Industrial production and synthesis method of spice 5-methyl-2-heptene-4-ketone

Abstract

The invention belongs to the field of chemical synthesis, and particularly relates to an industrial production and synthesis method of spice 5-methyl-2-heptene-4-ketone, which comprises the following steps: reacting butanone serving as a raw material with 2-methylbutyryl chloride under alkaline conditions, creating an alkaline environment by using a solid base catalyst, filtering and separating the catalyst after the reaction is finished, and purifying filtrate by using a molecular sieve to obtain the spice 5-methyl-2-heptene-4-ketone. The preparation method comprises the following steps: taking 3-methyl-2-pentanone as a raw material to obtain an intermediate 3-methyl-2-pentanone, then reacting the intermediate 3-methyl-2-pentanone with acetaldehyde under an acidic condition, creating an acidic environment by using a solid acid catalyst, and carrying out a continuous flow reaction in a microchannel reactor to obtain the spice 5-methyl-2-heptene-4-ketone. By adjusting the process and raw materials, the yield and purity of the product are improved, the catalyst can be recycled, the emission of three wastes is less, the reaction is efficient, and the energy consumption is low.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, specifically a method for the industrial production synthesis of the fragrance 5-methyl-2-hepten-4-one. Background Technology

[0002] 5-Methyl-2-hepten-4-one is an olefinic ketone synthetic fragrance containing eight carbon atoms. Its molecular structure includes a double bond, a ketone group, and a methyl group at the 5-position, with the molecular formula C8H14O. It has two degrees of unsaturation, is chemically stable, and is a widely used flavoring ingredient in food and cosmetic fragrances. It possesses nutty and roasted aromas, imparting a natural and vibrant texture to fragrance systems. This fragrance is primarily prepared through chemical synthesis. Due to its excellent aroma expression, it is often used in soft drinks, ice cream, and candies to enhance the realism of fruity aromas. In cosmetic fragrances, it can be used in perfumes, shampoos, and skincare products to improve the complexity and freshness of the fragrance. Its safety meets international fragrance standards; when used within specified limits, it is harmless to the human body and is an important component in perfumery for enhancing the naturalness of aromas.

[0003] In the existing technology, the synthesis of 5-methyl-2-hepten-4-one usually adopts a batch process with liquid acid-base catalysis. Due to the dispersed steps of the traditional process, the intermediates need to be separated and purified multiple times, resulting in a long production cycle, high energy consumption, and the inability to efficiently recover and reuse the catalyst, which leads to serious waste of raw materials and a large amount of waste emissions. Summary of the Invention

[0004] The purpose of this invention is to provide an industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide an industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one, comprising the following steps: A1. Butanone was reacted with 2-methylbutyryl chloride under alkaline conditions. An alkaline environment was created using a solid base catalyst. After the reaction was completed, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. A2. Then, the intermediate 3-methyl-2-pentanone obtained in A1 is reacted with acetaldehyde under acidic conditions. An acidic environment is created with a solid acid catalyst. The reaction is carried out in a microchannel reactor in a continuous flow. After the reaction, the product is separated by vacuum distillation and the fraction is collected. At the same time, a biomimetic catalyst is introduced during the condensation reaction. Then, oxygen is activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one is obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration, and the regenerated solid acid catalyst is recovered and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0006] Optionally, the loading of the solid base catalytic resin is 30-50 wt%, the stirring speed during the reaction is 200-500 rpm, the dropping time of 2-methylbutyryl chloride is 30-60 min, and the reaction temperature fluctuation during the dropping process is kept not exceeding ±2℃.

[0007] Optionally, the solid acid catalyst is Nb-Sb-SBA-15, the molar amount of the solid acid catalyst is 3% to 8% of the molar amount of the intermediate 3-methyl-2-pentanone, and the molar ratio of the intermediate 3-methyl-2-pentanone to acetaldehyde is 1:1.1.

