Synthetic method of isopinopinone

Abstract

The invention belongs to the technical field of organic synthesis, and particularly discloses a synthesis method of isopinopinone, which comprises the following steps: (1) by taking alpha-pinene as a raw material, hydroborating by using a borane tetrahydrofuran complex, and oxidizing the hydroboration product by using a sodium hydroxide solution and hydrogen peroxide to obtain isopinopinol; (2) performing high-temperature dehydrogenation on the isopinopinol by taking Cu / Ni-Al-SBA-15 as a catalyst to obtain a product, namely isopinopinone; the total loading capacity of Cu and Ni in the Cu / Ni-Al-SBA-15 is 9-12%, the molar ratio of Cu to Ni is (8-10): 1, and the molar ratio of Si to Al in the carrier Al-SBA-15 is (9-11): 1. The conversion rate and the yield of the two-step reaction are relatively high, the dehydrogenation catalyst in the second step can be recycled for more than three times through filtration, and compared with a traditional copper-silicon catalyst, the mesoporous weak-acid molecular sieve serving as a carrier can effectively improve the product selectivity. The purity of the isopinopinone obtained through filtration and rectification can reach 99% or above, the cost can be effectively reduced, and industrial production can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and relates to the synthesis of fragrance compounds, specifically to a method for synthesizing isopinone. Background Technology

[0002] Isopentanone is an important monoterpenoid compound. Natural isopentanone exists in the secondary metabolites of some plants and animals. It is a major component of hyssop essential oil and castoreum. Hyssop essential oil is an important food additive and herb with good therapeutic effects on fever, chills, and liver and gallbladder diseases. Castoreum is one of the four major animal fragrances and has wide applications in the fragrance and cosmetics industries. Isopentanone can be isolated from natural essential oils or synthesized chemically, but both methods suffer from high cost and low yield. Traditional chemical synthesis involves epoxidation of α-pinene followed by ring-opening to obtain isopentanone. However, this method suffers from numerous epoxide ring-opening products and difficulties in separation. Patent CN103923022 describes the oxidation of isopentanol with PCC to obtain isopentanone, but PCC is highly toxic and cannot be industrialized. my country is a major producer of pine resin, with abundant turpentine resources and an annual output of over 100,000 tons. However, in recent years, research and utilization of turpentine's deep processing have remained at the level of the 1990s. The main products are still traditional products such as terpenoid resin, camphor, and borneol. Developing a high-efficiency, high-yield, and green method for synthesizing isopine pinone using α-pinene as a raw material is of great significance for broadening the application of turpentine in my country. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for synthesizing isopinone. This invention uses α-pinene as a raw material, and a boranetetrahydrofuran complex is used to generate isopinol via a hydroboration oxidation reaction. Isopinol is then dehydrogenated at high temperature using Cu / Ni-Al-SBA-15 as a catalyst to obtain the product isopinone. The two-step reaction of this invention exhibits high conversion and yield rates. The dehydrogenation catalyst in the second step can be recycled more than three times, effectively reducing costs and enabling industrial-scale production. Furthermore, compared to traditional copper-silicon catalysts, the use of mesoporous weak acid molecular sieves as a support effectively improves product selectivity.

[0004] This invention is achieved through the following technical solution: A method for synthesizing isopine pinone includes the following steps: (1) Using α-pinene as raw material, isopinepine alcohol is obtained by hydroboration of boranetetrahydrofuran complex and oxidation of the hydroboration product with sodium hydroxide solution and hydrogen peroxide. (2) Isopinol was dehydrogenated at high temperature using Cu / Ni-Al-SBA-15 as a catalyst to obtain the product isopinone; Step 1: Borohydride oxidation reaction:

[0005] Second step dehydrogenation reaction:

[0006] The total loading of Cu and Ni in the Cu / Ni-Al-SBA-15 is 9~12%, the molar ratio of Cu to Ni is 8~10:1, and the molar ratio of Si to Al in the Al-SBA-15 support is 9~11:1.

[0007] A further improvement to the present invention is as follows: The molar ratio of borane in the α-pinene-boranetetrahydrofuran complex is 1:0.35~0.5.

