JPS626701B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a fluorine-containing carboxylic acid ester. Fluorine-containing carboxylic acid esters, represented by perfluorocarboxylic acid esters, are quite thermally stable and have low surface energy properties, as described in US Pat. No. 2,567,011, so they are used in various It has many uses, and is also an important compound as a synthetic intermediate. Conventionally, fluorine-containing carboxylic acid esters have generally been synthesized mainly by two methods. For example, a method in which a fluorinated carboxylic acid fluoride obtained by electrolytic fluorination of a carboxylic acid or a derivative thereof is reacted with an alcohol, or a method in which a fluorinated carboxylic acid obtained by oxidizing perfluoroolefin, etc. is mixed with a concentrated mineral acid. A method of esterification using an alcohol in the presence of a catalyst is known. However, the former synthesis method has the disadvantage of generating hydrogen fluoride, which is highly toxic and difficult to handle, and the latter synthesis method also has the disadvantage of requiring heating in the presence of a considerable amount of concentrated mineral acid. . The present inventors have so far conducted systematic research on the reactions of various fluorine-based olefin compounds with halogenated formate esters and acid halides containing carboxylic acid ester groups. As a result, they discovered that fluorine-containing carboxylic esters can be produced by reacting perfluoroolefins with halogenated formic esters or halogenated glyogyzalic esters in an aprotic solvent in the presence of fluorides, and have already proposed did. Subsequently, the present inventors conducted further detailed research and found that various types of The present inventors have discovered that it is possible to produce a fluorine-containing carboxylic acid ester having the following structure, and have completed the present invention. That is, the present invention provides fluorine-containing -
This is a method for producing a fluorine-containing carboxylic acid ester, which is characterized by reacting an α,β-unsaturated ether compound with a halogenated formate or an acid halide containing a carboxylic acid ester group in the presence of a fluoride. The present invention is characterized by reacting various relatively easily available fluorine-containing α,β-unsaturated ethers with halogenated formate esters or carboxylic acid ester group-containing acid halides, which are difficult to produce by conventional methods. The advantage is that a fluorine-containing carboxylic ester having a carboxylic acid ester group or a keto acid ester group at the α- or β-position carbon of the ether oxygen can be produced. The contents of the present invention will be explained in detail below. Fluorine-containing α, β- used as raw material in the present invention
Unsaturated ether compounds have one or more

It is necessary to have the structure [Formula] and also to contain a fluorine atom. In this case, if at least one fluorine atom or a group containing a fluorine atom is directly bonded to a carbon atom forming a double bond represented by the above formula, the desired fluorine-containing carboxylic acid can be obtained with a preferable yield. An ester is obtained.
Regarding the position of the double bond in the molecule, it is between the terminal carbon atom and the adjacent carbon atom, or between the second carbon atom from the terminal and the third carbon atom.
Using an α,β-unsaturated ether compound present between the carbon atoms also gives favorable results in terms of yield. Particularly preferred is within the molecule.

A compound having one or more structures of the formula: (where A, B, and E are fluorine atoms or trifluoromethyl groups). In order to simplify the explanation, a compound having one of the above structures in the molecule will be specifically explained below, but the following explanation may be applied to compounds having two or more of the above structures in the molecule. Fluorine-containing α, which is one of the raw materials used in the present invention,
The β-unsaturated ether compound has the general formula

When represented by the formula, R is a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10; an alkenyl group such as an allyl group;
Suitable examples include cycloalkyl groups such as cyclohexyl groups; aralkyl groups such as phenethyl groups; and phenyl groups. Groups derived by substituting one or more hydrogen atoms in these hydrocarbon residues with other atoms or atomic groups can also be suitably used. The atoms or atomic groups that can be substituted for the above hydrogen atoms are not particularly limited, but those that are inert under the reaction conditions of the present invention are more preferable, such as halogens such as fluorine, chlorine, sulfur, and iodine; esters; sulfonic acids. Examples include atoms or atomic groups such as esters, ketones, thioketones, ethers, thioethers, and aldehydes. In particular, R is a linear or branched perfluoroalkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, or 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms having one or more ether bonds. Straight chain or branched perfluorinated groups are preferably used. In the present invention, in addition to the fluorine-containing α,β-unsaturated ether, a halogenated formate or a carboxylic acid ester group-containing acid halide is used as another raw material. Halogenated formate has the general formula

