JPS6411021B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing hexafluoropropylene oxide (hereinafter abbreviated as HFPO). More specifically, the present invention relates to a method for producing HFPO from hexafluoropropylene (hereinafter abbreviated as HFP) using hypochlorite as an oxidizing agent. HFPO is an intermediate for producing useful fluorine-containing compounds such as hexafluoroacetone and perfluorovinyl ether, and HFPO polymers have a wide range of uses such as heat transfer agents and lubricating oils. To date, several methods have been proposed for producing HFPO from HFP.
Neither of these methods can be said to be industrially advantageous.
For example, as described in US Pat. No. 3,358,003,
In alkaline hydrogen peroxide medium, HFP
A method of oxidizing HFPO to HFPO, or
The method described in Japanese Patent No. 11683, in which HFP is oxidized to HFPO with oxygen in the presence of an inert solvent, is known as a typical method for producing HFPO. However, in any of these methods, it is difficult to control the reaction, it is difficult to suppress the decomposition of the produced HFPO, or a large amount of by-products are produced, making it impossible to obtain HFPO in a high yield. do not have. Furthermore, in these methods, increasing the HFP conversion rate lowers the HFPO selectivity.
In order to use HFP effectively, it is necessary to stop the reaction at a low HFP conversion rate, separate and collect unreacted HFP from HFPO, and reuse it. However, HFP
The boiling point of (-29.4℃) and the boiling point of HFPO (-27.4℃)
Since they are very close to each other and it is difficult to separate them by distillation, a special separation operation is required for their separation. For example,
A method of reacting HFP and bromine to form a high-boiling dibromine compound and separating it from HFPO, or a US patent
Extractive distillation separation methods such as those described in No. 3,326,780 and US Pat. No. 4,134,796 have been proposed, but all of them are complicated separation methods and significantly increase the production cost of HFPO. The inventors of the present invention have conducted intensive studies to overcome the drawbacks of such conventional methods and to find a method for producing HFPO more easily and with higher yield than HFP.
We have discovered an industrially advantageous method for producing HFPO using hypochlorite as an oxidizing agent, and have completed the present invention. As an oxidation method using hypochlorite, it is known that HFPO is produced from HFP in a system in which a polar solvent such as acetonitrile or diglyme is added to an aqueous hypochlorite solution [IZV.AKAD.NAUK.
SSSR, SER.KHIM., 79 , (11) 2509, when the present inventors investigated this method, the selectivity of HFPO was around 10%, and it was not possible to obtain a high yield. The reason for this is thought to be that the reaction system is a homogeneous mixture of a polar solvent and an alkaline hypochlorite aqueous solution, so the generated HFPO easily reacts with water and decomposes under alkaline conditions. . Furthermore, this method requires a troublesome step of recovering the polar solvent from the reaction system after the reaction. From the above points, it seems that this reaction method cannot be used as a practical HFPO production technology. Therefore, the present inventors decided to use hypochlorite.
As a result of intensive studies to develop an effective oxidation method from HFP to HFPO, we found that the reaction is carried out in a two-phase system of an aqueous phase and an organic phase in the presence of a quaternary ammonium salt.
They discovered that HFPO can be obtained in higher yield than HFP, and completed the present invention. That is, the present invention uses hypochlorite as an oxidizing agent to produce HFPO from HFP.
A novel method characterized by carrying out the reaction in a two-phase system of an aqueous phase and an organic phase in the presence of a quaternary ammonium salt.
It provides a method for producing HFPO. In the two-phase reaction of the present invention, substantially all of the HFP and produced HFPO are contained in the organic phase. According to the method of the present invention, HFP
HFPO can be obtained with high selectivity even if the conversion rate of This is probably because it is less likely to occur. Therefore, according to the method of the present invention, by increasing the HFP conversion rate, it is also possible to omit the complicated process of separating HFP and HFPO and the process of recycling HFP. After the reaction, the organic phase and the aqueous phase are separated, and HFPO is easily isolated from the organic phase by a separation operation such as distillation. In addition, in the remaining organic phase from which HFPO has been removed,
It contains a quaternary ammonium salt, and the remaining organic phase can be recycled and reused in the reaction as it is, making it very easy to recover the solvent and catalyst. As described above, the method of the present invention can achieve high yield.
