Efficient peach aldehyde synthesis process capable of recycling n-caprylic alcohol
By utilizing n-octanol recycling and multi-stage distillation technology, the problems of difficult n-octanol recovery and imprecise reaction control in the existing peach aldehyde synthesis have been solved, achieving efficient and safe peach aldehyde production, reducing production costs and improving product purity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 徐俊
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-15
Smart Images
Figure CN122036656A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fragrance and organic synthesis technology, specifically to a highly efficient synthesis process of peach aldehyde using n-octanol recycling. Background Technology
[0002] Peach aldehyde, chemically known as γ-undecyl lactone, is an important lactone flavoring agent with a rich peach aroma, widely used in food, cosmetics, and daily chemical products. Currently, one of the mainstream industrial methods for synthesizing peach aldehyde is to use n-octanol and acrylic acid derivatives (such as methyl acrylate) as raw materials, through steps such as free radical addition, intramolecular transesterification (esterification), and cyclization.
[0003] However, existing production processes generally suffer from the following problems: First, to improve the conversion rate of acrylic acid derivatives and inhibit their self-polymerization, the reaction usually needs to be carried out in a large excess of n-octanol, resulting in a large amount of unreacted n-octanol remaining in the system after the reaction. Traditional processes are not efficient enough in recovering this portion of n-octanol or do not have a recycling design, resulting in serious waste of raw materials, high production costs, and an increased burden on subsequent waste treatment. Second, the free radical addition reaction process is highly exothermic, and if not properly controlled, it can easily lead to explosive polymerization or an increase in by-products, affecting product yield and purity. Furthermore, the separation and purification of the final product, peach aldehyde, usually requires multiple distillations. In the separation process of high-boiling-point, heat-sensitive lactones, prolonged high-temperature operation can easily lead to product decomposition or polymerization, affecting the final yield and aroma quality.
[0004] Therefore, developing a peach aldehyde synthesis process that enables efficient recycling of key raw materials, safe and controllable reaction process, and high product yield and purity is of great significance for improving the economic efficiency and green level of this fragrance production. Summary of the Invention
[0005] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a highly efficient synthesis process for octanol using recycled n-octanol. This process offers advantages such as high raw material recycling rate, safe and controllable reaction process, high product purity, and stable yield. It solves the problems of high n-octanol consumption, difficult recovery, insufficient reaction control precision, and high energy consumption and significant losses in product separation and purification in traditional processes.
[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a highly efficient synthesis process of peach aldehyde using n-octanol recycling, comprising the following steps: Step 1: Raw material preparation: Select reagent-grade n-octanol, methyl acrylate and di-tert-butyl peroxide as reaction raw materials. Prepare the reaction raw materials in proportion and divide them into two parts: bottom material and dropwise mixture, to lay the foundation for the subsequent dropwise synthesis reaction. Step 2, Free radical addition reaction: Under stirring and heating conditions, a free radical addition reaction is initiated by dropwise addition of the mixed liquid to generate crude peach aldehyde product; Step 3: Preliminary recovery of n-octanol: After the free radical addition reaction is completed, the unreacted n-octanol is recovered by high-vacuum distillation to achieve preliminary recycling of raw materials; Step 4: Initial vacuum distillation: The residue containing valerian after the recovery of n-octanol is purified for the first time, and the main fraction is collected to obtain valerian crude product with γ-undecyl lactone content ≥90%. Step 5, High Vacuum Secondary Distillation: The main fraction obtained from the primary distillation is subjected to secondary purification to obtain γ-undecyl lactone aldehyde product with a purity ≥97%, and collected according to purity grade. Step 6: Material recycling and unit consumption accounting: The recovered n-octanol is returned to the production system as a raw material for recycling, and the actual production unit consumption is calculated.
[0007] Preferably, the purity control of the raw materials in step one is as follows: n-octanol purity ≥ 99.0%; methyl acrylate purity ≥ 99.0%; di-tert-butyl peroxide purity ≥ 98.0%, and all of them meet the MSDS standard.
