A method for preparing γ-valerolactone

Abstract

The present invention discloses a method for highly selectively synthesizing γ-valerolactone. Using α-angelica lactone as a raw material, alcohol as a reaction solvent and reducing agent, and a metal salt as a catalyst, the reaction is carried out in a closed reactor under a certain temperature condition in a non-hydrogen atmosphere for a certain period of time. The present invention uses alcohol as a reducing agent instead of high-pressure hydrogen, with mild reaction conditions, greatly reducing potential hazards. The present invention uses an inexpensive and easily available metal salt instead of a noble metal catalyst, greatly reducing production costs. The catalyst of the present invention is highly efficient, used in small amounts, simple to obtain and easy to recycle, with high product yields and few by-products, and has great application potential.

Description

Technical Field

[0001] The present invention relates to the technical field of high - value utilization of biomass - based platform chemicals, and particularly relates to a method for preparing γ - valerolactone. Background Art

[0002] In recent years, it has been extremely urgent to develop green and renewable resources. Developing efficient biomass resource utilization technologies for the only renewable carbon resource in nature is the key to alleviating the current world energy crisis and improving the ecological system. Biomass - based platform chemicals, due to their wide variety and the ability to be further converted into other high - value products through chemical methods (such as hydrogenation, oxidation, etc.), have great application potential in future industries. As a biomass - based platform chemical, γ - valerolactone (C5H8O2) has broad application prospects in the food industry, organic synthesis, biorefining, and petrochemical industries, and has received extensive attention from scientists at home and abroad.

[0003] α - Angelica lactone (C5H6O2) can be extracted from plants such as grapes, soybeans, and licorice. Converting it into γ - valerolactone can achieve a 100% carbon atom utilization rate. Therefore, it is considered an ideal raw material for preparing γ - valerolactone. For example, the research group of Academician Zhang Suojiang used a 10% Pd / C catalyst and an ionic liquid as a solvent to achieve the process of converting α - angelica lactone to γ - valerolactone under 4.0 MPa H2. Similarly, catalysts such as Ru / C catalyst and Pd - NiO can also achieve the above - mentioned process under high - pressure H2. Although the current technology can convert α - angelica lactone to γ - valerolactone, aspects such as the potential hazards of high - pressure hydrogen and the high cost of noble - metal catalysts still need to be improved. Therefore, it is urgent to develop more economical and effective reaction methods to convert α - angelica lactone to γ - valerolactone with high efficiency and low cost, especially to achieve the above - mentioned conversion process in a non - hydrogen atmosphere. Summary of the Invention

[0004] The purpose of the present invention is to provide a new method for preparing γ - valerolactone in a non - hydrogen atmosphere. The γ - valerolactone is catalytically prepared from α - angelica lactone.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] Using α - angelica lactone as a reaction substrate, mixing it with a reaction solvent and a catalyst in a certain proportion in a pressure - resistant microwave reactor, and carrying out a closed - reaction for a certain time under certain temperature conditions. After the reaction, γ - valerolactone is obtained.

[0007] The reaction solvent is at least one of ethanol, n - propanol, isopropanol, n - butanol, 2 - butanol, and cyclohexanol.

[0008] The catalyst is a metal salt, including but not limited to at least one of La(OTf)3, Y(OTf)3, Yb(OTf)3, Sc(OTf)3, ScCl3, Sc(NO3)3, etc. The molar ratio between the catalyst and the reactants is 0.0125 - 0.075.

[0009] The reactor is a microwave pressurized reactor.

[0010] The reaction temperature can be 130 - 170 o °C, and the reaction time can be 1 - 6 h.

[0011] Compared with the prior art, the present invention has the following prominent advantages:

[0012] The present invention reports for the first time the preparation of γ-valerolactone from biomass-based α-angelica lactone under a non-hydrogen atmosphere. The present invention uses alcohol as a reducing agent instead of high-pressure hydrogen, and the reaction conditions are mild, greatly reducing potential risks. The present invention uses an inexpensive and easily available metal salt instead of a noble metal catalyst, greatly reducing production costs. The catalyst of the present invention is highly efficient, used in small amounts, simple to obtain and easy to recycle, with high product yields and few by-products. Description of the Drawings

[0013] Figure 1 It is the mass spectrum of the target product γ-valerolactone obtained. Detailed Embodiments

[0014] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following embodiments will further illustrate the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. On the contrary, the present invention covers any alternatives, modifications, equivalent methods and solutions made within the spirit and scope of the present invention defined by the claims. Further, in order to enable the public to have a better understanding of the present invention, in the following detailed description of the present invention, some specific details are described in detail. Those skilled in the art can fully understand the present invention without the description of these details.

