CN113307720B - Preparation method of 1, 1-difluoro-2-iodoethylene - Google Patents

Preparation method of 1, 1-difluoro-2-iodoethylene Download PDF

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CN113307720B
CN113307720B CN202110410002.8A CN202110410002A CN113307720B CN 113307720 B CN113307720 B CN 113307720B CN 202110410002 A CN202110410002 A CN 202110410002A CN 113307720 B CN113307720 B CN 113307720B
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iodoethylene
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吕杨
黄明星
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Zhejiang Juhua Technology Center Co Ltd
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    • C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
    • C07C17/04—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated halogenated hydrocarbons
    • C—CHEMISTRY; METALLURGY
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Abstract

The invention discloses a preparation method of 1, 1-difluoro-2-iodoethylene, which comprises the following steps: (1) introducing vinylidene fluoride and chlorine gas into a tubular reactor simultaneously for reaction, condensing and collecting reaction products to obtain 1, 2-dichloro-1, 1-difluoroethane; (2) reacting the 1, 2-dichloro-1, 1-difluoroethane with KI in a solvent, cooling and discharging after the reaction is finished, evaporating reaction liquid to dryness, and rectifying the obtained evaporated liquid to obtain 1-chloro-1, 1-difluoro-2-iodoethane; (3) reacting the obtained 1-chloro-1, 1-difluoro-2-iodoethane under the action of a magnetic catalyst, cooling and discharging after the reaction is finished, placing the reaction liquid in an external magnetic field to separate the catalyst, and rectifying to obtain the 1, 1-difluoro-2-iodoethylene product. The method has the advantages of simple process, easily available raw materials, high yield and environmental protection.

Description

Preparation method of 1, 1-difluoro-2-iodoethylene
Technical Field
The invention relates to a preparation method of a fluorine-containing elastomer, in particular to a preparation method of 1, 1-difluoro-2-iodoethylene.
Background
The fluorine-containing elastomer is a synthetic polymer elastomer containing fluorine atoms on main chain or side chain carbon atoms, is widely applied to the fields of aerospace, aviation, war industry, national defense, automobiles and the like, and particularly is widely applied to the aspect of sealing. In the nineties of the last century, iodine-containing vulcanization point monomers are introduced into the fluorine-containing elastomer, so that the low-temperature performance and the mechanical performance of vulcanized rubber can be obviously improved, 1, 1-difluoro-2-iodoethylene is taken as an important monomer for introducing vulcanization points into the fluorine-containing elastomer, the attention of various companies is attracted, and the preparation method of the iodine-containing vulcanization point monomers becomes a research hotspot.
Currently, 1, 1-difluoro-2-iodoethylene is generally synthesized by adding iodine chloride and vinylidene fluoride into 1-chloro-1, 1-difluoro-2-iodoethane, and then dehydrochlorinating the 1-chloro-1, 1-difluoro-2-iodoethane under alkaline conditions to synthesize the 1, 1-difluoro-2-iodoethylene. The chemical equation is:
ICl+CF2＝CH2→CF2ClCH2I
CF2ClCH2I→CF2＝CHI+HCl
for example, EP 845482 reports that vinylidene fluoride is bubbled into iodine chloride at 20 to 50 ℃, the reaction solution is washed with a reducing agent aqueous solution and dried to obtain 1-chloro-1, 1-difluoro-2-iodoethane, and then dehydrochlorination is carried out at 90 to 100 ℃ in the presence of a phase transfer catalyst, an alkali metal hydroxide and a polar solvent to obtain 1, 1-difluoro-2-iodoethylene with a total yield of less than 65%. Similarly Ehm, Christian fluidic Chemistry journal of fluidic Chemistry [ J ].131(11), 1173-1181; 2010 and Park, j.d.; abramo, John g.; hein, Morris; gray, d.n.; (iii) Lacher, J.R. preparation and solvent properties of carbohydrate fluorinated lipids and solvent fluorinated butadienes. journal of Organic Chemistry [ J ].23,1661-5.1958, and the like.