[0008] Preferably, in step one, the raw material ratio is as follows: n-octanol, methyl acrylate and di-tert-butyl peroxide are prepared in a molar ratio of (6.5-7.5):1:(0.12-0.18).
[0009] Preferably, the raw material premixing preparation in step one includes: S1.1 Using a three-necked reactor as the polymerization vessel, check the sealing performance, stirring system, and temperature control system of the three-necked reactor 1-4 hours in advance to ensure they are up to standard. S1.2. Add 80% to 90% of the total feed amount of n-octanol as bottom material into the reactor, close the feed inlet, and start nitrogen purging. Purify with nitrogen with a purity of ≥99.99% 3 to 5 times. S1.3 Next, mix the remaining n-octanol, all the methyl acrylate and all the di-tert-butyl peroxide in another closed mixing system with stirring and temperature control to form the dropwise mixture for the subsequent steps.
[0010] Preferably, the free radical addition reaction in step two is controlled by the following process: S2.1 Start the stirring paddle of the reactor and control the stirring speed between 80-100 r / min. At the same time, heat the reactor by jacket heating and control the heating rate at 5-8℃ / min. S2.2 When the temperature inside the reactor reaches a stable 178±2℃, turn on the dripping pump and drip the mixture prepared in step one into the feed pipe below the n-octanol liquid surface at a dripping rate of 150-180kg / h, guiding it to the strong mixing zone near the stirring blades, and control the temperature and duration inside the reactor during the dripping process. S2.3 After the addition is complete, maintain the temperature inside the vessel at 178±2℃ and continue stirring for 0.8-1 hour. After the reaction is complete, crude peach aldehyde product is obtained.
[0011] Preferably, in step S2.2, the temperature fluctuation inside the vessel during the dripping process is controlled to not exceed ±5℃, and the total dripping time is controlled to be 7.5-8.5 hours.
[0012] Preferably, in step three, n-octanol is initially recovered: S3.1 After the free radical addition reaction is completed, turn off the heating system and wait until the temperature inside the reactor is ≤120℃ before transferring the reaction solution to the feed tank of the distillation column. S3.2 Start the vacuum system of the distillation column and control the vacuum degree inside the distillation column at -0.095 to -0.098 MPa. Turn on the reboiler heating and control the heating rate at 3-5℃ / min to gradually increase the reboiler temperature. S3.3 When the temperature of the reboiler rises to 140±2℃, the flow rate of the distillate from the top of the column is detected. When the flow rate of the distillate is ≤0.5kg / h, the recovery operation is stopped, and the distillate is collected to recover n-octanol. At the same time, the residue containing the crude product of phenol in the reboiler is collected, and the weight and content of the recovered n-octanol and the residue are recorded.
[0013] Preferably, in step four, triethanolamine with a mass ratio of 0.1% to 0.3% is added to the residue containing crude aldehyde, and the mixture is stirred for 25 to 30 minutes to ensure uniform mixing. Then, vacuum distillation is carried out under conditions of absolute pressure ≤ 5 kPa and gradually increasing the temperature of the vessel to 210-220°C, with the reflux ratio controlled at (1:1) to (2:1). The residual n-octanol in the residue is distilled off first, with a distillation temperature between 90 and 134°C. After the n-octanol has been completely distilled off and the top temperature of the column has stabilized at 130-134°C, the distillation conditions are maintained, and the main fraction is collected to obtain crude aldehyde with a γ-undecyl lactone content ≥ 90%.
[0014] Preferably, in step five, the main fraction obtained in step four is subjected to high-vacuum precision fractionation. Different reflux ratios and temperature ranges are controlled by a program: first, the fore-fraction is removed at a reflux ratio of 8:1 to 10:1, and then the main product fraction is collected at a reflux ratio of 2:1 to 4:1. The top temperature is controlled to be stable within the range of 133-135℃, and the corresponding absolute pressure is maintained at 1-3 mmHg, to obtain γ-undecyl lactone aldehyde product with a purity ≥97%.