[0008] Furthermore, the boranetetrahydrofuran complex is added to the reaction system dropwise, with the temperature controlled at -10 to 0°C during the dropwise addition; the temperature for the hydroboration is 20 to 30°C, and the time is 2 to 4 hours.

[0009] Furthermore, the mass ratio of α-pinene to sodium hydroxide solution and hydrogen peroxide is 1:0.1~0.2:0.4~0.6; the mass concentration of sodium hydroxide solution is 30~50%; and the mass concentration of hydrogen peroxide is 40~60%.

[0010] Furthermore, the sodium hydroxide solution and hydrogen peroxide are added to the reaction system dropwise in sequence, with the sodium hydroxide solution added at a temperature of -5 to 5°C and the hydrogen peroxide added at a temperature of 30 to 45°C.

[0011] Furthermore, the amount of Cu / Ni-Al-SBA-15 catalyst fed is 4-10% of the mass of isopine pinol.

[0012] Furthermore, the high-temperature dehydrogenation temperature is 180~220℃, and the time is 2~10 h.

[0013] Furthermore, after the hydroboration reaction is completed, an alcohol is added dropwise to decompose the unreacted borane, wherein the alcohol is one or a mixture of two or more of methanol, ethanol, or isopropanol.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The isopyringone synthesis process provided by this invention is an industrially scalable production method. After filtration following the second-step dehydrogenation reaction, the product undergoes distillation to achieve a purity of over 99%, generating no wastewater and conforming to green chemistry principles. Furthermore, compared to traditional copper-silicon catalysts, the use of mesoporous weak acid molecular sieves as a support effectively improves product selectivity. This invention boasts high conversion and yield rates, offering significant profit potential. Once operational, this invention can contribute to the reduction of my country's massive annual consumption of α-pinene. Detailed Implementation

[0015] The present invention will now be described in detail with reference to specific embodiments.

[0016] The carrier Al-SBA-15 used in this embodiment of the invention can be obtained commercially or prepared according to the steps of Example 1.

[0017] Example 1: Preparation of Cu / Ni-Al-SBA-15 catalyst 17.5 g of Al(NO3)3·9H2O was dissolved in 100 mL of deionized water, and then 28.0 g of molecular sieve SBA-15 was added to obtain a mixture with a Si / Al molar ratio of 10:1. The mixture was mechanically stirred at 80 °C for 48 h. Subsequently, the mixture was rotary evaporated to obtain a white solid, which was calcined in a muffle furnace at 500 °C for 5 h (heating rate of 2.5 °C / min) to obtain 30.35 g of Al-SBA-15.

[0018] Copper and nickel were loaded onto Al-SBA-15 using a vacuum isovolume impregnation method: First, the saturated adsorption capacity of Al-SBA-15 for water was tested. Then, 13.71 g of Cu(NO3)2·6H2O and 1.62 g of Ni(NO3)2·6H2O were weighed and dissolved in 10 mL of deionized water (stirred at 50 °C), with a Cu / Ni molar ratio of 9:1. 30.35 g of Al-SBA-15 was placed in a single-necked flask with a rubber stopper and magnetic stirrer, and the flask was evacuated to 2.0 mmHg and allowed to stand for 30 min. Then, while stirring the powder, a hot mixed salt solution was added dropwise. After the addition was complete, the flask was allowed to stand at room temperature for 24 h and then dried at 110 °C with forced air to obtain a light blue solid. CuO / NiO-Al-SBA-15 was obtained by calcination in a muffle furnace at 500°C for 5 h (heating rate of 2.5°C / min), and then reduced in a tube furnace (10%H2 / 90%N2) at 550°C for 5 h to obtain 33.55 g of Cu / Ni-Al-SBA-15 catalyst.

[0019] Example 2: Preparation of isopine pinol 1000 g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -10℃. 1714 mL of 1.8 M boranetetrahydrofuran solution (0.42 eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25℃ and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0℃, and 200 g of methanol was added dropwise to decompose the unreacted borane over 2 hours. The system was controlled below 0℃, and 150 g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45℃, and 500 g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopine pinol was distilled off: 962.1 g, yield 85%.