HFPO can be obtained and the manufacturing process is very simple. Therefore, when carrying out the method of the present invention, the construction cost and operating cost of the reactor are low, and a very economical HFPO production process is possible. The present invention will be explained in more detail below. The hypochlorite used in the present invention may be one that liberates hypochlorite ions under the reaction conditions, and there are no further limitations. Examples of hypochlorites used in the present invention include alkali metal salts such as sodium hypochlorite and potassium hypochlorite, and alkaline earth salts such as calcium hypochlorite and barium hypochlorite. Examples include metal salts and quaternary ammonium salts such as tetra-n-butylammonium hypochlorite and tetraethylammonium hypochlorite. Among them, especially sodium hypochlorite and calcium hypochlorite, bleach,
It is industrially mass-produced for uses such as disinfectants and is available at low cost, making it suitable as the hypochlorite used in the method of the present invention. In the present invention, hypochlorite is mainly used dissolved in the aqueous phase, but there are no particular restrictions on its concentration. Usually, the effective chlorine concentration is preferably in the range of 3% to 25%, particularly preferably in the range of 8% to 20%. If the available chlorine concentration is too low, it is necessary to handle a large amount of aqueous phase;
Moreover, since a substantial reaction rate cannot be obtained, it is economically disadvantageous. Furthermore, if the available chlorine concentration is too high, hypochlorite becomes unstable and difficult to handle. The ratio of hypochlorite to HFP can be selected arbitrarily, but in order to obtain substantial reaction results, the ratio of hypochlorite ion to 1 mole of HFP is usually
A range of 0.5 gram equivalents to 30 gram equivalents is preferred, and a range of 0.8 gram equivalents to 10 gram equivalents is particularly preferred. The quaternary ammonium salt used in the present invention is
A substance having affinity for the organic phase or both the organic phase and the aqueous phase is used. For example, the general formula ()
Various quaternary ammonium salts such as those represented by are used. However, in the formula (), R ₁ , R ₂ , R ₃ and R ₄ are the same or different, and are each substituted with a functional group that is inert under the reaction conditions, or are unsubstituted hydrocarbons. represents a group. The type and length of this hydrocarbon group are appropriately selected depending on the solvent used and the required reaction rate. Examples of the type of hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, an alkenylaryl group, and particularly preferably an alkyl group, an aryl group, an aralkyl group, etc. is used. or,
The length of the hydrocarbon group is usually selected from the range of 4 to 100 carbon atoms per quaternary ammonium ion as the total number of carbon atoms contained in R ₁ , R ₂ , R ₃ and R ₄ , and is preferably The number is selected from the range of 8 to 70, and particularly preferably selected from the range of 10 to 50. The inert functional groups that can be used to replace the above hydrocarbon groups are limited depending on the reaction conditions, but
Usually, halogen, acyl group, carboxyl group, ester group, nitrile group, alkoxyl group, etc. are used. In addition, in formula (), R ₁ , R ₂ or R ₁ ,
R ₂ and R ₃ may be linked to each other to form a nitrogen-containing heterocycle, and R ₁ , R ₂ , R ₃ or R ₄ may be part of a polymer compound. Examples of quaternary ammonium ions include tetramethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, tri-n-octylmethylammonium ion, and cetyltrimethylammonium ion. , benzyltrimethylammonium ion,
Benzyltriethylammonium ion, cetylbenzyldimethylammonium ion, cetylviridinium ion, n-dodecylpyridinium ion, phenyltrimethylammonium ion,
Examples include phenyltriethylammonium ion, N-benzylpicolinium ion, pentamethonium ion, hexamethonium ion, and the like. The anion Y in formula () is not particularly limited and various anions can be used, but usually halogen ions, various mineral acid ions other than halogen ions, organic acid ions, hydroxide ions, etc. are used. . Examples of the anion Y include chloride ion, bromide ion, iodide ion, fluoride ion, hydrogen sulfate ion, sulfate ion, nitrate ion, phosphate ion, perchlorate ion, hydroxide ion, acetate ion, and benzoic acid. ion, benzenesulfonate ion, p-toluenesulfonate ion, etc., but particularly preferred are chloride ion, hydrogen sulfate ion, and hydroxide ion. The amount of quaternary ammonium salt used in the method of the present invention is appropriately selected depending on the type of solvent, the required reaction rate, etc., but usually, the amount of quaternary ammonium salt used is selected from the range of 0.0001 mol to 1 mol, particularly preferably 0.001 mol