[0008] Optionally, the reaction is carried out under acidic conditions in an imidazole salt ionic liquid medium, wherein the imidazole salt ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the mass ratio of the ionic liquid to the intermediate 3-methyl-2-pentanone is 1:3. After the reaction is completed, the ionic liquid is recovered by vacuum distillation at a temperature of 80-100℃ and a pressure of 10-20 mmHg. The ionic liquid can be reused.

[0009] Optionally, the microchannel reactor integrates online infrared spectroscopy monitoring and a PLC control system. The online infrared spectroscopy monitoring monitors the concentration changes of intermediates and products in real time during the reaction process, while the PLC control system adjusts the reaction temperature, flow rate, and catalyst concentration.

[0010] Optionally, in step A1, the molar ratio of butanone, solid base catalyst, and 2-methylbutyryl chloride is 1:2:1, and the solid base catalyst is sodium ethoxide, sodium hydroxide, or potassium hydroxide.

[0011] Optionally, in step A1, the reaction temperature of butanone, solid base catalyst and 2-methylbutyryl chloride is 35-45℃, the reaction time is 4-5h, and after the reaction of butanone, solid base catalyst and 2-methylbutyryl chloride is completed, the pH of intermediate 3-methyl-2-pentanone is adjusted to 7-9.

[0012] Optionally, the reaction temperature of the microchannel reactor is 50-70℃, the reaction time is 3-6h, the flow rate of the microchannel reactor is 5-15mL / min, the pressure inside the reactor is controlled at 0.1-0.3MPa, and the parameters for fraction collection are 60-65℃ / 20mmHg.

[0013] Optionally, the condensation reaction process uses supercritical CO2 as a solvent and employs supercritical CO2 extraction to separate the products by vacuum distillation.

[0014] Optionally, the solid acid catalyst is regenerated using microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 5-15 minutes. The conversion rate of the regenerated solid acid catalyst decreases by ≤3% compared with the fresh catalyst.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses solid alkali and solid acid catalysts to replace traditional liquid acids and alkalis, and achieves continuous flow production through a microchannel reactor. It integrates intermediate preparation and condensation reaction into a continuous process, reducing the number of intermediate separation and purification steps, achieving precise control of reaction parameters and a significant reduction in side reactions. At the same time, the solid catalyst can be quickly separated by filtration, avoiding the corrosion of equipment by liquid acids and alkalis. Therefore, the production process is more stable, the emission of waste is greatly reduced, and the problems of long production cycle and high energy consumption caused by the dispersed process steps of traditional processes are solved, meeting the needs of modern fragrance industry for efficient and environmentally friendly production. This invention introduces a catalyst regeneration and recycling mechanism. The solid acid catalyst can be rapidly regenerated with microwave assistance to restore its activity, and the metal ions recovered from wastewater can be reused in catalyst preparation, enabling closed-loop use of the catalyst and achieving efficient resource utilization. At the same time, the introduction of biomimetic catalysts promotes the directionality of the reaction, reduces raw material loss, significantly reduces raw material waste in production, lowers production costs, and solves the resource waste problem caused by the inefficient recovery of catalysts in traditional processes. This invention replaces the traditional wastewater discharge mode with wastewater recycling. The treated wastewater can be directly reused in the washing process, achieving pollution source control. Meanwhile, the online monitoring of the continuous flow system ensures the stability of product quality. The entire production process meets the requirements of green chemistry, and the emission of waste gas, wastewater, and solid waste is rapidly reduced, solving the problems of large emissions and heavy environmental pressure in traditional processes, and achieving more efficient and environmentally friendly production and synthesis processing. Detailed Implementation

