Alkyl tertiary amine quaternization reaction preparation process based on microchannel reactor

Abstract

The invention relates to an alkyl tertiary amine quaternization reaction preparation process based on a micro-channel reactor, which comprises the following steps: mixing aliphatic tertiary amine and an alkylating agent, adding into a solvent, diluting into a mixed diluent, conveying to the micro-channel reactor, controlling the reaction temperature at 70-120 DEG C, and carrying out quaternization reaction to generate a reaction mixture containing target alkyl tertiary amine quaternary ammonium salt. The alkyl tertiary amine quaternary ammonium salt is synthesized by utilizing the micro-channel reactor, and compared with a traditional reaction kettle method production process, efficient mass and heat transfer and process enhancement in the reaction process can be realized, and continuity and accurate control of the reaction process can be realized, so that the reaction efficiency and the product quality of alkyl tertiary amine quaternization reaction are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fine chemical synthesis, and relates to a method for preparing quaternary ammonium salt by quaternary ammoniation of alkyl tertiary amine, in particular to a preparation process for quaternary ammoniation reaction of alkyl tertiary amine by using a micro-channel reactor to realize continuous, efficient and controllable synthesis. BACKGROUND

[0002] Quaternary ammonium salt is a kind of organic compound with significant antibacterial performance. Its molecular structure contains a positively charged nitrogen atom, which enables it to effectively destroy the cell membrane of microorganisms, thereby exhibiting strong killing effect on bacteria, fungi and viruses. In addition to excellent antibacterial performance, quaternary ammonium salt also has high stability, low toxicity, excellent surface activity and other advantages, and is widely used in medical, public health, personal care products, industry, agriculture, household cleaning products and other fields.

[0003] Among them, alkyl tertiary amine quaternary ammonium salt occupies an important position, and is favored due to its unique molecular structure and performance. Compared with ordinary quaternary ammonium salt, quaternary ammonium salt prepared from long-chain alkyl tertiary amine usually has stronger antibacterial activity and lower irritation, and the long-chain alkyl structure in its molecule endows it with excellent surface activity, making it outstanding in emulsification, dispersion and wetting. In addition, quaternary ammonium salt with such structure has high chemical stability, can maintain activity in a wide range of pH and temperature, and has low toxicity to the environment and human body, meeting the requirements of modern green chemistry. These advantages make it widely used in many fields, such as being used as a mild and efficient bactericide and softener in daily chemical products, as a corrosion inhibitor and antistatic agent in the industrial field, as a bactericide and insecticide in agriculture, and as a disinfectant and antibacterial agent in the medical field.

[0004] Quaternization reaction is the main method for preparing quaternary ammonium salt, which is usually prepared by reacting suitable fatty tertiary amine with alkylating agents such as methyl chloride, dimethyl sulfate, benzyl chloride, etc.

[0005] At present, the production of quaternization of alkyl tertiary amine mainly adopts the reaction kettle method, which has two typical modes: Batch reaction kettle: batch production is carried out by using a kettle reactor, which has high operation flexibility and is suitable for small-batch and multi-variety production, but needs to go through the complete process of charging, reaction and unloading repeatedly, has relatively low production efficiency, and the reaction time is usually long, increasing the production cost.

[0006] Multi-vessel series reactor: Unlike batch reactors, multi-vessel series reactors can continuously input raw materials into the reactor and continuously output reaction products from the reactor, which is suitable for large-scale, continuous production, has high production efficiency, and can save cleaning and preparation time. However, it has higher requirements for raw material quality and process conditions, and requires precise control and adjustment technology to ensure the stability of the raw materials and the controllability of the reaction process.

[0007] Overall, the reaction kettle method (especially batch) is more difficult to achieve ideal continuous production during operation, and there are certain limitations in the instantaneous and accurate regulation of reaction conditions (such as temperature, mixing). At the same time, this method usually takes a long time, significantly prolonging the production cycle.

[0008] Furthermore, based on the strong exothermicity, fast kinetics and high sensitivity characteristics of the quaternization reaction of alkyl tertiary amine, there are the following problems in using traditional reaction kettle method for quaternization reaction of alkyl tertiary amine:

[0009] 1. Strong exothermic runaway risk

[0010] Severe heat release makes it easy to overheat locally in the reaction kettle, inducing Hofmann elimination, hydrolysis and other side reactions, reducing the yield and selectivity of the target product; and due to the limited heat exchange efficiency of the reaction kettle, it is difficult to quickly remove a large amount of reaction heat, which requires the slow addition of quaternization reagent to control the temperature rise, which greatly prolongs the reaction time.

[0011] 2. Mass transfer limitation and mixing defect

[0012] The mixing efficiency of the reaction kettle is low, and when the raw materials have different viscosities or are incompatible, the diffusion control mechanism causes the reaction rate to be inhibited, and the local concentration gradient caused by macroscopic mixing unevenness exacerbates the generation of by-products (such as bis-quaternary ammonium salt).