Although the method can obtain the product, the method has the defects of high price of ICl (the market price is about 100 ten thousand per ton), difficult acquisition and storage, low total yield (less than or equal to 85 percent), high cost, complex operation conditions and the like.
Disclosure of Invention
The invention aims to provide a preparation method of 1, 1-difluoro-2-iodoethylene, which has the advantages of simple process, easily obtained raw materials, low cost and high yield, aiming at the defects of the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that: a preparation method of 1, 1-difluoro-2-iodoethylene comprises the following steps:
(1) introducing vinylidene fluoride and chlorine gas into a tubular reactor simultaneously for reaction, condensing and collecting reaction products to obtain 1, 2-dichloro-1, 1-difluoroethane;
(2) reacting the 1, 2-dichloro-1, 1-difluoroethane obtained in the step (1) with KI in a solvent, cooling and discharging after the reaction is finished, evaporating reaction liquid to dryness, and rectifying the obtained evaporated liquid to obtain 1-chloro-1, 1-difluoro-2-iodoethane;
(3) and (3) reacting the 1-chloro-1, 1-difluoro-2-iodoethane obtained in the step (2) under the action of a magnetic catalyst, cooling and discharging after the reaction is finished, placing the reaction liquid in an external magnetic field to separate the catalyst, and rectifying to obtain the 1, 1-difluoro-2-iodoethylene product.
According to the invention, when the intermediate 1, 2-dichloro-1, 1-difluoroethane is prepared in the step (1), normal pressure gas phase reaction is adopted, the conversion rate of the reaction is greatly reduced when the temperature is too low, the reaction selectivity is reduced when the temperature is too high, the content of polychlorinated byproducts is increased, and the energy consumption is increased. In a preferred embodiment of the present invention, the temperature of the reaction in step (1) is 60 to 130 ℃, more preferably 90 to 110 ℃, the pressure is normal pressure, and the molar ratio of chlorine to vinylidene fluoride is 0.9 to 1.0: 1.
In a preferred embodiment of the present invention, the material of the tubular reactor is one of 316L, hastelloy, 304 stainless steel and silicon carbide, and the inside of the tubular reactor is random-stacked with glass packing.
In a preferred embodiment of the present invention, the reaction temperature in step (2) is 100 to 160 ℃, the reaction time is 0.5 to 5 hours, and the mass ratio of KI to 1, 2-dichloro-1, 1-difluoroethane is 1.0 to 2.0: 1.
In a preferred embodiment of the present invention, the solvent is at least one of tetrahydrofuran, 2-methyltetrahydrofuran, N-dimethylformamide, and dimethylsulfoxide.
As a preferred embodiment of the invention, the magnetic catalyst is C/Y-Fe2O3Or C/Fe3O4And loading an active component, wherein the loading amount of the active component is 0.5-3 wt% (wt%, mass percentage).
As a preferred embodiment of the present invention, the active component is a metal chloride or a metal iodide.
As a preferred embodiment of the present invention, the metal chloride is FeCl3、ZnCl2、MgCl2、ZrCl4、BiCl3At least one of (1), the metal iodide is ZnI2、MgI2、ZrI4At least one of (1).
In a preferred embodiment of the present invention, the magnetic catalyst has a particle size of 300 to 500 mesh.
As a preferred embodiment of the invention, the reaction temperature in the step (3) is 120-170 ℃, more preferably 120-140 ℃, the reaction time is 2-7 h, and the dosage of the magnetic catalyst is 0.5-3% of the mass of the 1-chloro-1, 1-difluoro-2-iodoethane.
