JP5411494B2 - Method for producing 1,4-bis (difluoromethyl) tetrafluorobenzene - Google Patents

Description

  The present invention relates to a method for halogen exchange reaction, and more particularly to a simple and high-yield production method of 1,4-bis (difluoromethyl) tetrafluorobenzene.

  With the progress of integrated circuit technology, semiconductor components are designed for miniaturization and high speed. In order to place as many components as possible on a finite area of the chip, i.e. to upgrade the integration of the components on the chip, two or more metal interconnect layers are required to reduce the signal between the component and the external environment. It can provide enough area to transmit and thus interconnect. Thus, the transmission rate between the internal components and the external environment is measured by the interconnect capacitance, or RC delay, rather than the gate switching rate. Many studies are currently interested in the development of low dielectric constant materials, since the RC delay can be mitigated by using low dielectric constant materials.

  Currently, organic polymers containing fluorine are widely used because of their low dielectric constant and easy use in current semiconductor technology processes. In general, methods for reducing the dielectric constant of organic materials can be classified into physical methods and chemical methods. In the physical method, the dielectric constant is decreased by increasing the thickness of the thin film. Regarding chemical methods, there are two general methods as follows. The first is to increase the amount of fluorine in the molecule, but by introducing fluorine atoms into the monomer of the molecule by chemical methods to increase the amount of fluorine, thereby increasing the atom or molecule packing density. The second is to increase the free volume, which introduces a large capacity atom or molecular group into the polymer film to reduce the atom or molecule packing density, resulting in a decrease in dielectric constant.

しかし、この方法自体、以下に記載する短所を有する：(1)CsFおよびCoF_３等の錯体金属フッ化物は非常に高価である；(2)ベンゼン環および側鎖水素のフッ素化は、高温条件下（360℃）で実施する必要がある；(3)気相フッ素化反応で実施するため、複雑な装置が必要である；および(4)種々の過剰な副生物により、精製が困難である。 Fluorine-containing aromatic polymers generally have advantageous characteristics such as transparency, heat resistance and chemical resistance, water repellency, low dielectric constant, low reflectivity, and the like. J. Fluor. Chem., 1987, 37: 1-14) discloses a method for producing an aromatic compound having a benzene ring substituted with four fluorine atoms and a side chain substituted with fluorine. . Specifically, in this method, the benzene ring and side chain of p-xylene are fluorinated with a complex metal fluoride. The fluorination is carried out as described in reaction (I) below.

However, the process itself has the disadvantages described below: (1) Complex metal fluorides such as CsF and CoF ₃ are very expensive; (2) Fluorination of benzene ring and side chain hydrogen is a high temperature condition Need to be carried out under (360 ° C); (3) complex equipment is required to carry out in the gas phase fluorination reaction; and (4) purification is difficult due to various excess by-products .

  As integrated circuit manufacturing technology is gradually being upgraded, there is a demand for dielectric materials with lower dielectric constants for industrial use, and in order to increase industrial competitiveness, the cost must be commensurate. Therefore, how to provide a method for producing a fluorine-containing monomer of a low dielectric constant polymer that can be used for mass production with a simple reaction is a current problem that is expected to be solved. The present invention achieves the above-mentioned objective of being mass-produced by a simple reaction, and is an important precursor of 1,4-bis (bromodifluoromethyl) tetrafluorobenzene, 1,4-bis (difluoromethyl) tetra A method for producing fluorobenzene is provided.

In view of the above-mentioned drawbacks, the present invention provides a method for producing 1,4-bis (difluoromethyl) tetrafluorobenzene. This method can reduce the manufacturing cost of 1,4-bis (difluoromethyl) tetrafluorobenzene and simplify the process. The reaction is a typical halogen substitution as shown in Reaction (II) below.

