A preparation method of 5-methyltetrahydrofurfuryl alcohol

Abstract

The present invention discloses a method for preparing 5-methyltetrahydrofurfuryl alcohol. The method uses 5-hydroxymethylfurfural (HMF) as a raw material and one or more of palladium on carbon, Raney nickel, and sulfonated silica as a catalyst. HMF, a reaction solvent, and the catalyst are added to a reactor. Amberlyst 15 strong acid resin is added as a second catalyst to provide an acidic environment. The reactor is stirred and reacted in a hydrogen atmosphere to produce 5-methyltetrahydrofurfuryl alcohol. The present invention provides a method for preparing 5-methyltetrahydrofurfuryl alcohol that is simple, easy to separate, high in purity, and high in yield. The addition of Amberlyst 15, a second catalyst, to the reaction provides an acidic environment without affecting the activity of the Raney nickel, thereby facilitating the cleavage of the carbon-oxygen bond to produce the target product, 5-methyltetrahydrofurfuryl alcohol (MTHFM). The synergistic effect of Amberlyst 15 and the Raney nickel catalyst greatly enhances the activity of the catalytic reaction.

Description

Technical Field

[0001] The invention relates to a preparation method of 5-methyltetrahydrofurfuryl alcohol. Background Art

[0002] With the increasing consumption of fossil energy and the resulting increasingly serious environmental problems, renewable, environmentally friendly biomass energy has attracted considerable attention in recent years. 5-Hydroxymethylfurfural (HMF) is one of the most important platform compounds in biomass conversion. HMF and its derivatives, such as 2,5-furandicarboxylic acid (FDCA), 2,5-tetrahydrofuran dimethanol (THFDM), 2,5-furandimethylamine (BAMF), and 2,5-dimethylfuran (DMF), can serve as precursors for important chemical substances such as pharmaceutical intermediates, daily chemical products, fuels, and polymers. Numerous literature has reported on the properties, uses, and synthesis methods of these compounds.

[0003] 5-Methyltetrahydrofurfuryl alcohol (MTHFM), a derivative of 5-hydroxymethylfurfural (HMF), is the product of the hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) and is expected to show significant potential as a biofuel and solvent. However, existing reports on the synthesis of 5-methyltetrahydrofurfuryl alcohol (MTHFM) are limited, with most reports occurring as intermediates or by-products in the research of other substances, and generally resulting in low yields. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the purpose of this application is to provide a method for preparing 5-methyltetrahydrofurfuryl alcohol.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for preparing 5-methyltetrahydrofurfuryl alcohol comprises using 5-hydroxymethylfurfural (HMF) as a raw material and one or more of palladium-carbon, Raney nickel, and sulfonated silica as a catalyst. HMF, a reaction solvent, and the catalyst are added to a reactor, and Amberlyst 15 strong acid resin is added as a second catalyst to provide an acidic environment. The mixture is stirred and reacted in a hydrogen atmosphere in the reactor to produce 5-methyltetrahydrofurfuryl alcohol. The reaction path is as follows:

[0007]

[0008] Furthermore, the reaction solvent is one or more of water, methanol, ethanol, 1,4-dioxane, and isopropanol, and the mass concentration of HMF in the reaction solvent is 10-50%.

[0009] Furthermore, the reaction solvent is ethanol, and the mass concentration of HMF in the reaction solvent is 10-25%.

[0010] Furthermore, the hydrogen pressure of the reaction is 3-6 MPa, the reaction temperature is 100-150° C., the reaction time is 4-12 h, and the stirring rate is 400-700 rpm.

[0011] Furthermore, the hydrogen pressure of the reaction is 4-5 MPa, the reaction temperature is 120-130° C., the reaction time is 8-10 h, and the stirring rate is 500-600 rpm.

[0012] Furthermore, the catalyst is Raney nickel, and the amount of the catalyst is 5-25% of the mass of HMF.

[0013] Furthermore, the amount of catalyst used is 15-25% of the mass of HMF, preferably 20-25%.

[0014] Furthermore, the amount of the Amberlyst 15 strong acid resin used is 0.1-0.8% of the mass of HMF.

[0015] Furthermore, the amount of Amberlyst 15 strong acid resin used is 0.4-0.6% of the mass of HMF.

[0016] The beneficial effects achieved by the present invention are:

[0017] 1) The preparation method of the present invention adds a second catalyst, Amberlyst 15, to the reaction. Amberlyst 15 can provide an acidic environment without affecting the activity of Raney nickel, which is conducive to the cleavage of the carbon-oxygen bond to generate the target product 5-methyltetrahydrofurfuryl alcohol (MTHFM). Amberlyst 15 and the Raney nickel catalyst work together to greatly improve the activity of the catalytic reaction.

