Synthesis method of 2-chloromethyl-1,3-dioxolane based on uniform chlorination reactor

Abstract

The invention relates to the technical field of chemical synthesis, and in particular to a 2-chloromethyl-1,3-dioxolane synthesis method based on a uniform-speed chlorination reactor. The method comprises: mixing vinyl acetate, methanol and DMF and replacing them with nitrogen; introducing chlorine gas and an alkaline solution, stirring and standing, and then performing vacuum reduced-pressure distillation on an organic phase; placing a distillation product, ethylene glycol and a catalyst in a second reactor, stirring, steam heating, and then performing normal pressure multi-stage reflux, and performing vacuum distillation after the reflux is completed to obtain a crude target product; repeatedly washing the crude target product to obtain the target product; wherein, an optimal chlorine-passing speed is determined according to a reaction rate and an impurity generation rate; temperature change curves of several positions in a chlorination process are constructed based on temperature data at several detection time points and an optimal stirring speed is determined; and after each washing, standing and stratifying is performed based on a preset standing time, and a washing stop time is determined. The invention effectively optimizes a 2-chloromethyl-1,3-dioxolane synthesis process and improves the yield.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle. Background Art

[0002] 2-Chloromethyl-1,3-dioxolane, also known as chloroacetaldehyde glycol acetal and chloroacetaldehyde glycol acetal, is an important organic compound. Due to its good chemical stability and solubility, it is widely used in many fields. For example, in the pesticide industry, it is used as a raw material for synthesizing insecticides and herbicides to produce new high-efficiency, low-toxic and environmentally friendly pesticides; in the pharmaceutical field, it is used as an intermediate for synthesizing drugs for the treatment of asthma, Alzheimer's disease, etc.; in the field of polymer materials, it is used as a raw material for the preparation of coatings, adhesives, sealants, etc.; in the field of fine chemicals, it is used as a raw material for industrial products such as detergents, emulsifiers and lubricants; in the field of electronic chemistry, it is often used as an electrolyte additive because it can improve the performance of electrolytes.

[0003] At present, there are several synthetic routes for 2-chloromethyl-1,3-dioxolane, such as the synthesis of 2-chloromethyl-1,3-dioxolane from chloroacetaldehyde and ethylene glycol; or the synthesis of 2-chloromethyl-1,3-dioxolane from 2-chloroacetaldehyde dimethyl acetal and ethylene glycol. When synthesizing 2-chloromethyl-1,3-dioxolane based on these synthetic routes, there are problems such as the difficulty in obtaining synthetic raw materials, high preparation cost, low yield and excessive impurities.

[0004] Therefore, there is an urgent need for a method for synthesizing 2-chloromethyl-1,3-dioxolane that can improve the yield and optimize the production process. Summary of the invention

[0005] To this end, the present invention provides a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-rate chlorination reactor, so as to overcome the problems in the prior art of synthesizing 2-chloromethyl-1,3-dioxolane, namely, that the synthetic raw materials are not easily available, the preparation cost is high, and the yield is low.

[0006] To achieve the above object, the present invention provides a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-rate chlorination reactor, comprising:

[0007] Step S1, putting vinyl acetate, methanol and DMF in a weight ratio of 0.85 to 0.95 parts: 0.9 to 1.2 parts: 0.1 to 0.2 parts into a first reaction kettle, stirring and mixing them evenly, and replacing the first reaction kettle with nitrogen;

[0008] Step S2, introducing chlorine gas into the first reactor at a preset chlorine-passing speed and stirring, introducing an alkaline solution into the first reactor after the chlorination reaction is completed, stirring and standing to separate the impurities to obtain an aqueous phase and an organic phase, performing vacuum decompression distillation on the organic phase, and collecting a distillation product;

[0009] Step S3, placing the distillation product, ethylene glycol and catalyst in a weight ratio of 1.1 to 1.15 parts: 0.95 to 1.05 parts: 0.93 to 0.94 parts into a second reaction kettle, stirring and mixing them evenly, steam heating and then reflux at normal pressure in multiple stages, and vacuum distilling after the reflux to obtain a crude target product;

[0010] Step S4, placing the crude target product into a washing kettle for cooling and stirring, and repeating the washing several times to obtain the target product;

[0011] Wherein, in step S2, the reaction solution is taken to detect the concentration and impurity content of the reaction solution at several detection time points, the reaction rate is determined according to the concentration of the reaction solution, and the impurity generation rate is determined according to the impurity content, and the optimal chlorine flow rate is determined according to the reaction rate and the impurity generation rate;

[0012] Based on the several detection time points, temperature data of several positions in the first reaction kettle are collected, temperature change curves of several positions during the chlorination process are constructed according to the temperature data, and an optimal stirring speed is determined according to the temperature change curve and a preset stirring speed;

[0013] In step S4, standing and stratification are performed based on a preset standing time after each wash, and after a single standing is completed, the transparency of the upper aqueous phase is detected, and the time to stop washing is determined based on the transparency and the preset transparency, or the degree of improvement in the transparency of the upper aqueous phase after each wash is determined, and the time to stop washing is determined based on the improvement degree and the preset improvement degree.

