Method for producing perfluoroalkyltrimethylsilane

Abstract

To provide a novel production method for perfluoroalkyl trimethylsilane that is simpler and more suitable for industrial use, utilizing perfluoroalkyl iodide, which is not subject to production regulations, as the raw material.SOLUTION: A production method for perfluoroalkyl trimethylsilane represented by the general formula (3) includes reacting perfluoroalkyl iodide represented by the general formula (1) with halogenated trimethylsilane represented by the general formula (2) in a polar aprotic solvent in the presence of aluminum. The formula (1) is Rf-I (where Rf represents a C1-3 perfluoroalkyl group). The formula (2) is X-SiMe3 (where X represents a chlorine, bromine, or iodine atom). The formula (3) is Rf-SiMe3 (where Rf represents a C1-3 perfluoroalkyl group).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel method for producing perfluoroalkyltrimethylsilane using perfluoroalkyliodide as a raw material. [Background technology]

[0002] Fluorine atoms have a similar atomic size to hydrogen atoms but possess high electronegativity, allowing for significant alterations to the chemical properties of compounds without changing their three-dimensional structure. For this reason, the synthesis of compounds containing perfluoroalkyl groups is particularly active in the fields of medicine and agrochemicals. Perfluoroalkyltrimethylsilanes, including the Ruppert-Prakash reagent, are widely used as a method for nucleophilically introducing perfluoroalkyl groups.

[0003] Until now, perfluoroalkyltrimethylsilanes have mainly used perfluoroalkyl bromides as raw materials. However, these compounds are known to have a very long environmental lifespan due to their persistence (e.g., Non-Patent Document 1). Bromotrifluoromethane (halon 1301) in particular has a high GWP (Global Warming Potential) (e.g., Non-Patent Document 1), and based on the resolution of the 1990 Meeting of the Parties to the Montreal Protocol, its manufacture and other activities have been regulated as a specified halon since 1992 under domestic laws aimed at protecting the ozone layer.

[0004] Patent Document 1 discloses a method for producing perfluoroalkyltrimethylsilane using hexaalkylphosphontriamide in combination with halogenated trimethylsilane and perfluoroalkyl bromide. However, hexaalkylphosphontriamide is difficult to handle due to its toxicity and is also difficult to obtain, making this method unsuitable for industrial use.

[0005] Non-patent document 2 discloses a method for reacting a halide trimethylsilane with a perfluoroalkyl bromide using aluminum. However, this method has the problem of requiring high pressure due to the high vapor pressure of perfluorobromide, thus necessitating high-pressure gas equipment. In fact, the inventors' own studies also showed that it was difficult to obtain perfluoroalkyltrimethylsilane in good yield under atmospheric pressure.

[0006] On the other hand, a method for producing perfluoroalkyltrimethylsilane using perfluoroalkyl iodides, which have a relatively small environmental impact and whose manufacture is not regulated, is also known. For example, Non-Patent Literature 2 discloses a method for deriving perfluoroalkyltrimethylsilane from halogenated trimethylsilane and perfluoroalkyl iodides using tetrakis(dimethylamino)ethylene. However, tetrakis(dimethylamino)ethylene is very expensive, making industrial use difficult. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3200099 [Non-patent literature]

[0008] [Non-Patent Document 1] Scientific Assessment of Ozone Depletion:2018, Chapter 6, Section 24, Table6-2 [Non-Patent Document 2] Journal of Fluorine Chemistry, 1989, Vol. 42, pp. 429-433. [Non-Patent Document 3] SYNLETT, 1995, Vol. 6, pp. 641-642 [Overview of the project] [Problems that the invention aims to solve]

[0009] In view of the above-mentioned background art, the object of the present invention is to provide a novel method for producing perfluoroalkyltrimethylsilane that is simpler and more suitable for industrialization, using perfluoroalkyl iodide, which is not subject to production restrictions, as a raw material. [Means for solving the problem]

[0010] As a result of diligent research to solve the above problems, the present inventors discovered that perfluoroalkyltrimethylsilane can be produced under atmospheric pressure by reacting perfluoroalkyl iodide with halide trimethylsilane in a polar aprotic solvent in the presence of aluminum, thus completing the present invention.