Those represented by [Formula] and acid halides containing carboxylic acid ester groups have the general formula

[Formula] or

Any compound represented by the formula can be used without particular limitation. However, in the above general formula, X is a halogen atom selected from fluorine, chlorine, silium, and iodine, and R _M is a difunctional organic group. Below, R ₁ in the above general formula
and R _M will be explained in detail. R ₁ is a hydrocarbon residue, generally having 1 to 20 carbon atoms such as methyl, ethyl, isoamyl, octyl, nonyl, etc.
Preferably 1 to 12 straight-chain or branched alkyl groups;
These include alkenyl groups such as allyl groups; cycloalkyl groups such as cyclohexyl groups; aralkyl groups such as phenethyl groups; and phenyl groups. They also contain one or two hydrogen atoms in the hydrocarbon residue.
Groups derived by substituting one or more atoms or atomic groups with other atoms or atomic groups can also be preferably used. The atoms or atomic groups that replace the above hydrogen atoms are not particularly limited, but are more preferably inert under the reaction conditions of the present invention, such as fluorine, chlorine, silium,
Preferred are atoms or atomic groups such as halogen atoms such as iodine; esters; sulfonic acid esters; ketones; thioketones; ethers; thioethers; aldehydes. Further, R _M is generally a difunctional organic group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. Examples of the difunctional organic group include linear or branched difunctional alkylene groups, and those in which one or more of these hydrogen atoms are replaced with other atoms or atomic groups. The substituent atoms or atomic groups are not particularly limited, but are preferably inert under the conditions of the present invention, such as halogens such as fluorine, chlorine, sulfur, and iodine; esters; sulfonic acid esters; ketones; thieketones; ethers. Atoms or atomic groups such as; thioether; aldehyde are preferred. In particular, R
_M is a linear or branched bifunctional perfluoroalkylene group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms;
Or, in the case of a linear or branched bifunctional perfluorinated group having one or more ether bonds having 1 to 20 carbon atoms, preferably 1 to 10, the target fluorine-containing carboxylic acid ester Very favorable results are obtained in terms of yield. More specifically, what is most commonly and suitably used is, for example:
FOC―CF ₂ ―COOC ₂ H ₅ , FOC―(CF ₂ ) ₃ ―
COOCH ₃ ,