[0014] Furthermore, the first reactor has an upper chlorine inlet and a lower chlorine inlet, the upper chlorine inlet is located at the top of the first reactor, the upper chlorine inlet is connected to a first chlorine pipeline, the lower chlorine inlet is located near the outer side of the bottom of the first reactor, and is connected to a second chlorine pipeline, wherein:

[0015] The upper chlorine inlet and the lower chlorine inlet both pass chlorine into the first reaction kettle at a preset chlorine passing speed.

[0016] Further, a reaction rate variation curve is determined according to the reaction rate, an impurity generation rate variation curve is determined according to the impurity generation rate, a reaction characterization state is determined according to the reaction rate variation curve, an impurity characterization state is determined according to the impurity generation rate variation curve, and an optimal chlorine flow rate is determined according to the reaction characterization state and the impurity characterization state;

[0017] Among them, the reaction characterization state is the reaction rate decrease and the reaction rate increase, and the impurity characterization state is the impurity generation rate decrease and the impurity generation rate increase.

[0018] Furthermore, if the reaction characterization state is a decrease in reaction rate and the impurity characterization state is an increase in impurity generation rate, the optimal chlorine supply rate is determined based on a preset chlorine supply rate, a first linear relationship coefficient between the chlorine supply rate and the reaction rate, and a second linear relationship coefficient between the chlorine supply rate and the impurity generation rate.

[0019] Furthermore, the inflection points of the temperature change curve corresponding to several positions are determined, the slope of the line segment between the inflection points is determined according to the inflection point positions, the consistency of the temperature change curve is determined according to the inflection point positions and the line segment slope, and the optimal stirring speed is determined according to the consistency, the preset consistency and the preset stirring speed.

[0020] Further, determining the consistency includes: determining the inflection point position difference according to the inflection point positions corresponding to different temperature change curves, determining the slope difference according to the line segment slope, and determining the consistency according to the inflection point position difference, the slope difference, the preset slope difference and the preset position difference.

[0021] Furthermore, the transparency is compared with a preset transparency, and the washing stop timing is determined according to the comparison result, wherein:

[0022] If the transparency is less than the preset transparency, repeat washing;

[0023] If the transparency is greater than or equal to the preset transparency, washing is stopped.

[0024] Further, the improvement degree is compared with a preset improvement degree, and the washing stop timing is determined according to the comparison result, wherein:

[0025] If the improvement degree is less than the preset improvement degree, stopping washing;

[0026] If the improvement degree is greater than or equal to the preset improvement degree, the washing is repeated.

[0027] Furthermore, the height of the end of the first chlorine-passing pipe is located at 1 / 2 of the height of the liquid level of the mixed solution in the first reactor, and the end of the second chlorine-passing pipe is bent downward.

[0028] Furthermore, the pipe ends of the first chlorine-passing pipe and the pipe ends of the second chlorine-passing pipe are both provided with arc-shaped sealing heads, and a plurality of air holes are opened on the arc-shaped sealing heads.

[0029] Compared with the prior art, the beneficial effect of the present invention is that the present invention uses vinyl acetate and methanol as substrates, nitrogen and DMF as catalysts to form dual catalytic protection, inhibits side reactions and impurity generation, and obtains the target product 2-chloromethyl-1,3-dioxolane through chlorination reaction and condensation reaction. At the same time, the optimal chlorine flow rate is determined according to the concentration of the reaction solution and the impurity content at several detection time points, and the temperature data of several positions in the first reactor are collected to determine the corresponding temperature change curve, and the optimal stirring speed is determined according to the temperature change curve and the preset stirring speed, and the washing stop time is determined to improve the yield of the target product, further avoid the generation of impurities, and optimize the production process of 2-chloromethyl-1,3-dioxolane.

[0030] Furthermore, the present invention arranges upper and lower double-point chlorine inlets on the first reactor to introduce chlorine gas for chlorination reaction, so that the contact distribution of chlorine gas and substrate is more uniform, the side reaction is suppressed and the completion time of the chlorination reaction is reduced by 20% compared with the ordinary reactor device, the production cost is saved and the yield of the target product is improved, the generation of impurities is further avoided, and the production process of 2-chloromethyl-1,3-dioxolane is optimized.

[0031] Furthermore, the present invention determines the optimal chlorine-feeding speed based on the reaction characterization state and the impurity characterization state according to the preset chlorine-feeding speed, the first linear relationship coefficient between the chlorine-feeding speed and the reaction rate, and the second linear relationship coefficient between the chlorine-feeding speed and the impurity generation rate, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0032] Furthermore, the present invention determines the consistency of the temperature change curve according to the inflection point positions of the temperature change curve corresponding to several positions and the slope of the line segment between the inflection points, and determines the optimal stirring speed according to the consistency, the preset consistency and the preset stirring speed, so as to further promote the contact between chlorine and the reaction substrate, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0033] Furthermore, the present invention determines the timing to stop washing based on the comparison result between the transparency of the upper aqueous phase after a single washing and a preset transparency, and the comparison result between the improvement degree and a preset improvement degree, thereby further improving the yield of the target product, further avoiding the formation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0034] Furthermore, the end of the first chlorine-passing pipeline of the present invention is located 1 / 2 below the liquid level of the mixed solution in the first reactor, the end of the second chlorine-passing pipeline is bent downward, and the ends of the pipelines are both provided with arc-shaped heads with a plurality of air holes, which further facilitates the sufficient and uniform contact between chlorine and the reaction substrate, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-rate chlorination reaction kettle according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the reaction system structure of an embodiment of the present invention;

