CN107311970B - A kind of method for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone - Google Patents

Abstract

The invention discloses a method for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone, which comprises the following steps: mixing a triacetyl lactone raw material and an alcohol compound with a hydrogen donor, adding the mixture into a closed high-pressure reaction kettle, and carrying out hydrogen transfer reaction for 0.5-48h under the conditions that the nitrogen pressure is 1-12MPa, the reaction temperature is room temperature-150 ℃ and a catalyst exists to obtain the 4-hydroxy-6-methyltetrahydro-2-pyrone, wherein the catalyst is non-noble metal nano-particles. The method does not need to use noble metal, has low cost, is easy to separate, can be repeatedly used, has a simple reaction system, and is easy to industrialize.

Description

A kind of method for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone

technical field

The invention specifically relates to a method for preparing 4-hydroxy-6-methyltetrahydropyranone.

Background technique

Biomass is the only renewable organic carbon resource and an ideal candidate to replace petroleum in the production of fuels and chemicals. Therefore, it has become a research hotspot in the field of new energy and new materials to make full use of the organic carbon resources in biomass and develop new routes and methods for converting biomass into fuels and chemicals. Microbially synthesized platform molecules provide new opportunities for the conversion of carbohydrates into commercial chemicals. Such microbial-derived platform molecules are the products of a single metabolic pathway of microorganisms and have flexible and controllable functional groups. Chemical catalysis upgrades can convert these platform molecules. Converted into a variety of end products to replace existing petrochemical products. Triacetic acid lactone (4-hydroxy-6-methyl-2-pyrone, Triacetic acid lactone) is such a new generation platform molecule of microbial origin, which can be derived either from nature (plants and microorganisms) or from Acetic acid synthesis, considered as a "bridge compound linking biocatalysis and chemical catalysis", research on its efficient conversion and utilization helps to overcome the shortcomings of single chemical method or single biological method to prepare bio-based high-value chemicals. Triacetin can be converted into a variety of commercially valuable chemical intermediates and end products through catalytic upgrading. The first step of triacetin conversion is catalytic hydrogenation. The existing problem is that triacetin is easily degraded in an aqueous solution. The hydrogenation step requires n-butanol as a solvent, hydrogen as a hydrogen source, and precious metal as a catalyst.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a method for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone so as to overcome the deficiencies in the prior art.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

The triacetate lactone raw material and the alcohol compound with hydrogen donor are mixed and added into the closed autoclave, and the hydrogen transfer reaction is carried out under the condition that the nitrogen pressure is 1-12MPa, the reaction temperature is room temperature-150℃, and the catalyst exists. 0.5-48h, 4-hydroxy-6-methyltetrahydro-2-pyranone is obtained, and the catalyst is non-precious metal nanoparticles.

Further, the alcohol compounds include primary alcohol and secondary alcohol, the primary alcohol is methanol, ethanol, n-propanol, n-butanol, n-pentanol or cyclohexanol, and the secondary alcohol is isopropyl alcohol Propanol, isobutanol, or sec-butanol.

Further, the ratio of the alcohol compound to the triacetin is 5-50 mL:1 g.

Further, the non-precious metal includes one or more of nickel, cobalt and copper.

Further, the dosage ratio of the non-precious metal nanoparticle catalyst to triacetin is 0.03-2.0g:1g.

Further, it also includes the steps of recovering and reusing the non-precious metal nanoparticle catalyst; the method for recovering the catalyst includes centrifugal separation, washing and drying.

Compared with the prior art, the advantages of the present invention include: in the hydrogen transfer reaction, the alcohol compound both serves as a solvent and provides a hydrogen source, no additional hydrogen source is needed, the catalyst used is a common and readily available non-precious metal, the cost is low, and the cost is low. recycle and re-use. Compared with the prior art, the process of the present invention does not require additional hydrogen, and the operation is simple and safe.

Description of drawings

Fig. 1 is the high-performance liquid chromatography detection result diagram of the product of Example 1.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to several embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Examples 1-4:

This embodiment provides the preparation of different metal nanoparticles, and the experiment of catalyzing hydrogen transfer of triacetin to prepare 4-hydroxy-6-methyltetrahydro-2-pyranone:

Preparation of nickel nanoparticles: 0.1 g of nickel nitrate was dissolved in 4 mL of water, added dropwise to a mixture of 40 mL of ethylene glycol and 40 mL of water, ultrasonically dispersed for 30 min, and 16 mL of sodium borohydride aqueous solution (0.01 g/mL) was added dropwise to the above. The solution was stirred at room temperature for 8h, filtered, and dried under vacuum at 80°C for 24h.

Preparation of cobalt nanoparticles: 0.1 g of cobalt nitrate was dissolved in 4 mL of water, added dropwise to a mixture of 40 mL of ethylene glycol and 40 mL of water, ultrasonically dispersed for 30 min, and 16 mL of sodium borohydride aqueous solution (0.01 g/mL) was added dropwise to the above. The solution was stirred at room temperature for 8h, filtered, and dried under vacuum at 80°C for 24h.

Preparation of copper nanoparticles: 0.1 g of copper nitrate was dissolved in 4 mL of water, added dropwise to a mixture of 40 mL of ethylene glycol and 40 mL of water, ultrasonically dispersed for 30 min, and 16 mL of sodium borohydride aqueous solution (0.01 g/mL) was added dropwise to the above. The solution was stirred at room temperature for 8h, filtered, and dried under vacuum at 80°C for 24h.