[0016] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] Example 1 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of solid base catalyst, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde, 4.5 kg of solid acid catalyst and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with a solid base catalyst. The reaction was carried out under alkaline conditions at a temperature of 45°C for 4 hours. The stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. The pH of the intermediate 3-methyl-2-pentanone was then adjusted to 7. A2. Acetaldehyde and a solid acid catalyst were added to the reaction vessel for reaction. Imidazole salt ionic liquid was added at the beginning of stirring. The reaction was carried out in a microchannel reactor with continuous flow. The reaction temperature of the microchannel reactor was 60℃, the reaction time was 3.5h, the flow rate of the microchannel reactor was 7mL / min, and the pressure inside the reactor was controlled at 0.2MPa. After the reaction, the product was separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0018] Example 2 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of sodium hydroxide, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde, 4.5 kg of solid acid catalyst and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with sodium hydroxide, to allow the butanone and 2-methylbutyryl chloride to react under alkaline conditions. The reaction temperature was 45℃, the reaction time was 4 hours, and the stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration, and the filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. Then, the pH of the intermediate 3-methyl-2-pentanone was adjusted to 7. A2. Acetaldehyde and a solid acid catalyst were added to the reaction vessel for reaction. Imidazole salt ionic liquid was added at the beginning of stirring. The reaction was carried out in a microchannel reactor with continuous flow. The reaction temperature of the microchannel reactor was 60℃, the reaction time was 3.5h, the flow rate of the microchannel reactor was 7mL / min, and the pressure inside the reactor was controlled at 0.2MPa. After the reaction, the product was separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0019] In this embodiment, the solid base catalyst is changed to sodium hydroxide, while the other raw materials and preparation process remain the same as in Example 1.

[0020] Example 3 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of potassium hydroxide, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde, 4.5 kg of solid acid catalyst and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with potassium hydroxide, to allow the butanone and 2-methylbutyryl chloride to react under alkaline conditions. The reaction temperature was 45℃, the reaction time was 4 hours, and the stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration, and the filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. Then, the pH of the intermediate 3-methyl-2-pentanone was adjusted to 7. A2. Acetaldehyde and a solid acid catalyst were added to the reaction vessel for reaction. Imidazole salt ionic liquid was added at the beginning of stirring. The reaction was carried out in a microchannel reactor with continuous flow. The reaction temperature of the microchannel reactor was 60℃, the reaction time was 3.5h, the flow rate of the microchannel reactor was 7mL / min, and the pressure inside the reactor was controlled at 0.2MPa. After the reaction, the product was separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0021] In this embodiment, the solid base catalyst is changed to potassium hydroxide, while the other raw materials and preparation process remain the same as in Example 1.

[0022] Example 4 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of solid base catalyst, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde, 4.5 kg of Nb-SBA-15 and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with a solid base catalyst. The reaction was carried out under alkaline conditions at a temperature of 45°C for 4 hours. The stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. The pH of the intermediate 3-methyl-2-pentanone was then adjusted to 7. A2. Acetaldehyde and Nb-SBA-15 were added to the reaction vessel for reaction. Imidazole salt ionic liquid was added at the beginning of stirring. The reaction was carried out in a microchannel reactor with continuous flow. The reaction temperature of the microchannel reactor was 60℃, the reaction time was 3.5h, the flow rate of the microchannel reactor was 7mL / min, and the pressure inside the reactor was controlled at 0.2MPa. After the reaction, the product was separated by vacuum distillation at 90℃ and 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The Nb-SBA-15 after the reaction is regenerated by microwave-assisted regeneration under the conditions of 300W microwave radiation for 8 minutes. After regeneration, Nb-SBA-15 is recovered and recycled. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0023] In this embodiment, the solid acid catalyst was changed to Nb-SBA-15, while the other raw materials and preparation process remained the same as in Example 1.

[0024] Example 5 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of solid base catalyst, 120.6 kg of 2-methylbutyryl chloride, 52.8 kg of acetaldehyde, 4.5 kg of solid acid catalyst and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with a solid base catalyst. The reaction was carried out under alkaline conditions at a temperature of 45°C for 4 hours. The stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. The pH of the intermediate 3-methyl-2-pentanone was then adjusted to 7. A2. Acetaldehyde and a solid acid catalyst were added to the reaction vessel for a continuous flow reaction in a microchannel reactor. The reaction temperature in the microchannel reactor was 60℃, the reaction time was 3.5h, the flow rate in the microchannel reactor was 7mL / min, and the pressure inside the reactor was controlled at 0.2MPa. After the reaction, the product was separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced oxidation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0025] This embodiment does not add imidazole salt ionic liquid, and the remaining raw materials and preparation process are the same as in Example 1.