[0037] Figure 3 This is a top plan view of the first reaction kettle according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the inflection point position of an embodiment of the present invention;

[0039] In the figure: 1, upper chlorine inlet; 2, lower chlorine inlet; 3, electromagnetic flowmeter; 4, pressure gauge; 5, temperature gauge; 6, vacuum gauge; 7, reducer; 8, motor; 9, pressure relief pipeline; 10, nitrogen pipeline; 11, vacuum pipeline; 12, material pipeline; 13, pressure relief buffer tank; 14, first metering tank; 15, second metering tank; 16, cooling water outlet; 17, cooling water drain valve; 18, cooling water inlet; 19, sight glass; 20, manhole; 21, material outlet. DETAILED DESCRIPTION

[0040] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0042] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0043] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] See also Figure 1 As shown, Figure 1 The present invention is a flow chart of a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor according to an embodiment of the present invention; specifically, the present invention provides a method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor, comprising:

[0045] Step S1, putting vinyl acetate, methanol and DMF in a weight ratio of 0.85 to 0.95 parts: 0.9 to 1.2 parts: 0.1 to 0.2 parts into a first reaction kettle, stirring and mixing them evenly, and replacing the first reaction kettle with nitrogen;

[0046] Step S2, introducing chlorine gas into the first reactor at a preset chlorine-passing speed and stirring, introducing an alkaline solution into the first reactor after the chlorination reaction is completed, stirring and standing to separate the impurities to obtain an aqueous phase and an organic phase, performing vacuum decompression distillation on the organic phase, and collecting a distillation product;

[0047] Step S3, placing the distillation product, ethylene glycol and catalyst in a weight ratio of 1.1 to 1.15 parts: 0.95 to 1.05 parts: 0.93 to 0.94 parts into a second reaction kettle, stirring and mixing them evenly, steam heating and then reflux at normal pressure in multiple stages, and vacuum distilling after the reflux to obtain a crude target product;

[0048] Step S4, placing the crude target product into a washing kettle for cooling and stirring, and repeating the washing several times to obtain the target product;

[0049] Wherein, in step S2, the reaction solution is taken to detect the concentration and impurity content of the reaction solution at several detection time points, the reaction rate is determined according to the concentration of the reaction solution, and the impurity generation rate is determined according to the impurity content, and the optimal chlorine flow rate is determined according to the reaction rate and the impurity generation rate;

[0050] Based on the several detection time points, temperature data of several positions in the first reaction kettle are collected, temperature change curves of several positions during the chlorination process are constructed according to the temperature data, and an optimal stirring speed is determined according to the temperature change curve and a preset stirring speed;

[0051] In step S4, standing and stratification are performed based on a preset standing time after each wash, and after a single standing is completed, the transparency of the upper aqueous phase is detected, and the time to stop washing is determined based on the transparency and the preset transparency, or the degree of improvement in the transparency of the upper aqueous phase after each wash is determined, and the time to stop washing is determined based on the improvement degree and the preset improvement degree.

[0052] It can be understood that the present invention uses vinyl acetate and methanol as substrates, nitrogen and DMF as catalysts to form dual catalytic protection, inhibit side reactions and impurity generation, and obtain an intermediate, i.e., the distillation product 2-chloro-1,1-dimethoxyethane, through a chlorination reaction. 2-chloro-1,1-dimethoxyethane and ethylene glycol are mixed with a catalyst for a condensation reaction to obtain 2-chloromethyl-1,3-dioxolane.

[0053] In a specific embodiment, vinyl acetate, methanol and DMF in a weight ratio of 0.9 parts: 1 parts: 0.15 parts are put into a first reactor and stirred to mix evenly, the preset chlorine flow rate is 2kg / h, and the preset chlorine flow rate is calculated according to the weight of the chlorine gas bottle. Chlorine is introduced into the first reactor and stirred. After the chlorination reaction is completed, an alkaline solution is introduced into the first reactor. The alkaline solution can be ammonia water, sodium thiosulfate aqueous solution or sodium bisulfate aqueous solution. Preferably, the alkaline solution is ammonia water; after collecting the distillation product by vacuum distillation, the weight The distillation product (2-chloro-1,1-dimethoxyethane), ethylene glycol and catalyst in the proportion of 1.12 parts: 1 part: 0.935 parts are placed in the second reaction kettle and stirred and mixed evenly. The catalyst can be a sulfonate such as p-toluenesulfonic acid, manganese methanesulfonate, aluminum methanesulfonate, etc.; steam heating is followed by multi-stage reflux at normal pressure, and vacuum distillation is performed after the reflux is completed to obtain the target product crude 2-chloromethyl-1,3-dioxolane; the target product crude product is placed in a washing kettle to cool and stir, and the washing is repeated twice to obtain the target product 2-chloromethyl-1,3-dioxolane. In implementation, the weight proportion of vinyl acetate, methanol and DMF, the preset chlorine flow rate, the alkaline solution, the weight proportion of the distillation product (2-chloro-1,1-dimethoxyethane), ethylene glycol and the catalyst, the type of catalyst, and the number of washing times can all be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0054] In a specific embodiment, the time intervals of several detection time points range from 1h to 3h, preferably, the time intervals of the several detection time points are 2h; temperature data of several positions in the first reactor are collected based on the several detection time points, and the several positions are the upper reactor wall, the middle reactor wall, and the bottom reactor wall close to the mixed solution in the first reactor. The preset stirring speed is 80-100rpm, and the preset standing time is 1h. In implementation, the time intervals of the several detection time points, the several positions, the preset stirring speed, and the preset standing time can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0055] The present invention uses vinyl acetate and methanol as substrates, nitrogen and DMF as catalysts to form dual catalytic protection, inhibits side reactions and impurity generation, and obtains the target product 2-chloromethyl-1,3-dioxolane through chlorination reaction and condensation reaction. At the same time, the optimal chlorine flow rate is determined according to the concentration of the reaction solution and the impurity content at several detection time points, and the temperature data of several positions in the first reactor are collected to determine the corresponding temperature change curve, and the optimal stirring speed is determined according to the temperature change curve and the preset stirring speed, and the washing stop time is determined to improve the yield of the target product, further avoid the generation of impurities, and optimize the production process of 2-chloromethyl-1,3-dioxolane.

