JP2020111522A - Method for producing easily decomposable stable perfluoroalkyl radical and its easily decomposable stable perfluoroalkyl radical reagent - Google Patents

Abstract

To provide a method for producing easily decomposable stable perfluoroalkyl radicals which easily generate trifluoromethyl radicals, and to provide an easily decomposable stable perfluoro radical reagent.SOLUTION: In a reaction system in which reaction active species in a fluorination reaction become fluorine radicals, a highly hindered perfluoroalkene is fluorinated by the fluorine radical to release a trifluoromethyl radical with decomposition due to β-elimination. In addition, an easily decomposable stable perfluoroalkyl radical whose half-life in the β- elimination reaction is from 0.5 to 24 hours in the range of 50 to 70°C is produced.EFFECT: An easily decomposable stable perfluoroalkyl radical can be provided by adding fluorine radicals to C=C double bonds of highly hindered perfluoroolefin by fluorination using fluorine radicals.SELECTED DRAWING: Figure 1

Description

The present invention provides a readily decomposable stable perfluoroalkyl radical reagent that easily and cleanly generates a trifluoromethyl radical at low temperature, and that it is possible to provide a recycling system thereof that does not contain side reactions. This is an issue. In the present specification, a readily decomposable stable perfluoroalkyl radical is defined as a substance which is stable to some extent but has the contradictory property of being easily decomposed by heat.

As a reagent for generating a trifluoromethyl radical, thermal decomposition of an extremely stable perfluoroalkyl radical has been conventionally used. However, since the reagent is extremely stable, a high temperature is required for its thermal decomposition, and its use is limited.

On the other hand, as a reagent for generating a trifluoromethyl radical at low temperature, bis(perfluoroacyl)peroxide is disclosed in US Pat. No. 2,559,630, but it is explosive and is dangerous for industrial use. Due to its complicity, its use was limited to the laboratory level.

The trifluoromethyl radical is not only useful for the synthesis of various functional compounds such as pharmaceuticals, agricultural chemicals and liquid crystals, but also as a radical initiator in the surface treatment of various materials such as resins and polymer synthesis. Is known to be highly valuable. However, as described above, the conventional trifluoromethyl radical requires a high temperature for its thermal decomposition, and is an extremely stable perfluoroalkyl radical that can be used only in a high temperature region, or it is explosive even if it can be used at a low temperature. Etc. had various problems. Therefore, in recent years, it has been desired to develop a new reagent for generating a trifluoromethyl radical, which can be used safely and easily at a low temperature, in place of the conventional trifluoromethyl radical.

Compounds containing fluorine have been widely used from partially fluorinated compounds such as pharmaceuticals and agricultural chemicals to completely fluorinated compounds such as Teflon (registered trademark) and fluorochemical surfactants. Demand for fluoromethyl groups is high, and various methods for introducing trifluoromethyl groups have been developed. In particular, in recent years, the use of trifluoromethyl radical has attracted attention and has been developed in the synthesis of partially fluorinated compounds. However, the use of a metal catalyst or the need for light irradiation has led to its industrial application. Had various problems.

As described above, the trifluoromethyl radical generating reagent developed so far has been hindered from industrial development due to problems such as instability and risk of explosion. Based on such a background, it has been desired to develop a simple reagent for generating a trifluoromethyl radical, which can be handled safely and does not require light irradiation or metal. Examples of prior art relating to a reagent for generating a trifluoromethyl radical having such desirable performance include Patent Documents 1 to 3 and Patent Documents 4 to 5, for example.

The permanent perfluoroalkyl free radical useful as a polymerization catalyst disclosed in the above-mentioned Patent Document 1 is perfluoro-3-ethyl-2,4-dimethyl-3-obtained by fluorinating a hexafluoropropene trimer. Pentyl (hereinafter referred to as PPFR1) and perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl (hereinafter referred to as PPFR2) obtained by heating a mixture of hexafluoropropene trimer and PPFR1. Is a perfluoroalkyl radical (Example of Patent Document 1; FIG. 1, Formula 1 and 2).

Further, in the above-mentioned Patent Document 2, by directly fluorinating a precursor perfluoroolefin derived from a hexafluoropropene trimer and a Ruppert-Prakash reagent (trialkylperfluoroalkylsilane:RP reagent) with fluorine gas, Methods of making perfluoroalkyl radicals of corresponding structure are disclosed. However, in Patent Document 2, only the extremely stable perfluoroalkyl radical PPFR2 described in the Example of Patent Document 1 actually succeeds in the synthesis (Example of Patent Document 2).

On the other hand, the trifluoromethyl radical generating reagent disclosed in the present invention includes perfluoro-3-ethyl-2,2,4-trimethyl-3-pentyl and perfluoro-2,2,4-trimethyl-3-isopropyl. The present invention relates to a perfluoroalkyl radical called -3-pentyl (hereinafter referred to as an easily decomposable stable perfluoroalkyl radical I and an easily decomposable stable perfluoroalkyl radical II, respectively).

These structures are described in Patent Document 2 of the prior patent, but in the document, the manufacturing method thereof is not clear, and in the document, the physical/chemical properties necessary for specifying the substance are disclosed. Information is not listed at all. In particular, for the latter easily degradable stable perfluoroalkyl radical II, perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl, the precursor perfluoro-2,4,4-trimethyl-3 is used. Even if isopropyl-2-pentene (hereinafter referred to as precursor olefin II) is fluorinated with undiluted fluorine gas, perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl (easily decomposable) It is described that stable perfluoroalkyl radical II) is not obtained, and perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl of PPFR2 is obtained (Example 7 of Patent Document 2; FIG. 1, FIG. Formula 3).

In fact, in Example 7 of Patent Document 2, a precursor olefin II of perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl (easily decomposable stable perfluoroalkyl radical II) (perfluoro- Fluorination of 2,4,4-trimethyl-3-isopropyl-2-pentene) with pure fluorine gas at 0°C for 4 hours yielded 35.2% by weight of PPFR2 perfluoro-2,4-. Dimethyl-3-isopropyl-3-pentyl is stated to be obtained (Fig. 1, Formula 3). Further, in Patent Document 2, based on this Example 7, a precursor olefin II of perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl (easily decomposable stable perfluoroalkyl radical II) A method of fluorinating PPFR2 to synthesize PPFR2 is described as a method for producing a carbon-reduced ultra-stable perfluoroalkyl radical. Therefore, in the patent document 2 of the prior patent, including examples, even if the precursor olefin II is fluorinated, perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl (easily decomposable stable perfluoro) is used. This is equivalent to proving that the alkyl radical II) cannot be synthesized.