[0018] 2) The choice of reaction solvent also has a great influence on the experimental results. In the present invention, the use of ethanol as a solvent can greatly improve the reaction effect.

[0019] 3) The present invention provides a method for preparing 5-methyltetrahydrofurfuryl alcohol with simple separation, high purity, and high yield. As a derivative of 5-hydroxymethylfurfural (HMF), 5-methyltetrahydrofurfuryl alcohol (MTHFM) is expected to show significant potential as a biofuel and solvent. 5-Methyltetrahydrofurfuryl alcohol (MTHFM) can also be used to prepare herbicides. For example, in Example 19 of patent CN88102313A, 5-methyltetrahydrofurfuryl alcohol was used as a raw material to prepare herbicide Compound 17. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is the chromatogram of 5-methyltetrahydrofurfuryl alcohol (cis and trans isomers are eluted separately);

[0021] Figure 2 This is the gas phase mass spectrum of 5-methyltetrahydrofurfuryl alcohol (trans);

[0022] Figure 3 This is the gas phase mass spectrum of 5-methyltetrahydrofurfuryl alcohol (cis). DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0024] Example 1

[0025] 3g of 5-hydroxymethylfurfural (HMF) and 27g of ethanol were added to a polytetrafluoroethylene (PTFE)-lined reactor and stirred to dissolve the HMF. The HMF-ethanol solution now had a HMF mass fraction of 10%. 0.15g of commercial Raney nickel catalyst was then added, resulting in a Raney nickel catalyst dosage of 5% of the HMF mass. The PTFE-lined reactor was transferred to an autoclave. After three inert gas-exchanged air cycles, hydrogen was introduced to a reaction pressure of 3 MPa. The reaction temperature was set to 110°C, the speed was adjusted to 600 rpm, and the reactor was started. Samples were taken after 5 hours and at the end of the reaction for analysis. The results are shown in Table 1.

[0026] Example 2

[0027] The reaction temperature was set at 120° C., the reaction pressure was 4 MPa, the amount of Raney nickel catalyst used was 8% (0.24 g) of the mass of HMF, and the other conditions were the same as those in Example 1.

[0028] Example 3

[0029] The reaction temperature was set at 130° C., the reaction pressure was 5 MPa, the amount of Raney nickel catalyst used was 10% (0.3 g) of the mass of HMF, and other conditions were the same as those in Example 1.

[0030] Example 4

[0031] The mass fraction of 5-hydroxymethylfurfural raw material in the HMF-ethanol solution was adjusted to 15%, and other conditions were the same as those in Example 3.

[0032] Example 5

[0033] The mass fraction of 5-hydroxymethylfurfural raw material in the HMF-ethanol solution was adjusted to 20%, and other conditions were the same as those in Example 3.

[0034] Example 6

[0035] The mass fraction of 5-hydroxymethylfurfural raw material in the HMF-ethanol solution was adjusted to 25%, and other conditions were the same as those in Example 3.

[0036] Example 7

[0037] The mass fraction of 5-hydroxymethylfurfural raw material in the HMF-ethanol solution was adjusted to 30%, and other conditions were the same as those in Example 3.

[0038] Table 1 Experimental results of Examples 1-7

[0039]

[0040] Comparison of Examples 1-3 shows that a longer reaction time is required to achieve substantially complete conversion of HMF, and increasing the reaction pressure, temperature, and catalyst dosage is beneficial to the conversion of HMF to MTHFM.

[0041] Comparative Examples 3-7 show that while HMF conversion decreases with increasing HMF mass fraction, selectivity and yield generally improve. Due to solubility issues, preparing HMF ethanol solutions with higher concentrations is difficult. The following examples attempt to add a second catalyst, Amberlyst 15, to provide an acidic environment for testing.

[0042] Example 8

[0043] The mass fraction of 5-hydroxymethylfurfural raw material in the HMF-ethanol solution was 10%. A second catalyst, Amberlyst 15, was added to provide an acidic environment. The amount of Amberlyst 15 added was 0.1% by mass of the HMF. All other conditions were the same as in Example 3. At the end of the reaction, samples were collected for testing and analysis. The results are shown in Table 2.

[0044] Example 9

[0045] The mass fraction of 5-hydroxymethylfurfural raw material in HMF-ethanol solution was 10%. A second catalyst Amberlyst 15 was added to provide an acidic environment. The amount of Amberlyst 15 added was 0.2% of the mass of HMF. Other conditions were the same as those in Example 3.

[0046] Example 10

[0047] The mass fraction of 5-hydroxymethylfurfural raw material in HMF-ethanol solution was 10%. A second catalyst Amberlyst 15 was added to provide an acidic environment. The amount of Amberlyst 15 added was 0.4% of the mass of HMF. Other conditions were the same as those in Example 3.