【formula】

[Formula] etc. are suitable. In the present invention, a fluoride is used when reacting a fluorine-containing α,β-unsaturated ether with a halogenated formate or a carboxylic acid ester group-containing acid halide. The fluoride is not particularly limited, but fluorides of alkali metals or alkaline earth metals are generally preferred. Also used are tetraalkylammonium fluoride, silver fluoride, thallium fluoride, and the like. Among these, alkali metal fluorides such as cesium fluoride, rubidium fluoride, and potassium fluoride are particularly suitable. The amount of the fluoride used varies depending on the type of raw materials such as the fluorine-containing α,β-unsaturated ether and the halogenated formate or carboxylic acid ester group-containing acid halide, reaction conditions, etc. For example, when using a fluoroformate as a halogenated formate, the fluoride is usually 0.1 to 100% by mole based on the fluoroformate.
It is preferable to use it between. Further, when a chloro, bromo, or iodoformate is used as the halogenated formate, it is preferable to use the fluoride in an amount equal to or more than the mole of the halogenated formate.
When using the latter, that is, halogenated formate esters other than fluoroformate esters, the fluoride reacts with these halogenated formate esters to produce fluoroformate esters, and then fluorine-containing esters are formed by the catalytic action of the remaining fluoride. Reacts with an α,β-unsaturated ether compound to obtain a fluorine-containing carboxylic acid ester. Therefore, when a halogenated formate other than a fluoroformate is used, it is necessary to use at least an equimolar amount of the fluoride to the halogenated formate. The same applies when using an acid halide containing a carboxylic acid ester group instead of a fluoroformic acid ester. Since it is necessary to generate a fluoride, it is necessary to use at least an equimolar amount of the fluoride with respect to the carboxylic acid ester group-containing acid halide. Furthermore, it is a preferred embodiment to stir the reaction mixture as a means of uniformly dispersing the fluoride in the reaction system during the reaction. Although the reaction for producing a fluorine-containing carboxylic acid ester in the present invention can be carried out without using a solvent, it is usually preferable to carry out the reaction in the presence of a solvent.
The solvent is not particularly limited and can be used as long as it is an aprotic solvent that does not react with the raw materials. The amount of the aprotic solvent to be used varies depending on the amount of the fluorine-containing α, β-unsaturated ether compound and the fluoride, and cannot be absolutely limited, but in general, the amount of the fluorine-containing α, β-unsaturated ether for compounds
The amount may be selected from the range of 0.1 to 100 mol.
Typical solvents that can be suitably used in the present invention include diglyme, triglyme, tetraglyme,
Sulfolane, hexamethylphosphotriamide, dimethylformamide, dimethylsulfoxide, acetonitrile, benzonitrile, dioxane, N
Examples include methylpyrrolidone. In particular, it is preferable to use a glyme-based solvent because the desired fluorine-containing carboxylic acid ester can be obtained in high yield. Since the generated fluorine-containing carboxylic acid ester is usually isolated by distillation under normal pressure or reduced pressure, it is often advantageous in isolation operations to select a solvent with a boiling point that is significantly different from the boiling point of the product. . The reaction between a fluorine-containing α,β-unsaturated ether and a carboxylic acid ester group-containing acid halide such as a fluoroformic acid ester or a fluorogliogyzalic acid ester will be briefly described below. The reaction between a fluorine-containing α,β-unsaturated ether and a fluoroformic acid ester is shown as follows. or (1) and (2) Which structure is more likely to produce fluorine-containing carboxylic acid esters? Fluorine-containing - α, β
- It depends on the type of unsaturated ether and reaction conditions, so it cannot be generalized. Generally fluorine-containing - α, β
-The type of atoms or atomic groups bonded to the α and β carbons of unsaturated ethers tends to have a particularly large effect. For example, if two fluorine atoms are bonded to the carbon at the β position of a fluorine-containing α,β-unsaturated ether, the one having the structure (1) will have at least one carbon at the β position. When a trifluoromethyl group is bonded, a product having the structure (2) tends to be preferentially produced. A case where a fluorine-containing α,β-unsaturated ether is reacted with a carboxylic acid ester group-containing acid halide will be explained using a fluoroglyogyzalic acid ester as a representative example.

【formula】

【formula】

【formula】 or

【formula】

[Formula] The fluorine-containing carboxylic acid esters that can be obtained are four types having the structures shown in (3) to (6). Compounds having structures (4) and (6) correspond to those obtained by deketing compounds having structures (3) and (5), respectively. The question of whether fluorine-containing carboxylic acid esters having the structure (3), (4) or (5), (6) are more likely to be formed is determined by the fact that fluorine-containing -α ，
It can be determined from the structure of β-unsaturated ether. For example, when two fluorine atoms are bonded to the β-carbon of a fluorine-containing α,β-unsaturated ether,
Those having structures (3) and (4) or, if at least one trifluoromethyl group is bonded to the carbon at the β position, those having structures (5) and (6) are preferential. There is a tendency for this to occur.