[0026] Example 6 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of solid base catalyst, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde and 4.5 kg of solid acid catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with a solid base catalyst. The reaction was carried out under alkaline conditions at a temperature of 45°C for 4 hours. The stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. The pH of the intermediate 3-methyl-2-pentanone was then adjusted to 7. A2. Acetaldehyde and a solid acid catalyst are added to the reaction vessel for reaction. Imidazole salt ionic liquid is added at the beginning of stirring. The reaction is carried out in a microchannel reactor with continuous flow. The reaction temperature of the microchannel reactor is 60℃, the reaction time is 3.5h, the flow rate of the microchannel reactor is 7mL / min, and the pressure inside the reactor is controlled at 0.2MPa. After the reaction, the product is separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg is collected and then a condensation reaction is carried out. Then, oxygen is activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one is obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0027] In this embodiment, no biomimetic catalyst is added, and the remaining raw materials and preparation process remain unchanged from Example 1.

[0028] Example 7 An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one includes the following steps: Weigh out 72.1 kg of butanone, 24 kg of solid base catalyst, 120.6 kg of 2-methylbutyryl chloride, 50 kg of imidazole salt ionic liquid, 52.8 kg of acetaldehyde, 4.5 kg of solid acid catalyst and 0.5 kg of biomimetic catalyst; A1. Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor, along with a solid base catalyst. The reaction was carried out under alkaline conditions at a temperature of 45°C for 4 hours. The stirring speed was 450 rpm. After the reaction, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. The pH of the intermediate 3-methyl-2-pentanone was then adjusted to 7. A2. Acetaldehyde and a solid acid catalyst were added to the reaction vessel to carry out the reaction. Imidazole salt ionic liquid was added at the beginning of stirring. The reaction temperature was 60℃, the reaction pressure was 0.2MPa, and the reaction time was 3.5h. After the reaction, the product was separated by vacuum distillation at a temperature of 90℃ and a pressure of 16mmHg. The fraction with parameters of 62℃ / 20mmHg was collected. At the same time, a biomimetic catalyst was introduced during the condensation reaction. Then, oxygen was activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one was obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 8 minutes. The solid acid catalyst is recovered after regeneration and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

[0029] This embodiment omits the microchannel reactor and uses a reaction vessel for the reaction. The remaining raw materials and preparation process remain the same as in Embodiment 1.

[0030] Comparative Example Weigh out 72.1 kg of butanone, 120 kg of liquid sodium hydroxide, 120.6 kg of 2-methylbutyryl chloride, 5 kg of concentrated sulfuric acid, and 52.8 kg of acetaldehyde; Butanone and 2-methylbutyryl chloride were added to a stainless steel reactor along with liquid sodium hydroxide. The mixture was then reacted at 45°C for 4 hours. The waste liquid was removed by separation, and the intermediate was obtained by distillation. The intermediate was then reacted with acetaldehyde at 60°C for 5 hours under concentrated sulfuric acid catalysis. The acid was removed by washing with water, and the product was obtained by vacuum distillation. The catalyst was discarded directly, and the wastewater was discharged after filtration.

[0031] Tests and trials Product yield: Based on butanone, the percentage of actual yield to theoretical yield of the target product 5-methyl-2-hepten-4-one was calculated. This was achieved by accurately weighing the amount of butanone added in each example and comparative example. After the reaction, the target fraction was collected by vacuum distillation, and the product mass was weighed. The calculation formula is as follows:

[0032] in: For product yield, For actual output, This represents the theoretical yield.

[0033] Product purity: Gas chromatography was used for testing. The chromatographic column was a DB-5 capillary column, the carrier gas was nitrogen, the injection port temperature was 250℃, the detector temperature was 280℃, the initial temperature was 60℃ and held for 2 min, and then increased to 200℃ at a rate of 10℃ / min and held for 5 min. The product purity was calculated as the percentage of the target peak area to the total peak area.

