JP2759182B2 - Method for producing perfluoroethyl methyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Industrial applications]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for producing perfluoroethyl methyl ether. [Prior Art] Perfluoroethyl methyl ether (ie, CF ₃ O
CF2CF2CF3) is a refrigerant (eg, US Pat. No. 3,362,18)
It is useful as, for example, the specifications of JP-A Nos. 0, 3,394, and 878) and as a suction anesthetic (see Bagnall, et al., J. Fluorine Chem., 1979, 13, 123;). As a conventional method for producing perfluoroethyl methyl ether, a method by electrolytic fluorination of ethylene glycols or 1,4-dioxane (Berenblit, et al., 1974, 10, 2)
031; Zh.HPrikl.Khim., 1975, 48, 2206; or Zh.Prik
l.Khim., 1980, 53, 858) and a method of reacting dioxygen difluoride (O ₂ F ₂ ) with tetrafluoroethylene (Holzmann, et al. Inorg. Chem., 1962, 1,
972) is known. However, this method has a problem that the yield of perfluoroethyl methyl ether is extremely low, about 1%. Further, in the above method, the yield of perfluoroethyl methyl ether is unknown because it is not described in the article, but in addition to the ether, seven types of by-products are generated, and the selectivity is extremely low. There are problems such as. That is, the conventional method for synthesizing perfluoroethyl methyl ether is not practical at all in terms of yield and selectivity. A method for producing perfluoroethyl methyl ether using fluorine gas has not been known until now. Tetrafluoroethyl trifluoromethyl ether (CF) which can be used as a starting compound (or an intermediate starting compound) of the perfluoroethyl methyl ether of the present invention
₃ OCHFCF ₃ and CF ₃ OCF ₂ CHF ₂ )
The following methods are known. (A) A method of obtaining a mixture of CF ₃ OCHFCF ₃ and CF ₃ OCF ₂ CHF ₂ by electrolytic fluorination of β-methoxypropionic esters (Berenblit, et al., Zh. Org. Khim., 1976, 12, 76
7), (b) by the reaction of trifluoromethoxytrifluoroethylene with hydrogen fluoride in the presence of potassium fluoride
Method for obtaining CF ₃ OCHFCF ₃ (Gubanov, et al., Zh.Obschch.Kh
im., 1964, 34, 2802), (c) A method of obtaining CF ₃ OCF ₂ CHF ₂ by a thermal decomposition method (170 ° C.) of perfluoro- (β-methoxypropionic acid sodium salt) (Gubanov, et al., Zh. Obschch, Khim., 1964, 34,
2802), (d) Method of obtaining CF ₃ OCF ₂ CHF ₂ by electrolytic decarboxylation of perfluoro- (β-methoxypropionic acid sodium salt) (Berenblit, et al., Novesti Elektrokhim. Or
g.Soedin.Tezsiy Dokl.Vses.Soveshch Elekutorokhim.,
Org. Siedin. 8th. 1973, 31), (e) A method of obtaining CF ₃ OCHFCF ₃ by a thermal decomposition reaction of perfluoro- (2-methoxypropyl peroxide) (Komendantov, et al., Zh. Vses. Khim. O- va., 1984,29,1
13). However, since these are all electrolytic reactions or thermal decomposition reactions, the yield is low (however, the yield is not described in the above-mentioned article (c)), and there are many by-products and the selectivity is remarkable. There are drawbacks such as low. In addition, although there is a report (Johri, et al., J. Org. Chem., 1983, 48, 242) on the reaction of CF ₃ OF with an olefin,
No reaction between CF ₃ OF and trifluoroethylene is shown. One of the starting compounds for perfluoroethyl methyl ether
Conventional methods for producing CF ₃ OCH ₂ CH ₂ F as a seed include the following methods. (G) A method of obtaining CF ₃ OCH ₂ CH ₂ F by reacting CF ₃ OCH ₂ CH ₂ OCOF with sulfur tetrafluoride in the presence of hydrogen fluoride (Aldri
ch, et al., J. Org. Chem., 1964, 29, 11), (h) Method of obtaining CF ₃ OCH ₂ CH ₂ CH ₂ F by reacting ethylene with CF ₃ OF under irradiation of ultraviolet rays (Allison, et al., J. Am.