[0013] 3. Intrinsic safety hazard

[0014] Exothermic runaway during the reaction may cause temperature runaway, material overflow, and even explosion, especially when high-activity alkylating agents (such as benzyl chloride, dimethyl sulfate) are used.

[0015] Micro-channel reactor is a micro-reaction device manufactured by micro-processing technology, with internal feature size between 10-1000 μm. Its narrow micron-scale regular channel greatly shortens the distance and time of molecular diffusion, and its huge specific surface area can realize fast and sufficient mixing of materials within a microsecond time scale, thereby greatly strengthening the mass transfer process and improving the mixing efficiency.

[0016] Based on the excellent mass transfer and heat transfer performance, the small residence volume, the strong reaction control ability and other characteristics of the micro-channel reactor, it is particularly advantageous for strong exothermic reaction. Therefore, it is used in the production process of quaternization reaction of alkyl tertiary amine to help improve the reaction control precision, shorten the reaction time and reduce the side reaction, but it is necessary to adjust the appropriate process parameters to ensure that the material has enough residence time in the micro-channel reactor to complete the reaction and the quaternary ammonium salt product does not crystallize and block the micro-channel. SUMMARY

[0017] The purpose of the present application is to provide a preparation process for quaternization reaction of alkyl tertiary amine based on micro-channel reactor, which uses micro-channel reactor to synthesize quaternary ammonium salt of alkyl tertiary amine, realizes continuous and precise control of the reaction process, and improves the reaction efficiency and product quality.

[0018] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the preparation process for quaternization reaction of alkyl tertiary amine based on micro-channel reactor is as follows:

[0019] The fatty tertiary amine and the alkylating agent are mixed in a molar ratio of 1:(0.5-1.5), and then diluted in a solvent to form a mixed diluent;

[0020] The mixed diluent is continuously and stably delivered to the inlet of the micro-channel reactor by a high-pressure infusion pump at a flow rate of 1-10 mL / min, and the quaternization reaction is carried out at a temperature of 70-120℃ to generate a reaction mixture containing the target quaternary ammonium salt of alkyl tertiary amine;

[0021] The reaction mixture output from the micro-channel reactor is subjected to rotary evaporation under reduced pressure at 40-60℃ and 0.07-0.09 MPa to remove the solvent, thereby preparing the target quaternary ammonium salt of alkyl tertiary amine.

[0022] Preferably, the preparation process further comprises connecting a length of 3-5 m of aging coil to the outlet of the micro-channel reactor, maintaining the temperature of the aging coil at 70-120℃, and ensuring that the material remains in the micro-channel reactor and the aging coil for 20-120 min to fully carry out the quaternization reaction.

[0023] Further, the outlet and the aging coil are continuously heated by an electric heating tape to maintain the temperature required for the reaction.

[0024] Further, the temperature of the micro-channel reactor and the aging coil is preferably set to 90-110℃.

[0025] Preferably, the micro-channel reactor is heated by a constant temperature oil bath to control the reaction temperature.

[0026] The solvent for diluting the mixed diluent of the fatty tertiary amine and the alkylating agent is selected from water, ethanol or isopropanol.

[0027] Further, the mixed diluent can be further filtered by using a microporous filter membrane with a pore size of no more than 0.45 microns to remove particulate matter that may block the microchannel reactor.

[0028] Further, the molar ratio of the fatty tertiary amine to the alkylating agent is preferably 1:(0.8-1), and the quaternary ammonium reaction effect is better at this ratio.

[0029] Further, the flow rate of the mixed diluent is preferably 4-8 mL / min.

[0030] The reaction mixture is preferably reduced pressure rotary evaporated for 1-1.5 hours to separate and remove the solvent to obtain the alkyl tertiary amine quaternary ammonium salt.

[0031] The alkyl tertiary amine quaternary ammonium salt obtained is sampled, and qualitative and quantitative analysis is performed by infrared spectroscopy, gas chromatography, liquid chromatography, etc., to determine the composition and purity of the product, and the cationic active matter content of the sample is determined by referring to GB / T 5174-2018 "Surface-Active Agents, Detergents, Determination of Cationic Active Matter Content, Direct Two-Phase Titration Method", and the reaction conversion rate and yield are calculated.

[0032] Compared with the traditional reaction kettle production process, the alkyl tertiary amine quaternization reaction preparation process based on the microchannel reactor provided by the present application has the following significant beneficial effects:

[0033] 1. Efficient mass transfer and heat transfer and process intensification: The microchannel reactor has a very high specific surface area (about 40-60% higher than traditional reactors) and a very small characteristic size (micron level), which realizes efficient mixing (mass transfer coefficient increases by 2-3 orders of magnitude) and precise temperature control of the materials in the reaction system, significantly shortens the time required for the reaction to reach equilibrium, effectively inhibits side reactions caused by uneven local mixing or temperature loss of control, thereby improving the main reaction rate and selectivity.