[0056] See also Figure 2 and Figure 3 As shown, Figure 2 A schematic diagram of the reaction system structure of an embodiment of the present invention; Figure 3 The top plan view of the first reactor of the embodiment of the present invention; specifically, the first reactor has an upper chlorine port 1 and a lower chlorine port 2, the upper chlorine port 1 is located at the top of the first reactor, the upper chlorine port 1 is connected to the first chlorine pipeline, the lower chlorine port 2 is located near the outer side of the bottom of the first reactor, and is connected to the second chlorine pipeline, wherein,

[0057] The upper chlorine inlet 1 and the lower chlorine inlet 2 both pass chlorine into the first reactor at a preset chlorine passing speed.

[0058] from Figure 2It can be seen that the first reactor includes an upper chlorine port 1, a lower chlorine port 2, an electromagnetic flowmeter 3, a pressure gauge 4, a thermometer 5, a vacuum gauge 6, a reducer 7, a motor 8, a pressure relief pipeline 9, a nitrogen pipeline 10, a vacuum pipeline 11, a material pipeline 12, a pressure relief buffer tank 13, a first metering tank 14, a second metering tank 15, a cooling water outlet 16, a cooling water drain valve 17, a cooling water inlet 18, a sight glass 19, a manhole 20 and a material outlet 21, and the first reactor is connected to a 5.5kw stirring reducer, and the reaction system is respectively from Chlorine is introduced into the upper chlorine inlet 1 and the lower chlorine inlet 2 based on the preset chlorine introduction speed, so that the chlorine is more evenly and quickly distributed, which is beneficial to the chlorination reaction. The nitrogen pipeline and the vacuum pipeline are designed as downward insertion pipes, and the end of the nitrogen pipeline is inserted deeper into the first reactor, that is, to ensure nitrogen flow, but not to be immersed below the liquid level in the reactor, to ensure that nitrogen is continuously introduced during the reaction; the tail gas is connected to the pressure relief buffer tank, and the pressure relief buffer tank is connected to the total production tail gas system, which ensures production safety, prevents hazardous waste from sucking back into the first reactor, and prevents the material in the first reactor from spraying into the tail gas system.

[0059] It can be understood that the novel chlorination synthesis reactor developed by the present invention abandons the traditional chlorine-passing method, increases the contact points between chlorine and substrate, keeps nitrogen isolated, makes the contact between substrate and chlorine more uniform, shortens the chlorine-passing time by 20% compared with the past, makes the production easy to control and safe; and two chlorine-passing ports are sufficient to achieve uniform distribution of chlorine, and further increasing the chlorine-passing points cannot speed up the reaction, because the increase in chlorine-passing points weakens the ventilation pressure of each chlorine-passing port, which is not conducive to the reaction.

[0060] The present invention arranges upper and lower double-point chlorine inlets on the first reaction kettle to introduce chlorine for chlorination reaction, so that the contact distribution of chlorine and substrate is more uniform, the side reaction is suppressed and the completion time of the chlorination reaction is reduced by 20% compared with that of a common reaction kettle device, the production cost is saved and the yield of the target product is improved, the generation of impurities is further avoided, and the production process of 2-chloromethyl-1,3-dioxolane is optimized.

[0061] Specifically, a reaction rate variation curve is determined according to the reaction rate, an impurity generation rate variation curve is determined according to the impurity generation rate, a reaction characterization state is determined according to the reaction rate variation curve, an impurity characterization state is determined according to the impurity generation rate variation curve, and an optimal chlorine flow rate is determined according to the reaction characterization state and the impurity characterization state;

[0062] Among them, the reaction characterization state is the reaction rate decrease and the reaction rate increase, and the impurity characterization state is the impurity generation rate decrease and the impurity generation rate increase.

[0063] Specifically, if the reaction characterization state is a decrease in reaction rate and the impurity characterization state is an increase in impurity generation rate, the optimal chlorine flow rate is determined based on a preset chlorine flow rate, a first linear relationship coefficient between the chlorine flow rate and the reaction rate, and a second linear relationship coefficient between the chlorine flow rate and the impurity generation rate.

[0064] It is understandable that, under normal circumstances, in the initial stage of chlorination reaction, the substrate concentration is high, then the reaction solution concentration and impurity generation amount will be more, and as the reaction proceeds, the concentration of vinyl acetate decreases, and the collected reaction solution concentration and impurity generation amount will decrease. However, the change in impurity content is also affected by factors such as the activation energy of the side reaction and the speed of chlorine introduction. If the activation energy of the side reaction is low, when the chlorine introduction speed is fast, the rate of impurity generation may be accelerated, and even if the reactant concentration of the main reaction is declining, the impurity content may also increase.