[0015] Preferably, in step six, the n-octanol recovered in step three and the remaining n-octanol recovered during the distillation process in step four, after passing quality inspection, are added as recycled octanol to the next batch of step one and used in combination with the freshly added n-octanol.
[0016] Compared with the prior art, the present invention provides a highly efficient synthesis process for peach aldehyde by recycling n-octanol, which has the following beneficial effects: 1. This invention uses n-octanol as both a reactant and a solvent, and innovatively designs a bottom-feeding method with drip feeding and a multi-stage high-vacuum / reduced-pressure distillation recovery system to achieve efficient separation and recycling of unreacted n-octanol. The experimental results of the examples show that the n-octanol recovery rate exceeds 80%, which significantly reduces the consumption of fresh raw materials (the unit consumption is reduced from several times the theoretical value to close to the theoretical value). Ultimately, it achieves the beneficial effects of significantly reducing production costs, reducing material waste, and improving process economy and environmental friendliness.
[0017] 2. This invention ensures that the free radical addition reaction proceeds smoothly and uniformly by precisely controlling the temperature (178±2℃), dropping rate, and total duration of the free radical addition reaction, and by adding the mixture to the intensely mixing zone below the liquid surface. This optimized approach can effectively suppress side reactions such as the self-polymerization of methyl acrylate, thereby improving the selectivity and safety of the free radical addition reaction, and achieving the beneficial effects of increasing the yield and quality of crude phenolic resin and ensuring safe production operations.
[0018] 3. This invention employs a multi-stage purification strategy, combining primary vacuum distillation for neutralization and stabilization with programmed high-vacuum secondary distillation. Before purification, the product is stabilized by neutralization with triethanolamine, and precise separation is achieved under high vacuum by optimizing the reflux ratio. This results in the efficient purification of heat-sensitive peach aldehyde. This method can stably obtain high-quality γ-undecyl lactone with a purity ≥97%, achieving the beneficial effects of ensuring high product purity and excellent aroma quality, reducing product decomposition loss during high-temperature distillation, and meeting the requirements of the high-end market. Attached Figure Description
[0019] Figure 1 This is a flowchart of the peach aldehyde synthesis process of the present invention; Figure 2 This is a schematic diagram of the synthesis circuit of peach aldehyde in this invention. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Please see Figure 1 A highly efficient synthesis process for peach aldehyde using octanol recycling includes the following steps: Step 1: Raw material preparation: Select reagent-grade n-octanol, methyl acrylate and di-tert-butyl peroxide as reaction raw materials. Prepare the reaction raw materials in proportion and divide them into two parts: bottom material and dropwise mixture, to lay the foundation for the subsequent dropwise synthesis reaction. Step 2, Free radical addition reaction: Under stirring and heating conditions, a free radical addition reaction is initiated by dropwise addition of the mixed liquid to generate crude peach aldehyde product; Step 3: Preliminary recovery of n-octanol: After the free radical addition reaction is completed, the unreacted n-octanol is recovered by high-vacuum distillation to achieve preliminary recycling of raw materials; Step 4: Initial vacuum distillation: The residue containing valerian after the recovery of n-octanol is purified for the first time, and the main fraction is collected to obtain valerian crude product with γ-undecyl lactone content ≥90%. Step 5, High Vacuum Secondary Distillation: The main fraction obtained from the primary distillation is subjected to secondary purification to obtain γ-undecyl lactone aldehyde product with a purity ≥97%, and collected according to purity grade. Step 6: Material recycling and unit consumption accounting: The recovered n-octanol is returned to the production system as a raw material for recycling, and the actual production unit consumption is calculated.
[0022] Specifically, the purity control of raw materials in step one is as follows: n-octanol purity ≥ 99.0%, appearance as a colorless liquid; methyl acrylate purity ≥ 99.0%, appearance as a colorless liquid; di-tert-butyl peroxide purity ≥ 98.0%, appearance as a white solid, and all meet the MSDS standards (n-octanol CAS: 111-87-5; methyl acrylate CAS: 96-33-3; di-tert-butyl peroxide CAS: 110-05-4).
