JP2003073874A - Method for manufacturing hydrofluoroalkylether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hydrofluoroalkylether compound, which does not damage the ozonosphere at all, has a very little global warming coefficient, can be used for a foaming agent, a refrigerant, or a cleaner, and can be synthesized in an ordinary temperature and pressure, and even in a high yield. SOLUTION: This manufacturing method includes employing a Ni-NiO plate for an anode, a Ni plate for a cathode, a mixture solvent of a dialkyl carbonate and acetonitrile for an organic solvent, Et3 N.5HF for a fluorinating agent, and LiClO4 for a supporting electrolyte, adding a small amount of fluorine-based surfactant to the liquid, and potentiostatically electrolyzing the liquid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a hydrofluoroalkyl ether compound from an ether compound by electrolytic fluorination (anodic oxidation).

[0002]

2. Description of the Related Art Conventionally, CFC-12 (dichlorodifluoromethane) and HCHC-141b have been used as a foaming agent for highly foamed synthetic resins such as foamed polyethylene, foamed polystyrene, foamed polyurethane or synthetic rubber. Since the foaming agent destroys the ozone layer, CFC is completely abolished at the end of 1995 by the Montreal Protocol, and HCFC is scheduled to be abolished in developed countries in 2020. Methods for synthesizing hydrofluoroalkyl ether compounds with zero destruction coefficient and very low global warming potential have been studied. However, both methods are chemical fluorination methods using fluorine gas as the fluorinating agent, and fluorine gas is toxic and difficult to handle, and the reaction is a high-pressure reaction, so there is a problem in terms of safety as well. Since the selectivity is very small and various kinds of products are by-produced, it is difficult to isolate the main product, and very few are practically used industrially. Therefore, there is a demand for a new method for producing a hydrofluoroalkyl ether compound that can be produced at normal temperature and pressure, is easy to handle, and has few problems in terms of safety and that can be used as a foaming agent, a refrigerant, or a detergent.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is not to destroy the ozone layer at all, and it can be used as a foaming agent, a refrigerant or a cleaning agent having a very small global warming potential. Moreover, it is to provide a method for producing a hydrofluoroalkyl ether compound which can be synthesized in a high yield.

A further object of the present invention is to provide a foamed insulated wire, foamed tube or foamed sheet using these hydrofluoroalkyl ether compounds as a foaming agent and having a low dielectric constant and a low dielectric loss.

[0005]

The present inventor uses a nickel-nickel oxide plate electrode for an anode and a nickel plate electrode for a cathode, and uses a dialkyl carbonate / acetonitrile mixed solvent as an organic solvent capable of dissolving an ether compound. , The fluorinating agent is R ₃ N.nHF or R ₄ NF.
LiClO ₄ , LiPF ₆ was used as the supporting electrolyte by using nHF.
Alternatively, it was found that by using LiBF ₄ and adding a small amount of a fluorine-based surfactant to carry out potentiostatic electrolytic oxidation, a hydrofluoroalkyl ether compound can be obtained at a temperature of 10 ° C. or lower and under normal pressure in a high yield, The present invention has been completed. The hydrofluoroalkyl ether compound produced in the present invention can be used as a foaming agent for synthetic resin or synthetic rubber, or as a refrigerant for refrigerators and air conditioners.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As an ether compound, diethyl ether, methyl ethyl ether, and as an organic solvent, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, acetonitrile, tetrahydrofuran, etc. can be used, and dimethyl carbonate (bp = 90 ° C.). ) And acetonitrile (bp = 81 ° C.) mixed solvent is desirable. Platinum, nickel, nickel-nickel oxide, etc. can be used as the anode, but the nickel-nickel oxide composite electrode containing 5 mol% of nickel oxide has a very small amount of dissolved electrode, is stable, and is the most inexpensive. preferable. The nickel-nickel oxide composite electrode is prepared by wet-mixing nickel powder, 5 mol% nickel oxide powder and an organic binder in an organic solvent such as acetone or methylbutylketone for 24 to 48 hours with a ball mill, filtering and drying. It can be produced by filling the obtained powder in a mold, press-molding at a pressure of 1 to 2 t, and firing in a nitrogen atmosphere at 900 ° C. As the cathode, platinum, nickel, graphite or the like can be used, but inexpensive and stable nickel is most preferable.
Et ₃ N ・ 3HF, Et ₃ N ・ 4H as fluorinating agent
F, Et ₃ N · 5HF, Et ₄ NF · 2HF and the like can be used, but Et ₃ N · 5HF is most preferable. LiClO ₄ , LiPF ₆ , LiBF as the supporting electrolyte
_{4 and the} like can be used, but LiClO ₄ is most preferable. Fluorine-based surfactant such as F (CF ₂ CF ₂ ).
_It is desirable to add ₅ SO ₃ NH ₄ in a small amount because the current efficiency is remarkably improved.