[0065] In a specific embodiment, according to the reaction solution detection reaction solution concentration and impurity content based on several detection time points, the reaction rate at adjacent detection time points is the ratio of the reaction solution concentration difference at adjacent detection time points to the detection time interval, and the impurity generation rate at adjacent detection time points is the ratio of the impurity content difference at adjacent detection time points to the detection time interval. The reaction rate at several detection time points is formed into a reaction rate variation curve, and the impurity generation rate at several detection time points is formed into an impurity generation rate variation curve. As the reaction proceeds, as the reaction proceeds, if the reaction characterization state is that the reaction rate decreases and the impurity characterization state is that the impurity generation rate increases, then the optimal chlorine flow rate is determined, and the optimal chlorine flow rate should be less than the preset chlorine flow rate to avoid side reactions from generating excess impurities. The first linear relationship coefficient between the chlorine flow rate and the reaction rate can be determined in several chlorine flow experiments. For example, chlorination reaction is carried out based on the gradient chlorine flow rate, and the reaction rate is indirectly characterized by the reaction solution concentration after the chlorination reaction ends. Then different chlorine flow rates correspond to different reaction solution concentrations. According to the linear relationship, the first linear relationship coefficient between the chlorine flow rate and the reaction rate can be obtained. The second linear relationship coefficient between the chlorine flow rate and the impurity generation rate can be determined in several chlorine flow experiments. For example, chlorination reaction is carried out based on the gradient chlorine flow rate, and the impurity generation rate is indirectly characterized by the impurity content after the chlorination reaction ends. Then different chlorine flow rates correspond to different impurity contents. Then according to the linear relationship, the second linear relationship coefficient between the chlorine flow rate and the impurity generation rate can be obtained. Then the optimal chlorine flow rate is to minimize the impurity generation rate while maximizing the reaction rate. The optimal chlorine flow rate is obtained by constructing the objective function F (v). F (v) represents a certain trade-off between the reaction rate and the impurity generation rate. The limiting condition is: the reaction rate is greater than the impurity generation rate, and the reaction rate and the chlorine flow rate are related by the first linear relationship coefficient, and the impurity generation rate and the chlorine flow rate are related by the second linear relationship coefficient. In implementation, the objective function construction method of the first linear relationship coefficient, the second linear relationship coefficient, and the optimal chlorine flow rate can all be determined according to actual conditions, which is not specifically limited here and will not be repeated.

[0066] The present invention determines the optimal chlorine-feeding speed based on the reaction characterization state and the impurity characterization state according to a preset chlorine-feeding speed, a first linear relationship coefficient between the chlorine-feeding speed and the reaction rate, and a second linear relationship coefficient between the chlorine-feeding speed and the impurity generation rate, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0067] Specifically, the inflection points of the temperature change curve corresponding to several positions are determined, the slope of the line segment between the inflection points is determined according to the inflection point positions, the consistency of the temperature change curve is determined according to the inflection point positions and the line segment slope, and the optimal stirring speed is determined according to the consistency, the preset consistency and the preset stirring speed.

[0068] Specifically, determining the consistency includes: determining the inflection point position difference according to the inflection point positions corresponding to different temperature change curves, determining the slope difference according to the line segment slope, and determining the consistency according to the inflection point position difference, the slope difference, the preset slope difference and the preset position difference.

[0069] It is understandable that during the chlorination reaction, when the chlorine gas is in uniform contact with the reaction substrate, the temperature change curves detected at several positions are relatively similar, and there will be no local over-temperature or local over-temperature. If the chlorine gas is in uneven contact with the substrate, it may cause a violent local reaction and a sharp rise in temperature, while other parts react slowly and the temperature change is not obvious. Therefore, by adjusting the stirring speed, the chlorine gas and the reaction substrate can be quickly brought into uniform contact.

[0070] In a specific embodiment, the inflection points of the temperature change curves corresponding to the plurality of positions are determined, and based on the same temperature change curve, the slope of the line segment between adjacent inflection points is the ratio of the temperature difference corresponding to the adjacent inflection points to the time difference corresponding to the adjacent inflection points. Figure 4 As shown, Figure 4 It is a schematic diagram of the inflection point position of an embodiment of the present invention. The inflection point position difference is the time difference t1-t2 between the closest inflection points between any two temperature change curves, the slope difference is the difference k1-k2 between the slopes of the corresponding two segments between any two temperature change curves, and the consistency is the difference between the ratio of the product of the slope difference and the inflection point position difference and the product of the preset slope difference and the preset inflection point position difference and 1. The greater the slope difference and the inflection point position difference, the lower the consistency. The preset consistency value is 0.8 to 0.95. Preferably, the preset consistency value is 0.9. The adjustment coefficient of the stirring speed is the ratio of the preset consistency and the difference of the consistency to the preset consistency, and the speed adjustment amount is the product of the adjustment coefficient and the preset stirring speed. The optimal stirring speed is the sum of the preset stirring speed and the speed adjustment amount. In implementation, the value range and preferred value of the preset consistency, the calculation formula of the consistency, and the optimal stirring speed can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0071] The present invention determines the consistency of the temperature change curve according to the inflection point positions of the temperature change curve corresponding to a plurality of positions and the slope of the line segment between the inflection points, determines the optimal stirring speed according to the consistency, the preset consistency and the preset stirring speed, further promotes the contact between chlorine and the reaction substrate, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0072] Specifically, the transparency is compared with a preset transparency, and the washing stop timing is determined according to the comparison result, wherein:

[0073] If the transparency is less than the preset transparency, repeat washing;

[0074] If the transparency is greater than or equal to the preset transparency, washing is stopped.