Selected from a mole to 0.1 mole range. If the amount of the quaternary ammonium salt is too small, a substantial reaction rate cannot be obtained, and if it is too large, the reaction rate is too fast and it becomes difficult to control the reaction. This is economically disadvantageous as the cost burden increases. The reaction of the present invention is carried out in a two-phase system consisting of an aqueous phase and an organic phase. In this case, the organic phase only needs to contain HFP and form a phase different from the aqueous phase, and there is no particular restriction beyond that. The phase can be composed of a quaternary ammonium salt and HFP that is poorly soluble in the aqueous phase, and it can also be a phase composed of HFP and an inert solvent that is substantially immiscible or poorly miscible with the aqueous phase. I can do it. Furthermore, when carrying out the method of the present invention, it is sufficient to have an organic phase containing substantially most of HFP and an aqueous phase containing hypochlorite; It doesn't matter if there are other aspects of . For example, even when the organic phase is composed of two types of media with low compatibility, forming two phases, or when a quaternary ammonium salt is supported on an insoluble carrier and forming a third phase. The method of the invention can be carried out. Examples of inert solvents that are substantially immiscible or sparingly miscible with the aqueous phase for the organic phase used in the process of the invention include, for example, n-hexane, n-hexane,
-Aliphatic hydrocarbons such as octane and n-decane;
Alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, decalin; benzene, toluene,
Aromatic hydrocarbons such as xylene; ethers such as diisopropyl ether and di-n-butyl ether; methylene chloride, chloroform, carbon tetrachloride,
Chlorinated hydrocarbons such as 1,2-dichloroethane and chlorobenzene; 1,2-dichlorofluoroethane, fluorotrichloromethane, 1,1,2-trichlorotrifluoroethane, 1,1,2,2-
Chlorinated fluorinated hydrocarbons such as tetrachlorodifluoroethane; fluorinated hydrocarbons such as perfluorocyclobutane, perfluorodimethylcyclobutane, perfluorohexane, perfluorooctane, perfluorodecane, hexafluorobenzene; or mixed solvents thereof, etc. can be mentioned.
Among the above various solvents, fluorine-containing hydrocarbons such as chlorinated fluorinated hydrocarbons and fluorinated hydrocarbons are
The high solubility of HFP and HFPO makes them particularly suitable for the method of the invention. In addition, aliphatic hydrocarbons also show good results in the reaction of the present invention and are also inexpensive, so they are suitable for the method of the present invention. The volume ratio of the organic phase to the aqueous phase can be arbitrarily selected depending on the reaction method, reaction conditions, etc., but the organic phase is usually preferably 0.05 to 20 times the aqueous phase, and particularly preferably.
It ranges from 0.2 times to 5 times. The reaction temperature when carrying out the present invention is determined by the amount of catalyst,
Although it is determined depending on the reaction solution composition, the desired reaction rate, etc., the temperature is usually preferably in the range of -25°C to 100°C, and particularly preferably in the range of -15°C to 50°C. If the reaction temperature is too low, a substantial reaction rate may not be obtained or, in some cases, the aqueous phase may freeze, making it impossible to carry out the reaction. Also, if the reaction temperature is too high
HFPO decomposition becomes significant and HFPO selectivity decreases. The reaction pressure when carrying out the present invention is not particularly limited as long as it is a pressure sufficient to keep the organic phase in a liquid phase. Therefore, the reaction pressure is selected depending on the type and composition of the organic phase, but is usually preferably in the range of 1 atm to 20 atm. As a reaction method when carrying out the present invention, any of batch type, semi-flow type and flow type reaction methods can be used. Examples include, for example, a countercurrent reaction or a cocurrent reaction between an organic phase containing HFP and a quaternary ammonium salt and an aqueous phase containing hypochlorite. These methods are easily carried out in commonly used countercurrent or cocurrent reactors. Further, since substantially all of the HFPO produced by the reaction is contained in the organic phase, HFPO can be easily isolated and purified from the organic phase by a separation operation such as distillation. The residual organic phase from which HFPO has been removed contains quaternary ammonium salts, but this organic phase can be recycled and reused in the reaction as is. EXAMPLES The present invention will be explained in more detail below using Examples and Comparative Examples, but these explanations are not intended to limit the present invention in any way. Example 1 1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter referred to as F-
113), 20 ml of an aqueous sodium hypochlorite solution with an available chlorine concentration of 12%, 1.5 g (10 mmol) of HFP, and 0.12 g (0.3 mmol) of tri-n-octylmethylammonium chloride as a catalyst. Next, this reaction solution is cooled to 0° C., and then a magnetic stirrer is used to rotate a stirrer in the reaction container to mix the reaction solution and start the reaction. The reaction temperature is maintained at 0°C during the reaction. After 30 minutes, stop rotating the stirrer and let the reaction solution stand still to separate the aqueous phase and F.
