JPH0542421B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a method for producing a fluorinated ester having a trifluoromethyl group in high yield by an esterification reaction between 1.1.1-trifluoroethyl chloride and a carboxylate. Prior art and its disadvantages 2.2.2-trifluoroethanol easily obtained by hydrolyzing the above fluorinated ester
CF ₃ CH ₂ OH is a thermally extremely stable fluorine-containing alcohol, and is used as a working fluid for waste heat recovery in medium and low temperature ranges and waste heat recovery systems for large diesel engines, and has a low refractive index.
2.2.2 - Fluorine-containing acrylic polymers derived from trifluoroethanol and acrylic acid are used as sheath materials for optical fibers, and are also used as raw materials for phosphazene polymers that have excellent heat resistance, oil resistance, and flame retardancy. Its usefulness has been attracting attention in recent years. GP863190 discloses that 1.1.1-trifluoroethyl chloride and potassium acetate are mixed at 200°C to 250°C without a solvent or in glacial acetic acid for 80 to 90°C.
A method for synthesizing 2.2.2-trifluoroethyl acetate in a reaction time of 40 to 50 hours under atmospheric pressure is disclosed. Furthermore, JP-A-58-135836 describes a method for producing corresponding fluorinated esters from 1.1.1-trifluorohalogenated ethane and various carboxylic acid salts using γ-butyrolactone as a solvent. There is. Furthermore, USP4434297 specification (Japanese Patent Application Laid-open No.
13742), 1.1.1-trifluoroethyl chloride and an alkali metal salt of a carboxylic acid such as potassium acetate are reacted at about 150°C to 180°C using N-methylpyrrolidone as a solvent,
A method for obtaining a carboxylic acid ester of 2.2.2-trifluoroethanol is described, and this method is considered to be the best among the known methods. For example, the specification states that by increasing the molar ratio of 1.1.1-trifluoroethyl chloride to potassium acetate by 20 to 300%, a conversion rate of potassium acetate of 84% or more can be obtained. Are listed. However, this method requires the recovery and reuse of a large amount of the highly volatile 1.1.1-trifluoroethyl chloride added in excess, which complicates the recovery equipment, and the yield is only 88%. This method is not satisfactory for industrial implementation, as the degree of improvement is still not sufficient. On the other hand, as previously disclosed in Japanese Patent Application No. 58-228212, the present inventors made the molar ratio of 1.1.1-trifluoroethyl chloride smaller than that of the carboxylic acid salt in an aprotic polar solvent. The reaction proceeded satisfactorily, and the conversion rate of 1.1.1-trifluoroethyl chloride was also excellent. Since this 1.1.1-trifluoroethyl chloride is a highly volatile and expensive raw material, it is desirable to minimize the loss during recovery.
Rather than the method described in the specification, the molar ratio of potassium acetate to 1.1.1-trifluoroethyl chloride is equimolar or slightly excess to achieve a high conversion rate of 1.1.1-trifluoroethyl chloride in a single reaction. It is thought that a method that obtains
Furthermore, in this method, lowering the molar ratio of 1.1.1-trifluoroethyl chloride lowers the reaction pressure, and if the pressure remains the same, the production amount can be increased, so it can be said to be an excellent method. According to the method described in the above-mentioned Japanese Patent Application No. 58-228212, a conversion rate of about 90% of 1.1.1-trifluoroethyl chloride and a yield of about 94% of the produced ester can be obtained, and even this method is not sufficient. However, the present inventors further studied this reaction in detail in order to provide a production method with a high conversion rate of 1.1.1-trifluoroethyl chloride to nearly 100%, and found that They found that it contained acidic substances, and confirmed that most of them were carboxylic acids. The reason for the formation of this carboxylic acid is as follows:
A competitive reaction by the following formula CF ₃ CH ₂ Cl + CH ₃ COOK → KF + acidic substance described in the specification of USP 4434297 is also assumed, but analysis of the by-product fluorine ion also revealed that it was very small, so it is likely that the acidic substance is due to another reason. It is estimated that it will generate. Although the reason for the formation of carboxylic acid is not clear, a portion of the initially added carboxylate becomes carboxylic acid during the reaction, and the reaction does not proceed any further, resulting in the conversion of 1.1.1-trifluoroethyl chloride. The rate was found to be around 90%. Therefore, the present inventors believed that if this by-product carboxylic acid could be effectively utilized, the conversion rate of 1.1.1-trifluoroethyl chloride would be improved, and as a result of continued research, they found that The present inventors have discovered that the conversion rate of 1.1.1-trifluoroethyl chloride can be improved by adding a fluorine compound capable of producing fluorine anions to the fluorine anion. That is, the present invention is an improvement on the method described in the specification of Japanese Patent Application No. 58-228212, etc.