[0048] Example 11

[0049] The mass fraction of 5-hydroxymethylfurfural raw material in HMF-ethanol solution was 10%. A second catalyst Amberlyst 15 was added to provide an acidic environment. The amount of Amberlyst 15 added was 0.6% of the mass of HMF. Other conditions were the same as those in Example 3.

[0050] Example 12

[0051] The mass fraction of 5-hydroxymethylfurfural raw material in HMF-ethanol solution was 10%. A second catalyst Amberlyst 15 was added to provide an acidic environment. The amount of Amberlyst 15 added was 0.8% of the mass of HMF. Other conditions were the same as those in Example 3.

[0052] Table 2 Experimental results of Examples 8-12

[0053] Example Raw material conversion rate Selectivity of target product Yield of target product 8 99.32％ 28.96％ 28.76％ 9 99.03％ 45.55％ 45.11％ 10 98.76％ 68.71％ 67.86％ 11 96.57％ 84.11％ 81.23％ 12 88.12％ 72.17％ 63.60％

[0054] Comparative Examples 8-11 show that the conversion rate gradually increases with the increase in the amount of the precursor Amberlys15 added, and the selectivity and yield also increase significantly. Comparative Examples 11-12 show that further increasing the amount of Amberlyst15 reduces the conversion rate, selectivity and yield. This may be because the activity of the Raney nickel catalyst is affected by the more acidic environment.

[0055] Example 13

[0056] Methanol was used as the solvent to prepare a 10% 5-hydroxymethylfurfural solution. Other conditions were the same as in Example 11. Samples were taken at the end of the reaction for analysis. The results are shown in Table 3.

[0057] Example 14

[0058] Isopropyl alcohol was used as a solvent to prepare a 10% by mass 5-hydroxymethylfurfural solution. Other conditions were the same as those in Example 11.

[0059] Example 15

[0060] A 10% 5-hydroxymethylfurfural solution was prepared using 1,4-dioxane as the solvent. Other conditions were the same as in Example 11. Samples were taken at the end of the reaction and analyzed. The results are shown in Table 3.

[0061] Table 3. Analytical results of Examples 13-15

[0062] Example solvent Conversion rate Selectivity Yield 13 Methanol 93.87％ 77.23％ 72.50％ 14 Isopropyl alcohol 97.11％ 73.96％ 71.82％ 15 1,4-Dioxane 90.70％ 86.05％ 78.05％

[0063] Comparing the analysis results of Examples 11 and 13-15, it can be seen that ethanol is the best solvent for the reaction.

[0064] The solution obtained by the reaction in Example 11 was filtered and subjected to reduced pressure distillation to remove ethanol first, and then the vacuum degree was further increased to obtain the pure target product 5-methyltetrahydrofurfuryl alcohol by reduced pressure distillation. The sample was taken for GC analysis. The gas chromatogram was shown in FIG. Figure 1 (5-Methyltetrahydrofurfuryl alcohol cis and trans isomers are eluted separately, with retention times of 8.626min and 8.994min, respectively, and a purity of 99.5%), see the gas phase mass spectrum. Figure 2 、 Figure 3 .

[0065] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for preparing 5-methyltetrahydrofurfuryl alcohol, characterized in that 5-Hydroxymethylfurfural (HMF) is used as the raw material and Raney nickel is used as the catalyst. HMF, a reaction solvent, and the catalyst are added to a reactor. Amberlyst 15 strong acid resin is added as a second catalyst to provide an acidic environment. The mixture is stirred and reacted in a hydrogen atmosphere in the reactor to produce 5-methyltetrahydrofurfuryl alcohol. The reaction solvent is one or more of methanol, ethanol, 1,4-dioxane, and isopropanol, and the mass concentration of HMF in the reaction solvent is 10-50%; The hydrogen pressure of the reaction is 4-5 MPa, the reaction temperature is 120-130°C, the reaction time is 8-10 h, and the stirring rate is 500-600 rpm; The amount of Raney nickel catalyst used is 5-25% of the mass of HMF; The amount of the Amberlyst 15 strong acid resin used is 0.4-0.6% of the mass of HMF.

2. a preparation method of 5-methyltetrahydrofurfuryl alcohol as claimed in claim 1, is characterized in that The reaction solvent is ethanol, and the mass concentration of HMF in the reaction solvent is 10-25%.

3. A method for preparing 5-methyltetrahydrofurfuryl alcohol as claimed in claim 1, wherein The amount of catalyst used is 15-25% of the mass of HMF.

4. a preparation method of 5-methyltetrahydrofurfuryl alcohol as claimed in claim 3, is characterized in that The amount of catalyst used is 20-25% of the mass of HMF.

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