The preparation method of the 1, 1-difluoro-2-iodoethylene comprises the steps of simultaneously introducing vinylidene fluoride and chlorine into a tubular reactor to undergo free radical addition reaction to obtain a first intermediate 1, 2-dichloro-1, 1-difluoroethane; reacting the 1, 2-dichloro-1, 1-difluoroethane with KI in a solvent to obtain a second intermediate 1-chloro-1, 1-difluoro-2-iodoethane; and finally, reacting the 1-chloro-1, 1-difluoro-2-iodoethane under the action of a magnetic catalyst to obtain a 1, 1-difluoro-2-iodoethylene product.
The magnetic catalyst in the invention can be prepared by adopting a CVD chemical vapor deposition method which is conventional in the field: firstly, preparing active components and a carrier into sol-gel according to a certain molar ratio, then drying the sol-gel at 150 ℃ for 24 hours to obtain a catalyst precursor, and finally introducing methane gas into the catalyst precursor at 900 ℃ to carry out cracking carbon coating to synthesize the required magnetic catalyst.
The carbon-coated transition layer is arranged between the active component of the magnetic catalyst and the carrier, and can effectively prevent the carrier from losing in the reaction process, improve the activity of the catalyst and prolong the service life of the catalyst.
Compared with the prior art, the invention has the following advantages:
1. the invention has low cost, adopts vinylidene fluoride and chlorine as raw materials, has rich sources, low price and easy obtaining, has low cost and easy storage, and overcomes the problems of safety risk and high price of iodine chloride in the prior art; the magnetic catalyst and the solvent can be recycled, so that the cost is further reduced;
2. the yield is high, vinylidene fluoride and chlorine are used as raw materials, a carbon-coated transition layer is arranged between active components of the magnetic catalyst and the carrier in the preparation process through an optimized process, the carbon-coated transition layer can effectively prevent the carrier from losing in the reaction process, the activity and the service life of the catalyst are improved, the total yield of the reaction is effectively improved, the total yield of the reaction is over 90 percent, and the highest total yield can reach 92 percent;
3. the process is simple, the magnetic catalyst is adopted in the preparation process, after the reaction is finished, the reaction liquid is placed in an external magnetic field, and the magnetic catalyst can be completely separated and recovered and can be further recycled.
Drawings
FIG. 1 is a GC diagram of 1, 1-difluoro-2-iodoethylene prepared in example 1;
FIG. 2 is a MS diagram of 1, 1-difluoro-2-iodoethylene prepared in example 1.
Detailed Description
The present invention will be described in further detail with reference to examples, but the present invention is not limited to the following examples.
Example 1
(1) A316L material tubular reactor (Changsha facility instruments and equipment Co., Ltd.) has an inner diameter of 5cm, a wall thickness of 8mm, a tube length of 120cm, an effective height of glass filler filled inside of 100cm, a filler particle size of 2mm, an effective filler at an inlet of 30cm, and serves as a raw material preheating section, and the other effective fillers of 70cm serve as reaction sections. The temperature of the preheating section of the reactor is controlled to be 60 ℃ through three-stage electric heating, and the temperature of the reaction section is controlled to be 60 ℃. Controlling vinylidene fluoride with the flow rate of 640g/h (10mol/h) and chlorine with the flow rate of 710g/h (10mol/h) by a mass flow meter, simultaneously introducing the vinylidene fluoride into a tubular reactor, condensing a reaction product by a condenser, condensing crude 1, 2-dichloro-1, 1-difluoroethane into a crude product receiving bottle, and absorbing tail gas by 30 wt% KOH aqueous solution. The feed gas was continuously fed for 1 hour, and 1336g (content: 98.8%, 9.78mol) of crude 1, 2-dichloro-1, 1-difluoroethane was collected with a yield of 97.7%.
(2) In a 5L autoclave with stirring, 1336g of crude 1, 2-dichloro-1, 1-difluoroethane, 1L of tetrahydrofuran and 1624g (9.78mol) of anhydrous KI obtained in the step (1) are fully stirred and mixed, the stirring speed is 500rpm, then the temperature is raised to 100 ℃ for reaction for 4 hours, the reaction is finished, the temperature is reduced to room temperature, the materials are discharged, the reaction liquid is evaporated, the evaporation liquid is rectified and purified, 850ml of tetrahydrofuran solvent and 2137g (9.44mol) of 1-chloro-1, 1-difluoro-2-iodoethane are recovered, and the yield is 96.5%.