[0075] Specifically, the improvement degree is compared with a preset improvement degree, and the washing stop timing is determined according to the comparison result, wherein:

[0076] If the improvement degree is less than the preset improvement degree, stopping washing;

[0077] If the improvement degree is greater than or equal to the preset improvement degree, the washing is repeated.

[0078] In a specific embodiment, after washing, the color of the upper aqueous phase will become closer and closer to transparent, and the impurities will become less and less. Therefore, a turbidity meter is used to detect the clarity of the upper aqueous phase to characterize the transparency. The preset transparency range is 0.2NTU to 0.4NTU. Preferably, the preset transparency value is 0.3NTU. Similarly, after several consecutive washes, the degree of improvement in the transparency of the upper aqueous phase becomes smaller and smaller. For example, after one wash, the transparency drops rapidly from 2NTU to a relatively transparent 0.8NTU, and the degree of improvement is 1.2NTU. If the difference in transparency before and after subsequent washing, that is, the degree of improvement is 0.1NTU, which is less than the preset improvement degree of 0.3NTU, then stop washing. In implementation, the value range and preferred value of the preset transparency and the preset improvement degree can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0079] The present invention determines the washing stop timing according to the comparison result between the transparency of the upper aqueous phase after a single washing and the preset transparency, and the comparison result between the improvement degree and the preset improvement degree, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0080] Specifically, the height of the end of the first chlorine-passing pipe is located at 1 / 2 of the height of the liquid level of the mixed solution in the first reactor, and the end of the second chlorine-passing pipe is bent downward.

[0081] Specifically, the pipe end of the first chlorine-passing pipe and the pipe end of the second chlorine-passing pipe are both provided with arc-shaped sealing heads, and a plurality of air holes are opened on the arc-shaped sealing heads.

[0082] It is understandable that the end of the first chlorine-passing pipeline is located at a height 1 / 2 below the liquid level of the mixed solution in the first reactor, and the end of the second chlorine-passing pipeline is bent downward, which helps to distribute the chlorine more evenly in the reactor. This is because if the reactor has a large diameter, it is difficult to evenly distribute the chlorine in the entire reactor with a single chlorine-passing port.

[0083] In practice, the number of the ventilation holes can be determined according to actual conditions, and is not specifically limited here and will not be described in detail.

[0084] The end of the first chlorine-passing pipeline of the present invention is located 1 / 2 below the liquid level of the mixed solution in the first reactor, the end of the second chlorine-passing pipeline is bent downward, and the ends of the pipelines are both provided with arc-shaped heads with a plurality of air holes, which further facilitates the full and uniform contact between chlorine and reaction substrates, thereby further improving the yield of the target product, further avoiding the generation of impurities, and optimizing the production process of 2-chloromethyl-1,3-dioxolane.

[0085] Experiment with 10kg vinyl acetate to determine the reaction parameters:

[0086] 1. Chlorination reaction: -10° brine cooling, add 10kg vinyl acetate, 11.15kg methanol, 1.7kg DMF to the first reactor, sample the reaction liquid every 2 hours to detect the reaction rate. In order to eliminate the influence of different process conditions on the reaction rate, Table 1 uniformly takes the detection conditions of the reaction liquid when the reaction reaches the end point, and compares them with the impurity content.

[0087] Table 1 Impurity content in the reaction solution at different chlorine introduction rates

[0088]

[0089] As can be seen from Table 1, different chlorine flow rates are directly reflected in temperature changes. The higher the temperature, the greater the impurities produced. Data comparison shows that, combined with production conditions, it is best to control the temperature at 15℃~20℃.

[0090] Different catalytic conditions have different effects on the reaction. The temperature was lowered to -10° salt water. 10kg vinyl acetate, 11.15kg methanol, and 1.7kg DMF were added to the first reactor. Chlorine was passed at 15°C to 20°C. Table 2 uniformly takes the detection conditions of the reaction liquid when the reaction reaches the end point, and compares the impurity content:

[0091] Table 2 Impurity content in the reaction solution under different catalytic conditions

[0092]

[0093] It can be seen from Table 2 that under the dual catalytic protection of nitrogen and DMF, when other conditions remain unchanged, the impurity generation is minimal, and the catalytic protection is beneficial to inhibiting side reactions and impurity generation.

[0094] 2. Condensation reaction: The intermediate (distillation product) and ethylene glycol are subjected to condensation reaction, heated by atmospheric pressure steam at 70° reflux, and the catalyst is added at a fixed ratio of 10%. The effect of different ethylene glycol addition amounts on the yield is shown in Table 3:

[0095] Table 3 Effect of different ethylene glycol addition amounts on yield

[0096]

[0097]

[0098] As shown in Table 3, different amounts of ethylene glycol have a direct effect on the yield of the condensation reaction. When the substrate and ethylene glycol are added at a molar ratio of 1:1.8, the yield is the highest. Increasing the amount of ethylene glycol added will result in a decreasing yield, which may be related to the dilution of the substrate, resulting in a decrease in yield.