-113 phase is separated and contained in F-113 phase
When HFP and HFPO were quantified by gas chromatography, the conversion rate of HFP was 90% and the selectivity of HFPO was 89%. Comparative Example 1 A reaction similar to Example 1 was carried out without using the catalyst tri-n-octylmethylammonium chloride. As a result, only trace amounts of HFPO were produced, and almost all HFP was recovered. Example 2 The same reaction as in Example 1 was carried out at a reaction temperature of 20°C using 0.04 g of tri-n-octylmethylammonium chloride as a catalyst instead of 0.12 g, and the conversion rate of HFP was 74%. , selectivity of HFPO
It was 89%. Example 3 When the same reaction as in Example 2 was carried out at a reaction temperature of 40°C, the conversion rate of HFP was 92% and the selectivity of HFPO was 67%. Example 4 The same reaction as in Example 1 was carried out using 3.0 g (20 mmol) of HFP instead of 1.5 g (10 mmol) and with a reaction time of 1 hour instead of 30 minutes. The HFP conversion rate was 83% and the HFPO selectivity was 89%. Examples 5 to 10 The same reaction as in Example 1 was carried out using various tetra-n-butylammonium salts instead of 0.12 g of tri-n-octylmethylammonium chloride.
The experiment was carried out using 0.12 g as a catalyst. Table 1 shows the results.
Shown below. Examples 11 to 17 The same reaction as in Example 1 was carried out using 0.12 g of each of various quaternary ammonium salts as a catalyst instead of 0.12 g of tri-n-octylmethylammonium chloride. The results are shown in Table-2.

【table】

[Table] Examples 18 to 24 Using the same method as in Example 9, the amount of HFP was 1.5 g (10
The reaction was carried out using 0.45 g (3 mmol) instead of 4 mmol) and using the solvent, the amount of (n-Bu) ₄ NHSO ₄ and the reaction time as shown in Table 3. Table 3 also shows the reaction results.

[Table] * _{2Perfluorodimethylcyclobutane} Example 25 The same reaction as in Example 1 was carried out using dodecyl betaine (trade name Nitsusan Anon) instead of 0.12 g of tri-n-octylmethylammonium chloride as a catalyst.
BL, manufactured by Nippon Oil & Fats Co., Ltd.) The reaction time was 1.0 hour instead of 0.12 g and 30 minutes. As a result, the HFP conversion rate was 75%,
The HFPO selection rate was 57%. Example 26 The same operation as in Example 1 is carried out, but instead of 20 ml of a sodium hypochlorite aqueous solution with an effective chlorine concentration of 12%, highly refined white powder with an effective chlorine content of 65% (the main component is calcium hypochlorite) is used. ) Aqueous solution containing 4.6g
Use 20ml, reaction temperature 0℃, reaction time 30
When the reaction was carried out at a reaction temperature of 20°C and a reaction time of 15 minutes instead of 15 minutes, the conversion rate of HFP was 98%, HFPO
The selection rate was 39%. Example 27 The same operation as in Example 1 was carried out, but the reaction was carried out using 30 ml of a potassium hypochlorite aqueous solution with an effective chlorine concentration of 7% instead of 20 ml of a sodium hypochlorite aqueous solution with an effective chlorine concentration of 12%. As I was doing it,
The HFP conversion rate was 41% and the HFPO selectivity was 53%.

Claims (1)

[Claims] 1. In producing hexafluoropropylene oxide from hexafluoropropylene using hypochlorite as an oxidizing agent, in the presence of a quaternary ammonium salt, two phases of an aqueous phase and an organic phase are produced. A method for producing hexafluoropropylene oxide, which is characterized by carrying out the reaction in a system. 2. The method for producing hexafluoropropylene oxide according to claim 1, wherein sodium hypochlorite or calcium hypochlorite is used as the hypochlorite. 3 The number of carbon atoms contained in the quaternary ammonium ion is 4 per quaternary ammonium ion.
The method for producing hexafluoropropylene oxide according to claim 1, characterized in that a quaternary ammonium salt having a number of quaternary ammonium salts in a range of from 1 to 100 is used.