CN113860308B - Method for continuously preparing thiophosgene by using sulfur dioxide - Google Patents
Method for continuously preparing thiophosgene by using sulfur dioxide Download PDFInfo
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Abstract
The invention provides a method for continuously preparing thiophosgene by using sulfur dioxide, belonging to the technical field of organic synthesis. The method comprises the following steps: introducing perchloromethylmercaptan and sulfur dioxide into a continuous flow reactor, firstly reacting under the action of a catalyst, and then reacting the mixture obtained by the reaction with water to obtain the perchloromethylmercaptan sulfur dioxide catalyst. The synthesis method has the advantages of simple process, mild reaction conditions, high reaction speed, less side reactions, convenient post-treatment, high purity of the obtained product and high yield; meanwhile, the synthesis method is high in safety, green and environment-friendly, and effectively reduces the production cost; in addition, the synthesis method is suitable for large-scale production and has wide application prospect in the synthesis of the thiophosgene.
Description
Technical Field
The invention belongs to the technical field of organic synthesis, and particularly relates to a method for continuously preparing thiophosgene by using sulfur dioxide.
Background
The dichlorocarbon sulfide, also known as thiophosgene, is widely applied to organic synthesis, can be used for preparing isothiocyanate compounds and various heterocycles, and is an important intermediate in the field of organic synthesis. Among them, thiophosgene is an important intermediate for preparing diafenthiuron as an acaricide, and is also an important intermediate for preparing thiocarbamate insecticides and herbicides.
At present, the preparation methods of thiophosgene mainly comprise the following steps:
1. perchloromethanethiol reduction elimination, the specific synthetic route is as follows (Gharda, keki Hormou, australia, AU 2010100462A 4 2010-06-17):
the traditional kettle type intermittent preparation method comprises the steps of adding potassium iodide into a mixture of perchloromethylmercaptan, dichloromethane and water, stirring, introducing sulfur dioxide at room temperature, automatically heating in the reaction, adjusting the ventilation rate, and keeping the temperature at 50-70 ℃. When the temperature of the reaction solution does not rise any more and the sulfur dioxide is not absorbed obviously any more, the aeration is stopped, and the yield of the method is 82 percent. However, the method continuously releases heat in the ventilation process, and the amplification is difficult to control along with the increase of the system, so that the method has potential safety hazards. But also consumes a large amount of excessive sulfur dioxide, which is not environment-friendly and has high cost.
2. Perchloromethanethiol cleavage, a specific synthetic route is as follows (Orwoll, edward F., united States, US2668853 1954-02-09):
the yield of the synthesis method is 82%, but the synthesis method has high reaction temperature (140 ℃), and the cracking reaction is difficult to control and has safety risk.
3. The reaction of chlorine and carbon disulphide to thiophosgene (Organic Syntheses (1926), VI, 86-91) gives very low yields of only 24%.
Therefore, the methods for preparing thiophosgene in the prior art have problems, such as low yield, certain potential safety hazards and environmental protection hazards. At present, a safe, environment-friendly and high-yield production mode of thiophosgene is urgently needed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for continuously preparing thiophosgene by using sulfur dioxide, which comprises the following steps:
introducing perchloromethylmercaptan and sulfur dioxide into a continuous flow reactor, firstly reacting under the action of a catalyst, and then reacting the mixture obtained by the reaction with water to obtain the perchloromethylmercaptan sulfur dioxide catalyst.
Further, the continuous flow reactor consists of a continuous flow reaction unit I and a continuous flow reaction unit II; the continuous flow reaction unit I comprises a gas-liquid mixing module, a reaction module I and a gas-liquid separation module which are sequentially connected; the continuous flow reaction unit II comprises a reaction module II and a liquid-liquid separation module which are sequentially connected;
the reaction is carried out in a continuous flow reaction unit I under the action of a catalyst; the reaction with water is carried out in a continuous flow reaction unit II.