The present inventors describe the structure in Patent Document 2 of the prior patent, but rather, in the Examples, perfluoro-2,2,4-trimethyl-3-isopropyl- which has been shown to be incapable of synthesis. A method for synthesizing 3-pentyl (easily decomposable stable perfluoroalkyl radical II) was discovered, and its physicochemical properties were clarified. In addition, the present inventors similarly describe the structure in Patent Document 2 of the prior patent, but there are no examples, and there is no physicochemical data necessary for specifying the structure. A radical (perfluoro-3-ethyl-2,2,4-trimethyl-3-pentyl (easily decomposable stable perfluoroalkyl radical I) was also discovered, and its physicochemical properties were clarified. ..

Moreover, the present inventors have found that these perfluoroalkyl radicals (perfluoro-3-ethyl-2,2,4-trimethyl-3-pentyl, and perfluoro-2,2,4-trimethyl-3-isopropyl). -3-Pentyl) to obtain spectral information such as MS (mass spectrum) and ESR (electron spin resonance spectrum) necessary for identifying the structure, and to isolate them to isolate thermal stability, boiling point, melting point, etc. We succeeded in clarifying physicochemical properties.

As a result, unlike the super-stable perfluoroalkyl radicals disclosed in Patent Documents 1 and 2 of the prior patents, these perfluoroalkyl radicals are easily decomposed at a temperature of about 70° C. from around room temperature. It was found that the trifluoromethyl radical was released. These perfluoroalkyl radicals are stable enough to be easily handled at room temperature in air, but have the property of easily decomposing at a temperature of about 50 to 70° C., and there is a clear difference in their stability. .. The present inventors call these perfluoroalkyl radicals an easily decomposable stable perfluoroalkyl radical because they are stable but easily decomposable, and clarify the difference from the conventional ultra-stable perfluoroalkyl radicals. Turned into

In fact, taking the easily degradable stable perfluoroalkyl radical II as an example, the radical is gradually decomposed even at room temperature (around 20° C.), and for example, the temporal stability of the sample left in the laboratory was traced. The results show that the half-life is about one month or less, and although it is easily degradable, it is stable at room temperature to the extent that handling problems do not occur. On the other hand, when this radical is heated to 60° C., decomposition due to β-elimination accompanied by release of trifluoromethyl radical described later occurs, and the half-life of the radical is as short as less than 3 hours (superstable perfluoroalkyl radical). It can be understood that the radical is stable at this temperature) and is easily decomposable (for the details of the thermal stability of the easily decomposable stable perfluoroalkyl radical, the easily decomposable stable perfluoroalkyl radical I described below, and (See the thermal decomposition properties of II).

In other words, the easily decomposable stable perfluoroalkyl radical is a substance that possesses exquisite stability and decomposability, which can be handled stably at room temperature and generate a trifluoromethyl radical at a considerable rate when the temperature is raised slightly above room temperature. It can be understood that there is a significant difference in industrial chemistry when compared with the ultra-stable perfluoroalkyl radical.

Thus, in the present specification, a readily decomposable stable perfluoroalkyl radical as a reagent capable of providing a trifluoromethyl radical at room temperature or a relatively low temperature (for example, 50 to 70° C.) can be easily obtained in a high yield. The details of the physicochemical properties, including the thermal stability, of these easily decomposable stable perfluoroalkyl radicals are disclosed as well as the production method, and trifluoromethyl, which is easily decomposable, safe and easy to handle. The characteristics as a novel substance having the characteristics as a radical generating reagent were clarified.

INDUSTRIAL APPLICABILITY The present invention can provide a readily decomposable stable perfluoro radical reagent that easily and cleanly generates a trifluoromethyl radical at low temperature, and can provide a recycling system that does not include its side reaction. (See Formulas AF of Chemical Formula 1). Among them, the recycling system is described in a patent of Daikin Industries, Ltd. (Japanese Patent Laid-Open No. 2003-147008 of Patent Document 3, title of invention: low-molecular radical supply method, radical-transporting molecule, polymer production method and polymer). Of the three trifluoromethyl groups of the perfluoro-tertiary-butyl group contained in the structure of the easily decomposable stable perfluoroalkyl radical, which is included in the content and not exceeding it, as described below. Decomposition via a single decomposition reaction, which is limited to one, is not foreseeable and has been clarified by experiments. To do.

That is, in the reaction that goes through this single decomposition process, perfluoro-3-ethyl-2,4-dimethyl-2-pentene (hereinafter, T- 3), but perfluoro-2,4-dimethyl-3-isopropyl-2-pentene (hereinafter referred to as PPFR2 precursor) is obtained from the easily decomposable perfluoroalkyl radical II (formula A, B), these pyrolysis products perfluoroolefins can be derived into precursor olefins of readily degradable stable perfluoroalkyl radicals I and II. That is, by trifluoromethylating these perfluoroolefins with an RP reagent, perfluoro-4,4-dimethyl-3-isopropyl-2- that is a precursor olefin of the easily decomposable stable perfluoroalkyl radicals I and II. Pentene (hereinafter referred to as precursor olefin I) and perfluoro-2,4,4-trimethyl-3-isopropyl-2-pentene (precursor olefin II) are respectively synthesized (formula C, D). In addition, these thermal decomposition products, perfluoroolefins, can be used as precursors for the synthesis of ultra-stable perfluoroalkyl radicals at the same time (formula E and F), which means that they are decomposed through this single decomposition process. It can be said that this is an important feature of doing. The recycling system consists of two routes, which include not only the easily decomposable stable perfluoroalkyl radicals I and II but also the extremely stable perfluoroalkyl radicals (PPFR1 and PPFR2). Therefore, a system that is excellent in industrial chemistry, very clean, and environmentally friendly is built.

As described above, as a reagent for generating a trifluoromethyl radical, thermal decomposition of an extremely stable perfluoroalkyl radical has been conventionally used. However, as can be seen from the name of the ultra-stable perfluoroalkyl radical, its thermal decomposition requires high temperature, and its use is limited.

On the other hand, as a reagent for generating a trifluoromethyl radical at low temperature, bis(perfluoroacyl)peroxide is disclosed in US Pat. No. 2,559,630, but it is explosive and is dangerous for industrial use. Due to its complicity, its use was limited to the laboratory level.