[0023] Specifically, in step one, the raw material ratio is as follows: n-octanol, methyl acrylate and di-tert-butyl peroxide are prepared in a molar ratio of (6.5-7.5):1:(0.12-0.18) (in large-scale production, the weight of raw materials is scaled up proportionally according to the equipment capacity by weight ratio), and the corresponding weight ratio is (10.0-11.0):1:(0.25-0.28).
[0024] Specifically, in step one, the raw material premixing preparation is as follows: S1.1 Using a three-necked reactor as the polymerization vessel, check the sealing performance, stirring system, and temperature control system of the three-necked reactor 1-4 hours in advance to ensure that the equipment operates normally; S1.2. Add 80% to 90% of the total feed amount of n-octanol as bottom material into the reactor, close the feed inlet, turn on nitrogen purging, and purge with nitrogen gas of ≥99.99% 3 to 5 times to remove air from the reactor and prevent oxidation from interfering with the reaction. S1.3 Next, mix the remaining 10% to 20% of n-octanol, all of the methyl acrylate and all of the di-tert-butyl peroxide (initiator) in another dry and clean closed batching system with stirring and temperature control to form the dropwise mixture for the subsequent steps. The equipment should be able to ensure that the components are mixed evenly at room temperature or under temperature control, and should have an inert gas protection interface to prevent premature decomposition of the initiator or volatilization of the raw materials during the mixing process.
[0025] The advantages are: by using a pre-mixing and feeding method, a set proportion of n-octanol is used as the solvent at the bottom of the reactor. The initiator is then pre-mixed with the remaining n-octanol and other raw materials before being added dropwise, thereby achieving precise control of the reaction process. This design can effectively prevent premature decomposition of the initiator and ensure the stable initiation and continuous progress of the free radical reaction. At the same time, the slow dropwise addition of methyl acrylate can avoid side reactions (such as self-polymerization) caused by excessively high local concentrations, which is beneficial to improving the selectivity of the target product and the safety of the reaction. The nitrogen replacement operation eliminates oxygen interference, ultimately ensuring the smooth progress of the free radical reaction.
[0026] Specifically, the free radical addition reaction controls the process in step two: S2.1 Start the stirring paddle of the reactor and control the stirring speed between 80-100 r / min. At the same time, heat the reactor by jacket heating and control the heating rate at 5-8℃ / min. S2.2 When the temperature inside the reactor reaches a stable 178±2℃, turn on the dropping pump and drop the mixture prepared in step one at a dropping rate of 150-180kg / h through the pump to the feed pipe below the n-octanol liquid surface and guide it to the strong mixing zone near the stirring blades. Control the temperature and time inside the reactor during the dropping process. S2.3 After the addition is complete, maintain the temperature inside the vessel at 178±2℃ and continue stirring for 0.8-1 hour to ensure the reaction proceeds fully. After the reaction is complete, crude peach aldehyde product is obtained. During the reaction, the pressure (pressure range is 0.05-0.1MPa) and temperature changes inside the vessel are monitored in real time through an online monitoring system, and the reaction data are recorded.
[0027] Specifically, in S2.2, the temperature fluctuation inside the vessel during the dripping process is controlled to not exceed ±5℃, and the total dripping time is controlled to be 7.5-8.5 hours.
[0028] The advantages are: by strictly controlling the dropping rate, reaction temperature and total dropping time, it can ensure that the reactants are in uniform and gentle contact and conversion at high temperature. The mixture is dropped into the strongly mixed zone below the liquid surface, which promotes rapid dispersion and mass transfer, which is conducive to the occurrence of the main reaction. Stable temperature and time control, combined with online monitoring, ensures that the free radical addition reaction is complete and controllable, thereby maximizing the conversion rate of methyl acrylate and inhibiting the formation of by-products, laying the foundation for obtaining a high yield of crude peach aldehyde.