Chem. Soc., 1959, 81, 1089). The above method (g) is not practical as an industrial production method because the raw material compound is complicated and hardly available, and the yield of CF ₃ OCH ₂ CH ₂ F is not so high as about 18%. There is a problem. On the other hand, the above method (h) uses ultraviolet light and is disadvantageous as an industrial production method. Although the yield is not described in the article of (h), it is generally known that radiation reactions such as ultraviolet irradiation generally have low yield and selectivity. In any case, a reaction between ethylene and CF ₃ OF without using ultraviolet irradiation or in the absence of a catalyst has not been known. In addition, the reaction between CF ₃ OF and ethylene is not known in the above report (f). Since CF ₃ OF normally undergoes a runaway reaction with hydrocarbon compounds, it was not clear whether the reaction with ethylene consisting of carbon and hydrogen proceeds. [Problem to be Solved by the Invention] The present invention has been made in view of the above circumstances. The object of the present invention is to solve the above problems, using relatively easily available or relatively easily synthesized raw materials,
It is an object of the present invention to provide a method for producing perfluoroethyl methyl ether with a high yield and a high selectivity, which was conventionally obtained only at a low yield and a low selectivity. [Means for Solving the Problems] As a result of intensive studies to achieve the above object, the present inventors have found that a specific starting compound (ie, ethyl trifluoromethyl ether, mono- or tetrafluoroethyl trifluoromethyl ether) or The inventors have found that perfluoroethyl methyl ether can be efficiently obtained with high yield and high selectivity by a simple method of reacting these mixtures with fluorine gas, and have completed the present invention. That is, the following general formula CF ₃ OCH _m F _n CH _j F _k (I) (where m and n represent 0, 1 or 2, and j and k
Represents 0, 1, 2 or 3, respectively, but m +
n = 2, j + k = 3, and m + j is not zero. The present invention provides a method for producing perfluoroethyl methyl ether, characterized in that the compound represented by the formula (1) is fluorinated using fluorine gas or fluorine gas diluted with an inert gas. In the present invention, as the compound represented by the general formula [I], ethyl trifluoromethyl ether (CF ₃ OCH
₂ CH ₃ ), 2-fluoroethyl trifluoromethyl ether (CF ₃ OCH ₂ CH ₂ F), 1-fluoroethyl trifluoromethyl ether (CF ₃ OCHFCH ₃ ), 1,1-difluoroethyl trifluoromethyl ether (CF ₃ OCF ₂ CH ₃ ), 1,
2-difluoroethyl trifluoromethyl ether (CF
₃ OCHFCH ₂ F), 2,2-difluoroethyl trifluoromethyl ether (CF ₃ OCH ₂ CHF ₂ ), 1,1, ₂ -trifluoroethyl trifluoromethyl ether (CF ₃ OCF ₂ CH ₂
F) 1,2,2-trifluoroethyl trifluoromethyl ether (CF ₃ OCHFCHF ₂ ), 2,2,2-trifluoroethyl trifluoromethyl ether (CF ₃ OCH ₂ C
F ₃ ) 1,1,2,2-tetrafluoroethyltrifluoromethyl ether (CF ₃ OCF ₂ CHF ₂ ) and 1,2,2,
2-tetrafluoroethyl trifluoromethyl ether (CF ₃ OCHFCF ₃₎ can be exemplified. Among them, CF ₃ OCH ₂ CH ₃ , CF ₃ OCH ₂ CH ₂ F, CF ₃ OCH ₂
CF ₃ , CF ₃ OCF ₂ CHF ₂ , CF ₃ OCHFCF _{3 and the} like are preferable. These may be used singly or two or more of them may be used in combination as a mixture or the like, and may be subjected to a reaction as a mixture with other components as long as the object of the present invention is not impaired. Is also good. Further, a mixture of CF ₃ OCF ₂ CHF ₂ and CF ₃ OCHFCF _3, and CF ₃ OC
H ₂ CH ₂ F is particularly preferable because it can be efficiently produced from inexpensive ethylene or trifluoroethylene. That is, using these as an intermediate raw material or an intermediate, perfluoroethyl methyl ether can be advantageously produced from trifluoroethylene or ethylene and trifluoromethyl hypofluorite by a stepwise reaction or a one-step reaction. In the method of the present invention, the fluorine gas used in the reaction with the compound represented by the general formula may be undiluted, may be diluted with an inert gas, Can also be used in combination. These inert gases are not particularly limited as long as they do not inhibit the object of the present invention. Usually, argon, helium, nitrogen or the like or a mixed gas thereof is suitably used. The dilution ratio of the fluorine gas is not particularly limited.