[0034] 2. Continuous production and precise control: The reaction process realizes continuous feeding, continuous reaction and continuous discharging, and through precise control of the molar ratio of raw materials, feed flow rate, reaction temperature (including the microchannel reactor and the aging coil temperature zone) and residence time, etc. Key parameters, the reaction process is precisely controlled to ensure the high stability of the product quality and eliminate batch differences; the process has strong scalability, and linear scaling can be realized by increasing or decreasing modules or parallel operation.

[0035] 3. Improved reaction efficiency and product quality: Efficient mass and heat transfer and precise control result in more complete and efficient reactions. Specifically, this manifests as a significant reduction in reaction time, an increase in the yield of the target product and the content of active ingredients, while effectively reducing the amount of by-products generated.

[0036] 4. Resource efficiency and environmental friendliness: Continuous flow operation and precise material metering minimize raw material waste, closed reaction system reduces the release of volatile substances, solvent recovery is convenient, and the overall process generates less waste, which is more in line with the principles of green chemistry.

[0037] 5. Ease of operation and improved safety: The continuous flow mode reduces manual intervention, has a high degree of automation, the microchannel reactor has a very small liquid holdup, and can quickly remove the heat of reaction, which significantly reduces the safety risks such as temperature runaway and runaway caused by heat accumulation during the strongly exothermic quaternization reaction. Attached Figure Description

[0038] Figure 1 This is the infrared spectrum of dodecyl dimethyl ammonium chloride prepared in Example 1 of the present invention.

[0039] Figure 2 This is the infrared spectrum of dodecyl dimethyl ammonium chloride prepared in Example 3 of the present invention. Implementation

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can better understand and utilize the present invention, and are not intended to limit the scope of protection of the present invention.

[0041] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, which are very clear and distinct in the relevant application areas. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0042] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art.

[0043] The following examples of the present application are based on the continuous reaction preparation of relevant alkyl tertiary amine quaternary ammonium salt in a microchannel reactor, aiming to utilize the excellent mass and heat transfer performance and precise fluid control capability of the microchannel reactor to realize the continuous, efficient and precise control of the reaction process, significantly improve the reaction efficiency, product yield, active substance content and product quality stability of the quaternization reaction, and reduce the generation of by-products. Example

[0044] Example 1

[0045] Take 21.34 g (0.1 mol) of dodecyl dimethyl tertiary amine and 12.66 g (0.1 mol) of benzyl chloride, add them to 350 mL of deionized water and mix uniformly, then enter the microchannel reactor at a flow rate of 4 mL / min, control the reaction temperature at 50°C, connect a length of 3 m of aging coil at the outlet of the microchannel reactor, and obtain a dodecyl dimethyl benzyl ammonium chloride aqueous solution at the outlet of the aging coil after 65 min of reaction time.

[0046] The active substance content of the dodecyl dimethyl benzyl ammonium chloride aqueous solution is determined by GB / T 5174-2018 "Surface-Active Agents - Detergents - Determination of Cationic Active Content - Direct Two-Phase Titration Method", which is 12.3%, and the reaction conversion rate of dodecyl tertiary amine is calculated to be 99.72%, and the yield of dodecyl dimethyl benzyl ammonium chloride is calculated to be 97.09%.

[0047] The pH value of the dodecyl dimethyl benzyl ammonium chloride aqueous solution is determined by HG / T 2230-2006 "Water Treatment Agent - Dodecyl Dimethyl Benzyl Ammonium Chloride", which is 7.95.

[0048] The dodecyl dimethyl benzyl ammonium chloride aqueous solution is placed in a rotary evaporator, heated to 45°C, vacuumed to reduce the internal pressure to 0.08 MPa, and the solution is continuously rotary evaporated for 1 h to obtain liquid dodecyl dimethyl benzyl ammonium chloride, and its infrared spectrum is shown in FIG. 1. Figure 1

[0049] Example 2

[0050] Take 24.12 g (0.1 mol) of tetradecyl dimethyl tertiary amine and 12.41 g (0.098 mol) of benzyl chloride, add them to 325 mL of deionized water and mix uniformly, then enter the microchannel reactor at a flow rate of 5 mL / min, control the reaction temperature at 80°C, connect a length of 5 m of aging coil at the outlet of the microchannel reactor, and obtain a tetradecyl dimethyl benzyl ammonium chloride aqueous solution at the outlet of the aging coil after 30 min of reaction time.

[0051] ​The active matter content of the tetradecyl dimethyl benzyl ammonium chloride aqueous solution was determined by GB / T 5174-2018 “Surface-active agents - Detergents - Determination of cationic active matter content - Direct two-phase titration method”, and the reaction conversion rate of tetradecyl tertiary amine was calculated as 95.48%, and the yield of tetradecyl dimethyl benzyl ammonium chloride was calculated as 94.05%.