[0020] Example 3: Preparation of isopine pinol 1000 g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -5°C. 1714 mL of 1.8 M boranetetrahydrofuran solution (0.42 eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25°C and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0°C, and 200 g of methanol was added dropwise to decompose the unreacted borane over 2 hours. The system was kept below 0°C, and 150 g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45°C, and 500 g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopinepinol was distilled off: 956.4 g, yield 84.5%.

[0021] Example 4: Preparation of isopine pinol 1000 g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -0℃. 1714 mL of 1.8 M boranetetrahydrofuran solution (0.42 eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25℃ and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0℃, and 200 g of methanol was added dropwise to decompose the unreacted borane over 2 hours. The system was kept below 0℃, and 150 g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45℃, and 500 g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopine pinol was distilled off: 928.14 g, yield 82%.

[0022] Example 5: Preparation of isopine pinol 1000 g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -0℃. 1714 mL of 1.8 M boranetetrahydrofuran solution (0.42 eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25℃ and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0℃, and 200 g of ethanol was added dropwise to decompose the unreacted borane over 2 hours. The system was kept below 0℃, and 150 g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45℃, and 500 g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopine pinol was distilled off: 950.8 g, yield 84%.

[0023] Example 6: Preparation of isopine pinol 1000g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -0℃. 1427mL of 1.8M boranetetrahydrofuran solution (0.35eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25℃ and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0℃, and 200g of ethanol was added dropwise to decompose the unreacted borane over 2 hours. The system was controlled below 0℃, and 150g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45℃, and 500g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopine pinol was distilled off: 939.5g, yield 83%.

[0024] Example 7: Preparation of isopine pinol 1000g of α-pinene was added to a reaction vessel, and the vessel temperature was lowered to -0℃. 2000ml of 1.8M boranetetrahydrofuran solution (0.50eq) was added dropwise over 3 hours. After the addition was completed, the temperature was raised to 25℃ and the reaction was stopped over 3 hours. Then, the temperature was lowered to 0℃, and 200g of ethanol was added dropwise to decompose the unreacted borane over 2 hours. The system was kept below 0℃, and 150g of 40% sodium hydroxide solution was added dropwise. After the addition was completed, the vessel temperature was controlled at 30-45℃, and 500g of 50% hydrogen peroxide was added dropwise over 2 hours. After the addition was completed, the temperature was maintained for 1 hour to stop the reaction. After the reaction was completed, the oil phase was separated, and the aqueous phase was extracted twice with toluene. After the pH of the oil phase was neutralized to 7, isopine pinol was distilled off: 966.6g, yield 85.4%.