The present invention includes the following steps:
(A) mixing 1,4-bis (dichloromethyl) tetrafluorobenzene, a catalyst, an aprotic polar solvent, and an alkali metal fluoride to form a reaction mixture;
(B) heating the reaction mixture to carry out the reaction; and (c) purifying the reaction mixture to obtain 1,4-bis (difluoromethyl) tetrafluorobenzene. A method for producing (difluoromethyl) tetrafluorobenzene is provided.

In the method of the present invention, each reactant in step (a) may be added in any order. In a preferred aspect of the invention, step (a) comprises the following steps:
(A1) mixing 1,4-bis (dichloromethyl) tetrafluorobenzene, catalyst, and aprotic polar solvent in a reactor to form a mixture;
(A2) heating the mixture until 1,4-bis (dichloromethyl) tetrafluorobenzene is dissolved; and (a3) adding an alkali metal fluoride to the mixture to form a reaction mixture. .

  In the process of the present invention, the reaction time of step (b) can be in the range of 1 to 48 hours. When the reaction time in step (b) is less than 2 hours, the reaction yield is relatively low. If the reaction time of step (b) exceeds 24 hours, the reaction yield does not increase dramatically. Accordingly, the reaction time in step (b) is preferably in the range of 2 to 24 hours.

  In the process of the present invention, the reaction temperature of step (b) can be in the range of 40-120 ° C. When the reaction temperature in step (b) is less than 50 ° C., the reaction is slow. When the reaction temperature in step (b) exceeds 110 ° C., rubberization can easily occur in the reaction. Therefore, the reaction temperature in step (b) is preferably in the range of 50 to 110 ° C.

  In the process of the present invention, the catalyst may belong to a phase transfer catalyst. Preferably, the catalyst may be at least one selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, and crown ethers.

式中、XはCl、Br、またはIであり；R₁、R₂、R₃、およびR₄はアルキル基、アリール基またはそれらの組み合わせである。これらのアルキル基は、好ましくは、C₁〜C₈アルキル基である。これらのアリール基は、好ましくは、フェニル基またはベンジル基である。例えば、(CH₃)₄NCl、(C₄H₉)₄NBr、C₈H₁₇(CH₃)₃NBr、C₆H₅(CH₃)₃NCl等であり、中でも塩化テトラメチルアンモニウム((CH₃)₄NCl)が最適である。 Any of the common quaternary ammonium salts can be used in the process of the present invention. The quaternary ammonium salt has a structure represented by the following formula (III):

Where X is Cl, Br, or I; R ₁ , R ₂ , R ₃ , and R ₄ are alkyl groups, aryl groups, or combinations thereof. These alkyl groups, preferably a C ₁ -C ₈ alkyl group. These aryl groups are preferably a phenyl group or a benzyl group. For example, (CH ₃ ) ₄ NCl, (C ₄ H ₉ ) ₄ NBr, C ₈ H ₁₇ (CH ₃ ) ₃ NBr, C ₆ H ₅ (CH ₃ ) ₃ NCl, etc., among them tetramethylammonium chloride (( CH ₃ ) ₄ NCl) is optimal.

式中、XはCl、Br、またはIであり；R₁、R₂、R₃、およびR₄はアルキル基、アリール基またはそれらの組み合わせである。これらのアルキル基は、好ましくは、C₁〜C₈アルキル基である。これらのアリール基は、好ましくは、フェニル基またはベンジル基である。例えば、 (Ph)₄PBr, (C₄H₉)₄PBr, (Ph)₄PCl等であり、中でも臭化テトラフェニルホスホニウム((Ph)₄PBr)が最適である。 Any common quaternary phosphonium salt may be used in the process of the present invention. The quaternary phosphonium salt has a structure represented by the following formula (IV):

Where X is Cl, Br, or I; R ₁ , R ₂ , R ₃ , and R ₄ are alkyl groups, aryl groups, or combinations thereof. These alkyl groups, preferably a C ₁ -C ₈ alkyl group. These aryl groups are preferably a phenyl group or a benzyl group. For example, (Ph) ₄ PBr, (C ₄ H ₉ ) ₄ PBr, (Ph) ₄ PCl, etc. Among them, tetraphenylphosphonium bromide ((Ph) ₄ PBr) is most suitable.