Further, the aforementioned method comprises the steps of:
(1) Respectively introducing a mixture obtained by mixing perchloromethane methanol and a catalyst and sulfur dioxide into a gas-liquid mixing module for mixing, and introducing the mixture into a reaction module I for reaction;
(2) The reaction mixture reacted in the reaction module I enters a gas-liquid separation module, and the obtained reaction liquid enters a reaction module II; meanwhile, water is introduced into the reaction module II; reacting the reaction solution with water in a reaction module II;
(3) The reaction mixture after reaction in the reaction module II enters a liquid-liquid separation module to obtain a thiophosgene crude product;
(4) And purifying the obtained crude thiophosgene to obtain the thiophosgene.
Further, the air conditioner is provided with a fan,
in the step (1), the weight ratio of the perchloromethionol to the catalyst is 1;
and/or in the step (1), the flow rate ratio of the mixture and the sulfur dioxide to the gas-liquid mixing module is 1.
Further, the air conditioner is provided with a fan,
in the step (1), the weight ratio of the perchloromethionol to the catalyst is 1;
and/or, in step (1), the mixture and the sulfur dioxide are fed into the reaction module I at a flow rate ratio of 1.
Further, the air conditioner is provided with a fan,
in the step (1), the catalyst is selected from sodium bromide, potassium bromide, sodium iodide or potassium iodide;
preferably, in step (1), the catalyst is potassium bromide.
Further, the air conditioner is provided with a fan,
in the step (2), the flow rate ratio of the reaction liquid and water introduced into the reaction module II is 1;
preferably, in the step (2), the flow rate ratio of the reaction liquid and the water introduced into the reaction module II is 1.
Further, the air conditioner is provided with a fan,
in the step (1), the reaction time in the reaction module I is 5-25 min;
and/or in the step (1), the temperature of the reaction in the reaction module I is-10-60 ℃;
and/or in the step (2), the reaction time in the reaction module II is 1-5 min;
and/or in the step (2), the temperature of the reaction in the reaction module II is 0-25 ℃.
Further, the air conditioner is provided with a fan,
in the step (1), the reaction temperature in the reaction module I is-10-50 ℃;
and/or, in the step (2), the temperature of the reaction in the reaction module II is 0 ℃;
preferably, in the step (1), the temperature of the reaction in the reaction module I is 0-40 ℃;
more preferably, in the step (1), the temperature of the reaction in the reaction module I is 10-20 ℃.
Further, the air conditioner is provided with a fan,
in the step (4), the purification is fractional distillation;
preferably, the fractionation is an atmospheric fractionation, and the temperature of the fraction is 73 ± 3 ℃.
Compared with the prior art, the invention has the following beneficial effects:
(1) Compared with the kettle-type sulfur dioxide preparation method, three improvements are provided: (1) no solvent is needed, and the use of excessive sulfur dioxide is avoided, so that the cost and three wastes are reduced; (2) the reaction temperature is obviously reduced by the staged reaction, the reaction condition is milder, and the reaction speed is faster; in the first stage, the quantitative reaction is carried out to generate the thiophosgene and the by-product sulfonyl chloride, in the second stage, the water quenching is added to kill the by-product sulfonyl chloride, and the thiophosgene and the by-products sulfuric acid and hydrochloric acid are continuously separated; (3) the problems that hydrolysis occurs simultaneously in the ventilation process of the traditional method, the reaction temperature is continuously increased and is difficult to control, the amplification effect is poor, potential safety hazards exist and the like can be solved.
(2) Compared with the perchloromethylmercaptan pyrolysis preparation method, the method avoids uncontrollable reaction and amplified safety risk.
(3) Compared with the chlorine preparation method, the method has obvious advantage in yield.
In conclusion, the present invention provides a continuous flow process for the synthesis of thiophosgene. According to the invention, the raw materials are synthesized into the thiophosgene in a micro-channel reactor in a continuous flow manner, the synthesis method has the advantages of simple process, mild reaction conditions, high reaction speed, less side reactions, convenient post-treatment, high purity of the obtained product and high yield; meanwhile, the synthesis method is high in safety, green and environment-friendly, and effectively reduces the production cost; in addition, the synthesis method is suitable for large-scale production and has wide application prospect in the synthesis of the thiophosgene.