[0011] In other words, the present invention relates to the following invention. [1] A method for producing a perfluoroalkyltrimethylsilane represented by the following general formula (3), comprising reacting a perfluoroalkyl iodide represented by the following general formula (1) with a halogenated trimethylsilane represented by the following general formula (2) in the presence of aluminum in a polar aprotic solvent. Rf-I (1) (In formula (1), Rf represents a perfluoroalkyl group having 1 to 3 carbon atoms.) X-SiMe3(2) (In formula (2), X represents a chlorine atom, a bromine atom, or an iodine atom.) Rf-SiMe3(3) (In formula (3), Rf represents a perfluoroalkyl group having 1 to 3 carbon atoms.) [2] The method for producing the product according to [1], wherein the polar aprotic solvent is one or more selected from the group consisting of N-methyl-2-pyrrolidone, dimethylformamide, and acetonitrile. [3] The manufacturing method according to [1], wherein the halogenated trimethylsilane is chlorotrimethylsilane. [4] The production method according to [1], wherein the perfluoroalkyl iodide is trifluoroiodomethane or pentafluoroiodoethane, the polar aprotic solvent is N-methyl-2-pyrrolidone, and the trimethylsilyl halide is chlorotrimethylsilane. [5] The production method according to any one of [1] to [4], wherein the perfluoroalkyl iodide is trifluoroiodomethane. [6] The production method according to any one of [1] to [4], wherein the amount of the trimethylsilyl halide used is 1.0 mol to 4.0 mol with respect to 1.0 mol of the perfluoroalkyl iodide. [7] The production method according to any one of [1] to [4], wherein the amount of the aluminum used is 0.5 mol to 3.0 mol with respect to 1.0 mol of the perfluoroalkyl iodide. [8] The production method according to any one of [1] to [4], wherein the aluminum is powdered aluminum. [9] The production method according to any one of [1] to [4], wherein the amount of the polar aprotic solvent used is 2 parts by weight to 20 parts by weight with respect to 1 part by weight of the perfluoroalkyl iodide.

[10] The production method according to any one of [1] to [4], wherein the temperature of the reaction is in the range of 0°C to 60°C.

Advantages of the Invention

[0012] According to the present invention, there can be provided an industrial production method of perfluoroalkyltrimethylsilane that can be easily carried out under atmospheric pressure, using a perfluoroalkyl iodide with a relatively small environmental load and not subject to production regulations as a raw material.

[0013] Hereinafter, the present invention will be described in detail. In the perfluoroalkyl iodide represented by the general formula (1) of the present invention, Rf is preferably a linear perfluoroalkyl group having 1 to 3 carbon atoms, and particularly preferably a perfluoroalkyl group having 1 to 2 carbon atoms.

[0014] In the halogenated trimethylsilane represented by the general formula (2) of the present invention, considering the availability of raw material costs, X is preferably a chlorine atom or a bromine atom, and a chlorine atom is particularly preferred. The halogenated trimethylsilane used in the present invention is preferably chlorotrimethylsilane, bromotrimethylsilane, or iodotrimethylsilane, and chlorotrimethylsilane is more preferred.

[0015] The polar aprotic solvent of the present invention is not particularly limited as long as it is a solvent that is inert to the reaction, but specific examples include dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, and acetonitrile. Of these, N-methyl-2-pyrrolidone, dimethylformamide, and acetonitrile are preferred, and N-methyl-2-pyrrolidone is particularly preferred. These can be used individually, or two or more can be used in combination.

[0016] The amount of halide trimethylsilane used in the present invention is preferably 1.0 mol to 4.0 mol, more preferably 1.0 mol to 2.0 mol, per 1.0 mol of perfluoroalkyl iodide present in the reaction.

[0017] In this invention, the aluminum used can be either aluminum or a metal containing aluminum. Commercially available aluminum can be used directly. Aluminum can be used in any form, such as powder (e.g., spray powder, dry-ground powder (flake powder), or wet-ground powder (aluminum paste)) or granular form, but powder form is preferred from the viewpoint of dispersibility in the solvent and reactivity. Furthermore, the amount of aluminum used in this invention is preferably 0.5 mol to 3.0 mol, more preferably 0.5 mol to 1.5 mol, per 1.0 mol of perfluoroalkyl iodide contained in the reaction.

[0018] The amount of polar aprotic solvent used in the present invention is preferably 2 to 20 parts by weight, and more preferably 5 to 10 parts by weight, per 1 part by weight of perfluoroalkyl iodide in the reaction.

[0019] The reaction temperature in this invention is usually preferably in the range of 0°C to 60°C, and more preferably in the range of 20°C to 40°C. The reaction in this invention is preferably carried out under an inert gas atmosphere such as nitrogen or argon.

[0020] The reaction time in this invention is preferably in the range of 8 to 30 hours, and more preferably in the range of 10 to 24 hours.

[0021] The post-reaction treatment of the present invention can be carried out by known methods, and the reaction product can be purified directly or after adding water. The target compound of the present invention can be isolated or purified by distillation under atmospheric pressure or reduced pressure. For example, a crude product may be obtained by simple distillation and then further purified by precision distillation as needed. [Examples]

[0022] Examples of the present invention are shown below, but the present invention is not limited to these examples.

