JPS6045620B2 - Method for producing perfluorovinyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing perfluorovinyl ether.

Many fluorine-containing vinyl compounds are known, such as mCF2C.
F2CF2C00M has two reactive non-conjugated terminal double bonds.
Few have more than one.

For example, CF2=CFCF2CF=CF2
-25437), CF2■CF-O-CF■CF2 (Special Publication No. 44-20734), CF. ■CFO (CF.C
F. O)nCF■CF2 (Special Publication No. 15426, Showa 44)
, CH2(H(CF2)ni(N"C-(CF2)nC
H(H2NNc/N (US Pat. No. 3,847,916),
CF2■CF0(CF,)0CF=CF2,CF2=C
F0CF2CF=CFCF3(R, 5u] ivan, J
, 0, C, , 34.1841 (1969)), and these divinyl compounds are
Except for the last example, the reactivities of the two double bonds are equal.

According to the research of the present inventor, when a divinyl compound whose two double bonds have the same reactivity is copolymerized with a vinyl compound, both double bonds react, resulting in a copolymerization reaction. It is difficult to leave double bond-containing side chains in the polymer.

For example, even if such a divinyl compound as described above is used as a monomer for the crosslinking site of a fluoropolymer, it is difficult to obtain residual double bonds, and the efficiency of improving crosslinking properties thereby is extremely low. Based on the recognition of the above-mentioned problems, the present inventor conducted various studies and studies on fluorine-containing vinyl compounds having two double bonds with different reactivities, and found that one end is a perfluorovinyl ether group. It has been found that a fluorine-containing vinyl compound having a perfluoroallyl group at the other end is suitable for the purpose.

In order to provide a means for smoothly and advantageously producing such a specific fluorine-containing vinyl compound, various studies and studies have been conducted, and as a result, the following interesting findings have been obtained. That is, CF2=CFO group at one end and -(C
F2) When a metal salt having a 3C00M group is used and subjected to a specific thermal decomposition reaction, surprisingly, -(CF
2) It has been discovered that 3C00M group can be easily converted to -CF2CF=CF2 group.

By this method, perfluorovinyl ether having two double bonds with different reactivities can be synthesized in good yield. Thus, the present invention has been completed based on the above findings, and consists of the general formula (where n is 0 or 1).
~3 integer, m is 0 or an integer from 1 to 4, and n(5m
are never 0, M is an alkali metal) at a temperature of 230 to 400'C.
Provides a new method for producing perfluorovinyl ether, which is characterized by producing a compound represented by the general formula (where n and m are the same as above) by thermal decomposition in a residence time of ~30 seconds. It is something to do.

The thermal decomposition reaction of the present invention is carried out at a temperature of 230-400°C with a residence time of 0.1-30 seconds.

The thermal decomposition temperature is preferably a relatively low temperature of about 250 to 300°C. If the temperature is too high, the proportion of unidentified high-boiling compounds in the product increases, and if the temperature is too low, the rate of thermal decomposition tends to be very low. Furthermore, thermal decomposition with a short residence time of 0.1 to 30 seconds at the above-mentioned temperature is important.

If the residence time is too long, the allyl vinyl ether produced will further react, and the yield of the target product will tend to decrease. Generally, it is desirable to shorten the residence time when the temperature is high. The raw material for the thermal decomposition reaction in the present invention is desirably used with a water content of 100 ppm or more.

If the thermal decomposition reaction is carried out in a state where more water is contained, the proportion of various by-products contained in the product will increase, making it difficult to preserve double bonds in particular, and the yield of the target product will decrease. Show trends. Of course, it is desirable to manage the water content in the thermal decomposition reaction zone from the above point of view, and for example, care must be taken in conditioning the reactor or dehydrating and drying the heat medium, which will be described later. In the thermal decomposition reaction, it is also possible to perform the decomposition reaction under heating using the raw materials as they are.

It is also possible to carry out the reaction in the presence of an alkali metal salt, such as NaF or NaCI, which is stable under the reaction conditions of the present invention as a heating medium. In the general formula, it is desirable to conduct the thermal decomposition reaction in the presence of an alkali metal salt from the viewpoint of improving heat conduction and ease of controlling residence time. Further, as mentioned above, since this reaction is strongly affected by moisture, it is important to sufficiently dehydrate and dry the alkali metal salt that is coexisting. A common method for drying raw materials is to calcinate them at high temperatures, but this method is difficult to apply because the metal salts of the raw materials are thermally decomposed. Therefore, C
After dispersing the raw materials in a solvent that is azeotropic with water, such as Cl4,
An effective method is to azeotropically distill off the solvent along with the water. In the present invention, raw materials can be obtained by various means.