[0052] The pH value of the tetradecyl dimethyl benzyl ammonium chloride aqueous solution was determined by HG / T 2230-2006 “Water treatment agent - Tetradecyl dimethyl benzyl ammonium chloride”, and the pH value of the tetradecyl dimethyl benzyl ammonium chloride aqueous solution was 7.88.

[0053] The tetradecyl dimethyl benzyl ammonium chloride aqueous solution was placed in a rotary evaporator and heated to 40 DEG C, the internal pressure was reduced to 0.08 MPa by vacuumizing, and the solution was continuously rotary evaporated for 1 h to obtain liquid tetradecyl dimethyl benzyl ammonium chloride.

[0054] Example 3

[0055] In the reaction kettle, 21.34 g (0.1 mol) of dodecyl dimethyl tertiary amine, 0.04 g of EDTA-2Na, and 306 g of deionized water were added; the stirring was started, and the system was replaced with nitrogen three times; the temperature of the reaction kettle was increased to 80 DEG C, 12.66 g (0.1 mol) of benzyl chloride was added at a constant speed, and the reaction temperature was controlled to be less than 105 DEG C during the addition; after the addition was completed, the reaction was continued at 80-100 DEG C for 2 h to prepare a dodecyl dimethyl benzyl ammonium chloride aqueous solution.

[0056] The active matter content of the dodecyl dimethyl benzyl ammonium chloride aqueous solution was determined by the method of Example 1, and the conversion rate of dodecyl tertiary amine was calculated as 98.30%, and the yield of dodecyl dimethyl benzyl ammonium chloride was calculated as 96.39%. The infrared spectrum is shown in FIG. 2. Figure 2

[0057] The above examples of the present application do not describe all the details, and the present application is not limited to the above described examples. Various changes, modifications, replacements and variations of these examples made by those skilled in the art without departing from the principles and purposes of the present application shall be included in the protection scope of the present application.​

Claims

1. A process for preparing quaternary ammonium salt of tertiary alkyl amine based on micro-channel reactor, comprising: mixing fatty tertiary amine and alkylating agent in a molar ratio of 1:(0.5-1.5), adding solvent to dilute to form a mixed diluent; continuously and stably feeding the mixed diluent into the inlet of the micro-channel reactor by high-pressure infusion pump at a flow rate of 1-10 mL / min, controlling the temperature of the micro-channel reactor at 70-120℃ to carry out quaternization reaction, and generating a reaction mixture containing the target quaternary ammonium salt of tertiary alkyl amine; removing the solvent from the reaction mixture output from the micro-channel reactor at 40-60℃ and 0.07-0.09 MPa by rotary evaporation under reduced pressure to obtain the target quaternary ammonium salt of tertiary alkyl amine.

2. The process for the preparation of quaternary alkyl tertiary amine according to claim 1, characterized in that The molar ratio of the fatty tertiary amine to the alkylating agent is 1:(0.8-1).

3. The process for the preparation of quaternary alkyl tertiary amines according to claim 1, characterized in that The solvent used to dilute the fatty tertiary amine and the alkylating agent to form the mixed diluent is water, ethanol or isopropanol.

4. The process for the preparation of quaternary alkyl tertiary amines according to claim 1, characterized in that The flow rate of the mixed diluent is 4-8 mL / min.

5. The process for the preparation of quaternary alkyl tertiary amines according to claim 1, characterized in that It also includes a length of 3-5 m of aging coil connected to the outlet of the micro-channel reactor, maintaining the temperature of the aging coil at 70-120℃, ensuring that the material remains in the micro-channel reactor and the aging coil for 20-120 min of residence time, and fully carrying out the quaternization reaction.

6. The process for the preparation of quaternary alkyl tertiary amines according to claim 5, characterized in that The outlet and the aging coil are continuously heated by using an electric heating tape to maintain the required temperature conditions for the reaction.

7. The process for the preparation of quaternary alkyl tertiary amines according to claim 5, characterized in that The temperature of the micro-channel reactor and the aging coil is 90-110℃.

8. The process for the preparation of quaternary alkyl tertiary amine according to claim 1, characterized in that The micro-channel reactor is heated by using a constant temperature oil bath to control the reaction temperature.

9. The process for the preparation of quaternary alkyl tertiary amine according to claim 1, characterized in that The flow rate of the mixed diluent is not greater than 10 mL / min. The mixed diluent is precisely filtered by using a microporous filter membrane with a pore size of not greater than 0.45 μm.

10. The process for the preparation of quaternary alkyl tertiary amines according to claim 1, characterized in that The time for rotary evaporation under reduced pressure is 1-1.5 h.

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