Preparation method of linalyl acetate
By performing a one-step reaction distillation method under a composite catalyst system of acetic anhydride and linalool, the problems of low catalyst efficiency and wastewater generation in the prior art are solved, and high yield and high purity linaloacetate preparation and The reuse of catalysts optimizes the economic and environmental performance of the process.
Patent Information
- Application Number
- CN202311790585.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2024-12-13
AI Technical Summary
In the existing preparation methods for lilylone acetate, the catalyst is low in efficiency, serious equipment corrosion, low yield, and wastewater is generated during the production process, and the product aroma is poor.
Acetic anhydride and linalool were used in a one-step reaction and rectification method under the composite catalyst system, and the distillation base was used as a catalyst for reuse, temperature and vacuum were controlled, and efficient preparation was achieved through magnetic stirring and a constant pressure droplet funnel.
The yield and purity of lilylacylate is improved, the catalyst recycling is realized, wastewater is avoided, and the economic and environmental performance of the process is optimized.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fine chemicals, and in particular to a method for preparing linalyl acetate. Background Art
[0002] Linalyl acetate series products are relatively expensive spices and are widely used in food flavors.
[0003] In the existing preparation method, linalool or linalool acetate is mainly prepared by acylation reaction with acetic anhydride. The esterification method is divided into acid catalysis method and base catalysis method according to the different catalysts.
[0004] The acid catalysis method uses phosphoric acid, p-toluenesulfonic acid, solid acid, strong acid resin, etc. as catalysts. The reaction time is long, the equipment is seriously corroded, and the yield is generally not high, only about 70%, and the product has a bad aroma. The base catalysis method generally uses carbonates, methylaminopyridine, etc. The disadvantages of the above method are long reaction time and low yield, usually only 60% to 85%; The reactive distillation preparation method requires an entrainer.
[0005] Therefore, a preparation method of linalyl acetate is proposed in view of the above problems. Summary of the invention
[0006] The object of the present invention is to provide a method for preparing linalyl acetate, so as to solve the problems raised in the above-mentioned background technology.
[0007] To achieve the above object, the present invention provides the following technical solutions: A method for preparing linalyl acetate comprises the following steps: Step 1: Put the raw materials into a three-necked flask, prepare a distillation head with a reflux ratio, a thermometer and a constant pressure dropping funnel containing the remaining amount of acetic anhydride, turn on the vacuum pump, magnetic stirring, and slowly increase the temperature; Step 2: Control the reflux ratio and slowly add the remaining acetic anhydride dropwise. The dropping speed should be consistent with the withdrawal speed. The dropping should be completed in 3-10 hours. Step 3: Increase the vacuum degree and take fractions, which are acetic acid, acetic anhydride, a small amount of unreacted linalool and finished linalyl acetate series.
[0008] Preferably, the raw materials in step 1 are acetic anhydride, a catalytic amount of DMAP and linalool or ethyl linalool.
[0009] Preferably, in step 1, the temperature is controlled between 70-100° C., the vacuum degree is between 0.07-0.085 KPa, and the reaction system is in a weak reflux state.
[0010] Preferably, the remaining distillation bottoms in step three are used as a catalyst sleeve for the next batch of feeding and reused.
[0011] Preferably, in step 1, the speed of magnetic stirring is controlled between 100-1000 rpm.
[0012] Preferably, in step 2, the stable reflux time is controlled between 1-2 hours.
[0013] Preferably, in step 3, after increasing the vacuum degree, acetic anhydride is added dropwise, and the fraction is slowly taken out, and the addition time is controlled between 6-8 hours. After the addition is completed, the reaction is continued until the raw material is less than 1% and then the reaction is stopped.
[0014] Compared with the prior art, the invention has the following beneficial effects: acetic anhydride and linalool are prepared by a one-step reaction distillation method under a composite catalyst system, and the obtained distillation bottom material is used as a catalyst for repeated use. The invention optimizes the existing process from the perspectives of economy and environmental protection, solves the problem of catalyst recycling, and no sewage is generated during the production process, and a high-content linalyl acetate product is prepared with a high yield. DETAILED DESCRIPTION
[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0016] The present invention provides a technical solution: A method for preparing linalyl acetate comprises the following steps: Step 1: In a three-necked flask, acetic anhydride, a catalytic amount of DMAP and linalool or ethyl linalool are added, a distillation head with a reflux ratio, a thermometer and a constant pressure dropping funnel containing the remaining amount of acetic anhydride are prepared, a vacuum pump and a magnetic stirrer are turned on, the temperature is slowly raised, the temperature is controlled between 70-100°C, the vacuum degree is between 0.07-0.085KPa, and the reaction system is in a weak reflux state; Step 2: Control the reflux ratio and slowly add the remaining acetic anhydride dropwise. The dropping speed should be consistent with the withdrawal speed. The dropping should be completed in 3-10 hours. Step 3: increasing the vacuum degree and taking fractions, which are acetic acid, acetic anhydride, a small amount of unreacted linalool and finished linalyl acetate series; The remaining distillation bottoms are used as catalyst sleeves for the next batch of feed and are reused.