In the general formula of the raw material, M is an alkali metal, and usually Na or K is employed. Also, n is 0 or 1 to 3
, but those where n is O or 1 are easily available. m
is O or an integer from 1 to 4, but usually m is 0 or 1 to 4.
2 are easy to obtain. In the present invention, both n and m are never 0. For example, it is possible to synthesize the ester 1 (R is an alkyl group) by hydrolyzing it with HCI or the like and then reacting it with NaOH.

In this case, when the ester is directly hydrolyzed with NaOH, the perfluorovinyl ether group is also decomposed, resulting in a perfluoro acid dimetallic salt. Alternatively, the ester may be obtained by reacting an alcohol called ROH with the acid fluoride, or the acid fluoride may be directly reacted with Na2cO3. For example, as a method for synthesizing esters, JP-A-52-10511
No. 8, JP-A-52-78827, etc. others,
As described in Japanese Patent Publication No. 45-22327, etc., it is also possible to synthesize it and then partially thermally decompose it.

The perfluorovinyl ether obtained by the present invention has reactive double bonds -CF, CF=CF in the polymer.

It is effective as a monomer for introducing rubber, especially as a vulcanization site for rubber. In addition, a homopolymer of this monomer or a copolymer with some second component has -CF in the molecule.
. CF=CF. By containing a high concentration of groups, it can also be applied as a thermosetting resin using peroxide or the like. Furthermore, for copolymers containing this monomer,
It is also possible to impart new properties through various reactions, such as radical grafting reactions with other monomers and reactions with nucleophilic reagents. Next, embodiments of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such explanations. Example 1 According to the method described in Japanese Patent Application No. 53-18144, methanol and -1 ゛ - ' - were reacted in a reaction molar amount r at a ratio of 1.1/1 and a reaction temperature of 10°C. At the very least, Ichikami 1 ゛ − ′ − 1 ι was synthesized and used as a raw material.

Add 0.2 mol of this ester to acetone/water (80/20)
Add to mixed solvent 11, add hydrochloric acid to a concentration of 0.2 mol/l, reflux for 20 hours to hydrolyze, and then add KOH aqueous solution, being careful not to make the reaction system alkaline. When neutralized, potassium salt CF2,
-CFOCF2CFO(CF2)SCO2Kl is obtained.

CFa CCI 52 da of the obtained potassium salt.

The mixture was azeotropically dried to a water content of 7 ppm, and then subjected to a thermal decomposition reaction. Soybean powder was placed in a flask connected to a vacuum pump via a dry ice trap, and heated to 240°C in a silicone oil bath. The dry potassium salt was added little by little into the flask under reduced pressure to carry out a thermal decomposition reaction. The obtained product 42y was subjected to gas chromatograph direct mass spectrometry, nuclear magnetic resonance spectroscopy ("°C and 1
°F), infrared absorption spectrum, gas chromatography, etc., it was confirmed that it consisted of the following components.

The desired product, a divinyl compound, was a colorless and transparent liquid with a boiling point of 109.6°C.

The attached drawing is an infrared absorption spectrum of the target object. C.F.
Absorptions of (9) d-1 and 1760c7n-1, which are characteristic absorptions of 2=CFO- and CF2=CFCF2-, are observed. Example 2 In the same manner as in Example 1, except that ゜D? Using 1゛-゜, ■2-VlV! i゛2EyuuiA
12-5, υ2 and Ni were formed.

Next, according to the same recipe as in Example 1, hydrolysis and neutralization reaction with NaOH were carried out to obtain ----゜゜゜゜゛゛゛゛''-.The obtained sodium salt 35y was After drying with carbon chloride, 270℃
Thermal decomposition was carried out at The recovered liquid product was 25y, and gas chromatography etc.≦? As a result of the analysis, the following components were identified.

[Brief explanation of the drawing]

The attached drawing shows the infrared absorption spectrum of the target product in Example 1.

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, n in the formula is 0 or an integer from 1 to 3, m is 0 or 1
~4 integer, n and m are never both 0, M is an alkali metal) at 230~400℃
The compound represented by the general formula ▲ has a mathematical formula, chemical formula, table, etc. ▼ (however, n and m in the formula are the same as above) by thermal decomposition at a temperature of 1. A method for producing perfluorovinyl ether, characterized by producing perfluorovinyl ether. 2. The manufacturing method according to claim 1, which uses a metal salt represented by ▲a mathematical formula, a chemical formula, a table, etc.▼ (where M is an alkali metal).