[0099] Similarly, with other conditions unchanged, the effects of different catalyst addition amounts on the yield are shown in Table 4:

[0100] Table 4 Effect of different catalyst addition amounts on yield

[0101] Intermediate: Catalyst (molar ratio) Yield / % 100：5 58.0 100:7 88.9 100:10 87.1

[0102] As shown in Table 4, the molar ratio of substrate intermediate to catalyst is 100:7 for the best yield. The yield tends to decrease with the increase of catalyst. It is possible that the catalyst has a capping effect, or the reaction system has a capping effect. Adding catalyst instead triggers other side reactions.

[0103] Similarly, in the condensation reaction, the effects of reflux time and temperature on the yield were verified. A 10 kg pilot test was conducted using a two-stage condenser. The first condenser was filled with normal temperature tap water, and the second condenser was filled with 5° cold water. The effects of reflux time and temperature on the yield are shown in Table 5:

[0104] Table 5 Effect of reflux time and temperature on yield

[0105]

[0106] According to Table 5, when the reflux temperature is kept relatively stable, the yield is the highest when the reflux time is 1.5 hours. Prolonging the time does not increase the yield. On the contrary, the impurities tend to increase. The temperature is kept at 65-70° because during the condensation reaction, the by-products generated are mainly lower alcohols. The reflux reaction at this temperature is enough to reach the boiling point of the lower alcohol. If the temperature is too high, the reaction system will boil violently, and even unsafe situations such as spraying will occur.

[0107] Example:

[0108] A. Chlorination addition reaction: In a 3000-liter chlorination reactor (first reactor), open the jacket -10° refrigerant circulation to cool down, add 400kg vinyl acetate, 446kg methanol and 68kg DMF and stir and mix evenly; after N2 replacement in the reactor, slowly pass N2; slowly pass chlorine, control the temperature of the reaction system at about 15-20°C, continue to pass chlorine until the end of the reaction, and pass about 740 kg; close the jacket to cool down the refrigerant, continue stirring at room temperature for 5-6 hours to complete the chlorination reaction, pump 450kg of ammonia water from the high-level tank into the reactor at a uniform rate to neutralize the acidity, keep the reaction system at 20-30°C, continue stirring for 1 hour, and the reaction solution is neutral or weakly alkaline when tested by Ph test paper. If ammonia water is not enough, it can be appropriately supplemented until neutralization is complete;

[0109] Stop stirring, let stand for 1 hour to separate layers, release the water phase, add 300 kg of pure water for secondary washing, stir for half an hour, let stand for 1 hour to separate layers, release the water phase, and obtain 545 kg of 2-chloro-1,1-dimethoxyethane;

[0110] Open the vacuum, distill the organic phase under reduced pressure at 50° and collect the distillation product, evaporate until there is no fraction, close the vacuum, add a small amount of water to the kettle, stir and wash the kettle for half an hour, release the kettle residue and transport it for sewage treatment, and obtain about 516 kg of 2-chloro-1,1-dimethoxyethane with a content of ≥98%. The yield of this step is 88.75%;

[0111] B. Condensation reaction: 516 kg of 2-chloro-1,1-dimethoxyethane was pumped into a 2000L sandwich reactor (second reactor), stirring was started, 460 kg of ethylene glycol and 49 kg of p-toluenesulfonic acid catalyst were added in sequence, stirring and mixing, steam was started to slowly increase the temperature, the reactor temperature was maintained at 65-70°C, atmospheric reflux was performed for 1.5 hours, and the fraction at the lower end of the condenser was collected; after atmospheric reflux was completed, vacuum distillation was started, and the fraction was collected, which was 2-chloromethyl-1,3-dioxolane. The reactor was maintained at 90° for 1.5 hours until there was no fraction, and the target product, crude 2-chloromethyl-1,3-dioxolane, was obtained, which was light yellow and slightly turbid;

[0112] The obtained 2-chloromethyl-1,3-dioxolane is pumped into a washing kettle, stirred and cooled to room temperature, 1000 liters of purified water is added, stirred and washed for 30 minutes, allowed to stand for 1 hour to separate the layers, the aqueous phase is discharged, 500 liters of purified water is added to the organic phase again to repeat the above washing operation, the aqueous phase is discharged, and the transparency of the upper aqueous phase is detected at the same time to determine the time to stop washing. After several times of washing, the finished product is colorless and transparent or light yellow and transparent, weighing about 440 kg, with a content of> 98%, and the reaction yield of this step is 88.6%.

[0113] In the condensation reaction, the last aqueous phase in the washing operation can be collected and applied to the first water washing phase of the next batch of 2-chloromethyl-1,3-dioxolane production, so as to achieve the purpose of rational water use and water conservation; at the same time, the kettle residue after vacuum distillation can be collected, the content of each component in the kettle residue can be analyzed, and each component can be added according to the ratio, which can be applied to the next batch of production to achieve the purpose of cost saving.

[0114] The present invention uses vinyl acetate and methanol as substrates, nitrogen and DMF as catalysts to form dual catalytic protection, inhibits side reactions and impurity generation, and obtains the target product 2-chloromethyl-1,3-dioxolane through chlorination reaction and condensation reaction. At the same time, the optimal chlorine passing speed, the optimal stirring speed and the washing stop time are determined to improve the yield of the target product, further avoid the generation of impurities, and optimize the production process of 2-chloromethyl-1,3-dioxolane.