Which of the structures (3) and (5) having a keto acid ester group represented by [Formula] or the structures (4) and (6) having an ester group represented by -COOR ₁ is produced? It is not possible to make a general statement as to whether the process is easy or not, as it depends on the type of raw material compound used, reaction conditions, etc. Therefore, it is better to check the product according to these conditions beforehand. Acid halides containing carboxylic acid ester groups other than the above-mentioned fluorogliogyzalic acid esters also have the same tendency as described above. As already mentioned, in the present invention, fluorine-containing α, β
- Various unsaturated ethers can be used, but among them, those with special structures will be explained below. Fluorine-containing - α, β -
General formula as unsaturated ether

[Formula] (where A, B, E and A', B', E' are fluorine atoms or trifluoromethyl groups; R _N is a difunctional perfluorinated group having 1 to 10 carbon atoms; 1 is 0 or A compound or general formula having the structure shown in 1)

[Formula] (where A'', B'', E'' and A, B, E are fluorine atoms or trifluoromethyl groups; n is 0 or 1) can also be preferably used. For example: CF ₂ =CF-CF ₂ -O-CF ₂ CF ₂ -O-CF=
CF ₂ , CF ₂ =CF-O-CF=CF ₂ , CF ₂ =CF-
Examples include CF ₂ -O-CF=CF ₂ . Especially CF ₂
=CF-O-(CF ₂ ) _n -O-CF=CF ₂ (m is 1 to 10) For example, CF ₂ =
CF-O-CF ₂ CF ₂ -O-CF=CF ₂ , CF ₂ =CF-
Preferable results can be obtained by using O-(CF ₂ ) ₄ -CF=CF ₂ or the like. Also, among the α,β-unsaturated ethers shown in the above general formula,

When using a compound having the structure of [Formula] at both ends of the molecule, it is a product obtained by reacting an acid fluoride containing a fluoroformate or carboxylic acid ester group with one or both of its double bonds, or a mixture of both. is obtained. In this case, if a halogenated formate or acid halide containing a carboxylic acid ester group is used in a molar ratio of 2 to 10, preferably 2 to 4, to the unsaturated ether compound, the fluorinated dicarboxylic acid ester can be obtained efficiently. Further, when used at a molar ratio of 2 or less, preferably 1.5 or less, a fluorine-containing monocarboxylic acid ester is easily obtained. At one end of the molecule in the α,β-unsaturated ether shown by the general formula above,

The structure of [Formula] is also bonded with oxygen at the other end. I haven't done it

When using a compound having the structure of [Formula], in some cases, the acid fluoride containing a fluoroformate or carboxylic acid ester group may react not only with the former but also with the latter to give a fluorine-containing dicarboxylic acid ester. , such items can also be used separately. As is clear from the above explanation, fluorine-containing α, β
- Various fluorine-containing carboxylic esters can be obtained by reacting an unsaturated ether with a halogenated formate or an acid halide containing a carboxylic ester group. In particular, by adjusting the molar ratio of the two raw materials and reacting them, it is possible to obtain a fluorine-containing carboxylic acid ester having both a double bond and an ester group in one molecule. The fluorine-containing carboxylic acid ester having a double bond and an ester group in one molecule may be used as it is or, if necessary, may be subjected to a keto reaction or the carboxylic acid ester group may be converted to other groups such as an amide group or a carboxyl group. Afterwards, it can be copolymerized with tetrafluoroethylene, hexafluoropropylene, etc. The copolymer is useful as a raw material for producing cation exchange membranes. The reaction temperature in the present invention varies depending on the type of raw materials, the type of fluoride, the type of solvent if used, etc., and cannot be absolutely limited, but is generally in the range of -20°C to 200°C. You can choose from. It is usually preferable to carry out the reaction between -20°C and 170°C. In the reaction of a fluorine-containing α,β-unsaturated ether with a carboxylic acid ester group-containing acid halide, the fluorine-containing keto acid ester or the fluorine-containing keto acid ester undergoes a deketo reaction depending on the reaction temperature, as described above. A fluorine-containing non-keto acid ester is obtained. In the reaction of a fluorine-containing α,β-unsaturated ether with a carboxylic acid ester group-containing acid halide, the reaction temperature at which a fluorine-containing non-keto acid ester can be obtained in high yield without a ketosis reaction is generally set at a temperature that is suitable for the reaction. It varies depending on the type of fluoride used. For example, when using cesium fluoride as the fluoride, the temperature is preferably 60°C or higher, usually between 80°C and 170°C. Further, when potassium fluoride or quaternary alkyl ammonium fluoride is used, the temperature is preferably 120°C or higher. Under conditions below these temperatures, fluorine-containing keto acid esters usually tend to be produced. However, if the reaction temperature is extremely high, the raw materials or reaction products may decompose, so it is preferable to select a suitable reaction temperature in advance. The pressure may be elevated, normal pressure, or reduced pressure, but when the boiling point of the raw materials is low, it is convenient for operation to carry out the reaction under natural pressure with the raw materials charged. Note that the reaction atmosphere may or may not be replaced with an inert gas. The reaction time is not particularly limited and can be selected from several tens of minutes to several days, but generally several hours to several tens of hours is sufficient. The type of reaction vessel is not particularly limited, and those made of glass, metal, etc. are preferably used. EXAMPLES Examples are shown below to explain the present invention more specifically, but the present invention is not limited to these Examples. In addition, the reaction yield in the examples is based on the weight of the fluorine-containing carboxylic acid ester theoretically produced from the fluorine-containing α,β-unsaturated ether compound used as the raw material, and the weight of the fluorine-containing carboxylic acid ester actually isolated by distillation from the reaction mixture. It is expressed as a weight ratio of the fluorine-containing carboxylic acid ester. Example 1 15 ml of tetraglyme and 3 g of cesium fluoride were placed in a 50 ml eggplant-shaped flask, and after stirring thoroughly, CF ₂ =
5.5 g of CF--O--C ₃ F ₇ and 2.2 g of FOC-COOCH ₃ were added and reacted at room temperature for 2 hours. Next, add this reaction solution to
Distilled under reduced pressure at 5 mmHg on an oil bath at 50°C, distillate liquid 6.5
I got g. This product is further rectified with a boiling point of 143-145
℃