[0023] The following equipment was used for the analysis. <nmr> 1 H-NMR (400MHz), 19 F-NMR (376MHz): Bruker AVANCE II 400

[0024] Example 1 Synthesis of trifluoromethyltrimethylsilane using trifluoroiodomethane In a 3L glass flask equipped with a cooling circulator, 2088g (21.1 mol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 37g (1.4 mol, manufactured by Minalco Corporation) of aluminum powder were added at room temperature under a nitrogen atmosphere, and stirring was started. Subsequently, 380g (3.5 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) of chlorotrimethylsilane was added at room temperature, and the internal temperature was raised to 30°C. Then, 392g (2.0 mol, manufactured by Tosoh Finechem) of trifluoroiodomethane was added intermittently through an inlet tube immersed in the liquid phase, while maintaining an internal temperature of 30°C to 40°C. The mixture was aged for 17 hours while maintaining an internal temperature of 25°C to 30°C, and then 360g (20.0 mol) of pure water was added under ice water cooling and stirred for 30 minutes. Subsequently, 177g of a colorless and transparent distillate was obtained by simple distillation at 100°C to 140°C under atmospheric pressure. Benzotrifluoride is used as the internal standard. 19 F-NMR analysis revealed that the distillate contained 55% by weight of trifluoromethyltrimethylsilane (yield 62%). The yield was based on the starting material RF-X (trifluoroiodomethane) (molar yield). The same applies below. Furthermore, 143 g of trifluoromethyltrimethylsilane was obtained by precision distillation of the resulting distillate at atmospheric pressure at 80°C to 120°C (isolation yield 50%). The yield was defined as the ratio (molar yield) of the amount of isolated Rf-TMS (trifluoromethyltrimethylsilane) to the starting material RF-X (trifluoroiodomethane). The same method was used for subsequent calculations.

[0025] The analysis results were as follows: 1 1H-NMR (solvent: deuterated chloroform, internal standard: chloroform) δ (ppm): 0.27 (s, 9H, CH3) 19 F-NMR (solvent: deuterated chloroform, internal standard: benzotrifluoride) δ (ppm): -67.3 (s, 3F, CF3)

[0026] Example 2 Synthesis of pentafluoroethyltrimethylsilane using pentafluoroiodoethane In a 100 mL glass flask equipped with a cooling circulator, 38 g of N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 0.4 mol) and 0.7 g of aluminum powder (manufactured by Minalco, Inc., 0.03 mol) were added at room temperature under a nitrogen atmosphere, and stirring was started. Subsequently, 7.4 g of chlorotrimethylsilane (manufactured by Tokyo Chemical Industry Co., Ltd., 0.07 mol) was added at room temperature, and the internal temperature was raised to 30°C. Then, 9.1 g of pentafluoroiodoethane (manufactured by Tosoh Finechem, 0.04 mol) was added intermittently through an inlet tube immersed in the liquid phase, while maintaining the internal temperature at 30°C to 40°C. The mixture was aged for 16 hours while maintaining the internal temperature at 25°C to 40°C, and then 6.6 g (0.4 mol) of pure water was added while maintaining the internal temperature at 25 to 35°C, and the mixture was stirred for 30 minutes. Subsequently, 7.8 g of a colorless, transparent distillate was obtained by simple distillation at 100°C to 140°C under atmospheric pressure. Benzotrifluoride is used as the internal standard. 19 F-NMR analysis revealed that the distillate contained 59% by weight of pentafluoroethyltrimethylsilane (yield 65%).

[0027] The analysis results were as follows: 1 1H-NMR (solvent: deuterated chloroform, internal standard: chloroform) δ (ppm): 0.29 (s, 9H, CH3) 19 F-NMR (solvent: deuterated acetone, internal standard: benzotrifluoride) δ(ppm): -82.5(s,3F,CF3), -131.9(s,2F,CF2)

[0028] Comparative Example 1: Synthesis of trifluoromethyltrimethylsilane using bromotrifluoromethane In a 100 mL glass flask equipped with a cooling circulator, 45 g (0.5 mol) of N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Corporation) and 0.9 g (0.03 mol) of aluminum powder (manufactured by Minako Co., Ltd.) were added at room temperature, and stirring was started. Subsequently, 8.6 g (0.08 mol) of chlorotrimethylsilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added at room temperature, and after the internal temperature was raised to 30 °C, 6.5 g (0.05 mol) of bromotrifluoromethane (manufactured by Nippon Halon) was intermittently added through an introduction tube immersed in the liquid phase while maintaining the internal temperature at 30 °C to 40 °C. Aging was carried out for 17 hours while maintaining the internal temperature at 25 °C to 40 °C, and at room temperature, 8.0 g (0.5 mol) of pure water was added and stirred for 30 minutes. Subsequently, 7.8 g of a colorless and transparent distillate was obtained by simple distillation at 100 °C to 140 °C under normal pressure. Using benzotrifluoride as an internal standard 19 From 19F-NMR analysis, the distillate contained 0.5 wt% of trifluoromethyltrimethylsilane (yield 0.2%).