[0034] Catalyst regeneration performance: The test object was the recovered solid acid catalyst. During the test, the regenerated catalyst was repeatedly used in the reaction system corresponding to the example for 5 consecutive cycles. After each reaction, the product yield was calculated, and the difference between the yield of the 5th cycle and the yield of the first use was recorded to evaluate the stability of the catalyst.

[0035] Table 1 shows the test results of the synthesis yield, product purity, and resource regeneration performance of 5-methyl-2-hepten-4-one in industrial production.

[0036] Table 1

[0037] Wastewater discharge indicators: Wastewater from each embodiment and comparative example was collected, and the chemical oxygen demand (COD) was measured using a COD analyzer; Nb in the wastewater was detected using an atomic absorption spectrometer. 3+ and Sb 5+ The concentration of the wastewater was recorded, along with the discharge volume and reuse rate after treatment. The waste discharge per unit product was calculated by weighing the waste catalyst and non-renewable solid waste residue after the reaction. The concentration of volatile organic solvents (such as methyl ethyl ketone and acetaldehyde) during the reaction was measured using a gas collection device, and gas chromatography was used to analyze the gas and assess the difficulty of waste gas treatment.

[0038] Reaction rate and energy consumption: Record the total time from raw material input to final product collection, record the energy consumption of the reactor, microchannel reactor, distillation unit, etc. through the equipment power meter, and calculate the energy consumption per unit mass of product.

[0039] Table 2 shows the waste emission indicators, reaction rate, and energy consumption test results of the industrial production synthesis process of 5-methyl-2-hepten-4-one.

[0040] Table 2

[0041] As shown in Table 2, the yield (89.2%) and purity (99.6%) of the synthesized product in Example 1 were significantly higher than those in other examples and the comparative examples. This is because the synergistic effect of the solid base catalyst (supported resin) and the solid acid catalyst (Nb-Sb-SBA-15), combined with the solubilizing effect of the imidazole salt ionic liquid and the directional catalysis of the biomimetic catalyst, reduced the occurrence of side reactions. In Examples 2 and 3, the catalytic activity was slightly lower and the yield decreased due to the replacement of the solid base with sodium hydroxide / potassium hydroxide. In Example 4, Nb-Sb-15 was used instead of Nb-SBA-15, and the lack of Sb co-catalytic effect resulted in a more significant decrease in yield. In Example 5, the absence of ionic liquid resulted in poor substrate dispersibility and decreased purity. In Example 6, the absence of a biomimetic catalyst resulted in low efficiency of oxidative dehydrogenation and a decrease in yield. In Example 7, the absence of a microchannel reactor resulted in low reaction mass transfer efficiency and a yield of only 68.7%. The comparative examples used liquid acid and base, resulting in more side reactions and a yield of less than 50%. The solid acid catalyst in Example 1 still achieved a yield of 87.5% after 5 cycles, indicating that microwave-assisted regeneration was highly effective. In Example 4, the catalyst was Nb-SBA-15, and its activity decreased significantly after regeneration, indicating that the introduction of Sb improved the catalyst's stability. In the comparative example, the liquid catalyst was directly discarded, had no regeneration value, and was costly and polluting. The wastewater discharge of Example 1 is only 0.3 mg / L, with a COD value of 85 mg / L, and can be completely reused; the wastewater discharge of the comparative example is 3.2 mg / L, with a COD value of 2500 mg / L, requiring complex treatment to meet the standards; the concentration of organic solvents in the exhaust gas of Example 1 is low and easy to treat, which improves the environmental friendliness of the synthesis process of the fragrance 5-methyl-2-hepten-4-one.