Trifluoromethylfluoroethyl ether (CF ₃ OCHFCH ₃ ) which is one of the blowing agents is
It can be synthesized according to the synthetic scheme shown in the following formula. Other hydrofluoroalkyl ether compounds according to the present invention can be synthesized according to a similar synthetic scheme.

[0008]

[Chemical 1]

The hydrofluoroalkyl ether compound can be easily produced at room temperature under normal pressure by the electrolytic fluorination method (anodic oxidation) of the ether compound. The potentiostatic electrolyzer is shown in FIG. 1. The electrolyzer was made of Teflon (registered trademark) (PFA), and used was 1 L with a porous Teflon (PTFE) diaphragm. The fluorinating agent is Et ₃ N.
5 HF, a dimethyl carbonate / acetonitrile (50/50) mixed solvent was used as a solvent. The bath voltage can be reduced by adding LiClO ₄ as a supporting electrolyte. The anode is a nickel-nickel oxide plate, the cathode is a nickel plate, and the reference electrode is Ag / Ag.
A + / MeCN electrode was used. The constant potential electrolysis is preferably performed at a temperature of 5 to 10 ° C. and a potential of 2.5 V to 2.8 V (vsAg / Ag +) for 12 hours to 24 hours.

Trifluoromethyl fluoroethyl ether (CF ₃ OCHFCH ₃ , bp prepared according to the present invention)
(−18 ° C.) to synthetic resin or synthetic rubber, it is possible to obtain a highly foamed resin or rubber-insulated electric wire having low electrical characteristics, particularly low dielectric constant or dielectric loss. As synthetic resins to which the present invention is applied, polyethylene, polypropylene, polystyrene, molten fluororesin (PFA, FE
P, ETFE), polyamide, polyester, polycarbonate, silicone resin, acrylic resin, polyvinyl chloride, ABS and the like. As a thermosetting resin,
Examples thereof include polyurethane resin, melamine resin, phenol resin, epoxy resin, polyimide resin, diaryl phthalate resin, unsaturated polyester resin and furan resin. Examples of the elastomer and synthetic rubber include thermoplastic polyurethane resin, thermoplastic fluororubber, polybutadiene rubber, polyisobutylene rubber, nitrile rubber, epichlorohydrin rubber, chloroprene rubber, polysulfide rubber, EPDM, SBR and the like.

Polyolefin resin such as polyethylene, polypropylene, polystyrene or PFA, FEP,
A core having a particle size of 10 to 30 μm such as sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, magnesium hydrogen carbonate, calcium hydrogen carbonate, alumina, boron nitride, or silicon carbide based on 100 parts by weight of a molten fluororesin such as ETFE. 0.05 to 0.5 parts by weight of the agent is dry blended with a V-type mixer or a Henschel mixer and supplied to the hopper of the extruder, and 90 to 100 kg from the low pressure part of the cylinder by the compressor.
/ Fluorocarbon ether with a constant flow rate increased to / cm ² is extruded onto a soft copper wire with a conductor diameter of 4 mm while continuously pressurizing it with a metering pump, and the outer diameter is 17 mm.
After foaming so as to obtain a high-foam insulated electric wire, the high-foam insulated electric wire was sufficiently dried in a vacuum oven and covered with an aluminum outer conductor to prepare a coaxial cable having a length of 100 m. Dielectric constant, attenuation (dB / km) and characteristic impedance were measured by conventionally known methods. Insulator ta
nδ was calculated from the slope of the attenuation curve (dB / km-MHz).

The nucleating agent thermally decomposes to form metal oxides and carbon dioxide gas, and metal oxides such as Na ₂ O, K ₂ O,
Li ₂ O, MgO, CaO, and ZnO affect the dielectric loss of the insulator, so it is desirable that the addition amount be as small as possible, but if it is 0.05 parts by weight or less, foaming will not occur,
If it is 0.5 parts by weight or more, the tan δ of the high-foaming insulating material becomes large, so 0.05 to 0.5 parts by weight is desirable, and 0.2 to 0.4 parts by weight is particularly desirable. The nucleating agent preferably has a narrow particle size distribution, such as 1 to 50 μm, and particularly 10 to
A closed cell insulator is obtained when a nucleating agent having a particle size distribution of 30 μm is used. Examples of hydrofluoroalkyl ether compounds that can be used as a foaming agent include CF ₃ O.
CHFCH ₃ , CF ₃ OCH ₂ CH ₂ F, CF ₃ OCF
₂ CH ₃ , CF ₃ OCHFCH ₂ F, CF ₃ OCF ₂ C
H ₂ F, CF ₃ OCHFCHF _{2 and the} like can be mentioned, but C
F ₃ OCHFCH ₃ is the most preferable in terms of boiling point. Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