Preparation of nickel-cobalt bimetallic nanoparticles: 0.05g of nickel nitrate and 0.05g of cobalt nitrate were dissolved in 4mL of water, added dropwise to a mixture of 40mL of ethylene glycol and 40mL of water, ultrasonically dispersed for 30min, and 16mL of sodium borohydride aqueous solution (0.01 g/mL) was added dropwise to the above solution, stirred at room temperature for 8 h, filtered, and dried under vacuum at 80 °C for 24 h.

The prepared metal nanoparticles were added to the autoclave, and then 0.25 g of triacetate lactone and 5 mL of isopropanol (both as a hydrogen donor and a reaction solvent) were added, and after sealing, they were replaced with nitrogen five times, and then filled with nitrogen. Introduce 0.1MPa nitrogen, react at 50°C for 10h, after the reaction, the composition of the product is analyzed and quantified by high performance liquid chromatography. The specific results are shown in Table 1:

Table 1. Catalytic results of different catalysts

Examples 5-10:

This example provides an experiment for preparing 4-hydroxy-6-methyltetrahydro-2-pyranone by hydrogenation of triacetin when different alcohol compounds are used as hydrogen donors:

Add 0.02g of nickel nanoparticles into the autoclave, then add 0.25g of triacetate lactone and 5mL of different alcohol compounds (both as a hydrogen donor and as a reaction solvent), after sealing, replace with nitrogen five times, and then fill with Introduce 0.1MPa nitrogen, react at 50°C for 10h, after the reaction, the composition of the product is analyzed and quantified by high performance liquid chromatography. The specific results are shown in Table 2:

Table 2. Catalytic results when using different alcohols as hydrogen donors

Example different alcohol compounds Conversion rate(%) Selectivity (%) Yield(%) 5 n-Propanol 40 70 twenty four 6 n-butanol 50 54 27 7 n-pentanol 48 31 15 8 cyclohexanol 45 44 20 9 sec-butanol 52 65 34 10 isopropyl alcohol 100 89 89

Examples 11-13:

This example provides the experiment of preparing 4-hydroxy-6-methyltetrahydro-2-pyranone by hydrogenation of triacetin at different reaction temperatures:

Add 0.02g of nickel nanoparticles into the autoclave, then add 0.25g of triacetate lactone and 5mL of different alcohol compounds (both as a hydrogen donor and as a reaction solvent), after sealing, replace with nitrogen five times, and then fill with Enter 0.1MPa of nitrogen, and react at different temperatures for 10h. After the reaction, the composition of the product is analyzed and quantified by high performance liquid chromatography. The specific results are shown in Table 3:

Table 3. Catalysis results at different temperatures

Example temperature(℃) Conversion rate(%) Selectivity (%) Yield(%) 11 50 100 89 89 12 75 100 90 90 13 100 100 75 75

Examples 14-17:

The reaction conditions used in this experiment are the same as the experimental conditions in Example 1, except that the steps of recovering and reusing the catalyst are added.

The operation steps of recovery and reuse are as follows: after the reaction is completed, the catalyst is centrifuged, the supernatant is poured out, the precipitate is washed three times with ethanol, and vacuum-dried at 80 ° C for the next reaction. The test results of repeated use are shown in Table 4. :

Table 4. Catalytic results for catalyst recovery and reuse

Example Cycle times Conversion rate(%) Selectivity (%) Yield(%) 14 1 100 89 89 15 5 100 88 88 16 10 100 88 88 17 20 100 85 85

Referring to the foregoing content, it can be proved that the present invention prepares 4-hydroxy-6-methyltetrahydro-2-pyranone by catalyzing hydrogen transfer of triacetolactone by non-precious metal nanoparticles, does not require additional hydrogen and precious metal catalysts, and has low cost, The catalyst can be recycled.

It should be understood that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. A process for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone comprising the steps of:

mixing a triacetyl lactone raw material and an alcohol compound with a hydrogen donor, adding the mixture into a closed high-pressure reaction kettle, and carrying out hydrogen transfer reaction for 0.5-48h under the conditions that the nitrogen pressure is 0.1MPa, the reaction temperature is 50-75 ℃ and a catalyst exists to obtain 4-hydroxy-6-methyltetrahydro-2-pyrone, wherein the catalyst is non-noble metal nano-particles;

the alcohol compound with the hydrogen donor is isopropanol;

the non-noble metal nanoparticles are nickel nanoparticles, cobalt nanoparticles or cobalt-nickel bimetallic nanoparticles.

2. The process for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone according to claim 1, characterized in that: the ratio of the alcohol compound to the triacetic acid lactone is 5-50 mL: 1g of the total weight of the composition.

3. The process for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone according to claim 1, characterized in that: the non-noble metal nanoparticles are cobalt-nickel bimetallic nanoparticles.

4. The process for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone according to claim 1, characterized in that: the dosage ratio of the non-noble metal nano-particle catalyst to the triacetic acid lactone is 0.03-2.0 g: 1g of the total weight of the composition.

5. The process for preparing 4-hydroxy-6-methyltetrahydro-2-pyrone according to claim 1, characterized in that: also comprises the steps of recovering and recycling the non-noble metal nano-particle catalyst; the catalyst recovery method comprises centrifugal separation, washing and drying.