The trifluoromethyl radical is not only useful for the synthesis of various functional compounds such as pharmaceuticals, agricultural chemicals and liquid crystals, but also as a radical initiator in the surface treatment of various materials such as resins and polymer synthesis. Is known to be highly valuable. However, conventional trifluoromethyl radicals have various problems such as an extremely stable perfluoroalkyl radical that can be used only in a high temperature region and an explosive property that can be used at low temperatures as described above. In the technical field, in particular, there has been a demand for the development of a new trifluoromethyl radical generating reagent that can be used safely and easily at low temperatures.

JP-A-60-64935 (Title of invention: Permanent perfluoroalkyl free radical useful as a polymerization catalyst and polymerization method using the free radical) JP-A-2003-155257 (Title of invention: highly branched perfluoroolefin, ultra-stable perfluoroalkyl radical, and methods for producing these) JP, 2003-147008, A (invention title: low-molecular radical supply method, radical-transporting molecule, polymer production method and polymer) US Pat. No. 4,626,608 (Title of Invention: Fluorinated acyl peroxides) European Patent No. 0121898 (name of invention: Persistent perfluoroalkyl free radicals, a polymerization catalyst containing them and processes for polymerization)

In view of the above situation, the present invention is capable of generating a trifluoromethylalkyl radical at a low temperature, which was impossible in the prior art, and is a safe and easily handleable degradable stable perfluoroalkyl radical generation. It is an object to provide a reagent.

The present invention for solving the above problems, a method of synthesizing a readily decomposable stable perfluoroalkyl radical by fluorinating a highly shielded perfluoroalkene having a highly branched structure with a fluorine radical, It is a feature of the invention to provide a method of using the obtained easily decomposable stable perfluoroalkyl radical as a reagent for generating a trifluoromethyl radical. Here, in the present invention, the highly shielded perfluoroalkene having a highly branched structure means perfluoro-4,4-dimethyl-3-isopropyl-2-pentene or perfluoro-alkene used in the present invention. It means a perfluoroalkene having a branched structure equivalent to that of 2,4,4-trimethyl-3-isopropyl-2-pentene.

According to the present invention, conventionally, a perfluoroalkene that does not undergo a reaction due to steric hindrance even when reacted with a fluorine gas can be synthesized only by fluorinating with a fluorine radical. The details will be described below.

The content disclosed in the present invention is described in Patent Document 2 of the prior patent, but the document does not have a chemical species (perfluoro-3-ethyl- 2,2,4-trimethyl-3-pentyl and perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl) were successfully synthesized for the first time, including MS and ESR. The physical and chemical data and their thermal decomposition characteristics at 50 to 70° C. reveal the nature of the chemical species.

In the patent document 2 of the prior patent, a perfluoroalkyl radical (perfluoro-3-ethyl-2,2,4-trimethyl-3-pentyl, and perfluoro-2,2,4-trimethyl-3-isopropyl- 3-pentyl; referred to in the present specification as easily decomposable stable perfluoroalkyl radical I and easily decomposable stable perfluoroalkyl radical II, respectively, as their precursor perfluoroolefin (perfluoro). -4,4-Dimethyl-3-isopropyl-2-pentene and perfluoro-2,4,4-trimethyl-3-isopropyl-2-pentene) are described as being synthesizable by fluorinating with fluorine gas. ing.

However, in the above-mentioned Patent Document 2, there is no example relating to fluorination of the former precursor perfluoroolefin (perfluoro-4,4-dimethyl-3-isopropyl-2-pentene), and the latter precursor. Regarding the fluorination of the body perfluoroolefin, in the first place, Example 7 is described.

Then, in the above-mentioned Example 7, an example in which the precursor olefin II (perfluoro-2,4,4-trimethyl-3-isopropyl-2-pentene) was actually fluorinated with undiluted fluorine gas at 0° C. is described. doing. However, the result is not perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl of the easily decomposable stable perfluoroalkyl radical II, but perfluoro-2,4-dimethyl-3-isopropyl- It is stated that a mixture of 2-pentene and PPFR2 (perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl) derived therefrom is obtained.

Patent Document 2 of the prior patent shows that there is a lack of examples, and that even if there are examples, the synthesis thereof is difficult, and furthermore, physical and chemical information of the obtained compound is shown at all. Therefore, Patent Document 2 discloses that the substances called easily decomposable stable perfluoroalkyl radicals I and II clarified by the present inventors in the present specification exist as known substances within the range described in the patent. It cannot be said that it has been proved. Rather, it should be considered within the scope of the patent to be equivalent to proving that the syntheses of these materials are not practical.

The present inventors also considered that it is difficult to synthesize easily decomposable stable perfluoroalkyl radicals I and II based on the contents of Patent Document 2 of the prior patent. However, the present inventors are based on the "work hypothesis" that "the extremely sterically crowded perfluoroolefin reacts only with fluorine radicals" (including the case where the reaction rate with fluorine gas is extremely low). , As a result of diligent efforts to synthesize easily decomposable stable perfluoroalkyl radicals I and II, fluorination is performed using a substance that promotes the generation of fluorine radicals from fluorine molecules represented by hexafluorobenzene. Then, a new finding was found that the synthesis of easily decomposable stable perfluoroalkyl radicals I and II can be achieved.

Here, the "work hypothesis" that triggered the development of the present invention will be described in more detail. The "work hypothesis" is the present work hypothesis by the present inventors, namely, perfluoro-4-, which is two kinds of precursor olefins in PPFR1 synthesis. Methyl-3-isopropyl-2-pentene (hereinafter referred to as T-2) and perfluoro-3-ethyl-2,4-dimethyl-2-pentene (hereinafter referred to as T-3) with fluorine gas It is based on the discovery of differences in fluorination behavior.

That is, in the reaction between perfluoroolefin and fluorine, the present inventors have found that when T-2 perfluoro-4-methyl-3-isopropyl-2-pentene is fluorinated with undiluted fluorine gas, T-2 Is a first-order reaction with respect to T-2, whereas in the case of perfluoro-3-ethyl-2,4-dimethyl-2-pentene of T-3, a zero-order reaction with respect to T-3 is obtained. I found that.