Obviously, many modifications, substitutions, and variations are possible in light of the above teachings of the invention, without departing from the basic technical spirit of the invention, as defined by the following claims.
The present invention will be described in further detail with reference to the following examples. This should not be understood as limiting the scope of the above-described subject matter of the present invention to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention.
Drawings
FIG. 1 is a block diagram of the design of a continuous flow reactor and a process for the synthesis of thiophosgene according to the present invention.
FIG. 2 shows the main reaction processes of each continuous flow reaction unit.
Detailed Description
The raw materials and equipment used in the embodiment of the present invention are known products and obtained by purchasing commercially available products.
In the examples, the module design and process flow of a continuous flow reactor is shown in FIG. 1. Comprises two continuous flow reaction units. The continuous flow reaction unit I comprises a gas-liquid mixing module, a reaction module (reaction module I) and a gas-liquid separation module which are sequentially connected. The continuous flow reaction unit II comprises a reaction module (reaction module II) and a liquid-liquid separation module which are connected in sequence. The specific structure of each module can be realized by adopting a conventional micro-channel or tubular reactor. The main reaction process of each continuous flow reaction unit is shown in figure 2.
Example 1 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) After the perchloromethylmercaptan, the potassium bromide and the sulfur dioxide are uniformly mixed in the gas-liquid mixing module (the mixture stays for 0.5 to 1 minute), the mixture is introduced into a reaction module I for reaction, and the stay time in the reaction module I is 20min. The gas-liquid mixing module and the reaction module I were both set to 10 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated into a crude product and a byproduct, the crude product is fractionated at normal pressure, and fractions at 73 +/-3 ℃ are collected to obtain 97.8g of a purified thiophosgene product with the GC purity of 95% and the yield of 93%.
Example 2 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) The perchloromethylmercaptan, the potassium bromide and the sulfur dioxide are mixed in the gas-liquid mixing module for 1min, and then introduced into a reaction module I for reaction, wherein the retention time in the reaction module I is 20min. The gas-liquid mixing module and the reaction module I were set to 20 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 94.5g of a thiophosgene pure product, the GC purity is 96%, and the yield is 90%.
Example 3 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I were both set to 30 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 91.4g of a thiophosgene pure product, the GC purity is 96%, and the yield is 87%.
Example 4 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through the gas flowmeter at the flow speed regulated to be 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I were set to 40 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 88.2g of a thiophosgene pure product, wherein the GC purity is 97%, and the yield is 85%.
Example 5 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through the gas flowmeter at the flow speed regulated to be 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I are both set to 50 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 80.9g of a thiophosgene pure product, the GC purity is 96%, and the yield is 77%.
Example 6 continuous flow Synthesis of thiophosgene according to the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I are both set to be 60 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 44.1g of a thiophosgene pure product with the GC purity of 95% and the yield of 42%.
Example 7 continuous flow Sulfur phosgene Synthesis method of the invention
The method comprises the following specific steps:
(1) 170g of perchloromethylmercaptan is uniformly mixed with 1.7g of potassium bromide, and the mixture is conveyed into a gas-liquid mixing module through a metering pump at the flow rate of 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I are set to be 0 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 93.5g of a thiophosgene pure product, wherein the GC purity is 95% and the yield is 89%.
Example 8 continuous flow Synthesis of thiophosgene according to the invention
(1) 170g of perchloromethylmercaptan and 1.7g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I are set to be-10 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated to obtain a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 83.0g of a thiophosgene pure product with the GC purity of 95% and the yield of 79%.
Example 9 continuous flow Synthesis of thiophosgene according to the invention
(1) 170g of perchloromethylmercaptan and 2.4g of potassium iodide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through a gas flowmeter at the flow rate of 2L/min.