[0029] Specifically, in step three, n-octanol is initially recovered: S3.1 After the free radical addition reaction is completed, turn off the heating system. When the temperature inside the reactor is ≤120℃, transfer the reaction liquid to the feed tank of the distillation column. Check the vacuum system, condensation system and discharge system of the distillation column to ensure that there are no leaks in the equipment. S3.2 Start the vacuum system of the distillation column and control the vacuum degree in the distillation column at -0.095 to -0.098 MPa. Turn on the reboiler heating and control the heating rate at 3-5℃ / min to gradually increase the reboiler temperature and recover unreacted n-octanol. S3.3 When the temperature of the reboiler rises to 140±2℃, the flow rate of the distillate from the top of the column is detected. When the flow rate of the distillate is ≤0.5kg / h, the recovery operation is stopped, and the distillate is collected to recover n-octanol. At the same time, the residue containing the crude product of phenol in the reboiler is collected, and the weight and content of the recovered n-octanol and the residue are recorded.
[0030] The advantages are: by immediately using high-vacuum distillation to recover unreacted n-octanol after the reaction, the operating conditions are mild. This method can efficiently separate a large amount of n-octanol with a low boiling point from the crude reaction product, with a significant recovery rate. This not only enables the initial recycling of the main raw material n-octanol and reduces raw material costs, but also removes a large amount of light components for subsequent distillation steps, thereby reducing the subsequent processing load and improving the material utilization efficiency of the entire process.
[0031] Specifically, in step four, 0.1% to 0.3% of triethanolamine by mass is added to the residue containing crude aldehyde for neutralization and stabilization. The mixture is stirred for 25-30 minutes to ensure uniform mixing. Then, vacuum distillation is carried out under conditions of absolute pressure ≤5 kPa and gradually increasing the temperature of the vessel to 210-220℃, controlling the reflux ratio to (1:1) to (2:1). The residual n-octanol in the residue is distilled off first, with a distillation temperature between 90 and 134℃. After the n-octanol has been completely distilled off and the top temperature of the column has stabilized at 130-134℃, the distillation conditions are maintained, and the main fraction is collected to obtain crude aldehyde with a γ-undecyl lactone content ≥90%.
[0032] The advantages are: by adding a set proportion of triethanolamine before distillation for neutralization and stabilization, trace amounts of acidic substances that may remain in the reaction solution can be effectively eliminated, preventing the decomposition or side reactions of pyruvate (γ-undecyl lactone) during subsequent high-temperature distillation, thereby ensuring product stability and yield. By using vacuum distillation (≤5kPa) and controlling the reflux ratio, the small amount of residual n-octanol is first separated, and then the main fraction is precisely cut and collected to achieve effective enrichment of crude pyruvate (content ≥90%), ultimately providing qualified feed for subsequent high-purity refining.
[0033] Specifically, in step five, the main fraction obtained in step four is subjected to high-vacuum precision fractionation. Different reflux ratios and temperature ranges are controlled by a program: first, the fore-fraction is removed at a reflux ratio of 8:1 to 10:1, and then the main product fraction is collected at a reflux ratio of 2:1 to 4:1. The top temperature is controlled to be stable within the range of 133-135℃, and the corresponding absolute pressure is maintained at 1-3 mmHg (0.13-0.4 kPa) to obtain γ-undecyl lactone aldehyde product with a purity ≥97%, which is then collected according to purity grade.
[0034] The advantages are: by using a higher vacuum and a programmed reflux ratio for precision fractionation, the fore-fraction (containing impurities) is first removed under a high reflux ratio, and then the main product is collected under an optimized reflux ratio, thus achieving deep purification of the peach aldehyde product. This method has high separation efficiency and can effectively remove impurities with boiling points close to peach aldehyde, ultimately obtaining high-quality γ-undecyl lactone with a purity ≥97%. It can also be collected in stages according to purity to meet different market demands, thereby improving product value while maintaining the flexibility of the preparation process.