Differences in fluorination behavior of the T-2 and T-3, compared T-2 to proceed the reaction with molecular fluorine (reaction with F _2), fluorine radicals (F ₂ fluorine molecules generated by dissociation →·F+·F) (diffusion-controlled reaction of fluorine radicals; reaction with F) was interpreted as a difference in the reaction mechanism called T-3 in which fluorination proceeds.

Therefore, it was interpreted that the reaction of T-3 proceeds independently of the concentration of T-3, that is, it is a diffusion-controlled reaction of fluorine radicals. FIG. 2 is an explanatory diagram showing that T-2 and T-3 have different reaction mechanisms.

T-2 and T-3 of the above-mentioned two kinds of precursor olefins in PPFR1 synthesis are structural isomers represented by the same chemical formula, and are positional isomers of C=C double bond. Structurally, T-2 is a tri-substituted olefin and T-3 is a tetra-substituted olefin.

Therefore, the C=C double bond of T-3 of a tetra-substituted olefin having more substituents is more sterically shielded than the C=C double bond of T-2 of a tri-substituted olefin. There is. That is, the fluorine molecule does not come close enough to the C=C double bond of the more screened tetra-substituted olefin, T-3, but the C= of the less screened tri-substituted olefin, T=. It is understood that the C double bond is approached to reach the reaction.

On the other hand, the fluorine radical generated by dissociation of the fluorine molecule is more reactive than the fluorine molecule, and due to its small size, more like the C=C double bond of T-3, The C=C double bond of the screened tetrasubstituted olefin is accessible and thus reacts to produce PPFR1.

The 0th order reaction of T-3 is that the dissociation constant of the fluorine molecule is very small and the amount of the generated fluorine radicals is small, so that the diffusion rate of the fluorine radicals is rate-determined and the concentration of T-3 increases. Interpreted as independent.

The present inventors have thus noted the change in the reaction mechanism due to the steric shielding of the C=C double bond of perfluoroolefin. Chemical formula 2 below is an explanation showing a change in the reaction mechanism due to steric shielding of the C═C double bond of perfluoroolefin.

In the above formula, 3 T-2 substituted olefins, C = C double bond, but close the F ₂ is a reagent, the T-3 of 4-substituted olefins, C = C double bond is sterically completely It is shielded and F ₂ cannot get close to it. On the other hand, the F radical (.F) can react because it can approach a C=C double bond in any case. The difference in steric hindrance makes such a difference in reaction mechanism.

In particular, the easily decomposable stable perfluoroalkyl radical I or the precursors olefins I and II (perfluoro-4,4-dimethyl-3-isopropyl-2-pentene and the easily decomposable stable perfluoroalkyl radical II) In the case of a highly shielded perfluoroolefin such as fluoro-2,4,4-trimethyl-3-isopropyl-2-pentene), a fluorine radical is formed in the same manner as the C=C double bond of T-3. It was expected to react only.

Based on the above consideration, the inventors of the present invention produced a large amount of fluorine radicals in the fluorination reaction of perfluoroolefin, which is a precursor of the easily decomposable stable perfluoroalkyl radical that is sterically shielded from T-3. We believe that the formation of a reaction system that makes an important contribution to the synthesis, repeat experiments, and perform fluorination in a system in which hexafluorobenzene coexists with fluorine gas (generates a large amount of fluorine radicals). Perfluoro-3-ethyl-2,2,4-trimethyl-3-pentyl of easily degradable stable perfluoroalkyl radical I and perfluoro-2,2,4-trimethyl of easily degradable stable perfluoroalkyl radical II It was discovered that -3-isopropyl-3-pentyl can be synthesized in good yield (the yields obtained by gas chromatography are about 90% each).

Since the easily decomposable stable perfluoroalkyl radicals I and II can be analyzed by gas chromatography (GC), the present inventors have analyzed their thermal decomposition behavior by GC to show that they are easily decomposable stable perfluoroalkyl radicals. Regarding I, the half-lives of the thermal decomposition reaction at 49.0° C., 58.8° C., and 68.0° C. were 23.9 hr, 6.5 hr, and 1.9 hr, respectively, and the easily decomposable stable perfluoroalkyl was obtained. Regarding the radical II, it was found that the half-lives of the thermal decomposition reaction at 49.0° C., 58.5° C. and 67.7° C. were 10.5 hr, 2.64 hr and 0.80 hr, respectively (for details, (See the thermal decomposition characteristics of easily decomposable stable perfluoroalkyl radicals I and II below).

That is, the present inventors have pointed out that the easily decomposable stable perfluoroalkyl radicals I and II are extremely stable as described in Patent Documents 1 and 2 of the prior patent (henceforth, they are called super-stable perfluoroalkyl radicals). However, as shown by the above-mentioned half-life, it has been found that it decomposes at a considerable rate even at around room temperature.

Therefore, these easily decomposable stable perfluoroalkyl radicals I and II have greatly different thermal decomposition characteristics from the super stable perfluoroalkyl radicals known so far. , Which was clearly distinguished from the conventional superstable perfluoroalkyl radical.

The easily decomposable stable perfluoroalkyl radicals I and II each generate a trifluoromethyl radical through the thermal decomposition process represented by the formula (formula A, B) to decompose. From the analysis of the decomposition products, the thermal decomposition process of the above-mentioned easily decomposable stable perfluoroalkyl radicals I and II shows that the trifluoromethyl group constituting the sterically most crowded perfluorotertiary-butyl group is β-deprotected. It was found that only the separated route was taken.

It was thought that such a single thermal decomposition process would be difficult to predict from its structure, and rather, it would be a complicated decomposition reaction including multiple decomposition pathways. For example, in the easily decomposable stable perfluoroalkyl radical II, a plurality of decomposition processes shown in the following chemical formula 3 are expected, but in reality, three trifluoromethyl groups constituting the perfluorotertiary-butyl group are actually used. It was found that one of them decomposed by β-elimination. The present invention means that a clean trifluoromethyl radical generation source containing no active species other than trifluoromethyl radical can be provided as an effect of passing through such a single thermal decomposition process.

As shown in the above chemical formula 3, although it is expected that a plurality of easily decomposable stable perfluoroalkyl radicals II are present in the thermal decomposition process, in reality, they are decomposed by a single decomposition route.