[0015] Example 1: Weigh 2.0 mmol of α-angelica lactone, 0.1 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressurized reactor. After sealing, heat up to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α-angelica lactone is 97%, and the yield of γ-valerolactone is 60.1%.

[0016] Example 2: Weigh 2.0 mmol of α - angelica lactone, 0.1 mmol of La(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave - pressurized reactor. After sealing, heat it to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α - angelica lactone is 81.1%, and the yield of γ - valerolactone is 3.7%.

[0017] Example 3: Weigh 2.0 mmol of α - angelica lactone, 0.1 mmol of Y(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave - pressurized reactor. After sealing, heat it to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α - angelica lactone is 82.9%, and the yield of γ - valerolactone is 5.4%.

[0018] Example 4: Weigh 2.0 mmol of α - angelica lactone, 0.025 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave - pressurized reactor. After sealing, heat it to 160 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α - angelica lactone is 100%, and the yield of γ - valerolactone is 36.0%.

[0019] Example 5: Weigh 2.0 mmol of α - angelica lactone, 0.05 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave - pressurized reactor. After sealing, heat it to 160 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α - angelica lactone is 100%, and the yield of γ - valerolactone is 55.4%.

[0020] Example 6: Weigh 2.0 mmol of α - angelica lactone, 0.075 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave - pressurized reactor. After sealing, heat it to 160 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and quantitatively analyze it by using a Shimadzu 2010 Plus gas chromatograph. The conversion rate of α - angelica lactone is 100%, and the yield of γ - valerolactone is 76.0%.

[0021] Example 7: Weigh 2.0 mmol of α-angelica lactone, 0.1 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat to 160 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 96.4%.

[0022] Example 8: Weigh 2.0 mmol of α-angelica lactone, 0.125 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat to 160 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 96.3%.

[0023] Example 9: Weigh 2.0 mmol of α-angelica lactone, 0.1 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat to 130 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 25.2%.

[0024] Example 10: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat to 140 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 56.5%.

[0025] Example 11: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat to 150 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 76.9%.

[0026] Example 12: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat it to 170 o °C and react for 3 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 93%.

[0027] Example 13: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat it to 160 o °C and react for 4 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 96.2%.

[0028] Example 14: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat it to 160 o °C and react for 2 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 83%.

[0029] Example 15: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat it to 130 o °C and react for 6 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 54.6%.

[0030] Example 16: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of ethanol solvent and place them in a microwave pressure reactor. After sealing, heat it to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 22.2%.

[0031] Example 17: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of n-propanol solvent and place them in a microwave pressure reactor. After sealing, heat up to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 16.7%.

[0032] Example 18: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of n-butanol solvent and place them in a microwave pressure reactor. After sealing, heat up to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 29.9%.

[0033] Example 19: Weigh 2.0 mmol of α-angelica lactone, 0.01 mmol of Sc(OTf)3 and 15.0 mL of 2-butanol solvent and place them in a microwave pressure reactor. After sealing, heat up to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 58.1%.

[0034] Example 20: After subjecting the reaction liquid in Example 1 to vacuum distillation, the catalyst was recovered. Then, weigh 2.0 mmol of α-angelica lactone and 15.0 mL of isopropanol solvent and place them in a microwave pressure reactor. After sealing, heat up to 160 o °C and react for 1 h. After the reaction is completed, add naphthalene as an internal standard and perform quantitative analysis by Shimadzu 2010 Plus gas chromatography. The conversion rate of α-angelica lactone is 100%, and the yield of γ-valerolactone is 59.8%.

[0035] The embodiments of the present invention are not limited by the above examples. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing γ-valerolactone, characterized in that: Using α-angelica lactone as a raw material, alcohol as a reaction solvent and a reducing agent, and a metal salt as a catalyst, the reaction is carried out in a closed reactor under a certain temperature condition in a non-hydrogen atmosphere for a certain time, realizing the highly selective synthesis of γ-valerolactone. The metal salt includes at least one of La(OTf)3, Y(OTf)3, Yb(OTf)3, Sc(OTf)3, ScCl3, and Sc(NO3)3.

2. The method according to claim 1, wherein The reactor used includes a microwave pressure reactor.

3. The method according to claim 1, characterized in that The catalyst used is a metal salt, and the molar ratio between the catalyst and the reactants is 0.0125 - 0.

075.

4. The method according to claim 1, characterized in that The solvent used is at least one of ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, and cyclohexanol.

5. The method according to claim 1, wherein The temperature used is in the range of 130 - 170 °C.

6. The method according to claim 1, wherein The time used is in the range of 1 - 6 h.

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