CN-121974802-A - Continuous flow synthesis method and system of alkyl gallate compound

CN121974802ACN 121974802 ACN121974802 ACN 121974802ACN-121974802-A

Abstract

The invention discloses a continuous flow synthesis method and a continuous flow synthesis system of an alkyl gallate compound. The method takes gallic acid and C1-C18 straight chain alkyl alcohol as raw materials, and realizes continuous flow esterification synthesis in a microstructure reactor in the presence of an acid catalyst. By precisely controlling the reaction temperature, pressure and residence time, the process can prepare various alkyl gallate esters with high efficiency and high selectivity. The invention solves the problems of long reaction time, easy side reaction, uneven product quality, difficult amplification and the like of the traditional intermittent process, has the outstanding advantages of high reaction speed, high product purity, high yield, safe and environment-friendly production process, easy amplification, strong universality and the like, and is suitable for green manufacture of products such as propyl gallate, octyl gallate, lauryl gallate and the like.

Inventors

LUO BO
LUO ZHIJUN
WANG SHAOJIANG
HU WEI

Assignees

贵阳倍隆生物科技有限公司
贵州理工学院

Dates

Publication Date: 20260505
Application Date: 20260309

Claims (10)

1. A continuous flow synthesis method of an alkyl gallate compound is characterized by comprising the following steps: (1) Preparing a first feed liquid containing gallic acid or derivatives thereof, and a second feed liquid containing C1-C18 linear alkyl alcohol and an acidic catalyst; (2) Continuously reacting, namely continuously introducing the first feed liquid and the second feed liquid into the microstructure reactor at a constant flow rate, so that materials continuously flow and perform esterification reaction in an environment of 80-150 ℃ and 0.2-3.0 MPa, wherein the residence time of the materials in the microstructure reactor is 5-120 minutes; (3) Collecting the reaction liquid flowing out of the microstructure reactor, and processing to obtain the required alkyl gallate compound.
2. A continuous flow synthesis method of alkyl gallate compound according to claim 1, wherein the linear alkyl alcohol is linear C3-C12 alkyl alcohol.
3. A continuous flow synthesis method of alkyl gallate compound according to claim 2, wherein the straight-chain alkyl alcohol is n-propanol, n-octanol or lauryl alcohol.
4. The method for continuous synthesis of alkyl gallate compound according to claim 1, wherein the first feed liquid is a solution or suspension formed by mixing gallic acid with an inert solvent, the mass ratio of gallic acid to inert solvent is 1:1-50, and the inert solvent can be selected from toluene, xylene or cyclohexane.
5. The continuous flow synthesis method of the alkyl gallate compound according to claim 1, wherein in the second feed liquid, the amount of the linear alkyl alcohol and the amount of the liquid acid catalyst are calculated according to the amount of the gallic acid in the first feed liquid, wherein the mass ratio of the gallic acid to the linear alkyl alcohol is 1:1-10, the catalyst is a liquid acid catalyst or a solid acid catalyst, the liquid acid catalyst is selected from concentrated sulfuric acid, p-toluenesulfonic acid or methanesulfonic acid, the amount of the liquid acid catalyst is 1% -15% of the mass of the gallic acid, the amount of the solid acid catalyst is 0.06% -6% of the total mass of the reaction materials, and the solid acid catalyst is cation exchange resin, solid super acid or heteropolyacid.
6. The method for continuous synthesis of alkyl gallate compound according to claim 1, wherein the micro-structural reactor is a micro-channel reactor, a capillary reactor, a tubular micro-reactor or a combination thereof.
7. The continuous flow synthesis method of the alkyl gallate compound according to claim 1, wherein the reaction temperature is 90-130 ℃, and the residence time of the material in the microstructure reactor is 15-60 minutes.
8. A continuous flow synthesis method of alkyl gallate compound according to claim 1, wherein said treatment comprises continuous neutralization, continuous separation, continuous crystallization, continuous filtration and continuous drying.
9. The method for continuous synthesis of alkyl gallate compound according to claim 1, wherein in the step b), before the first feed liquid and the second feed liquid are continuously introduced into the microstructure reactor, the first feed liquid and the second feed liquid are continuously introduced into the preheater for uniform mixing and preheating to a temperature required for the reaction.
10. A continuous flow reaction system for carrying out the method of any one of claims 1 to 9, characterized in that it comprises: a first feeding unit and a second feeding unit for storing and outputting a first feed liquid and a second feed liquid; The precise conveying pump is connected with the feeding unit and used for pumping the first feeding liquid and the second feeding liquid into the preheater; the pre-heater is used for uniformly mixing and preheating the first feed liquid and the second feed liquid to the temperature required by the reaction; The microstructure reactor is formed by connecting one or more microstructure reactor modules in series and is used for realizing continuous flow esterification reaction of the first feed liquid and the second feed liquid; The temperature control unit is arranged on the microstructure reactor module and used for controlling the temperature of the microstructure reactor module; The pressure control unit is arranged at the outlet end of the microstructure reactor module and used for maintaining the pressure of the system; the product receiving and continuous post-processing unit is connected with the outlet of the pressure control unit and is used for carrying out subsequent processing and product storage; And the on-line monitoring unit is used for monitoring the reaction progress or the product quality.