[0013]

EXAMPLES Example 1 The potentiostatic electrolysis apparatus shown in FIG. 1 was used. 1. In a Teflon (PFA) anode tank with a porous Teflon diaphragm having a volume of 1 L, 100 ml of dimethyl carbonate, 100 ml of acetonitrile, 150 g of Et ₃ N.5HF, 12.0 g of methyl ethyl ether (0.2 mol), LiClO ₄ 2.
0 g, 1.0 g of F (CF ₂ CF ₂ ) ₅ SO ₃ NH ₄ was charged, 100 ml of dimethyl carbonate, 100 ml of acetonitrile, and 150 g of Et ₃ N.5HF were charged in the cathode tank, and at a potential of 2.8 V (vsAg / Ag +), Constant-potential electrolysis was performed for 12 hours at a temperature of 5 ° C or lower. The amount of electricity is 4F
/ Mol, the current efficiency was 100%. ▲ 11 in Fig. 1
When the low boiling point liquid collected in the reaction product collection tank of ▼ was distilled by fractional distillation, Compound A having a boiling point of -18 ° C was 1%.
9.0 g (yield 72%) and 4.7 g of compound B having a boiling point of -15 ° C were obtained.

Gas mass spectrometer (AX505 manufactured by JEOL)
When the molecular weight was measured with a HA spectrum meter,
The molecular weights of Compound A and Compound B were both 132. _{When 1} H-NMR and ₁₉ F-NMR spectrum analyzes were performed, compound A was CF ₃ OCHFCH ₃ , compound B.
Was confirmed to be CF ₃ OCH ₂ CH ₂ F.

High density polyethylene (Hiz manufactured by Mitsui Chemicals, Inc.
ex1300J) 100 parts by weight, sodium hydrogencarbonate (particle size 20 ± 10 μm) 0.2 parts by weight, boron nitride (particle size 20 ± 10 μm) 0.2 parts by weight, dry blended for 15 minutes with a V-type mixer, and low pressure part Equipped with a screw and a gas injection device (quantitative pump, compressor, injection nozzle)
Supply to the hopper of 0mm (L / D = 28) extruder,
While continuously supplying trifluoromethylfluoroethyl ether at a flow rate of 100 ml / min and a pressure of 90 kg / cm ² , the extrusion temperature (180 ° 160 ° 150 ° 140 ° /
(135 ° C.) was extruded onto an annealed copper wire having a conductor diameter of 4 mm, and the resin was foamed after passing through a die to produce a highly foam insulated electric wire having an outer diameter of 17 ± 0.1 mm. Insulated wire in a vacuum pot 24
After drying under reduced pressure for an hour, a 0.8 mm thick aluminum outer conductor is coated on the high-expansion polyethylene insulated wire,
The electrical characteristics (dielectric constant, attenuation (dB / km), tan δ, characteristic impedance) of a 100 m long coaxial cable were measured. The measurement results are shown in Table 1, and tan δ was almost as small as that of the coaxial cable using the conventional CFC-12 as the foaming agent.

Example 2 Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (Neoflon PF manufactured by Daikin Industries, Ltd.
A AP-21) and boron nitride 0.2 as a nucleating agent.
Parts by weight, 0.2 parts by weight of magnesium hydrogen carbonate,
Extrusion temperature (390 ° 380 ° 370 ° 360 ° / 330
A coaxial cable was manufactured in the same manner as in Example 1 except that the coaxial cable was extruded at (° C). Table 1 shows the measurement results of the electrical characteristics.

Comparative Example 1 Table 1 shows the measurement results of the electrical characteristics of a commercially available highly expanded polyethylene insulated coaxial cable using CFC-12 (dichlorodifluoromethane) as a foaming agent and sodium hydrogen carbonate as a nucleating agent.

Example 3 Using the same electrolytic cell and electrolytic solution as in Example 1, 2.8
V potential for 4 hours, 2.9V potential for 4 hours, 3.0V
At constant potential, constant potential electrolysis was performed for 4 hours. The amount of electricity is 6.5F
/ Mol, the current efficiency was 92%. When the molecular weights of the obtained three kinds of products were measured by a gas mass spectrometer, all were 168. ₁ H-NMR, ₁₉ F-NMR
As a result of spectrum analysis, CF ₃ OCF ₂ CH ₂
F (bp = -28 ° C) 24.2 g (yield 72%), C
4.5 g of F ₃ OCHFCHF ₂ (bp = −30 ° C.)
(Yield 13.5%) and CF ₃ OCH ₂ CF ₃ (bp
= -32 ° C) was obtained (1.5 g, yield 4.5%).