(3) 2137g of 1-chloro-1, 1-difluoro-2-iodoethane obtained in step (2), 10.68g of FeCl having a particle size of 300 mesh, were placed in a 2.5L autoclave with stirring3/C/Y-Fe2O3(FeCl30.5 wt%) of the magnetic catalyst, fully stirring and mixing the mixture, wherein the stirring speed is 500rpm, then heating to 120 ℃ for reaction for 4 hours, cooling to room temperature, continuing stirring, applying an external magnetic field (with the strength of 400Gs) to a high-pressure kettle, then discharging, retaining the magnetic catalyst in the reaction kettle, and further carrying out rectification and purification on reaction liquid to obtain 1748.2g of the product 1, 1-difluoro-2-iodoethylene, wherein the purity is 99.5%, the yield is 97.5%, and the total yield is 91.9%.
Example 2
(1) The tubular reactor (Changsha facility instruments and equipment Co., Ltd.) made of Hastelloy is 5cm in inner diameter, 8mm in wall thickness, 120cm in tube length, 100cm in effective height of glass filler filled inside, 2mm in filler particle size, 30cm in effective filler at the inlet, and serves as a raw material preheating section, and the other 70cm in effective filler serves as a reaction section. The temperature of the preheating section of the reactor is controlled to be 60 ℃ through three-stage electric heating, and the temperature of the reaction section is controlled to be 100 ℃. Controlling vinylidene fluoride with the flow rate of 640g/h (10mol/h) by a mass flow meter, simultaneously introducing chlorine gas with the flow rate of 640g/h (9mol/h) into a tubular reactor, condensing a reaction product by a condenser, condensing crude 1, 2-dichloro-1, 1-difluoroethane into a crude product receiving bottle, and absorbing tail gas by 30 wt% KOH aqueous solution. The feed gas was continuously fed for 1 hour, and 1177g (content: 99.2%, 8.65mol) of crude 1, 2-dichloro-1, 1-difluoroethane was collected in total, with a yield of 96%.
(2) In a 5L autoclave with stirring, 1177g of crude 1, 2-dichloro-1, 1-difluoroethane, 1L N, N-dimethylformamide and 1723g (10.38mol) of anhydrous KI obtained in the step (1) are fully stirred and mixed, the stirring speed is 500rpm, then the temperature is raised to 130 ℃ for reaction for 3h, the reaction is finished, the temperature is reduced to room temperature, discharging is carried out, the reaction solution is evaporated, the evaporation solution is purified by rectification, 880ml of solvent and 1900g (8.39mol) of 1-chloro-1, 1-difluoro-2-iodoethane are recovered, and the yield is 97%.
(3) 1900g of 1-chloro-1, 1-difluoro-2-iodoethane obtained in step (2), 57g of ZrI having a particle size of 300 mesh, were placed in a 2.5L autoclave with stirring4/C/Y-Fe2O3(ZrI42.0 wt%) magnetic catalyst, stirring and mixing fully, the stirring speed is 500rpm, then heating to 150 ℃ for reaction for 7h, cooling to room temperature, stirring continuously, applying an external magnetic field (the strength is 700Gs) to a high-pressure kettle, then discharging, retaining the magnetic catalyst in the reaction kettle, and further rectifying and purifying the reaction liquid to obtain 1574.4g of the product 1, 1-difluoro-2-iodoethylene, the purity is 99.6%, the yield is 98.8%, and the total yield is 92%.