[0029] The analysis results were as follows. 1 1H-NMR (solvent: deuterated chloroform, internal standard substance: chloroform) δ (ppm): 0.27 (s, 9H, CH3) 19 19F-NMR (solvent: deuterated chloroform, internal standard: benzotrifluoride) δ (ppm): -67.3 (s, 3F, CF3)

[0030] Comparative Example 2 Synthesis of Pentafluoroethyltrimethylsilane Using Pentafluorobromoethane In a 100 mL glass flask equipped with a cooling circulator, 46 g of N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 0.5 mol) and 0.8 g of aluminum powder (manufactured by Minalco, Inc., 0.03 mol) were added at room temperature under a nitrogen atmosphere, and stirring was started. Subsequently, 8.6 g of chlorotrimethylsilane (manufactured by Tokyo Chemical Industry Co., Ltd., 0.08 mol) was added at room temperature, and the internal temperature was raised to 30°C. Then, 9.0 g of pentafluorobromoethane (manufactured by Nippon Halon, 0.05 mol) was added intermittently through an inlet tube immersed in the liquid phase, while maintaining the internal temperature at 30°C to 40°C. The mixture was aged for 17 hours while maintaining the internal temperature at 25°C to 40°C, and then 8.5 g (0.5 mol) of pure water was added while maintaining the internal temperature at 25 to 35°C, and the mixture was stirred for 30 minutes. Subsequently, 6.9 g of a colorless and transparent distillate was obtained by simple distillation at 100°C to 140°C under atmospheric pressure. Benzotrifluoride is used as the internal standard. 19 F-NMR analysis revealed that the distillate contained 35% by weight of pentafluoroethyltrimethylsilane (yield 37%).

[0031] The analysis results were as follows: 1 1H-NMR (solvent: deuterated chloroform, internal standard: chloroform) δ (ppm): 0.29 (s, 9H, CH3) 19 F-NMR (solvent: deuterated acetone, internal standard: benzotrifluoride) δ(ppm): -82.5(s,3F,CF3), -131.9(s,2F,CF2)

[0032] From the results above, it can be seen that using perfluoroalkyl iodide in the reaction yields perfluoroalkyltrimethylsilane in high yield under atmospheric pressure compared to using perfluoroalkyl bromide. [Industrial applicability]

[0033] The present invention provides a simple and industrially viable method for producing perfluoroalkyltrimethylsilane using perfluoroalkyl iodide, which has a low environmental impact and is not subject to manufacturing restrictions.< / nmr>

Claims

1. A method for producing a perfluoroalkyltrimethylsilane represented by the following general formula (3), comprising reacting a perfluoroalkyl iodide represented by the following general formula (1) with a halogenated trimethylsilane represented by the following general formula (2) in a polar aprotic solvent under atmospheric pressure and in the presence of aluminum. Rf-I (1) (In formula (1), Rf represents a perfluoroalkyl group having 1 to 3 carbon atoms.) X-Si-X ３ (2) (In equation (2), X represents a chlorine atom.) Rf-SiMe ３ (3) (In formula (3), Rf represents a perfluoroalkyl group having 1 to 3 carbon atoms.)

2. The production method according to claim 1, wherein the polar aprotic solvent is one or more polar aprotic solvents selected from the group consisting of N-methyl-2-pyrrolidone, dimethylformamide, and acetonitrile.

3. The production method according to claim 1, wherein the perfluoroalkyl iodide is trifluoroiodomethane or pentafluoroiodoethane, the polar aprotic solvent is N-methyl-2-pyrrolidone, and the halogenated trimethylsilane is chlorotrimethylsilane.

4. The manufacturing method according to any one of claims 1 to 3, wherein the perfluoroalkyl iodide is trifluoroiodomethane.

5. The manufacturing method according to any one of claims 1 to 3, wherein the amount of halide trimethylsilane used is 1.0 mol to 4.0 mol per 1.0 mol of perfluoroalkyl iodide.

6. The manufacturing method according to any one of claims 1 to 3, wherein the amount of aluminum used is 0.5 mol to 3.0 mol per 1.0 mol of perfluoroalkyl iodide.

7. The manufacturing method according to any one of claims 1 to 3, wherein the aluminum is in powder form.

8. The manufacturing method according to any one of claims 1 to 3, wherein the amount of the polar aprotic solvent used is 2 to 20 parts by weight per 1 part by weight of perfluoroalkyl iodide.

9. The manufacturing method according to any one of claims 1 to 3, wherein the reaction temperature of the above reaction is in the range of 0°C to 60°C.