Those containing volume% are preferably used. The fluorine gas or the fluorine gas diluted with the inert gas may be used as a mixture with another component as needed, as long as the object of the present invention is not impaired. In the method of the present invention, perfluoroethyl methyl ether is produced from the reaction between the compound represented by the above general formula and fluorine gas. The use ratio of fluorine gas in this reaction is usually in the range of 1 equivalent or more, preferably 1 to 1.5 equivalents to the hydrogen atoms of the substrate (the whole of the compound represented by the general formula (1) used). It is preferable to set within. If this ratio is out of the above range, one of the reaction raw materials becomes stoichiometrically excessively large, and the amount of unreacted raw materials increases, which may lower the efficiency in the process. In particular, if the reaction is carried out in less than 1 equivalent, a large amount of unreacted substrate or partially fluorinated ethyl trifluoromethyl ether remains in the reaction mixture, which may lower the reaction efficiency or complicate the separation and purification of the target product. . The method of mixing the fluorine gas and the substrate is not particularly limited, and a predetermined total amount may be mixed at the same time or may be mixed in a stepwise manner as appropriate, but is particularly represented by the general formula (1). For a substrate that reacts violently with fluorine gas during the fluorination of a compound, a method is known in which the amount of fluorine gas used is supplied to the reaction system in several appropriate portions in consideration of the intensity and progress of the reaction. The side reaction is further controlled by this method, and the yield of the target perfluoroethyl methyl ether can be further improved. The reaction temperature is usually -150 to 200 ° C, preferably -100.
It is appropriate to set the temperature in the range of ~ 20 ° C. If the reaction temperature is too high, a sufficient reaction temperature may not be obtained. On the other hand, if the reaction temperature is too high, side reactions such as a decomposition reaction may increase and selectivity may decrease. It is desirable that the reaction temperature is appropriately adjusted according to the intensity of the reaction, the degree of progress of the reaction, and the like. The reaction can be performed in various temperature modes such as a constant temperature,
For example, the temperature gradually increases from low temperature with the progress of the reaction,
Thereafter, a method of maintaining the temperature at an appropriate temperature can also be suitably adopted. In the above reaction, for example, hydrogen fluoride is generated as in the following formula: CF ₃ OCH ₂ CH ₂ F + 4F ₂ = CF ₃ OCF ₂ CF ₃ + 4HF. The reaction may be performed in the presence or absence of a hydrogen fluoride absorbent. By using the hydrogen fluoride absorbent, hydrogen fluoride generated (or contained in the raw material) can be absorbed, and the reaction and the separation of the product can be performed more efficiently. There are various types of the hydrogen fluoride absorbent, and specific examples include sodium fluoride and potassium fluoride. The reaction between the compound represented by the above general formula and fluorine gas can be usually suitably performed without a catalyst, but an appropriate catalyst may be used as desired. As described above, perfluoroethyl methyl ether can be efficiently synthesized with a high yield (for example, a high yield of 85% or more) and a high selectivity. The obtained perfluoroethyl methyl ether is separated and purified from the reaction mixture according to a conventional method, and can be used as a product having a desired purity. In addition, other components such as unreacted raw materials and partially fluorinated fluoroethyl trifluoromethyl ethers can be reused as the components for the above reaction, if necessary. The perfluoroethyl methyl ether produced as described above can be used as a chemical for various uses including a refrigerant and a suction anesthetic. The method for producing the substance represented by the general formula (1), which is a raw material for producing perfluoroethyl methyl ether of the present invention, is as follows. Reaction of ethylene or trifluoroethylene with trifluoromethyl hypofluorite (CF ₃ OF) to give 2-fluoroethyl trifluoromethyl ether or a mixture of 1,2,2,2-tetrafluoroethyl trifluoromethyl ether, respectively Are synthesized. The mixture of the above mono- and tetrafluoroethyl trifluoromethyl ethers can be obtained by reacting a mixture of ethylene and trifluoroethylene at an arbitrary ratio with trifluoromethyl hypofluorite. The reaction raw materials used in this reaction may be appropriately diluted with an inert gas or an inert solvent or the like, if desired, and may contain other components within a range not to impair the object of the present invention. Good. For example, the ethylene and / or trifluoroethylene can be used as a mixture with other fluoroethylenes. The reaction temperature is usually -150 to 200 ° C, preferably -100.