Further, in the easily decomposable stable perfluoroalkyl radicals I and II of the present invention, since thermal decomposition goes through a single route, the decomposition product is also single. Is only perfluoro-3-ethyl-2,4-dimethyl-2-pentene (T-3), but from the easily decomposable stable perfluoroalkyl radical II, perfluoro-2,4-dimethyl-3-isopropyl is obtained. Only 2-pentene is recovered (formula A, B of formula 1).

Therefore, the trifluoroolefins (perfluoro-3-ethyl-2,4-dimethyl-2-pentene, and perfluoro-2,4-dimethyl-3-isopropyl-2-pentene) thus recovered were treated with trisulfate. It is possible to provide a recycling system in which trifluoromethylation is performed using fluoromethyltrimethylsilane to regenerate the precursor olefins of the easily decomposable stable perfluoroalkyl radicals I and II. The methodologies relating to this recycling system are considered to be within the range described in Patent Document 2 of the preceding patent, but the fact that the thermal decomposition process of the easily decomposable stable perfluoroalkyl radicals I and II is single is It is necessary to prove it by an experiment, and this is the first thing to be revealed in the present invention.

The thermal decomposition behavior of the easily decomposable stable perfluoroalkyl radicals I and II is different from that of the conventional super-stable perfluoroalkyl radical, and it is an easily decomposable stable perfluoroalkyl radical that decomposes at low temperature. That is, a clean trifluoromethyl radical generating reagent, that the recycling system is a complete one that does not include side reactions, and the like are provided in the easily degradable stable perfluoroalkyl radicals I and II. It is a characteristic and the present invention makes it possible to provide an ideal trifluoromethyl radical generating reagent having all of these characteristics.

The structures of the easily decomposable stable perfluoroalkyl radicals I and II are supported not only by the structures of their thermal decomposition products, but also by MS and ESR. Radicals I and II correspond to novel substances whose existence was first revealed in the present invention along with their synthesis and physicochemical properties.

Perfluoro-4,4-dimethyl-3-isopropyl-2-pentene, which is a precursor olefin of easily decomposable stable perfluoroalkyl radicals I and II, and perfluoro-2,4,4-trimethyl-3-isopropyl- 2-Pentene was synthesized by the method described in the literature (J. Fluorine Chem., 196, 128-134). In the present invention, the “fluorine radical” is meant to include all materials regardless of the type as long as they are materials capable of generating a fluorine radical in the reaction system.

The present invention has the following special effects by adopting the above configuration.
(1) It is easy for the easily decomposable stable perfluoroalkyl radicals I and II to have superiority to conventional superstable perfluoroalkyl radicals at a lower temperature than in the case of superstable perfluoroalkyl radicals. In addition, it is possible to safely generate trifluoromethyl radicals. Particularly, in the surface treatment, for example, a polymer resin that swells or undergoes thermal deformation in the fluorination surface treatment step with the trifluoromethyl radicals. Can be applied to.

(2) Further, even if fluorinated surface treatment of a material in which deformation or swelling does not pose a problem, the same effect can be obtained at a lower temperature as compared with the superstable perfluoroalkyl radical, industrially It has a great meaning, and has a great advantage, for example, in connection with process management in the technical field and reduction of utility heat and water.

(3) Further, regarding the use as a radical initiator in polymer synthesis, when a monomer having high reactivity is used, if a conventional ultra-stable perfluoroalkyl radical is used as a trifluoromethyl source, the reaction will run away. There was a problem of, for example, the application was excluded from the beginning, or there was a problem with heat removal, scale-up, etc., but trifluoromethyl radicals at lower temperatures compared to superstable perfluoroalkyl radicals. The easily decomposable stable perfluoroalkyl radical according to the present invention, which is generated cleanly, can be applied to the polymerization of such a monomer, and its superiority in industrial application is clear.

(4) The importance of the trifluoromethyl group in medicines, agricultural chemicals, etc. is, of course, extremely important, and in particular, it has a large number of functional groups like pharmaceuticals and agricultural chemicals and has a complicated structure. In that case, treatment at a high temperature using a conventional ultra-stable perfluoroalkyl radical has a high possibility of inducing the production of a side reaction, but the easily decomposable stable perfluoroalkyl radical according to the present invention is low. It is possible to act the trifluoromethyl radical at a temperature and suppress the production of side reactions.
(5) Needless to say, if an extremely stable perfluoroalkyl radical and a readily decomposable stable perfluoroalkyl radical are mentioned as the selective branches, an organic synthetic chemist will choose the latter easily degradable stable perfluoroalkyl radical. The choice is obvious.

In the figure, Formula 1 shows a synthetic process of a perfluoroalkyl radical called perfluoro-3-ethyl-2,4-dimethyl-3-pentyl (PPFR1). In the figure, Formula 2 indicates a synthetic process of perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl (PPFR2). In the figure, Formula 3 is fluorine-containing perfluoro-2,4,4-trimethyl-3-isopropyl-2-pentene using fluorine gas in the absence of a substance that promotes the production of fluorine radicals such as hexafluorobenzene. However, the perfluoroalkyl radical II (perfluoro-2,2,4-trimethyl-3-isopropyl-3-pentyl) which is easily decomposable is not obtained even if it is converted to perfluoro-2,4-dimethyl-3-isopropyl. It shows that only -3-pentyl (PPFR2) is obtained. FIG. 2 is an explanatory diagram showing a difference in fluorination behavior of two precursor olefins (T-2, T-3) in PPFR1 synthesis. FIG. 3 shows a mass spectrum of the easily decomposable stable perfluoroalkyl radical I. FIG. 4 shows the ESR spectrum of the easily decomposable stable perfluoroalkyl radical I. FIG. 5 shows a mass spectrum of the easily decomposable stable perfluoroalkyl radical II. FIG. 6 shows the ESR spectrum of the easily decomposable stable perfluoroalkyl radical II. FIG. 7 shows a reaction for forming easily decomposable stable perfluoroalkyl radical II. FIG. 8 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical I at 49.0° C. FIG. 9 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical I at 58.8°C. FIG. 10 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical I at 68.0° C. FIG. 11 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical II at 49.0° C. FIG. 12 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical II at 58.5° C. FIG. 13 shows the thermal decomposition reaction characteristics of the easily decomposable stable perfluoroalkyl radical II at 67.7° C.

Next, the present invention will be specifically described based on test examples and examples.