    All common crown ethers can be used in the process of the present invention. For example, 12-crown-4-ether, 15-crown-5-ether, and 18-crown-6-ether, among which 18-crown-6-ether is preferred.

  Any common aprotic polar solvent may be used in the process of the present invention. For example, acetonitrile, sulfolane, or N, N-dimethylformamide, with acetonitrile being preferred.

  In the process of the present invention, all common alkali metal fluorides can be used. For example, LiF, NaF, KF and CsF are preferable, and KF or CsF is particularly preferable.

  In the method of the present invention, the number of moles of alkali metal fluoride is larger in the range of 1 to 16 times than that of 1,4-bis (dichloromethyl) tetrafluorobenzene, preferably in the range of 4 to 8 times. Is within.

  In the process of the present invention, the amount of catalyst is in the range of 1-40% by weight of 1,4-bis (dichloromethyl) tetrafluorobenzene, preferably in the range of 4-12% by weight.

  In the method of the present invention, the purification in step (c) may comprise filtration, extraction, distillation, or sublimation of the reaction mixture, or a combination thereof, and purification of 1,4-bis (difluoromethyl) tetrafluorobenzene For this, sublimation is most suitable.

  Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[Example 1]
A 150 mL reaction flask was equipped with a condenser and a magnetic heating plate / stirrer. 20 g (0.063 mol) of 1,4-bis (dichloromethyl) tetrafluorobenzene (DCMTFB), 2 g of 18-crown-6-ether, and 40 mL of acetonitrile were added to the reaction flask. The oil bath was heated with a hot plate / stirrer until the temperature reached 80 ° C. and all the organic compounds were dissolved. Subsequently, 60 g (0.39 mol) of CsF was added to the reaction flask, and then the temperature of the oil bath was raised to 100 ° C. After the reaction for 6 hours, the product was analyzed, and the conversion of 1,4-bis (difluoromethyl) tetrafluorobenzene reached 92% or more. The crude product was filtered, extracted, distilled, and sublimed to give 12 g of pure 1,4-bis (difluoromethyl) tetrafluorobenzene. The yield obtained was 76%.

The product obtained in this example was confirmed to be 1,4-bis (difluoromethyl) tetrafluorobenzene by chemical analysis. The chemical analysis data are listed below.
(A) Mass spectrum analysis: M ⁺ 250
(B) ¹ H NMR (tetramethylsilane, TMS):
Chemical shift 6.91ppm t, J = 53.8
(C) ¹⁹ F NMR (CFCl ₃ ):
Chemical shift 143.3 ppm s (aromatic F)
115.8 ppm d, J = 53.8 (Aliphatic F)
Integral ratio (aromatic F / aliphatic F) = 1/1

[Example 2]
A 150 mL reaction flask was equipped with a condenser and a magnetic heating plate / stirrer. 30 g (0.095 mol) 1,4-bis (dichloromethyl) tetrafluorobenzene (DCMTFB), 45 g KF, 45.8 g sulfolane, and 3 g tetraphenylphosphonium bromide were added to the reaction flask. The hot plate / stirrer was activated and the oil bath was set to a temperature of 125-130 ° C. and reacted for 48 hours. The outlet of the condenser could be blocked with a stopper to avoid sublimation of the product and prevent the reaction flask from overflowing. After the reaction was complete, the reaction mixture was cooled to room temperature. Subsequently, the reaction mixture was filtered to obtain a filtered solid. The filtered solid was washed with CH ₂ Cl _2, was distilled under reduced pressure to obtain CH ₂ Cl ₂ and 1,4-bis (difluoromethyl) tetrafluorobenzene (DFMTFB). Since 1,4-bis (difluoromethyl) tetrafluorobenzene can sublimate and condense in the condenser, the crude product is washed with CH ₂ Cl ₂ to give 1,4-bis (difluoromethyl) tetrafluorobenzene. It was collected. After removing CH ₂ Cl ₂ , 6.51 g of 1,4-bis (difluoromethyl) tetrafluorobenzene was obtained, and the yield obtained was 27.2%.