Example 3
(1) A304 stainless steel tubular reactor (Changsha wound instrument and equipment Co., Ltd.) has an inner diameter of 5cm, a wall thickness of 8mm, a tube length of 120cm, an effective height of glass filler filled inside of 100cm, a filler particle size of 2mm, an effective filler at an inlet of 30cm, and serves as a raw material preheating section, and the other effective fillers of 70cm serve as reaction sections. The temperature of the preheating section of the reactor is controlled to be 60 ℃ and the temperature of the reaction section is controlled to be 130 ℃ through three-stage electric heating. Controlling vinylidene fluoride flow rate to be 640g/h (10mol/h) by a mass flow meter, simultaneously introducing chlorine gas into a tubular reactor at the flow rate of 674.5g/h (9.5mol/h), condensing a reaction product by a condenser, condensing crude 1, 2-dichloro-1, 1-difluoroethane into a crude product receiving bottle, and absorbing tail gas by 30 wt% KOH aqueous solution. The feed gas was continuously fed for 1 hour, and 1316g (97.8% in content, 9.54mol) of crude 1, 2-dichloro-1, 1-difluoroethane was collected at a yield of 95.4%.
(2) 1316g of crude 1, 2-dichloro-1, 1-difluoroethane from step (1), 1L of dimethyl sulphoxide, 2375g (14.31mol) of anhydrous KI, are mixed thoroughly with stirring at 500rpm in a 5L stirred autoclave, and subsequently heated to 160 ℃ for 0.5h, sampled and analysed by gas chromatography. After the reaction is finished, the temperature is reduced to room temperature, discharging is carried out, the reaction solution is evaporated to dryness, the evaporated solution is purified by rectification, 920ml of solvent and 2080g (9.19mol) of 1-chloro-1, 1-difluoro-2-iodoethane are recovered, and the yield is 96.3%.
(3) 2080g of 1-chloro-1, 1-difluoro-2-iodoethane from step (2), 41.6g of MgCl having a particle size of 500 mesh, was placed in a 2.5L autoclave with stirring2/C/Y-Fe2O3(MgCl23.0 wt%) of the magnetic catalyst, fully stirring and mixing, wherein the stirring speed is 500rpm, then heating to 170 ℃ for reaction for 3h, cooling to room temperature, continuing stirring, applying an external magnetic field (with the strength of 600Gs) to the autoclave, then discharging, retaining the magnetic catalyst in the reaction kettle, and further rectifying and purifying the reaction liquid to obtain 1726.3g of the product 1, 1-difluoro-2-iodoethylene, wherein the purity is 99.8%, the yield is 98.9%, and the total yield is 90.9%.
Example 4
(1) The inner diameter of a silicon carbide tubular reactor (Changsha wound instrument and equipment Co., Ltd.) is 5cm, the wall thickness is 8mm, the tube length is 120cm, the effective height of glass filler filled in the reactor is 100cm, the particle size of the filler is 2mm, the inlet effective filler is 30cm, the reactor is used as a raw material preheating section, and the rest 70cm effective filler is used as a reaction section. The temperature of the preheating section of the reactor is controlled to be 60 ℃ through three-stage electric heating, and the temperature of the reaction section is controlled to be 110 ℃. Controlling vinylidene fluoride flow rate to be 640g/h (10mol/h) by a mass flow meter, simultaneously introducing chlorine gas into a tubular reactor at the flow rate of 710g/h (10mol/h), condensing a reaction product by a condenser, condensing crude 1, 2-dichloro-1, 1-difluoroethane into a crude product receiving bottle, and absorbing tail gas by 30 wt% KOH aqueous solution. The feed gas was continuously fed for 1 hour, and 1313g (content: 99.1%, 9.64mol) of crude 1, 2-dichloro-1, 1-difluoroethane was collected altogether, with a yield of 96.4%.
(2) 1313g of crude 1, 2-dichloro-1, 1-difluoroethane obtained in step (1), 1L of tetrahydrofuran and 1875g (11.3mol) of anhydrous KI were thoroughly mixed by stirring in a 5L autoclave with stirring at 500rpm, and then heated to 140 ℃ for reaction for 1 hour, followed by sampling and gas chromatography. After the reaction is finished, the temperature is reduced to room temperature, discharging is carried out, the reaction solution is evaporated to dryness, the evaporated solution is purified by rectification, 920ml of solvent and 2123.5g (9.38mol) of 1-chloro-1, 1-difluoro-2-iodoethane are recovered, and the yield is 97.3%.