A tetrafluoroethylene-hexafluoropropylene copolymer (Neoflon FEP NP-20 manufactured by Daikin Industries, Ltd.) was used as a fluororesin, and C was used as a foaming agent.
F ₃ OCF ₂ CH ₂ F (trifluoromethyl-1-difluoro-2-fluoroethyl ether) was used, 0.2 parts by weight of boron nitride and 0.2 parts by weight of magnesium hydrogen carbonate were used as a nucleating agent, and the extrusion temperature ( 370 ° 365 ° 360 ° 35
A coaxial cable was manufactured in the same manner as in Example 1 except that extrusion was performed at 0 ° / 340 ° C. Table 1 shows the measurement results of the electrical characteristics.

Comparative Example 2 24.0 g (0.4 mol) of methyl ethyl ether was charged into a 10 L stainless steel autoclave equipped with a stirrer, and F ₂ / N ₂ (fluorine gas concentration 30%) gas was supplied at a pressure of 10 kg /. It was press-fitted to have a pressure of cm ^2, and reacted at a temperature of 60 ° C. for 6 hours. After the reaction was completed, the product was -50
When cooled to 0 ° C., unreacted fluorine gas was released from the draft into the scrubber, and the liquid product was analyzed by a gas chromatograph analyzer. In addition to unreacted methyl ethyl ether, nine peaks were observed. These peaks are CF ₃ OCF ₂ CF ₃ , CF ₃ OCF ₂ CF ₂ H,
CF ₃ OCHFCF ₃ , CF ₃ OCHFCHF ₂ , CF
₃ OCH ₂ CF ₃ , CF ₃ OCHFCH ₂ F, CF ₃ O
CH ₂ CHF ₂ , CF ₃ OCH ₂ CH ₂ F, CF ₃ OC
Although considered to be H ₂ CH ₃ , these products were difficult to separate, the conversion rate of chemical fluorination was as low as 30%, and 16.2 g of unreacted methyl ethyl ether was recovered.

[0021]

[Table 1]

[0022]

EFFECT OF THE INVENTION Ni-NiO plate as the anode, Ni plate as the cathode,
Dimethyl carbonate / acetonitrile as organic solvent, Et ₃ N · 5HF as fluorinating agent, LiClO as supporting electrolyte
₄ and an electrolyte solution containing a small amount of a fluorine-based surfactant,
By the potentiostatic electrofluorination method, hydrofluoroether can be produced from methyl ethyl ether with high yield and high current efficiency at room temperature and atmospheric pressure. By using these compounds as a foaming agent, the dielectric constant and dielectric loss are small, the ozone depletion potential is zero, the global warming potential is very small, and the environment-friendly high-foam polyethylene insulated wire and high-foam fluororesin insulated wire are used. Can be manufactured. In particular, the high-foam polyethylene insulated electric wire is extremely useful as a CATV coaxial cable or a city coaxial cable. Also,
Hydrogen gas produced as a by-product in the cathode cell can be effectively used for fuel cells.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a manufacturing apparatus used for manufacturing a hydrofluoroether compound.

[Explanation of Codes] Teflon (PFA) electrolyzer (1 L) Potential electrolysis device (Yanagimoto Seisakusho) Porous Teflon diaphragm (1.5 mm thick) Cooling tube (-50 ° C) Ni-NiO plate Anode (3 × 6cm) ▲ 11 ▼ Hydrogen gas collection device (5L) Ni plate cathode (3 × 6cm) ▲ 11 ▼ Reaction product collection tank (1L) Cooling tank (-5 ° C) ▲ 12 ▼ Cooling device (-50 ° C) Stirring Device (Magnetic Stirrer) (13) Hydrogen cylinder reference electrode (Ag / Ag + / MeCN)

Claims (4)

[Claims] 1. An ether compound, an organic solvent soluble in ether, and R ₃ N.nHF or R ₄ as a fluorinating agent.
NF / nHF, an electrolyte containing inorganic acid, alkali hydroxide, LiClO ₄ , LiPF ₆ or LiBF ₄ and a fluorine-based surfactant as a supporting electrolyte, a nickel / nickel oxide electrode as an anode, and a nickel electrode as a cathode A method for producing a hydrofluoroalkyl ether compound, which is characterized in that it is produced by an electrolytic fluorination method (anodic oxidation). 2. The method for producing a hydrofluoroalkyl ether compound according to claim 1, wherein the ether compound is dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether or dipropyl ether. 3. A foamed resin, a foamed rubber, a foamed insulated wire, a foamed tube and a foamed sheet containing a hydrofluoroalkyl ether compound produced by an electrolytic fluorination method as a foaming agent. 4. A refrigerator and an air conditioner using a hydrofluoroalkyl ether compound produced by an electrolytic fluorination method as a refrigerant.