Test example 1
Mass spectrum of easily decomposable stable perfluoroalkyl radical I (physical property value: MS measurement method)
The easily decomposable stable perfluoroalkyl radical I (containing 9% of perfluoro-2,2,4-trimethyl-4-ethylpentane) obtained in Example 1 described later was added to a capillary column (VF-200 ms, 0.25 mm). x 60 m, 0.25 μ) equipped with a gas chromatography-mass spectrometry analyzer (Shimadzu GCMS-QP5050A).

Column temperature, separator and ion source temperature were set low so that decomposition would not occur (column temperature was 40° C. for 5 minutes, and after 5 minutes the temperature was raised at 5° C./min.; separator and ion source temperature were 200° C. ), was ionized by the electron impact ionization method (70 eV), and the mass spectrum was measured. The obtained mass spectrum is shown in FIG. The trifluoromethyl ion at m/z 69 appeared as a reference peak, and the intensity of the other fragment ions was extremely low. No parent ion was observed, and the (MF) ion (m/z 500) was observed as the highest mass ion at a relative intensity of 0.11. MS, which selectively generates only trifluoromethyl ion by electron impact ionization, decomposes by releasing β-elimination of trifluoromethyl radical when the easily decomposable stable perfluoroalkyl radical I undergoes thermal decomposition reaction. It corresponds to a single decomposition reaction that passes only through the pathway.

Test example 2
Electron Spin Resonance (ESR) Spectra of Easily Degradable Stable Perfluoroalkyl Radical I (Physical Properties: ESR Measurement Method)
The easily decomposable stable perfluoroalkyl radical I (containing 9% of perfluoro-2,2,4-trimethyl-4-ethylpentane) obtained in Example 1 to be described later was diluted with perfluorohexane, A sample having a concentration of 1 mM was placed in a quartz sample tube for ESR measurement (outer diameter 4 mm x 250 mm), and a process of Freeze-pump-thaw was performed 5 times using helium gas as a degassing gas, followed by sealing.

The measurement was carried out using an electron spin resonance measuring device (EMXplus type) manufactured by Bruker BioSpin Co., Ltd., magnetic field strength: 3340 G, microwave power: 0.1002 mW, modulating magnetic field: 0.1 G, magnetic field sweep time: 15 sec. , Magnetic field sweep: ±50 G was measured. The obtained ESR spectrum is shown in FIG. A hyperfine structure (hfs) in the center and two hyperfine structures (hfs) split with large coupling constants were observed on both sides. Therefore, it was speculated that the easily decomposable stable perfluoroalkyl radical I had two stable conformations at room temperature. It is expected that there are two conformations of the CF ₂ group located next to the radical central carbon, but a complete interpretation is not possible at this time.

Test example 3
Mass spectrum of easily decomposable stable perfluoroalkyl radical II A solution of the easily decomposable stable perfluoroalkyl radical II obtained in Example 2 described below in perfluorohexane at an appropriate concentration was used as a test sample, and a capillary column (VF) was used. -200 ms, 0.25 mm x 60 m, 0.25 [mu]) equipped with a gas chromatography-mass spectrometry analyzer (Shimadzu GCMS-QP5050A).

Column temperature, separator and ion source temperature were set low so that decomposition would not occur (column temperature was 40° C. for 5 minutes, and after 5 minutes the temperature was raised at 5° C./min.; separator and ion source temperature were 200° C. ), was ionized by the electron impact ionization method (70 eV), and the mass spectrum was measured. The obtained mass spectrum is shown in FIG. The trifluoromethyl ion at m/z 69 appeared as a reference peak, and the intensity of the other fragment ions was extremely low. Parent ion was not observed, as the highest mass ion (M-CF ₃₎ ion (m / z 500) was observed in the relative intensity 0.09. Similar to the easily decomposable stable perfluoroalkyl radical I, MS that selectively produces only trifluoromethyl ion by electron impact ionization is characterized by β- It corresponds to causing a single decomposition reaction that passes only through the pathway of desorbing and decomposing the trifluoromethyl radical.

Test example 4
Electron Spin Resonance (ESR) Spectrum of Easily Degradable Stable Perfluoroalkyl Radical II The easily degradable stable perfluoroalkyl radical II obtained in Example 2 described below was diluted with perfluorohexane to give a sample having a concentration of 0.1 mM. It was put in a quartz sample tube for ESR measurement (outer diameter 4 mm x 250 mm), and the process of Freeze-pump-thaw was performed 5 times using helium gas as a degassing gas, followed by sealing.

The measurement was performed using an electron spin resonance measuring device (EMXplus type) manufactured by Bruker BioSpin Co., Ltd., magnetic field strength: 3340 G, microwave power: 0.1002 mW, modulating magnetic field: 0.1 G, magnetic field sweep time: 15 sec. , Magnetic field sweep: ±50 G was measured. The obtained ESR spectrum is shown in FIG. A complex hyperfine structure (hfs) was observed because of the large number of fluorines that could be coupled.

Synthesis of Easily Degradable Stable Perfluoroalkyl Radical I Perfluoro-4,4,-dimethyl-3-isopropyl-2-pentene, which is a precursor olefin of the easily decomposable stable perfluoroalkyl radical I (as a geometric isomer, Z -Form is 76.1%, E-form is 16.7% (there are two types of rotamers, one of which is 11.1% and the other of which is 5.6%), and perfluoro as an impurity. 4 g of -3-ethyl-2,4-dimethyl-2-pentene and 1.7% of impurities of unknown structure were taken to obtain 3 g (5.7 mmole as a precursor olefin), and added to 150 ml of perfluorohexane. Dissolved. The obtained perfluorohexane solution was transferred to a 500 ml Teflon (registered trademark) reaction container, the system was purged with helium (24 ml/min for 30 minutes), and fluorine was added using 20% fluorine gas diluted with nitrogen. Was made. The reaction was carried out at room temperature (20 to 23° C.) in the presence of fluorine radicals for 9 hours.

That is, 0.75 g of hexafluorobenzene dissolved in 75 ml of perfluorohexane was introduced at a uniform rate (about 8.3 ml/hr) over the entire fluorination process for 9 hours. The flow rate of 20% fluorine gas is 5 ml/min, which is about twice the amount of fluorine gas flow (2.5 ml/min.) required for the introduced hexafluorobenzene to undergo complete fluorination. Introduced. By gas chromatography (GC) analysis of the reaction solution, the yield of the easily decomposable stable perfluoroalkyl radical I of the product was 91%, and the remaining 9% was the saturated perfluoro-3-ethyl-2,2. , 4-trimethylpentane (however, the conversion was 96% and 4% of the starting material remained).

