid, and the yield is low, so that the equipment is seriously corroded, and the atom utilization rate is low; the direct alcoholysis method of the carbohydrate has wide raw material source and simple process, and is a path with development prospect for producing the levulinate at present.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing levulinic acid ester, so as to solve the above technical problems.

In order to achieve the technical purpose, the invention provides a preparation method of levulinate, which comprises the following steps:

adding a hexose compound and a catalyst into trialkoxymethane, and generating levulinic acid ester by the hexose compound under the catalysis of the trialkoxymethane and the catalyst at a first preset temperature, a first preset pressure and a first preset length.

According to an embodiment of the present invention, the six-carbon sugar compound includes at least one of the following: fructose, glucose, maltose, sucrose, microcrystalline cellulose.

According to an embodiment of the present invention, the catalyst includes any one of the following: a catalyst loaded with phosphotungstic acid, a catalyst loaded with phosphomolybdic acid, a catalyst loaded with silicotungstic acid and a catalyst loaded with silicomolybdic acid.

According to an embodiment of the present invention, the carrier of the phosphotungstic acid-supported catalyst, the carrier of the phosphomolybdic acid-supported catalyst, the carrier of the silicotungstic acid-supported catalyst, and the carrier of the silicomolybdic acid-supported catalyst each include any one of: silicon dioxide, zirconium dioxide, titanium oxide and active carbon.

According to an embodiment of the present invention, wherein the trialkoxymethane comprises at least one of: trimethyl orthoformate, triethyl orthoformate.

According to an embodiment of the invention, the mass ratio of the six-carbon sugar compound to the trialkoxymethane is 1: 5-1: 100.

According to an embodiment of the present invention, the mass ratio of the catalyst to the hexose compound is 0.1 to 10.

According to an embodiment of the present invention, the first predetermined temperature includes 50 to 100 ℃.

According to an embodiment of the present invention, the first predetermined pressure is 0.1 to 5 Mpa.

According to an embodiment of the present invention, the first preset time period includes 1 to 48 hours.

The invention provides a preparation method of levulinate, which is characterized in that a hexose compound and a catalyst are added into trialkoxymethane, under the specific temperature and pressure and under the catalytic action of the catalyst, the hexose compound and the trialkoxymethane react to generate an intermediate product 5- (methoxymethyl) -2-furfural, and the intermediate product 5- (methoxymethyl) -2-furfural further reacts with the trialkoxymethane to generate the levulinate.

Drawings

Fig. 1 schematically shows a gas chromatogram for detecting methyl levulinate produced according to the present invention by gas chromatography.

FIG. 2 schematically shows a NMR spectrum of levulinate esters prepared according to the present invention.

FIG. 3 schematically shows the NMR carbon spectrum of levulinic acid esters prepared according to the invention.

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

In the related technology, the synthesis methods of the levulinic acid ester mainly comprise a levulinic acid direct esterification method, a furfuryl alcohol acid alcoholysis method and a 5-chloromethyl furfural alcoholysis method, and the three synthesis methods have the problems of high raw material price, difficulty in purification, high production cost, complex process, high equipment requirement, low product yield, serious equipment corrosion, low atom utilization rate and the like.

The method is characterized in that the glucide is directly subjected to an alcoholysis method, the glucide and a catalyst are added into an organic solvent and react in the presence of the catalyst to obtain the levulinate, the glucide is taken as a raw material and has wide source, the synthesis process is simple, and the levulinate prepared by the method is easy to separate and purify from a biomass solution, so that the method is a path which has the most development prospect in the prior production of the levulinate.

Accordingly, the present invention provides a process for the preparation of a levulinate ester, comprising: adding a hexose compound and a catalyst into trialkoxymethane, and generating levulinic acid ester by the hexose compound under the catalysis of the trialkoxymethane and the catalyst at a first preset temperature, a first preset pressure and a first preset length.

