CN111217668B - Synthesis method of perfluoromethylcyclohexane - Google Patents
Synthesis method of perfluoromethylcyclohexane Download PDFInfo
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- CN111217668B CN111217668B CN201811417324.XA CN201811417324A CN111217668B CN 111217668 B CN111217668 B CN 111217668B CN 201811417324 A CN201811417324 A CN 201811417324A CN 111217668 B CN111217668 B CN 111217668B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
- C07C17/04—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated halogenated hydrocarbons
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
- C07C2601/14—The ring being saturated
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
- C07C2601/16—Systems containing only non-condensed rings with a six-membered ring the ring being unsaturated
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Abstract
The invention relates to a method for synthesizing perfluoromethylcyclohexane, which comprises the following steps of taking trifluoromethyl benzene as a starting material, firstly generating trifluoromethyl tetrafluorocyclohexane through an addition reaction with fluorine gas, and then generating perfluoromethylcyclohexane through a substitution reaction with the fluorine gas. The synthesis route of the perfluoromethylcyclohexane is short, and the product can be obtained only by two-step reaction; the reaction is easy to control, and the production operation is simple. The method can prepare the perfluoromethylcyclohexane stably on a large scale.
Description
Technical Field
The invention relates to the technical field of fluoride synthesis, in particular to a method for preparing perfluoromethylcyclohexane by taking fluorine gas and trifluoromethyl benzene as raw materials.
Background
The perfluoromethylcyclohexane is one of fluorine cleaning agents, and because fluorine atoms contained in the perfluoromethylcyclohexane have strong electron-withdrawing capability, the fluorine cleaning agent can clean nonpolar organic pollutants, and simultaneously because the surface tension and viscosity of the perfluoromethylcyclohexane are low, compared with other solvents with the same boiling point, the perfluoromethylcyclohexane has the advantages of easiness in evaporation and the like, and is widely applied to cleaning of production enterprises such as precision instruments, liquid crystals and medical instruments. Besides, the perfluoromethoxycyclohexane is a perfluorinated solvent and can be applied to a fluorine two-phase reaction system. At present, the methods for synthesizing perfluoromethylcyclohexane mainly include a metal fluorination method and an electrolytic fluorination method, the process is relatively complex, and the by-product fluorine is more.
Disclosure of Invention
The invention aims to provide a synthesis method of perfluoromethylcyclohexane, which can solve the problems of complex process, high reaction control difficulty, high cost, complex operation, low selectivity of perfluoromethylcyclohexane and the like in the prior art.
The method of the invention comprises the following steps: the method comprises the steps of taking trifluoromethyl benzene as a starting material, firstly carrying out addition reaction with fluorine gas to generate trifluoromethyl tetrafluorocyclohexane, and then continuously carrying out substitution reaction with the fluorine gas to generate the perfluoromethylcyclohexane.
The method has simple reaction steps, and the perfluoromethylcyclohexane can be prepared by only two steps of reaction, and the reaction equation is as follows.
Preferably, both the addition reaction and the substitution reaction are carried out in a liquid diluent. The invention has the advantages of violent reaction degree, reaction in liquid diluent, reduction of side reaction, production safety improvement and raw material utilization rate improvement.
Further preferably, the liquid diluent is 1, 2-dichloro-trifluoromethyl vinyl ether. Such diluents are effective in reducing over-fluorination.
More preferably, the mass concentration of the trifluoromethyl benzene in the liquid diluent is 2 to 60 percent. The chain-breaking reaction of the materials can be caused by the over-high concentration of fluorine gas, and the full progress of the reaction can be ensured and the chain-breaking reaction can not be caused at the concentration.
Preferably, both the addition reaction and the substitution reaction are carried out at low temperatures. The reaction is carried out at low temperature, and side reactions can be reduced.
Preferably, the reaction is carried out at a temperature of-60 ℃ to-10 ℃.
Preferably, in the addition reaction, a mixed gas of fluorine gas and nitrogen gas is fed so that the concentration of the fluorine gas is 2% to 10%. The addition reaction proceeds favorably at such fluorine gas concentration, and the chain scission reaction occurs when the fluorine gas concentration is too high.
Preferably, the reaction temperature is controlled to be-60 ℃ to-25 ℃ in the addition reaction process. Addition reactions are very easy to occur and chain scission of over-fluorinated materials is also easy to occur, so that the reaction rate needs to be controlled at low temperature to reduce the chain scission reaction.
Preferably, in the substitution reaction, a mixed gas of fluorine gas and nitrogen gas is fed so that the concentration of the fluorine gas is 10% to 20%. After the addition reaction is completed, the substitution reaction requires a higher activation energy than that required for the addition reaction, so that the fluorine gas concentration is increased.
Preferably, the reaction temperature is controlled to be-50 ℃ to-10 ℃ in the process of the substitution reaction. Low temperature control of the reaction rate is required to reduce chain scission reactions.
It is further preferred that the temperature of the addition reaction is controlled to be 20 ℃ lower than the temperature of the substitution reaction.