The product obtained in this example was confirmed to be 1,4-bis (difluoromethyl) tetrafluorobenzene by chemical analysis. The chemical analysis data are listed below.
(A) Mass spectrum analysis: M ⁺ 250
(B) ¹ H NMR (tetramethylsilane, TMS):
Chemical shift 6.92ppm t, J = 53.8
(C) ¹⁹ F NMR (CFCl ₃ ):
Chemical shift 143.3 ppm s (aromatic F)
115.8 ppm d, J = 53.8 (Aliphatic F)
Integral ratio (aromatic F / aliphatic F) = 1/1

[Examples 3 to 10]
5.00 g (0.063 mol) 1,4-bis (dichloromethyl) tetrafluorobenzene (DCMTFB), 0.50 g tetraphenylphosphonium bromide (PTC (Br)), 8.50 g KF, and 30 g N, N- Dimethylformamide (DMF) was added to the reaction flask. The oil bath was heated to 120 ° C. and stirred with a stirrer to carry out the reaction for 17 hours. The product was analyzed by gas chromatography (GC) to give compound 4F / 2F / DCMTFB = 20.7 / 47.2 / 22.1 (GC area%). Compound 4F (formula (1)), 3F (formula (2)), 2F (formula (3)), 1F (formula (4)) and DCMMTFB (formula (5)) are respectively converted into the following formulas (1) to ( 5)

  All the methods of Examples 4 to 10 were performed in the same manner as in Example 3. The amounts of reactants, reaction conditions, and GC results for Examples 3-10 are all as described in Table 1.

Although described with respect to preferred embodiments of the present invention, it should be understood that numerous other possible modifications or changes may be made without departing from the scope of the present invention as claimed below.

Claims (8)

The following steps:
(A) mixing 1,4-bis (dichloromethyl) tetrafluorobenzene, a catalyst, an aprotic polar solvent, and an alkali metal fluoride to form a reaction mixture , wherein the catalyst is a crown ether The aprotic polar solvent is acetonitrile and the alkali metal fluoride is anhydrous CsF ;
(B) heating the reaction mixture to carry out the reaction; and (c) purifying the reaction mixture to obtain 1,4-bis (difluoromethyl) tetrafluorobenzene ;
A process for producing 1,4-bis (difluoromethyl) tetrafluorobenzene, comprising: The method of claim 1, wherein step (a) comprises the following steps:
(A1) mixing 1,4-bis (dichloromethyl) tetrafluorobenzene, catalyst, and aprotic polar solvent in a reactor to form a mixture , wherein the catalyst is a crown ether; The protic polar solvent is acetonitrile;
(A2) heating the mixture until 1,4-bis (dichloromethyl) tetrafluorobenzene is dissolved; and (a3) adding an alkali metal fluoride to the mixture to form a reaction mixture , wherein , The alkali metal fluoride is anhydrous CsF;
Including a method. The method of claim 1, wherein the reaction time of step (b) is in the range of 2 to 24 hours. The method according to claim 1, wherein the reaction temperature of step (b) is in the range of 50-110 ° C. The method of claim 1, wherein the crown ether is 18-crown-6-ether. The method according to claim 1, wherein the number of moles of alkali metal fluoride is larger within a range of 1 to 16 times than the number of moles of 1,4-bis (dichloromethyl) tetrafluorobenzene. The method of claim 1, wherein the amount of catalyst is in the range of 1 to 40% by weight of 1,4-bis (dichloromethyl) tetrafluorobenzene. The method according to claim 1, wherein the purification in step (c) is filtration, extraction, distillation and sublimation of the reaction mixture.