By removing perfluorohexane as a reaction solvent under reduced pressure, the total amount was concentrated to about 35 g. The concentrated reaction solution was distilled under reduced pressure to obtain three fractions (Fr.1 to Fr.3). Fr. No. 1 has a boiling point of 54 to 57° C./36 mmHg, 1.2 g, and Fr. 2 has a boiling point of 57 to 58° C./36 mmHg, 0.67 g, and Fr. No. 3 had a boiling point of 58° C./36 mmHg of 0.1 g and a residue of 0.4 g.

The results of the GC analysis are summarized in Table 1. As can be seen from Table 1, all the fractions contained the target compound at a concentration of 80% or more, but Fr. 1 is 5.4% of perfluoro-3-ethyl-2,4-dimethyl-3-pentyl, which has one less carbon number than the target compound, and perfluoro-3-ethyl-2,4-dimethyl-2-pentene is 5.4%. Content of 5.4%, indicating a somewhat lower boiling point range.

On the other hand, Fr. 2, the perfluoro-3-ethyl-2,4-dimethyl-3-pentyl content was reduced to 1.1% and the perfluoro-3-ethyl-2,4-dimethyl-2-pentene was reduced to 2.6%. , 85.1% of the fraction was the target compound (easily decomposable stable perfluoroalkyl radical I). Furthermore, Fr. In the case of 3, the contents were 0.5% and 2.0%, respectively, the target compound was 86.2%, and the remaining 8.5% was the saturated compound produced by further fluorination of the target compound. It was perfluoro-3-ethyl-2,2,4-trimethylpentane. Therefore, the boiling point of the target compound was in the range of 57 to 58° C./36 mmHg.

Synthesis of easily decomposable stable perfluoroalkyl radical II Perfluoro-2,4,4,-trimethyl-3-isopropyl-2-pentene (purity 100%) which is a precursor olefin of easily decomposable stable perfluoroalkyl radical II 3.8 g was taken and dissolved in 100 ml perfluorohexane. The obtained perfluorohexane solution was transferred to a reaction vessel made of Teflon having a capacity of 500 ml, and after purging the system with helium (30 minutes at 24 ml/min), fluorination was performed using 20% fluorine gas diluted with nitrogen. .. The reaction was carried out at room temperature (15 to 16° C.) in the presence of fluorine radicals until the starting materials were consumed (54 hours). That is, 1 g of hexafluorobenzene dissolved in 100 ml of perfluorohexane was introduced at a uniform rate (8.3 ml/hr) throughout the entire fluorination process. The flow rate of 20% fluorine gas corresponds to the amount of fluorine gas that is about 5 to 6 times the flow rate of fluorine gas (2.5 ml/min.) required for the introduced hexafluorobenzene to undergo complete fluorination. It was introduced at 15 ml/min. The reaction was followed every 6 hours by GC analysis and the curve plotting the data up to 42 hours was extrapolated and the starting material was determined to be zero by 54 hours reaction. Therefore, the reaction was terminated at 54 hours (see the reaction for forming easily decomposable stable perfluoro radical II in FIG. 7).

The yield of the easily decomposable stable perfluoroalkyl radical II of the product was 91% by gas chromatography (GC) analysis of the reaction solution, which was calculated from the peak area ratio. For the measurement of GC, a capillary column (Rtx200 0.25 mm x 60 m, 1 μ) was used, and temperature conditions (injection port temperature: 120° C., column temperature: 40° C., 5 minutes, and thereafter 5° C./min. Temperature rise). A FID (Frame Ionization Detector) was used as the detector. In addition to the target compound, the easily decomposable stable perfluoroalkyl radical II formed during the reaction with 4% of the unknown compound released and decomposed the trifluoromethyl radical by β-elimination. It contained 5% of perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl produced by fluorination of dimethyl-3-isopropyl-2-pentene.

The reaction solvent, perfluorohexane, was removed under reduced pressure, and the obtained concentrated liquid was distilled under reduced pressure (3.8 mmHg) to obtain Fr. 1 (35 to 40° C./3.8 mmHg; 0.4 g), Fr. 2 (40-43° C./3.8 mmHg: 2.0 g) and a residue of 0.2 g were obtained. Further, about 1 g of a colorless solid sublimated on the wall of the vacuum line was recovered. The Fr. 1 and Fr. 2 also became a solid immediately at room temperature. Fr. 2 was the easily decomposable stable perfluoroalkyl radical II of the target compound, which had a purity of 90.9%.

Impurities contained were 3.3% of the above compound perfluoro-2,4-dimethyl-3-isopropyl-2-pentene and 2. 3% of perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl. 5% and 3.3% of compounds of unknown structure. The purified product by sublimation recovered from the vacuum line was also the easily decomposable stable perfluoroalkyl radical II of the target compound and had a purity of 90.1%. The impurity composition is also Fr. Similar to 2, the perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl content was increased from 2.5% to 3.3%. The melting point was measured by packing the sublimated product in a glass capillary and using a melting point measuring device (Buchi B-545) to raise the temperature by 1° C./min. The temperature was raised and observed. Even if it was purified by sublimation, the melting point was in the range of 38 to 43° C., probably because the purity was only up to about 90%.

[Easily Decomposable Stable Perfluoroalkyl Radicals I and II for Thermal Decomposition]
(1) Kinetics of thermal decomposition reaction of easily decomposable stable perfluoroalkyl radical I A solution of easily decomposable stable perfluoroalkyl radical I (77 mg) obtained in Example 1 in perfluorohexane (3.63 g) Was used for the pyrolysis test. The prepared perfluorohexane solution of the easily decomposable stable perfluoroalkyl radical I was heated at a predetermined temperature for a predetermined time, and the decomposition process of the easily decomposable stable perfluoroalkyl radical I was traced by GC. The easily decomposable stable perfluoroalkyl radical I has a single decomposition route (the most crowded perfluoro-t-butyl group in β-elimination) in the measured temperature range (49.0°C to 68.0°C). One of the three trifluoromethyl groups is released to decompose through the decomposition product perfluoro-2.4-dimethyl-3-ethyl-2-pentene) (GC of all measured samples) Confirmed by analysis).