[0035] Specifically, in step six, the n-octanol recovered in step three and the remaining n-octanol recovered during the distillation process in step four, after passing quality inspection, are added as recycled octanol to the next batch of step one, and used in combination with the freshly added n-octanol to maintain a constant total feed amount; finally, the unit consumption is only calculated based on the consumption of fresh raw materials, so as to achieve efficient utilization of raw materials.
[0036] Example S1. Raw material preparation: Reagent-grade n-octanol, methyl acrylate and di-tert-butyl peroxide were selected as reaction raw materials for the synthesis experiment; The specifications of the raw materials are shown in Table 1 below: Table 1 Raw material name Specification Appearance content Octyl alcohol reagent grade colorless liquid ≥99.0% Methyl acrylate reagent grade colorless liquid ≥99.0% di-tert-butyl peroxide reagent grade White solid ≥98.0% The feeding ratios (molar ratio, weight ratio) are shown in Table 2 below: Table 2 Raw material name Feed amount (g) Moor ratio weight ratio Octyl alcohol 1322 7.00 10.58 Methyl acrylate 125 1.00 1 di-tert-butyl peroxide 33 0.15 0.264 S2. Synthesis reaction: 1134g of n-octanol was put into a three-necked flask. In addition, 188g of n-octanol, 125g of methyl acrylate and 33g of di-tert-butyl peroxide were mixed evenly and used for dropwise addition reaction. The stirrer was turned on and the temperature was raised at the same time. When the temperature inside the vessel reached 178℃, the mixture was added dropwise until it was below the n-octanol liquid surface. The addition was completed within 8 hours, and the reaction continued for another hour. S3. Recovery of n-Octanol: After the reaction is complete, n-octanol is recovered under high vacuum in the upper column. The recovery ends when the reactor temperature reaches 140℃; Table 3 batch Head (g) Recover octanol (g) Residual material (g) (TQ content) R-01 67.2 970.5 332.9 （69.3） R-02 60.4 1015.3 311.4 （72.5） R-03 55.8 1013.7 316.2 （73.3） R-04 58.9 1033.5 302.7 （74.1） R-05 68.4 986.2 338.7 （64.4） Note: The batch size of the headstock before octanol recovery was 310.7g. GC analysis showed that the octanol content was 90.1%.
[0037] S4. Initial Distillation: The batch reaction residue was combined to obtain a total of 1601.9g (18.5 / 67.2). 3g of triethanolamine was added, and the mixture was distilled under high vacuum in the column. The product was discharged at a 1:1 ratio, and the bottom temperature was raised to 220℃ to stop the distillation. 241.0g of n-octanol was recovered (98.9%), TQ fraction: 1007.3g (91.9%), and bottom liquid: 212.2g. The conditions for high-vacuum secondary distillation of S5 and TQ fractions are shown in Table 4 below: Table 4 distillate Quantity (g) content(%) Kettle temperature ℃ Top temperature℃ reflux ratio F1 78.7 TQ: 51.9 156 90~134 10:1 F2 279.4 TQ: 97.7 156~160 134 3:1 F3 518.2 TQ: 98.2 160 134 3:1 F4 147.9 TQ: 96.9 160~180 134 3:1 F5 82.3 TQ: 29.8 / / Undistilled Calculation of overall distillation losses (mainly retention within the column): 1601.9-241.0-1007.3-212.2=40.1g S6, Unit Consumption Calculation (1) Recovery of octanol: 970.5 + 1015.3 + 1013.7 + 1033.5 + 986.2 + 310.7 * 90.1% * 0.9 + 241 = 5512.1 (2) Consumption of octanol: 1322*5 - 5501.7 = 1097.9 (3) Consumption of methyl acrylate: 125 * 5 = 625 (4) Consumption of di-tert-butyl peroxide: 33 * 5 = 165 (5) Finished product conversion: 78.7*51.9%*0.8+518.2+279.4+147.9*0.969*0.9+82.3*29.8%*0.5+40.1*0.8=1003.6 The unit consumption is shown in the table below: Table 5 Raw material name Consumption (g) Finished product (g) Unit consumption kg / kg Theoretical unit consumption kg / kg Octyl alcohol 1097.9 1003.6 1.094 0.707 Methyl acrylate 625 1003.6 0.623 0.467 di-tert-butyl peroxide 165 1003.6 0.164 / Analysis of the examples shows that, based on the experimental data in Tables 3 to 5, the process performed stably in five batches of operation, with a total n-octanol recovery of 5501.7g (calculated value), demonstrating high recovery efficiency. After a complete recycling and distillation process, approximately 1003.6g of peach aldehyde was finally obtained. The calculated unit consumption shows that for every 1kg of peach aldehyde produced, 1.094kg of fresh n-octanol and 0.623kg of methyl acrylate are consumed. Although the actual unit consumption is slightly higher than the theoretical value (mainly due to distillation losses and side reactions), the efficient recycling (recovering more than 80% of the feed n-octanol) significantly reduces the consumption cost of fresh n-octanol, demonstrating the economic advantages of the n-octanol recycling process. The calculated data also verifies that the process scheme has good repeatability and raw material utilization efficiency.