(2) After the perchloromethylmercaptan, the potassium iodide and the sulfur dioxide are uniformly mixed in the gas-liquid mixing module (the mixture stays for 0.5 to 1 minute), the mixture is introduced into a reaction module I for reaction, and the stay time in the reaction module I is 20min. The gas-liquid mixing module and the reaction module I were both set to 10 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated into a crude product and a byproduct, the crude product is fractionated at normal pressure, and fractions at 73 +/-3 ℃ are collected to obtain 40.0g of a purified thiophosgene product with the GC purity of 90% and the yield of 70%.
EXAMPLE 10 scaled-up production of thiophosgene by continuous flow Synthesis of the invention
(1) 1700g of perchloromethylmercaptan and 17.0g of potassium bromide are uniformly mixed and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 100mL/min; meanwhile, the sulfur dioxide enters the gas-liquid mixing module through the gas flowmeter at the flow rate of 20L/min.
(2) Mixing perchloromethylmercaptan, potassium bromide and sulfur dioxide in a gas-liquid mixing module for 1min, introducing the mixture into a reaction module I for reaction, and keeping the reaction module I for 20min. The gas-liquid mixing module and the reaction module I were set to 10 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 250mL/min, the flow rate ratio of the reaction liquid to the water is 1.5, and the residence time in the reaction module II is 5min.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated into a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 955.5g of a thiophosgene pure product with the GC purity of 96% and the yield of 91%.
Comparative example 1 other continuous flow Synthesis of thiophosgene
(1) 170g of perchloromethylmercaptan is taken and conveyed into a gas-liquid mixing module through a metering pump, and the flow rate is 10mL/min; meanwhile, sulfur dioxide enters the gas-liquid mixing module through the gas flowmeter at the flow speed regulated to be 2L/min.
(2) The perchloromethanol and the sulfur dioxide are mixed in the gas-liquid mixing module for 1min, and then are introduced into the reaction module I to react, and the residence time in the reaction module I is 20min. The gas-liquid mixing module and the reaction module I were both set to 10 ℃.
(3) After reaction in the reaction module I, the reaction mixture enters a gas-liquid separation module, gas is discharged through the gas-liquid separation module, the obtained reaction liquid enters the next reaction module (reaction module II), and the temperature of the reaction module II is 0 ℃; meanwhile, water is input into the reaction module II through a metering pump, the flow rate is 25mL/min, the flow rate ratio of the reaction liquid to the water is 1.
(4) After the reaction in the reaction module II, the reaction mixture passes through a liquid-liquid separation module to be separated into a crude product and a byproduct, the crude product is subjected to normal pressure fractionation, and fractions at 73 +/-3 ℃ are collected to obtain 34.6g of a purified thiophosgene product with the GC purity of 95% and the yield of 33%.
From examples 1 to 10 and comparative example 1, it can be seen that: the invention uses sulfur dioxide and perchloromethylmercaptan as raw materials, and the reaction temperature of the perchloromethylmercaptan and the sulfur dioxide can be between 10 ℃ below zero and 60 ℃ in the continuous flow reactor to prepare the high-purity thiophosgene. Wherein, perchloromethanol reacts with sulfur dioxide, when the catalyst is potassium bromide and the reaction temperature is-10-50 ℃, high yield (the yield is more than or equal to 77%) can be obtained under the condition that the purity of thiophosgene is more than or equal to 95%; when the catalyst is potassium bromide, the reaction temperature is optimal at 10-20 ℃, and the yield can reach more than 90% under the condition of ensuring that the purity of the thiophosgene is more than or equal to 95%; meanwhile, when the amplification production is carried out, the reaction is stable, and the purity and the yield of the obtained thiophosgene can be guaranteed. Therefore, the method of the invention obtains high-purity thiophosgene under milder reaction conditions and improves the yield of the thiophosgene.