[0115] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform chlorination reactor, characterized in that: include: Step S1, putting vinyl acetate, methanol and DMF in a weight ratio of 0.85 to 0.95 parts: 0.9 to 1.2 parts: 0.1 to 0.2 parts into a first reaction kettle, stirring and mixing them evenly, and replacing the first reaction kettle with nitrogen; Step S2, introducing chlorine gas into the first reactor at a preset chlorine-passing speed and stirring, introducing an alkaline solution into the first reactor after the chlorination reaction is completed, stirring and standing to separate the impurities to obtain an aqueous phase and an organic phase, performing vacuum decompression distillation on the organic phase, and collecting a distillation product; Step S3, placing the distillation product, ethylene glycol and catalyst in a weight ratio of 1.1 to 1.15 parts: 0.95 to 1.05 parts: 0.93 to 0.94 parts into a second reaction kettle, stirring and mixing them evenly, steam heating and then reflux at normal pressure in multiple stages, and vacuum distilling after the reflux to obtain a crude target product; Step S4, placing the crude target product into a washing kettle for cooling and stirring, and repeating the washing several times to obtain the target product; Wherein, in step S2, the reaction solution is taken to detect the concentration and impurity content of the reaction solution at several detection time points, the reaction rate is determined according to the concentration of the reaction solution, and the impurity generation rate is determined according to the impurity content, and the optimal chlorine flow rate is determined according to the reaction rate and the impurity generation rate; Based on the several detection time points, temperature data of several positions in the first reaction kettle are collected, temperature change curves of several positions during the chlorination process are constructed according to the temperature data, and an optimal stirring speed is determined according to the temperature change curve and a preset stirring speed; In step S4, standing and stratification are performed based on a preset standing time after each wash, and after a single standing is completed, the transparency of the upper aqueous phase is detected, and the time to stop washing is determined based on the transparency and the preset transparency, or the degree of improvement in the transparency of the upper aqueous phase after each wash is determined, and the time to stop washing is determined based on the improvement degree and the preset improvement degree.

2. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle according to claim 1, characterized in that: The first reactor has an upper chlorine inlet and a lower chlorine inlet, wherein the upper chlorine inlet is located at the top of the first reactor and connected to a first chlorine pipeline, and the lower chlorine inlet is located near the outer side of the bottom of the first reactor and connected to a second chlorine pipeline, wherein: The upper chlorine inlet and the lower chlorine inlet both pass chlorine into the first reaction kettle at a preset chlorine passing speed.

3. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle according to claim 1, characterized in that: In step S2, a reaction rate variation curve is determined according to the reaction rate, an impurity generation rate variation curve is determined according to the impurity generation rate, a reaction characterization state is determined according to the reaction rate variation curve, an impurity characterization state is determined according to the impurity generation rate variation curve, and an optimal chlorine flow rate is determined according to the reaction characterization state and the impurity characterization state; Among them, the reaction characterization state is the reaction rate decrease and the reaction rate increase, and the impurity characterization state is the impurity generation rate decrease and the impurity generation rate increase.

4. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor according to claim 3, characterized in that: In step S2, if the reaction characterization state is a decrease in reaction rate and the impurity characterization state is an increase in impurity generation rate, the optimal chlorine flow rate is determined based on a preset chlorine flow rate, a first linear relationship coefficient between the chlorine flow rate and the reaction rate, and a second linear relationship coefficient between the chlorine flow rate and the impurity generation rate.

5. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor according to claim 1, characterized in that: In step S2, the inflection points of the temperature change curve corresponding to several positions are determined, the slope of the line segment between the inflection points is determined according to the inflection point positions, the consistency of the temperature change curve is determined according to the inflection point positions and the line segment slope, and the optimal stirring speed is determined according to the consistency, the preset consistency and the preset stirring speed.

6. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle according to claim 5, characterized in that: In step S2, the consistency is determined, including: determining the inflection point position difference according to the inflection point positions corresponding to different temperature change curves, determining the slope difference according to the line segment slope, and determining the consistency according to the inflection point position difference, slope difference, preset slope difference and preset position difference.

7. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle according to claim 1, characterized in that: In step S4, the transparency is compared with a preset transparency, and the washing stop timing is determined according to the comparison result, wherein: If the transparency is less than the preset transparency, repeat washing; If the transparency is greater than or equal to the preset transparency, washing is stopped.

8. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reaction kettle according to claim 7, characterized in that: In step S4, the improvement degree is compared with a preset improvement degree, and the washing stop timing is determined according to the comparison result, wherein: If the improvement degree is less than the preset improvement degree, stopping washing; If the improvement degree is greater than or equal to the preset improvement degree, the washing is repeated.

9. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor according to claim 2, characterized in that: The height of the end of the first chlorine-passing pipeline is located at 1 / 2 of the liquid level of the mixed solution in the first reactor, and the end of the second chlorine-passing pipeline is bent downward.

10. The method for synthesizing 2-chloromethyl-1,3-dioxolane based on a uniform-speed chlorination reactor according to claim 9, characterized in that: The pipe end of the first chlorine-passing pipe and the pipe end of the second chlorine-passing pipe are both provided with arc-shaped sealing heads, and a plurality of air holes are opened on the arc-shaped sealing heads.

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