[Formula] 5.8g was obtained. (Yield: 75.4%) The structure of this product was determined based on the following various measurement results. (a) Infrared absorption spectrum: CH absorption is observed at 2950 cm ^-1 and carbonyl (C=O) absorption is observed at 1770 cm ^-1 (Shoulder) and 1750 cm ^-1 . (b) ¹⁹ F―nmr (CFCl ₃ standard δppm). Two types of CF ₃ at −81.2 and −82.4ppm −
CF at 134.1ppm, CF ₂ at −129.9ppm, −78.8, −
83.7ppm (dieminal coupling) -
Absorption based on CF ₂ --O is observed. (c) ¹³ Cnmr (tetramethylsilane standard, δ
ppm, ¹ H and ¹⁹ F decoupling). 118.2, 117.5, 116.3, 107.0, 103.1, 53.1ppm
to 179.3 ppm with six absorptions of

[Formula] 158.6ppm

Absorption based on the carbonyl carbon of [Formula] was confirmed. (d) Elemental analysis value (%) Analysis value: C25.56, H0.82, F56.47; Theoretical value: C25.82, H0.81, F56.17 Example 2 20ml of tetraglyme in a 50ml eggplant-shaped flask, After adding 4g of cesium fluoride and stirring thoroughly, CF ₂ =
6.2 g of CF--O--C ₃ F ₇ and 2.5 g of FOC-COOCH ₃ were added, a ball reflux condenser was attached, and the mixture was reacted for 3 hours with stirring on an oil bath at 160°C. Thereafter, 6.7g of the liquid obtained by vacuum distillation at 25mmHg on an oil bath at 160°C was further rectified to achieve a boiling point of 105-107°C.

[Formula] 4.9g was obtained. (Yield: 61.1%) The structure was confirmed by infrared absorption spectra, ¹ H, ¹⁹ F, ¹³ C nuclear magnetic resonance spectra, mass spectrometry elemental analysis, etc. Example 3 After putting 20 ml of tetraglyme and 3 g of cesium fluoride into a 50 ml eggplant-shaped flask and stirring well, CF ₂ =
5.2 g of CF-O-C ₃ F ₇ and 1.6 g of F-COOCH ₃ were added and reacted at room temperature for 6 hours. Next, this reaction solution was heated to 80°C.
Distillation was carried out under reduced pressure on an oil bath to obtain 5.3 g of volatile matter. This product is further rectified and has a boiling point of 105-107℃.