Preferably, the pressure in the reaction kettle is controlled to be less than 0.1MPa in the process of the addition reaction and the substitution reaction.
Preferably, after the reaction is finished, the product is rectified in multiple steps to obtain the perfluoromethylcyclohexane.
Preferably, the trifluoromethyl benzene and the liquid diluent are fully mixed, and then fluorine gas is introduced for reaction;
preferably, after mixing the trifluoromethylbenzene with the liquid diluent, it is cooled to the temperature required for the addition reaction.
Preferably, the reactor used in the present invention is a pressure-resistant reactor equipped with a cooling device, a stirring device, and a conduit and a distribution device for introducing into the liquid diluent, and by adding the distribution device, uniform contact of the materials can be increased, and side reactions due to transition fluorination can be reduced to increase the material exchange force in the reaction. In addition, since the reaction of the present invention involves fluorine gas, the reactor, the stirring device, the conduit for introducing into the liquid phase, the distribution device, and the packing must be materials having corrosion resistance. It can be Hastelloy, nickel-chromium stainless steel, molybdenum-chromium stainless steel, etc.
Further preferably, the method of the present invention comprises the steps of:
1) introducing trifluoromethyl benzene into a reactor filled with a 1, 2-dichloro-trifluoromethyl vinyl ether solution, fully mixing the trifluoromethyl benzene and the 1, 2-dichloro-trifluoromethyl vinyl ether, and cooling to-60 to-25 ℃ to obtain a mixed solution;
2) introducing a mixed gas of fluorine gas and nitrogen gas, wherein the concentration of fluorine gas is 2-10%, into the mixed liquid to perform an addition reaction, the reaction temperature is maintained within the range of-60 ℃ to-25 ℃, and the reaction pressure is less than 0.1 MPa;
3) after the addition reaction is finished, introducing mixed gas of fluorine gas and nitrogen gas with the concentration of 10-20% of the fluorine gas into the mixed liquid obtained by the reaction in the step 2), carrying out substitution reaction, maintaining the reaction temperature at-50 ℃ to-10 ℃, and controlling the reaction pressure to be less than 0.1Mpa until the reaction is finished;
during the reaction, the temperature of the addition reaction was controlled to be 20 ℃ lower than the temperature of the substitution reaction.
Further preferably, the product is subjected to multi-step rectification to obtain perfluoromethylcyclohexane.
The invention has the following beneficial effects:
1) the synthesis route of the perfluoromethylcyclohexane is short, and the product is obtained only by two-step reaction and rectification purification;
2) the perfluoromethylcyclohexane prepared by the method has low reaction temperature, less side reaction and higher economic value of byproducts, and can be recycled as the byproducts; the reaction is easy to control, and the production operation is simple. Therefore, according to the process of the present invention, perfluoromethylcyclohexane can be produced industrially with high economy and stability.
Drawings
FIG. 1 is a schematic diagram of the apparatus and flow of the synthesis process of the present invention;
in the figure, 1 is a reactor for fluorine gas and trifluoromethyl benzene, 2 is a discharge kettle, 3 is a rectifying tower, 4 is a condenser, 5 is an alkaline substance contact tower, and 6 is a drying tower.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Examples
This example relates to a process for the synthesis of perfluoromethylcyclohexane, the reaction being carried out in the apparatus shown in FIG. 1, comprising the following steps:
1) 5L of a solution containing 99% of 1, 2-dichloro-trifluoromethyl vinyl ether was added to a 10-L reactor, the reaction was cooled to-20 ℃ and trifluoromethylbenzene was introduced at a flow rate of 1kg/h until the concentration thereof in the solution became 20%, and the pressure in the reactor was adjusted to 0.05 MPa.
2) Introducing a fluorine/nitrogen mixed gas with the fluorine content of 3% at the speed of 20L/h at the temperature of minus 40 ℃ to perform an addition reaction, controlling the pressure in the reactor to be 0.05Mpa in the reaction process, and continuously introducing for 20h until the addition reaction is finished.
3) Controlling the temperature of the system after the reaction in the step 2) to be-20 ℃, introducing fluorine/nitrogen mixed gas with the fluorine content of 20% into the system at the speed of 40L/h for substitution reaction, controlling the pressure in the reactor to be 0.05Mpa in the reaction process, and continuously introducing for 5h until the substitution reaction
Unreacted reactants and perfluoromethylcyclohexane are obtained by rectification, the products are analyzed by gas chromatography, the conversion rate of trifluoromethyl benzene is 99.26 percent by calculation, the selectivity of the trifluoromethyl benzene is 65.35 percent, and the perfluoromethylcyclohexane with the purity of 99.57 percent is obtained after the products containing the perfluoromethylcyclohexane are further rectified and purified.
Wherein the conversion rate of the trifluoromethyl benzene is calculated by dividing the total amount of the trifluoromethyl cyclohexane added by the trifluoromethyl consumed in the reaction, and the selectivity of the trifluoromethyl benzene is calculated by dividing the obtained perfluoromethylcyclohexane by the weight of the trifluoromethyl benzene involved in the reaction.