It is appropriate to set within the range of 2020 ° C. If the reaction temperature is too low, a sufficient reaction rate may not be obtained. On the other hand, if the reaction temperature is too high, the decomposition reaction may increase and the selectivity may decrease. It is desirable that the reaction temperature is appropriately adjusted according to the degree of progress of the reaction. The reaction can be performed in various temperature modes such as a constant temperature. For example, a method in which the temperature is gradually raised from a low temperature with the progress of the reaction, and then the temperature is maintained at an appropriate temperature can be suitably adopted. In this method, the reaction is carried out without irradiation with ultraviolet light and without using a catalyst. In general, it is known that, in a so-called non-catalytic thermal reaction, for example, the vessel walls and intermediates of the reaction vessel exert a catalytic action in a broad sense. Should not be interpreted in a broad sense. As described above, 2-fluoroethyltrifluoromethyl ether, 1,2,2,2-tetrafluoroethyltrifluoromethyl ether, 1,1,2,2 from ethylene or trifluoroethylene which is inexpensive as an industrial raw material.
-It is possible to obtain tetrafluoroethyltrifluoromethyl ether or a mixture thereof in high yield (for example, high yield of 75% or more) and high selectivity. The obtained mono- or tetratrifluoroethyltrifluoromethyl ether or a mixture thereof is obtained,
It can be appropriately purified to a desired purity as it is or according to a conventional method, and can be suitably used in various fields of use including the raw material or the raw material component in the method of the present invention. In addition, as described above, by combining the method of the present invention subsequent to the production of the raw materials, it is possible to use inexpensive ethylene or trifluoroethylene as an industrial raw material or a mixture thereof or an olefin containing at least one of them. From the mixed raw materials, industrially useful perfluoroethyl methyl ether can be produced more advantageously. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 A poly (chlorotrifluoroethylene) reaction vessel containing sodium fluoride (10 mmol) was cooled to -194 ° C,
1 mmol of CF ₃ OCH ₂ CF ₃ and 2.2 mmol of fluorine gas were added to the vessel, the reaction vessel was cooled to −111 ° C., and gradually cooled to room temperature.
The temperature was raised over time. After exhausting an excessive amount of fluorine gas, the obtained reaction mixture was changed in trap temperature,
Separation and purification yielded 0.94 mmol (94% yield, trap temperature -155 ° C) of perfluoroethyl methyl ether. The product was identified as perfluoroethyl methyl ether by the following analysis. In the infrared absorption spectrum of the obtained product, no absorption in the CH region was observed.
Absorption of C—O, C—F bonds (1145, 1310-1200, 1220,
1170, 1110 cm ^-1 ) were observed, and the measured molecular weight was 202.9.
And almost the same molecular weight as perfluoroethyl methyl ether (204.0). Example 2 Except that the amount of sodium fluoride used was changed to 20 mmol,
The reaction was carried out in the same manner as in Example 1. Table 1 shows the results. Example 3 A reaction was carried out in the same manner as in Example 1 except that sodium fluoride was not used. Table 1 shows the results. Example 4 Substitution of CF3OCH2CF3 for CF3OCHFCF3 and CF3OCF2CHF
The reaction was carried out in the same manner as in Example 1 except that the mixture of No. 2 (mixing ratio 67:33) was used. Table 1 shows the results. Example 5 A stainless steel container containing sodium fluoride (10 mmol) was cooled to −194 ° C., and 1 mmol of CF 3 OCH 2 CH 2 F was added to the container.
And 0.85 mmol of fluorine gas. Set the reaction vessel to -11.