HC(OCH₃)₃+2H₂O→HCOOH+3CH₃OH (1)(1)

In the embodiment of the invention, a hexose compound and a catalyst are added into trialkoxymethane, under the specific temperature and pressure and under the catalytic action of the catalyst, the hexose compound and the trialkoxymethane react to generate an intermediate product 5- (methoxymethyl) -2-furfural, and the intermediate product 5- (methoxymethyl) -2-furfural further reacts with the trialkoxymethane to generate levulinate.

According to an embodiment of the present invention, the hexose compound is catalyzed by the trialkoxymethane and the catalyst to produce 5- (methoxymethyl) -2-furfural; the 5- (methoxymethyl) -2-furfural generates levulinic acid ester under the catalytic action of the trialkoxymethane and the catalyst.

In the embodiment of the invention, under the catalysis of a catalyst at a first preset temperature and a first preset pressure, a hexose compound reacts with trialkoxymethane to generate an intermediate product 5- (methoxymethyl) -2-furfural, and then the intermediate product continuously reacts with trialkoxymethane to generate levulinic acid ester.

According to an embodiment of the present invention, the six-carbon sugar compound includes at least one of the following: fructose, glucose, maltose, sucrose, microcrystalline cellulose.

In the embodiment of the invention, the hexose compound serving as a reaction raw material comprises fructose, glucose, maltose, sucrose and microcrystalline cellulose, the main components of the raw materials are glucose and fructose, the fructose is easy to hydrolyze, and meanwhile, the maltose, the sucrose and the microcrystalline cellulose serving as the raw materials of the glucose structure can be isomerized into the fructose under the action of a catalyst, and the fructose is further hydrolyzed to participate in the next reduction reaction.

According to an embodiment of the present invention, the catalyst includes any one of the following: a catalyst loaded with phosphotungstic acid, a catalyst loaded with phosphomolybdic acid, a catalyst loaded with silicotungstic acid and a catalyst loaded with silicomolybdic acid.

According to an embodiment of the present invention, the carrier of the phosphotungstic acid-supported catalyst, the carrier of the silicotungstic acid-supported catalyst, and the carrier of the silicomolybdic acid-supported catalyst each include any one of: silicon dioxide, zirconium dioxide, titanium oxide and active carbon.

In the embodiment of the invention, the catalyst is a base metal-based supported catalyst system, has the advantages of low price, easiness in preparation, good cycle performance, long service life, high efficiency, stability, low cost, greenness and the like, and is used for catalyzing the hydrogenation of levulinate to prepare gamma-valerolactone, which is an important development trend at present.

According to an embodiment of the present invention, wherein the trialkoxymethane comprises any one of: trimethyl orthoformate, triethyl orthoformate.

In the embodiment of the invention, trialkoxymethane is easy to combine with two molecules of water at high temperature to react to generate formic acid and methanol, so that trialkoxymethane not only serves as a solvent but also serves as an alcohol reagent to participate in the generation of levulinate in the reaction process.

According to an embodiment of the invention, the mass ratio of the six-carbon sugar compound to the trialkoxymethane is 1: 5-1: 100.

In an embodiment of the present invention, the mass ratio of the six-carbon sugar compound to the trialkoxymethane is 1:5 to 1:100, for example, 1:5, 1:30, 1:50, 1:80, or 1: 100.

According to an embodiment of the present invention, the mass ratio of the catalyst to the hexose compound is 0.1 to 10.

In the embodiment of the present invention, the mass ratio of the catalyst to the hexose compound is 0.1 to 10, for example, 0.1, 5, 8, 10.

According to an embodiment of the present invention, the first predetermined temperature includes 50 to 100 ℃.

In an embodiment of the invention, the first predetermined temperature includes 50 to 100 ℃, for example, 50 ℃, 70 ℃, 85 ℃, 100 ℃.

According to an embodiment of the present invention, the first predetermined pressure is 0.1 to 5 Mpa.

In an embodiment of the invention, the first predetermined pressure includes 0.1 to 5Mpa, for example, 0.1Mpa, 1Mpa, 3Mpa, 5 Mpa.

According to an embodiment of the present invention, the first preset time period includes 1 to 48 hours.

In an embodiment of the invention, the first preset time period includes 1 to 48 hours, for example, 1 hour, 12 hours, 24 hours, 36 hours, and 48 hours.