[Formula] 4.9g was obtained (yield 71.5%). The structure was confirmed by infrared absorption spectrum, ¹ H, ¹⁹ F, ¹³ C nuclear magnetic resonance spectrum, mass spectrum, elemental analysis, etc. Example 4 Put 3 g of cesium fluoride and 20 ml of tetraglyme into a 50 ml eggplant-shaped flask and stir well.

[Formula] (cis-isomer, trans-isomer mixture) 6.7g was added and stirred at room temperature for 2 hours.
To this mixed solution, 7.2 g of FOC-COOC ₂ H ₅ was gradually added dropwise from the dropping funnel over 5 hours. 2 more at room temperature
Distilled under reduced pressure after stirring for days, boiling point 100-131℃/9
25 g of a fraction containing mmHg tetraglyme was obtained.
Next, this mixture was placed in a separatory funnel, washed twice with water, the lower layer was separated, and anhydrous sodium sulfate was added to
After drying in the sun, distill under reduced pressure to boiling point 107-110℃/3mm
Hg

[Formula] 8.3g was obtained (yield 80.7%). The structure was confirmed by infrared absorption spectrum, ¹ H, ¹⁹ F, ¹³ C nuclear magnetic resonance spectrum, mass spectrum, elemental analysis, etc. Example 5 40 ml of tetraglyme and 6 g of cesium fluoride were placed in a 100 ml eggplant-shaped flask, and after stirring well, CF ₂ =
10.4 g of CF—O—CF ₂ CF ₂ —O—CF=CF ₂ was added, and 10.0 g of FCOOCH ₂ CH=CH ₂ was gradually added dropwise from the dropping funnel over 2.5 hours while stirring at room temperature.
After further stirring at room temperature for 3 hours, the reaction solution was
Distilled under reduced pressure at 10mmHg on an oil bath at 140°C to yield 18.7g of distillate.
I got it. This distillate is rectified and the boiling point is 118-120℃/
10mmHg 15.5 g of CH=CH ₂ were obtained. (Yield 87.3%) The structure was confirmed by infrared absorption spectrum, ¹ H, ¹⁹ F, ¹³ C nuclear magnetic resonance spectrum, mass spectrum, elemental analysis, etc. Example 6 After putting 3 g of cesium fluoride and 20 ml of tetraglyme into a 50 ml eggplant-shaped flask and stirring well, CF ₂ =
Add 5.2 g of CF―O―CF ₂ CF ₂ -O―CF=CF ₂ from the dropping funnel at room temperature and stirring well.
A solution prepared by diluting 1.7 g of FCOOC ₂ H ₅ in 10 ml of tetraglyme was added dropwise over 4 hours. After further stirring at room temperature for 2 hours, the reaction solution was placed on an 80℃ oil bath.
Distillation was carried out under reduced pressure at 0.1 mmHg to obtain 4.8 g of a distillate mixture. This product was distilled again to give a boiling point of 65℃/26.5mmHg. 1.9g was obtained. (Yield 27.8%) Furthermore, from this distillation residue, the corresponding diester 0.7g was obtained. (Yield 8.3%) The structure was confirmed by infrared absorption spectrum, ¹ H, ¹⁹ F, ¹³ C nuclear magnetic resonance spectrum, mass spectrum, elemental analysis, etc. Example 7 In the same manner as in Example 1, various α,β-unsaturated ether compounds (raw material A) and halogenated formate esters (raw material B) or various acid halides containing carboxylic acid ester groups were prepared. (Raw material B)
were reacted under the conditions shown in Table 1. The structures and yields of the reaction products obtained in these cases are also shown in Table 1.

【table】

【table】

【table】

【table】

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【table】

Claims (1)

[Claims] 1. A method for producing a fluorine-containing carboxylic acid ester, which comprises reacting a fluorine-containing α,β-unsaturated ether compound with a halogenated formate or a carboxylic acid ester group-containing acid halide in the presence of a fluoride. .