[0017] The present invention will be further described below in conjunction with specific embodiments: Example
[0018] First batch: 336.5g of ethyl linalool, 2.92g of DMAP and 153g of acetic anhydride were directly put into a 1L three-necked flask, heated and evacuated. When the temperature reached 90°C, 153g of acetic anhydride was added dropwise after stable reflux for 1h, and the fraction was slowly removed for 8h. After the addition was completed, the reaction was continued until the raw material was less than 1% and then the reaction was stopped. The bottom material that did not slip out of the bottom of the bottle was used as a catalyst for the next batch of experiments. The fraction was distilled at 80-90°C to obtain 428.9g of ethyl linalyl acetate with a purity of 99.3%, and the yield was 95.8%.
[0019] The fourth batch of catalyst application: 336.5g of ethyl linalool and 153g of acetic anhydride were directly put into the 1L three-necked flask of the previous batch reaction, heated and evacuated, and when the temperature reached 70°C, 153g of acetic anhydride was added dropwise after stable reflux for 1h, and the fraction was slowly taken out, and the addition was continued for 4h. After the addition was completed, the reaction was continued until the raw material was less than 1% and then the reaction was stopped. The bottom material that did not slip out of the bottom of the bottle was used as a catalyst for the next batch of experiments. The fraction was distilled at 80-90°C to obtain 426.3 ethyl linalyl acetate with a purity of 99.4%, and the yield was 95.4%.
[0020] Catalyst application for the tenth batch: 336.5g of ethyl linalool and 153g of acetic anhydride were directly put into a 1L three-necked flask used in the previous batch of reactions, heated and evacuated, and when the temperature reached 80°C, 153g of acetic anhydride was added dropwise after stable reflux for 1h, and the fraction was slowly removed for 6h. After the addition was completed, the reaction was continued until the raw material was less than 1% and then the reaction was stopped. The bottom material that did not slip out of the bottom of the bottle was used as a catalyst for the next batch of experiments. The fraction was distilled at 80-90°C to obtain 426.3 ethyl linalyl acetate with a purity of 99.1%, and the yield was 95.2%.
[0021] Catalyst application batch Feeding amount mol Material purity% Product amount mol Product purity% Yield % First batch 2 99.1 1.91 99.3 95.8 The fifth batch 2 99.0 1.90 99.4 95.4 The eleventh batch 2 98.9 1.90 99.1 95.2 Note: The above table is a record of catalyst application experimental data, and the catalyst is DMAP.
[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing linalyl acetate, characterized in that: The steps include: Step 1: Put the raw materials into a three-necked flask, prepare a distillation head with a reflux ratio, a thermometer and a constant pressure dropping funnel containing the remaining amount of acetic anhydride, turn on the vacuum pump, magnetic stirring, and slowly increase the temperature; Step 2: Control the reflux ratio and slowly add the remaining acetic anhydride dropwise. The dropping speed should be consistent with the withdrawal speed. The dropping should be completed in 3-10 hours. Step 3: Increase the vacuum degree and take fractions, which are acetic acid, acetic anhydride, a small amount of unreacted linalool and finished linalyl acetate series.
2. A method for preparing linalyl acetate according to claim 1, characterized in that: The raw materials in step 1 are acetic anhydride, a catalytic amount of DMAP and linalool or ethyl linalool.
3. A method for preparing linalyl acetate according to claim 1, characterized in that: In step 1, the temperature is controlled between 70-100° C., the vacuum degree is between 0.07-0.085 KPa, and the reaction system is in a weak reflux state.
4. A method for preparing linalyl acetate according to claim 1, characterized in that: The remaining distillation bottom material in step 3 is used as a catalyst sleeve for the next batch of feeding and is reused.
5. A method for preparing linalyl acetate according to claim 1, characterized in that: In step 1, the speed of magnetic stirring is controlled between 100-1000 rpm.
6. A method for preparing linalyl acetate according to claim 1, characterized in that: In step 2, the stable reflux time is controlled between 1 and 2 hours.
7. A method for preparing linalyl acetate according to claim 1, characterized in that: In step 3, after increasing the vacuum degree, acetic anhydride is added dropwise, and the fraction is slowly taken out. The addition time is controlled between 6 and 8 hours. After the addition is completed, the reaction is continued until the raw material is less than 1% and then the reaction is stopped.