Description

Continuous flow synthesis method and system of alkyl gallate compound Technical Field The invention relates to a continuous flow synthesis method and a continuous flow synthesis system of an alkyl gallate compound, belonging to the technical field of organic synthesis chemistry and chemical process reinforcement. Background Alkyl gallate compounds are an important series of antioxidants for foods, cosmetics and medicines, and the general structure of the compounds is alkyl gallate. The general formula is as follows: Wherein R represents an alkyl group (e.g., n-propyl, n-octyl, lauryl, etc.). The traditional synthesis method mainly adopts an intermittent kettle reactor, takes gallic acid and corresponding alcohol (such as n-propanol, n-octanol and lauryl alcohol) as raw materials, and is prepared by heating, refluxing and esterifying in the presence of an acidic catalyst (such as concentrated sulfuric acid). The traditional process has the following remarkable defects: 1. the reaction efficiency is low, the esterification is reversible, long time (usually 6-15 hours) is needed, excessive alcohol or water-carrying agent is used to remove the generated water, and the reaction kinetics are slow. 2. The product quality problem is that the kettle reactor has poor mass and heat transfer efficiency, is easy to cause local overheating, causes side reactions such as oxidation, decarboxylation, polymerization and the like of the gallic acid mother core, has deep color and luster, contains more impurities and needs a complex refining process. 3. Process safety and equipment corrosion, namely, the use of a strong protonic acid catalyst severely corrodes equipment at high temperature, and thermal runaway risks exist for high-capacity intermittent operation. 4. High energy consumption, high sewage discharge capacity, long reaction time, high energy consumption, and heavy environmental burden, and a large amount of acidic organic wastewater is generated in post-treatment. 5. The amplification effect is obvious, and the reaction efficiency and the product index are difficult to stably reproduce when the reaction is amplified from a laboratory to industrial production. 6. The process has poor universality, and the reaction conditions (such as temperature, alcohol consumption and time) are required to be optimized again aiming at alcohols with different chain lengths, so that an efficient process with strong universality is lacked. Continuous flow chemical technology offers the potential to overcome the above-mentioned drawbacks by virtue of its extremely high mass and heat transfer efficiency, accurate parameter control, intrinsic safety, and ease of amplification. However, its application to the synthesis of alkyl gallate esters with polyphenol hydroxyl groups, sensitive to high temperatures and oxidation, faces special challenges of how to prevent side reactions, handle solids that may be produced (crystallization of gallic acid or its esters), and adapt to different viscosity reaction systems (especially long chain alcohols). Currently, there is a lack of a continuous flow universal process that systematically addresses these problems and is applicable to a variety of alkyl gallates. Disclosure of Invention The invention aims to provide a continuous flow synthesis method and a continuous flow synthesis system of an alkyl gallate compound. The method and the system have the advantages of high reaction speed, high product yield, good purity, safe and environment-friendly production process, easy amplification and suitability for various gallic acid alkyl ester compounds. The technical scheme of the invention is that the continuous flow synthesis method of the gallic acid alkyl ester compound comprises the following steps: (1) Preparing a first feed liquid containing gallic acid or derivatives thereof, and a second feed liquid containing C1-C18 linear alkyl alcohol and an acidic catalyst; (2) Continuously reacting, namely continuously introducing the first feed liquid and the second feed liquid into the microstructure reactor at a constant flow rate, so that materials continuously flow and perform esterification reaction in an environment of 80-150 ℃ and 0.2-3.0 MPa, wherein the residence time of the materials in the microstructure reactor is 5-120 minutes; (3) Collecting the reaction liquid flowing out of the microstructure reactor, and processing to obtain the required alkyl gallate compound. In the continuous flow synthesis method of the gallic acid alkyl ester compound, the linear alkyl alcohol is linear C3-C12 alkyl alcohol. In the aforementioned continuous flow synthesis method of the gallic acid alkyl ester compound, the linear alkyl alcohol is n-propanol, n-octanol or lauryl alcohol. In the continuous flow synthesis method of the gallic acid alkyl ester compound, the first feed liquid is a solution or suspension formed by mixing gallic acid and an inert solvent, the mass ratio of the gallic acid to the inert solvent