In conclusion, the present invention provides a continuous flow process for the synthesis of thiophosgene. According to the invention, the raw materials are synthesized into the thiophosgene in a micro-channel reactor in a continuous flow manner, the synthesis method has the advantages of simple process, mild reaction conditions, high reaction speed, less side reactions, convenient post-treatment, high purity of the obtained product and high yield; meanwhile, the synthesis method is high in safety, green and environment-friendly, and effectively reduces the production cost; in addition, the synthesis method is suitable for large-scale process production and has wide application prospect in the thiophosgene synthesis.
Claims (13)
1. A method for continuously preparing thiophosgene by using sulfur dioxide is characterized by comprising the following steps: the method comprises the following steps:
carrying out the synthesis of thiophosgene by raw materials in a microchannel reactor in a continuous flow mode, specifically, introducing perchloromethanol and sulfur dioxide into a continuous flow reactor, firstly reacting under the action of a catalyst, and then reacting the obtained mixture with water to obtain the thiophosgene;
the continuous flow reactor consists of a continuous flow reaction unit I and a continuous flow reaction unit II; the continuous flow reaction unit I comprises a gas-liquid mixing module, a reaction module I and a gas-liquid separation module which are sequentially connected; the continuous flow reaction unit II comprises a reaction module II and a liquid-liquid separation module which are connected in sequence;
the reaction is carried out in a continuous flow reaction unit I under the action of a catalyst; the reaction with water is carried out in a continuous flow reaction unit II;
the method specifically comprises the following steps:
(1) Respectively introducing a mixture obtained by mixing perchloromethane methanol and a catalyst and sulfur dioxide into a gas-liquid mixing module for mixing, and introducing the mixture into a reaction module I for reaction;
(2) The reaction mixture reacted in the reaction module I enters a gas-liquid separation module, and the obtained reaction liquid enters a reaction module II; meanwhile, introducing water into the reaction module II; reacting the reaction solution with water in a reaction module II;
(3) The reaction mixture after reaction in the reaction module II enters a liquid-liquid separation module to obtain a thiophosgene crude product;
(4) And purifying the obtained crude thiophosgene to obtain the thiophosgene.
2. The method of claim 1, wherein:
in the step (1), the weight ratio of the perchloromethionol to the catalyst is 1;
and/or in the step (1), the flow rate ratio of the mixture and the sulfur dioxide introduced into the gas-liquid mixing module is 1.
3. The method of claim 2, wherein:
in the step (1), the weight ratio of the perchloromethionol to the catalyst is 1;
and/or, in step (1), the mixture and the sulfur dioxide are fed into the reaction module I at a flow rate ratio of 1.
4. The method of claim 1, wherein: in the step (1), the catalyst is selected from sodium bromide, potassium bromide, sodium iodide or potassium iodide.
5. The method of claim 4, wherein: in the step (1), the catalyst is potassium bromide.
6. The method of claim 1, wherein: in the step (2), the flow rate ratio of the reaction liquid and water introduced into the reaction module II is 1 to 2-3.
7. The method of claim 6, wherein: in the step (2), the flow rate ratio of the reaction liquid and water introduced into the reaction module II is 1.
8. The method of claim 1, wherein:
in the step (1), the reaction time in the reaction module I is 5 to 25min;
and/or in the step (1), the temperature of the reaction in the reaction module I is-10 to 60 ℃;
and/or in the step (2), the reaction time in the reaction module II is 1 to 5min;
and/or in the step (2), the temperature of the reaction in the reaction module II is 0-25 ℃.
9. The method of claim 8, wherein:
in the step (1), the reaction temperature in the reaction module I is-10 to 50 ℃;
and/or, in the step (2), the temperature of the reaction in the reaction module II is 0 ℃.
10. The method of claim 9, wherein: in the step (1), the temperature for reaction in the reaction module I is 0 to 40 ℃.
11. The method of claim 10, wherein: in the step (1), the temperature for reaction in the reaction module I is 10 to 20 ℃.
12. The method of claim 1, wherein: in the step (4), the purification is fractional distillation.
13. The method of claim 12, wherein: the fractionation is normal pressure fractionation, and the temperature of the fractionation is 73 +/-3 ℃.
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