[0038] In summary, this invention provides a highly efficient, feasible, and circular economy-focused process for synthesizing peach aldehyde. Its core advantages are: 1. Optimized raw material premixing and dropwise reaction control ensure the safety, efficiency, and high selectivity of the free radical addition reaction; 2. Innovative integration of multi-stage high-vacuum / reduced-pressure distillation separation technology achieves high-purity (≥97%) peach aldehyde while efficiently recovering unreacted n-octanol (recovery rate >80%); 3. By establishing a complete material recycling and accounting system, the recovered n-octanol is returned to the production system, and only the consumption of fresh raw materials is accounted for, significantly reducing the actual unit consumption in production. This greatly improves the economic efficiency and environmental friendliness of the preparation process, making the entire process design reasonable and the operation controllable, providing an effective technical solution for the green and low-cost large-scale production of peach aldehyde.
[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A highly efficient synthesis process for peach aldehyde using n-octanol recycling, characterized in that, Includes the following steps: Step 1: Raw material preparation: Select reagent-grade n-octanol, methyl acrylate and di-tert-butyl peroxide as reaction raw materials. Prepare the reaction raw materials in proportion and divide them into two parts: bottom material and dropwise mixture, to lay the foundation for the subsequent dropwise synthesis reaction. Step 2, Free radical addition reaction: Under stirring and heating conditions, a free radical addition reaction is initiated by dropwise addition of the mixed liquid to generate crude peach aldehyde product; Step 3: Preliminary recovery of n-octanol: After the free radical addition reaction is completed, the unreacted n-octanol is recovered by high-vacuum distillation to achieve preliminary recycling of raw materials; Step 4: Initial vacuum distillation: The residue containing valerian after the recovery of n-octanol is purified for the first time, and the main fraction is collected to obtain valerian crude product with γ-undecyl lactone content ≥90%. Step 5, High Vacuum Secondary Distillation: The main fraction obtained from the primary distillation is subjected to secondary purification to obtain γ-undecyl lactone aldehyde product with a purity ≥97%, and collected according to purity grade. Step 6: Material recycling and unit consumption accounting: The recovered n-octanol is returned to the production system as a raw material for recycling, and the actual production unit consumption is calculated.
2. The efficient synthesis process of peach aldehyde using n-octanol recycling according to claim 1, characterized in that: In step one, the purity control of raw materials is as follows: octanol purity ≥ 99.0%; methyl acrylate purity ≥ 99.0%. The purity of di-tert-butyl peroxide is ≥98.0%, and all meet the MSDS standards.
3. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: In step one, the raw material ratio is as follows: n-octanol, methyl acrylate and di-tert-butyl peroxide are prepared in a molar ratio of (6.5-7.5):1:(0.12-0.18).
4. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: The raw material premixing preparation in step one: S1.1 Using a three-necked reactor as the polymerization vessel, check the sealing performance, stirring system, and temperature control system of the three-necked reactor 1-4 hours in advance to ensure they are up to standard. S1.
2. Add 80% to 90% of the total feed amount of n-octanol as bottom material into the reactor, close the feed inlet, and start nitrogen purging. Purify with nitrogen with a purity of ≥99.99% 3 to 5 times. S1.3 Next, mix the remaining n-octanol, all the methyl acrylate and all the di-tert-butyl peroxide in another closed mixing system with stirring and temperature control to form the dropwise mixture for the subsequent steps.
5. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: The free radical addition reaction control process in step two is as follows: S2.1 Start the stirring paddle of the reactor and control the stirring speed between 80-100 r / min. At the same time, heat the reactor by jacket heating and control the heating rate at 5-8℃ / min. S2.2 When the temperature inside the reactor reaches a stable 178±2℃, turn on the dripping pump and drip the mixture prepared in step one into the feed pipe below the n-octanol liquid surface at a dripping rate of 150-180kg / h, guiding it to the strong mixing zone near the stirring blades, and control the temperature and duration inside the reactor during the dripping process. S2.3 After the addition is complete, maintain the temperature inside the vessel at 178±2℃ and continue stirring for 0.8-1 hour. After the reaction is complete, crude peach aldehyde product is obtained.
6. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 5, characterized in that: In step S2.2, the temperature fluctuation inside the vessel during the dripping process is controlled to not exceed ±5℃, and the total dripping time is controlled to be 7.5-8.5 hours.
7. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: In step three, n-octanol is initially recovered. S3.1 After the free radical addition reaction is completed, turn off the heating system and wait until the temperature inside the reactor is ≤120℃ before transferring the reaction solution to the feed tank of the distillation column. S3.2 Start the vacuum system of the distillation column and control the vacuum degree inside the distillation column at -0.095 to -0.098 MPa. Turn on the reboiler heating and control the heating rate at 3-5℃ / min to gradually increase the reboiler temperature. S3.3 When the temperature of the reboiler rises to 140±2℃, the flow rate of the distillate from the top of the column is detected. When the flow rate of the distillate is ≤0.5kg / h, the recovery operation is stopped, and the distillate is collected to recover n-octanol. At the same time, the residue containing the crude product of phenol in the reboiler is collected, and the weight and content of the recovered n-octanol and the residue are recorded.
8. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: In step four, triethanolamine with a mass ratio of 0.1% to 0.3% is added to the residue containing crude aldehyde, and the mixture is stirred for 25 to 30 minutes to ensure uniform mixing. Then, vacuum distillation is carried out under conditions of absolute pressure ≤ 5 kPa and gradually increasing the temperature of the vessel to 210-220°C, with the reflux ratio controlled at (1:1) to (2:1). The residual n-octanol in the residue is distilled off first, with a distillation temperature between 90 and 134°C. After the n-octanol has been completely distilled off and the top temperature of the column has stabilized at 130-134°C, the distillation conditions are maintained, and the main fraction is collected to obtain crude aldehyde with a γ-undecyl lactone content ≥ 90%.
9. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 8, characterized in that: In step five, the main fraction obtained in step four is subjected to high-vacuum precision fractionation. Different reflux ratios and temperature ranges are controlled by a program: first, the fore-fraction is removed at a reflux ratio of 8:1 to 10:1, and then the main product fraction is collected at a reflux ratio of 2:1 to 4:
1. The top temperature is controlled to be stable within the range of 133-135℃, and the corresponding absolute pressure is maintained at 1-3 mmHg, to obtain γ-undecyl lactone aldehyde product with a purity ≥97%.
10. The efficient synthesis process of peach aldehyde by recycling n-octanol according to claim 1, characterized in that: In step six, the n-octanol recovered in step three and the remaining n-octanol recovered during the distillation process in step four, after passing quality inspection, are added as recycled octanol to the next batch of step one and used in combination with the freshly added n-octanol.