Therefore, assuming that the area of the easily decomposable stable perfluoroalkyl radical I in GC is S1 and the area of the decomposition product perfluoro-2.4-dimethyl-3-ethyl-2-pentene in GC is S2, If the logarithm of the abundance ratio of the readily decomposable stable perfluoroalkyl radical I plotted is linear with respect to time, this thermal decomposition reaction is the primary reaction of the easily decomposable stable perfluoroalkyl radical I. I know that there is.

Formula; abundance ratio of easily decomposable stable perfluoroalkyl radical I=S1/(S1+S2)
The thermal decomposition reaction was performed at 49.0° C. (analysis every 1 hour), 58.8° C. (analysis every 30 minutes) and 68.0° C. (analysis every 20 minutes). The decomposition process of the easily decomposable stable perfluoroalkyl radical I at each temperature is shown in FIGS.

A slight deviation from the linearity was observed at any temperature, and the reaction rate tended to be slightly higher at the initial stage of the thermal decomposition reaction. Especially, the tendency was remarkable at the low temperature, and the linearity was improved at the high temperature. Considering that the ESR of the easily degradable stable perfluoroalkyl radical I has a bimodal ESR signal having a large coupling constant and an ESR signal existing between the bimodal signals, The easily decomposable stable perfluoroalkyl radical I has two stable rotamers, which can be rationalized by considering that there are some differences in their thermal decomposition rates.

The half-life in the thermal decomposition reaction of the easily decomposable stable perfluoroalkyl radical I at each temperature was obtained from a regression curve including all measurement points, and it was determined that it represents an average image of two rotamers. To be done. That is, the half-lives in the thermal decomposition reaction of the easily decomposable stable perfluoroalkyl radical I at 49° C., 58.8° C., and 68.0° C. were 23.9 hr, 6.5 hr, and 1.9 hr, respectively. ..

(2) Kinetics of thermal decomposition reaction of easily decomposable stable perfluoroalkyl radical II A solution containing easily decomposable stable perfluoroalkyl radical II in an area ratio of about 2% with respect to perfluorohexane After heating for a predetermined time at temperature, the decomposition process of the easily decomposable stable perfluoroalkyl radical II was traced by GC. The easily decomposable stable perfluoroalkyl radical II has a single decomposition pathway (the most crowded perfluoro-t-butyl group in β-elimination) in the measured temperature range (49.0°C to 68.0°C). One of the three trifluoromethyl groups is released and decomposes through the decomposition product perfluoro-2.4-dimethyl-3-isopropyl-2-pentene) (GC of all measured samples) Confirmed by analysis).

Therefore, if the area of GC of the easily decomposable stable perfluoroalkyl radical II is S1 and the area of GC of the decomposition product perfluoro-2.4-dimethyl-3-isopropyl-2-pentene is S2, If the logarithm of the abundance ratio of the easily decomposable stable perfluoroalkyl radical II is plotted against time and it is linear, this thermal decomposition reaction is a primary reaction of the easily decomposable stable perfluoroalkyl radical II. I know that there is.

Formula; abundance ratio of easily decomposable stable perfluoroalkyl radical II=S1/(S1+S2)
The thermal decomposition reaction was performed at 49.0° C. (analysis every 1 hour), 58.5° C. (analysis every 40 minutes), and 67.7° C. (analysis every 20 minutes). The decomposition process of the easily decomposable stable perfluoroalkyl radical II at each temperature is shown in FIGS.

All of them showed good linearity, and it was confirmed that the thermal decomposition reaction of the easily decomposable stable perfluoroalkyl radical II was a first-order reaction. Based on these data, the first-order reaction rate constant was determined and the half-life at each temperature was determined. The half-lives at 49.0°C, 58.5°C, and 67.7°C were 10.5 hr, 2.64 hr, and 0.80 hr, respectively.

As described above in detail, the present invention is a method for producing an easily decomposable stable perfluoroalkyl radical, which is highly shielded in a reaction system in which a reactive radical in a fluorination reaction is a fluorine radical. The present invention relates to a method for producing a perfluoroalkyl radical characterized by synthesizing the above perfluoroalkyl radical by fluorinating a perfluoroalkene, without needing to mention the above specific examples. The present invention can provide a reagent that generates a trifluoromethyl radical at a low temperature, and the easily degradable stable perfluoroalkyl radical obtained in the present invention has superiority as a trifluoromethyl radical generating reagent. It is obvious from an industrial chemical point of view and is not limited to those mentioned here, but has the potential for widespread adaptation.
Although the market for fluorinated surface treatment is large in the current market such as textile products, it is expected to expand to plastic products, nanodiamond (nanodiamond), CNT, fullerenes, etc., and future market expansion is expected. Expected, in particular, disk coating, which has reached its limit with fluorinated lubricants, and a PTFE manufacturing method that does not use PFOA, where environmental problems have been pointed out, etc. , Has industrial applicability.

Claims (5)

A method for producing an easily decomposable stable perfluoroalkyl radical, which comprises fluorinating a highly shielded perfluoroalkene with a fluorine radical in a reaction system in which a reactive radical in a fluorination reaction is a fluorine radical. The method for producing a perfluoroalkyl radical is characterized by synthesizing the above perfluoroalkyl radical. The perfluoroalkyl radical according to claim 1, wherein the fluorine radical is used to fluorinate a highly shielded perfluoroalkene to synthesize a perfluoroalkyl radical that thermally decomposes via a single route. Production method. Perfluoro-3-ethyl-2,2, by fluorinating perfluoro-4,4-dimethyl-3-isopropyl-2-pentene as a highly shielded perfluoroalkene with a fluorine radical. The method for producing a perfluoroalkyl radical according to claim 2, wherein 4-trimethyl-3-pentyl (easily decomposable stable perfluoroalkyl radical I) is synthesized. Fluorination of perfluoro-2,4,4-trimethyl-3-isopropyl-2-pentene as a highly shielded perfluoroalkene with a fluorine radical results in perfluoro-2,2,4- The method for producing a perfluoroalkyl radical according to claim 2, wherein trimethyl-3-isopropyl-3-pentyl (easily decomposable stable perfluoroalkyl radical II) is synthesized. A perfluoroalkyl radical synthesized by the production method according to any one of claims 1 to 4, which is capable of releasing a trifluoromethyl radical upon decomposition by β-elimination, and A readily decomposable stable perfluoroalkyl radical in which the half-life of the perfluoroalkyl radical in the β-elimination reaction is in the range of 50 to 70°C and 0.5 to 24 hours.

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