[0042] The total reaction time in Example 1 was 8.5 hours, with a unit energy consumption of 0.85 kW·h / kg, thanks to the continuous flow process of the microchannel reactor. Example 7, due to the use of a batch reactor, had a reaction time extended to 14.3 hours, resulting in increased energy consumption. The comparative example, due to its dispersed steps and the need for multiple waste liquid treatments, had a time and energy consumption 2-3 times that of Example 1. This invention improves yield, purity, environmental friendliness, and resource utilization.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one, characterized in that, Includes the following steps: A1. Butanone was reacted with 2-methylbutyryl chloride under alkaline conditions. An alkaline environment was created using a solid base catalyst. After the reaction was completed, the catalyst was separated by filtration. The filtrate was purified by molecular sieve to obtain the intermediate 3-methyl-2-pentanone. A2. Then, the intermediate 3-methyl-2-pentanone obtained in A1 is reacted with acetaldehyde under acidic conditions. An acidic environment is created using a solid acid catalyst. The reaction is carried out in a microchannel reactor in a continuous flow. After the reaction, the product is separated by vacuum distillation and the fraction is collected. At the same time, a biomimetic catalyst is introduced during the condensation reaction. Then, oxygen is activated by photo-induced or thermal-induced activation to promote the oxidative dehydrogenation of the intermediate. After oxidative dehydrogenation, the fragrance 5-methyl-2-hepten-4-one is obtained. A3. The solid acid catalyst after the reaction is regenerated by microwave-assisted regeneration, and the regenerated solid acid catalyst is recovered and recycled again. A4. The acidic wastewater generated by the reaction is treated with ion exchange resin to recover Nb. 3+ and Sb 5+ Metal ions are used for catalyst regeneration, and the treated water is recycled for the washing process, achieving zero wastewater discharge and wastewater purification and reuse.

2. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The loading of the solid base catalytic resin is 30-50 wt%, the stirring speed during the reaction is 200-500 rpm, the dropping time of 2-methylbutyryl chloride is 30-60 min, and the reaction temperature fluctuation is kept within ±2℃ during the dropping process.

3. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The solid acid catalyst is Nb-Sb-SBA-15, and the molar amount of the solid acid catalyst is 3% to 8% of the molar amount of the intermediate 3-methyl-2-pentanone. The molar ratio of the intermediate 3-methyl-2-pentanone to acetaldehyde is 1:1.

1.

4. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The reaction under acidic conditions is carried out in an imidazole salt ionic liquid medium, wherein the imidazole salt ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the mass ratio of the ionic liquid to the intermediate 3-methyl-2-pentanone is 1:

3. After the reaction is completed, the ionic liquid is recovered by vacuum distillation at a temperature of 80-100℃ and a pressure of 10-20 mmHg. The ionic liquid can be reused.

5. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The microchannel reactor integrates online infrared spectroscopy monitoring and a PLC control system. The online infrared spectroscopy monitoring monitors the concentration changes of intermediates and products in the reaction process in real time, and the PLC control system adjusts the reaction temperature, flow rate and catalyst concentration.

6. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, In step A1, the molar ratio of butanone, solid base catalyst, and 2-methylbutyryl chloride is 1:2:1, and the solid base catalyst is sodium ethoxide, sodium hydroxide, or potassium hydroxide.

7. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, In step A1, the reaction temperature of butanone, solid base catalyst and 2-methylbutyryl chloride is 35-45℃, and the reaction time is 4-5h. After the reaction of butanone, solid base catalyst and 2-methylbutyryl chloride is completed, the pH of intermediate 3-methyl-2-pentanone is adjusted to 7-9.

8. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The reaction temperature of the microchannel reactor is 50-70℃, the reaction time is 3-6h, the flow rate of the microchannel reactor is 5-15mL / min, the pressure inside the reactor is controlled at 0.1-0.3MPa, and the parameters for fraction collection are 60-65℃ / 20mmHg.

9. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The process of separating the products by vacuum distillation uses supercritical CO2 as a solvent and employs supercritical CO2 extraction to separate the products by vacuum distillation.

10. The industrial synthesis method for the fragrance 5-methyl-2-hepten-4-one as described in claim 1, characterized in that, The solid acid catalyst is regenerated using microwave-assisted regeneration. The regeneration conditions are 300W microwave radiation for 5-15 minutes. The conversion rate of the regenerated solid acid catalyst decreases by ≤3% compared with the fresh catalyst.

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