[0025] Example 8: Preparation of isopinone 1000g of isopinol and 100g of conventional copper-silicon catalyst were added to a reactor, the temperature was raised to 200℃, and the reaction was carried out at a constant temperature for 6 hours. After filtration, the oil phase was directly distilled to obtain 812.4g of isopinone product, with a yield of 85% and a GC content of 99.2%. Example 9: Preparation of isopinone 1000g of isopinol and 100g of Cu / Ni-Al-SBA-15 catalyst were added to a reactor, the temperature was raised to 200℃, and the reaction was carried out at a constant temperature for 6 hours. After filtration, the oil phase was directly distilled to obtain 908g of isopinone product, with a yield of 92% and a GC content of 99.2%. Example 10: Preparation of isopinone 1000g of isopinol and 40g of Cu / Ni-Al-SBA-15 catalyst were added to a reactor, the temperature was raised to 200℃, and the reaction was carried out at a constant temperature for 10 hours. After filtration, the oil phase was directly distilled to obtain 868.54g of isopinone product, with a yield of 88% and a GC content of 99.1%. Example 11: Preparation of isopinone 1000g of isopinol and 100g of Cu / Ni-Al-SBA-15 catalyst were added to a reactor, the temperature was raised to 210℃, and the reaction was carried out at a constant temperature for 4 hours. After filtration, the oil phase was directly distilled to obtain 932.67g of isopinone product, with a yield of 94.5% and a GC content of 99.1%. Example 12: Preparation of isopinone 1000g of isopinol and 100g of Cu / Ni-Al-SBA-15 catalyst were added to a reactor, the temperature was raised to 180℃, and the reaction was carried out at a constant temperature for 18 hours. After filtration, the oil phase was directly distilled to obtain 858.65g of isopinone product, with a yield of 87% and a GC content of 99.1%. Example 13: Preparation of isopinone 1000g of isopinol and 100g of Cu / Ni-Al-SBA-15 catalyst were added to a reactor, the temperature was raised to 220℃, and the reaction was carried out at a constant temperature for 2 hours. After filtration, the oil phase was directly distilled to obtain 898.15g of isopinone product, with a yield of 91% and a GC content of 99.2%. Example 14: Preparation of isopinone 1000g of isopinol was added to the reactor, along with 98g of the catalyst filtered from Example 11. The temperature was raised to 210℃, and the reaction was carried out at a constant temperature for 4 hours. After filtration, the oil phase was directly distilled to obtain 947.5g of isopinone product, with a yield of 96% and a GC content of 99.2%. Example 15: Preparation of isopinone 1000g of isopypine alcohol was added to the reactor, and 97g of the catalyst filtered from Example 14 was added. The temperature was raised to 210℃ and the reaction was carried out at a constant temperature for 4 hours. After filtration, the oil phase was directly distilled to obtain 945.5g of isopypine ketone product, with a yield of 95.8% and a GC value of 99.2%.

[0026] The above description of the embodiments is only for illustrating the technical concept and features of the present invention. Its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. Those skilled in the art can obviously easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the above embodiments should not be used to limit the scope of protection of the present invention. All improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for synthesizing isopinene, characterized in that, Includes the following steps: (1) Using α-pinene as raw material, isopinepine alcohol is obtained by hydroboration of boranetetrahydrofuran complex and oxidation of the hydroboration product with sodium hydroxide solution and hydrogen peroxide. (2) Isopinol was dehydrogenated at high temperature using Cu / Ni-Al-SBA-15 as a catalyst to obtain the product isopinone; The total loading of Cu and Ni in the Cu / Ni-Al-SBA-15 is 9~12%, the molar ratio of Cu to Ni is 8~10:1, and the molar ratio of Si to Al in the Al-SBA-15 support is 9~11:

1.

2. The method for synthesizing isopine pinone according to claim 1, characterized in that: The molar ratio of borane in the α-pinene-boranetetrahydrofuran complex is 1:0.35~0.

5.

3. The method for synthesizing isopine pinone according to claim 1, characterized in that: The boranetetrahydrofuran complex is added to the reaction system dropwise, with the temperature controlled at -10 to 0°C during the dropwise addition; the temperature for the hydroboration is 20 to 30°C, and the time is 2 to 4 hours.

4. The method for synthesizing isopine pinone according to claim 1, characterized in that: The mass ratio of α-pinene to sodium hydroxide solution and hydrogen peroxide is 1:0.1~0.2:0.4~0.6; the mass concentration of sodium hydroxide solution is 30~50%; and the mass concentration of hydrogen peroxide is 40~60%.

5. The method for synthesizing isopine pinone according to claim 1, characterized in that: The sodium hydroxide solution and hydrogen peroxide are added to the reaction system dropwise in sequence. The sodium hydroxide solution is added at a temperature of -5 to 5°C, and the hydrogen peroxide is added at a temperature of 30 to 45°C.

6. The method for synthesizing isopine pinone according to claim 1, characterized in that: The amount of Cu / Ni-Al-SBA-15 catalyst fed is 4-10% of the mass of isopine pinol.

7. The method for synthesizing isopine pinone according to claim 1, characterized in that: The high-temperature dehydrogenation temperature is 180~220℃, and the time is 2~10h.

8. The method for synthesizing isopine pinone according to claim 1, characterized in that: After the hydroboration reaction is completed, an alcohol is added dropwise to decompose the unreacted borane. The alcohol is one or a mixture of two or more of methanol, ethanol, or isopropanol.

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