It was cooled to 1 ° C. and heated to room temperature over 20 hours. Thereafter, the reaction vessel was cooled again to -194 ° C, 0.86 mmol of fluorine gas was added into the vessel, and the temperature was raised to room temperature under the same reaction conditions as described above. The above operation was repeated, and 5.69 mmol of fluorine gas was charged in total. After exhausting an excessive amount of fluorine gas, the obtained reaction mixture was changed in trap temperature,
Separation and purification yielded 0.86 mmol of CF3OCF2CF3 (85% yield, trap temperature -153 [deg.] C). Example 6 CF3OCH2CHF2 and CF3OCHFCH2 instead of CF3OCH2CH2F
The reaction was carried out in the same manner as in Example 5 except that a mixture of F (mixing ratio 90:10) was used. Table 1 shows the results. Example 7 1 mmol of CF3OCH2CF3 was charged into a reaction vessel cooled to -194 ° C without using sodium fluoride. Reaction vessel at -70
Cooled to 5 ° C. and diluted with 5 mmol of 60% fluorine gas (F23mm
ol / N22 mmol), and the temperature was gradually raised to room temperature over 20 hours, and then left at room temperature for 2 days. After exhausting excess fluorine gas, the reaction mixture was trapped and the temperature was changed.
After separation and purification, CF3OCF2CF3 (trap temperature -153 ° C)
Was obtained in a yield of 58%. Reference Example 1 In a reactor cooled to -194 ° C, 5 mmol of ethylene and CF3OF5
mmol was charged. The reaction vessel was cooled to -153 ° C and gradually heated to room temperature over 20 hours. The reaction mixture was separated and purified by changing the trap temperature, and CF3OCH2CH2F
(Trap temperature -96 ° C) 4.15 mmol (89% yield) was obtained. Incidentally, the infrared absorption spectrum of the obtained product,
This was consistent with the infrared absorption spectrum of CF3OCH2CH2F shown in a known document (J. Am. Chem. Soc., 1959, 81, 1089). Reference Example 2 The same procedure as in Example 8 was carried out except that trifluoroethylene was used instead of ethylene as the raw material component, and CF3O
A mixture of CHFCF3 and CF3OCF2CHF2 (mixing ratio 67:33, mixing ratio is
Determined by ¹⁹ F-nuclear magnetic resonance spectrum. ) Was obtained in 75% yield. The product is CF3O for the following reasons.
CHFCF3 and CF3OCF2CHF2 were determined. The infrared absorption spectrum of the obtained product shows absorptions of CH, CO, CF bonds (3000, 1430, 1300, 121250 to 1190, 1170, 1130, 1110).
cm ^-1 ) was observed, and the measured molecular weights were almost the same (analytical value 185.4, calculated value 186.0). In addition, the ¹⁹ F-nuclear magnetic resonance spectrum was as follows: φ (CFCI ₃ standard): 5
Chemical shifts of the trifluoromethyl group of CF3OCHFCF3 and CF3OCF2CHF3 were observed at 5.5, 60.5, and 83.5 ppm, and other chemical shifts also supported the structures of CF3OCHFCF3 and CF3OCF2CHF3. ¹⁹ -nuclear magnetic resonance spectrum, φ (CFCI ₃ ): 55.5 (m, 3F, CF3OCHFCF3), 60.5 (s, 3F, CF3OCHFCF3), 83.5 (s, 3F, CF3OCHFCF3), 90.0 (m, 2F, CF3OCF2CHF2), 136.0 (Dd, 2F, _JH-Fgem. = _{65Hz JH-Fvic.} = 4Hz, CF3OCF2CHF2), 145.0 (dd.1F, _JH-Fgem. = 64Hz, _JH-Fvic. = 4Hz, CF3OCHFCF3) Effects] According to the method of the present invention, since the reaction is performed using a specific raw material, the following effects can be obtained. (1) Perfluoroethyl methyl ether, which was conventionally obtained only with low yield and low selectivity, can be efficiently produced with extremely high yield and high selectivity. (2) It is industrially advantageous because the reaction raw materials are relatively easily available or relatively easy to synthesize. (3) Since there are few side reactions, separation and purification are remarkably easy and economical.

Claims (1)

(57) [Claims] 1. The following general formula (I) CF ₃ OCH _m F _n CH _j F _k (I) (wherein m and n each represent 0, 1 or 2; and j and k
Represents 0, 1, 2 or 3, respectively, but m +
n = 2, j + k = 3, and m + j is not zero. A method for producing perfluoroethyl methyl ether, comprising fluorinating the compound represented by the formula (1) with fluorine gas or fluorine gas diluted with an inert gas.