(3) 2123.5g of 1-chloro-1, 1-difluoro-2-iodoethane obtained in step (2), 21.2g of ZnCl having a particle size of 400 mesh were placed in a 2.5L autoclave equipped with stirring2/C/Fe3O4(ZnCl21.5 wt%) magnetic catalyst, stirring and mixing them fully, stirring speed is 500rpm, then heating to 160 deg.C, reacting for 5h, cooling to room temperature, stirring continuously, applying external magnetic field (strength 1000Gs) to high-pressure kettle, then discharging, retaining magnetic catalyst in reaction kettle, further rectifying and purifying reaction liquor to obtain 1746g of product 1, 1-difluoro-2-iodoethylene, purity is 99.7%, yield is 98% and total yield is 91.9%.
Comparative example 1
(1) Adding 2kg (12.3mol) iodine monochloride into a 5L reaction kettle, cooling the reaction kettle to 5 ℃, then replacing the reaction kettle with nitrogen for 5 times, then replacing with raw material gas vinylidene fluoride (VDF) for 2 times, then heating the reaction kettle to 55 ℃, introducing VDF into the iodine monochloride for reaction, stopping introducing VDF when the molar ratio of the introduced VDF to the iodine monochloride is 8:1, continuing to react for 10 hours, cooling the reaction kettle to room temperature, replacing unreacted vinylidene fluoride with nitrogen, adding 7 wt% of potassium hydroxide aqueous solution and 7 wt% of sodium sulfite aqueous solution into the reaction solution, stirring for 22 minutes at 400rpm, layering the obtained mixed solution, separating out a lower organic phase, rectifying and purifying the organic phase to obtain 1-chloro-1, 1-difluoro-2-iodoethane with the purity of 99%, the selectivity of 99% based on the iodine monochloride, The yield is 98%;
(2) the reaction tube was charged with 2mL of LaCl2catalyst/AC (BaCl)2In an amount of15 wt.%), first 20mL/min of N was used2Activating for 2 hours at 400 ℃, then reducing the temperature to 370 ℃, then introducing the 1-chloro-1, 1-difluoro-2-iodoethane obtained in the step (1) by using a constant flow pump at the speed of 0.5mL/min for gas phase cracking reaction, washing the obtained reaction product with water for 5 times, and then drying for 8 hours by using anhydrous magnesium sulfate to obtain the 1, 1-difluoro-2-iodoethylene product. The reaction tube was sampled from the outlet thereof and analyzed, the conversion of 1-chloro-1, 1-difluoro-2-iodoethane was 82%, the selectivity of 1, 1-difluoro-2-iodoethylene was 88%, and the total yield was 71%.