From the above, it can be seen that the conversion of trifluoromethylbenzene is higher and the occurrence of side reactions is less.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (5)
1. A method for synthesizing perfluoromethylcyclohexane is characterized in that trifluoromethylbenzene is used as a starting material, and is subjected to addition reaction with fluorine gas to generate trifluoromethyltetrafluorocyclohexane, and then subjected to substitution reaction with the fluorine gas to generate perfluoromethylcyclohexane; the addition reaction and the substitution reaction are both carried out in a liquid diluent 1, 2-dichloro-trifluoromethyl vinyl ether;
in the addition reaction process, introducing a mixed gas of fluorine gas and nitrogen gas, wherein the fluorine gas has the mass concentration of 2-10%;
in the addition reaction process, the reaction temperature is controlled to be-60 ℃ to-25 ℃;
in the process of the substitution reaction, introducing a mixed gas of fluorine gas and nitrogen gas, wherein the fluorine gas has a concentration of 10-20% by weight;
in the process of the substitution reaction, the reaction temperature is controlled to be-50 ℃ to-10 ℃.
2. The synthesis method according to claim 1, wherein during the substitution reaction, the mass concentration of fluorine gas in the mixed gas of fluorine gas and nitrogen gas is larger than the mass concentration of fluorine gas during the addition reaction; and/or the temperature in the substitution reaction process is 15-25 ℃ higher than the temperature in the addition reaction process.
3. The method according to claim 1 or 2, wherein the pressure in the reaction vessel during the addition reaction and the substitution reaction is controlled to be less than 0.1 MPa.
4. The method according to any one of claims 1 to 3, wherein the product is rectified after the reaction to produce perfluoromethylcyclohexane.
5. A method according to any one of claims 1 to 4, comprising the steps of:
1) introducing trifluoromethyl benzene into a reactor filled with a 1, 2-dichloro-trifluoromethyl vinyl ether solution, fully mixing the trifluoromethyl benzene and the 1, 2-dichloro-trifluoromethyl vinyl ether, and cooling to-60 to-25 ℃ to obtain a mixed solution;
2) introducing a mixed gas of fluorine gas and nitrogen gas, wherein the concentration of the fluorine gas is 2-10%, into the mixed liquid to perform an addition reaction, the reaction temperature is maintained within the range of-60 ℃ to-25 ℃, and the reaction pressure is less than 0.1 MPa;
3) after the addition reaction is finished, introducing mixed gas of fluorine gas and nitrogen gas with the concentration of 10-20% of the fluorine gas into the mixed liquid obtained by the reaction in the step 2), carrying out substitution reaction, maintaining the reaction temperature at-50 ℃ to-10 ℃, and controlling the reaction pressure to be less than 0.1MPa until the reaction is finished;
in the reaction process, the temperature of the addition reaction is controlled to be 15-25 ℃ lower than that of the substitution reaction; in the substitution reaction process, the mass concentration of the fluorine gas in the mixed gas of the fluorine gas and the nitrogen gas is greater than the mass concentration of the fluorine gas in the addition reaction process.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2451006C1 (en) * | 2011-05-05 | 2012-05-20 | Общество с ограниченной ответственностью "ГалоПолимер Кирово-Чепецк" (ООО "ГалоПолимер Кирово-Чепецк") | Method of producing perfluorocycloalkanes |
| CN107119285A (en) * | 2017-03-10 | 2017-09-01 | 黎明化工研究设计院有限责任公司 | A kind of method for preparing perfluoromethylcyclohexane (PFMCH) |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2451006C1 (en) * | 2011-05-05 | 2012-05-20 | Общество с ограниченной ответственностью "ГалоПолимер Кирово-Чепецк" (ООО "ГалоПолимер Кирово-Чепецк") | Method of producing perfluorocycloalkanes |
| CN107119285A (en) * | 2017-03-10 | 2017-09-01 | 黎明化工研究设计院有限责任公司 | A kind of method for preparing perfluoromethylcyclohexane (PFMCH) |
Non-Patent Citations (3)
| Title |
|---|
| Direct Fluorination: A "New" Approach to Fluorine Chemistry;Richard J. Lagow;《Progress in Inorganic Chemistry》;19791231;第26卷;第161-210页 * |
| FLUORINATIONS WITH COMPLEX METAL FLUORIDES .9. FLUORINATIONS OF TOLUENE AND XYLENE DERIVATIVES BY MEANS OF CESIUM TETRAFLUOROCOBALTATE(III);John Bailey et al.;《Journal of Fluorine Chemistry》;19871031;第37卷(第1期);第1-14页 * |
| Fluorine as a Halogen - Reaction with a highly deactivated aromatic nucleus;Lucius Bigelow et al.;《Industrial & Engineering Chemistry》;19470301;第39卷(第3期);第360-364页 * |
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