The present invention will be explained in further detail with reference to specific examples.

Example 1

To 30ml of an aqueous solution containing 0.3g of phosphotungstic acid was added 1g of ZrO₂Stirring and dipping for 3h at room temperature, standing for 24h, evaporating redundant water, drying for 24h at 110 ℃, and then calcining for 3h at 300 ℃ to prepare the phosphotungstic acid/zirconia catalyst.

Example 2

To 30ml of an aqueous solution containing 0.3g of phosphomolybdic acid, 1g of TiO was added₂Stirring and immersing for 3h at room temperature, standing for 24h, evaporating excessive water, drying for 24h at 110 ℃, and then calcining for 3h at 300 ℃ to prepare the phosphomolybdic acid/titanium oxide catalyst.

Preparation of levulinic acid esters

The following examples were implemented in pressure resistant tubing.

Example 3

0.1g of fructose, 0.1g of phosphomolybdic acid/titanium oxide catalyst and 10mL of trimethyl orthoformate were put into a 15mL pressure-resistant tube, heated to 120 ℃ under magnetic stirring, and stirred for reaction for 10 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, transferred to a 100ml volumetric flask, diluted with methanol to a constant volume, and then subjected to detection of the product content by using a gas chromatography (GC 2104, Shimazu, FID) equipped with a DM-WAX (30 m. times.0.32 mm. times.0.25 μm) column. The gasification temperature is set to 250 ℃, the detection temperature is set to 280 ℃, and the temperature of the column box is set to 180 ℃ and kept for 20 min. The linear velocity was 45cm/s and the split ratio was 50. And detecting the product by adopting an external standard method. Diluting a certain amount of product with methanol, then fixing the volume to 100ml, sampling for gas phase detection, detecting for three times, and taking an average value. The product yield calculation method is as follows:

quantitative detection of the compound in the reaction system revealed that the yield of methyl levulinate was 95%.

Fig. 1 schematically shows a gas chromatogram for detecting methyl levulinate produced according to the present invention by gas chromatography.

By referring to the retention times of the standard substances, as can be seen from the retention times shown in fig. 1, the gas chromatography peak at a retention time of 1.35min is the peak of methyl levulinate produced by the reaction, and the gas chromatography peak at a retention time of 8.28min is the peak of 5- (methoxymethyl) -2-furfural, which is an intermediate product of the present invention.

Example 4

The specific reaction process and detection method were the same as in example 3 except that 5mL of the organic solvent was used. The product obtained as a result was methyl levulinate, and the yield was 92%.

Example 5

The specific reaction process and detection method are the same as those in example 3, except that fructose is changed to glucose. The product obtained as a result was methyl levulinate, and the yield was 72%.

Example 6

The specific reaction process and detection method are the same as those in example 3, except that fructose is changed to glucose. The product obtained as a result was methyl levulinate, and the yield was 70%.

Example 7

The specific reaction process and detection method were the same as in example 3 except that the phosphomolybdic acid/titanium oxide catalyst was changed to phosphotungstic acid/titanium oxide. The product obtained as a result was methyl levulinate and the yield was 90%.

Example 8

The specific reaction process and detection method were the same as in example 3 except that the phosphomolybdic acid/titanium oxide catalyst was changed to phosphotungstic acid/titanium oxide. The product obtained as a result was methyl levulinate and the yield was 84%.

Example 9

The specific reaction process and detection method were the same as in example 3 except that the reaction temperature was adjusted to 100 ℃. The product obtained as a result was methyl levulinate, and the yield was 81%.

Example 10

The specific reaction process and detection method were the same as in example 3 except that the reaction temperature was adjusted to 140 ℃. The product obtained as a result was methyl levulinate, and the yield was 88%.

Example 11

The specific reaction process and detection method were the same as in example 3 except that the reaction solvent was changed to triethyl orthoformate. The product obtained as a result was ethyl levulinate and the yield was 76%.

Example 12

The specific reaction process and detection method are the same as in example 3, except that the reaction time is changed to 24 h. The product obtained as a result was methyl levulinate, and the yield was 93%.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.