Comparative example 2
(1) Adding 2kg (12.3mol) iodine monochloride into a 5L reaction kettle, cooling the reaction kettle to 5 ℃, replacing the reaction kettle with nitrogen for 5 times, replacing with raw material gas vinylidene fluoride (VDF) for 2 times, heating the reaction kettle to 60 ℃, introducing VDF into the iodine monochloride for reaction, stopping introducing VDF when the molar ratio of the introduced VDF to the iodine monochloride is 7:1, continuing to react for 8 hours, cooling the reaction kettle to room temperature, replacing unreacted vinylidene fluoride with nitrogen, adding 8 wt% of sodium carbonate aqueous solution and 8 wt% of potassium sulfite aqueous solution into the reaction solution, stirring for 15 minutes at 380rpm, layering the obtained mixed solution, separating out a lower organic phase, rectifying and purifying the organic phase to obtain 99% of 1-chloro-1, 1-difluoro-2-iodoethane with the selectivity of 99% based on the iodine monochloride, the yield is 98%;
(2) the reaction tube was charged with 2mL of CaCl2-BaCl2/AC catalyst (CaCl)210 wt% of BaCl2Content of 10 wt%), first 20mL/min of N2Activating for 2 hours at 400 ℃, then reducing the temperature to 390 ℃, introducing the 1-chloro-1, 1-difluoro-2-iodoethane obtained in the step (1) by using a constant flow pump at the speed of 0.7mL/min for gas phase cracking reaction, washing the obtained reaction product with water for 5 times, and then drying for 10 hours by using anhydrous magnesium sulfate to obtain the 1, 1-difluoro-2-iodoethylene product. The reaction tube was sampled from the outlet thereof and analyzed, the conversion of 1-chloro-1, 1-difluoro-2-iodoethane was 80%, the selectivity of 1, 1-difluoro-2-iodoethylene was 85%, and the total yield was 67%.

Claims (6)

1. A preparation method of 1, 1-difluoro-2-iodoethylene is characterized by comprising the following steps:
(1) introducing vinylidene fluoride and chlorine gas into a tubular reactor simultaneously for reaction, condensing and collecting reaction products to obtain 1, 2-dichloro-1, 1-difluoroethane, wherein the reaction temperature is 60-130 ℃, the pressure is normal pressure, and the molar ratio of the chlorine gas to the vinylidene fluoride is 0.9-1.0: 1;
(2) reacting the 1, 2-dichloro-1, 1-difluoroethane obtained in the step (1) with KI in a solvent, cooling and discharging after the reaction is finished, evaporating reaction liquid to dryness, and rectifying the obtained evaporated liquid to obtain 1-chloro-1, 1-difluoro-2-iodoethane;
(3) reacting the 1-chloro-1, 1-difluoro-2-iodoethane obtained in the step (2) under the action of a magnetic catalyst, wherein the magnetic catalyst is C/Y-Fe2O3Or C/Fe3O4The catalyst comprises a loaded active component, wherein the load capacity of the active component is 0.5-3 wt%, the active component is metal chloride or metal iodide, and the metal chloride is FeCl3、ZnCl2、MgCl2、ZrCl4、BiCl3At least one of (1), the metal iodide is ZnI2、MgI2、ZrI4At least one of the two, cooling and discharging after the reaction is finished, placing the reaction solution in an external magnetic field to separate the catalyst, and rectifying to obtain the 1, 1-difluoro-2-iodoethylene product.
2. The method for preparing 1, 1-difluoro-2-iodoethylene according to claim 1, wherein in step (1), the material of the tubular reactor is one of 316L, Hastelloy, 304 stainless steel and silicon carbide, and the inside of the tubular reactor is random glass packing.
3. The method for preparing 1, 1-difluoro-2-iodoethylene according to claim 1, wherein the reaction temperature in the step (2) is 100-160 ℃, the reaction time is 0.5-5 h, and the mass ratio of KI to 1, 2-dichloro-1, 1-difluoroethane is 1.0-2.0: 1.
4. The method of claim 1, 1-difluoro-2-iodoethylene according to claim 1, wherein said solvent is at least one of tetrahydrofuran, 2-methyltetrahydrofuran, N-dimethylformamide, and dimethylsulfoxide.
5. The method for preparing 1, 1-difluoro-2-iodoethylene according to claim 1, wherein the particle size of the magnetic catalyst is 300-500 mesh.
6. The method for preparing 1, 1-difluoro-2-iodoethylene according to claim 1, wherein the reaction temperature in step (3) is 120-170 ℃, the reaction time is 2-7 h, and the amount of the magnetic catalyst is 0.5-3% of the mass of 1-chloro-1, 1-difluoro-2-iodoethane.
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US4422913A (en) * 1981-11-23 1983-12-27 The Dow Chemical Company Process for the production of 1,1,2-trichloro-2,2-difluoroethane
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