According to the present invention, the esterification reaction of 1.1.1-trifluoroethyl chloride CF ₃ CH ₂ Cl and a carboxylic acid salt is carried out in an aprotic polar solvent. A method for producing a fluorinated ester is obtained, which is characterized in that a fluorine compound capable of producing a fluorine anion is added to the reaction system. According to the present invention, desired fluorinated esters can be produced with extremely high yields and conversion rates.
Further, according to the present invention, since a recovery device for unreacted 1.1.1-trifluoroethyl chloride is virtually unnecessary, it is possible to reduce the cost of the recovery device and increase productivity by improving the conversion rate. Its industrial value is extremely high. The following carboxylic acid salts are suitable for use in the present invention. (1) Monocarboxylate, RCOOM (R is carbon number 18
The following alkyl group or phenyl group, M is Na,
K, Ca or Mg) (2) Dicarboxylate, MOOCRCOOM' (R is an alkylene group having 8 or less carbon atoms or a phenylene group, M and M' are Na, K or Mg and are the same or different) ). (3) Dicarboxylate with ether bond
MOOCROR'COOM' (R and R' are arekylene groups and may be the same or different, the total number of carbon atoms is 10 or less, and M and M' are
Na, K or Mg may be the same or different from each other). These carboxylic acid salts may be used alone or in the form of mixtures. For example,
_CH3COONa , _CH3COOK , ( _CH3COO ) _2Ca , sodium benzoate, potassium benzoate, potassium phthalate, sodium phthalate, potassium oxalate, or bis-(3-carboxyl-propyl)
- Potassium salts of ethers, etc., but are not limited to these. Regarding the amount of these carboxylates used, the molar ratio of carboxylate to 1.1.1-trifluoroethyl chloride (carboxylate/1.1.1-trifluoroethyl chloride) is in the range of 0.5 to 15, preferably 0.1. ~10 range. Solvents used in the present invention include N,N'-dimethylformamide, dimethyl sulfoxide,
It is in the form of one or a mixture of two or more of N,N'-dimethylacetamide, sulfolane and N-methylpyrrolidone. Molar ratio of solvent and 1.1.1-trifluoroethyl chloride (solvent/1.1.1-
trifluoroethyl chloride) ranges from 0.5 to 15, preferably from 0.6 to 10. If this molar ratio is less than 0.5, the solvent effect will not be sufficient,
Moreover, if it exceeds 15, the amount of solvent recovered becomes extremely large, which is not economical. The fluorine compounds added in the present invention that can generate fluorine anions are preferably alkali metal fluorides such as NaF, KF, and CsF, and ammonium salts such as (C ₄ H ₉ ) ₄ NF. The reason why the conversion rate is improved by the addition of a fluorine compound that can generate these fluorine anions is that if acetic acid is used as a carboxylic acid, the following formula CH ₃ COOH + FM → CH ₃ COO ...H F
...M (M is an alkali metal ion, a quaternary ammonium ion, etc.), it is presumed that this is because the fluorine compound that can generate fluorine anions increases the nucleophilicity of the by-produced carboxylic acid. do. That is, it is assumed that the by-produced carboxylic acid is utilized in the esterification reaction due to the action of the fluorine compound capable of producing a fluorine anion, resulting in an improvement in the conversion rate. The amount of the fluorine compound that can generate these fluorine anions is determined by the molar ratio of the fluorine compound that can generate fluorine anions and 1.1.1-trifluoroethyl chloride (fluorine compound that can generate fluorine anions/1.1 .1-trifluoroethyl chloride)
range of 0.02 to 0.6, preferably 0.05 to 0.5
is within the range of If this molar ratio is less than 0.02, the effect of addition is not sufficient, and even if it is greater than 0.6, there is no longer any effect of improving the conversion rate. The reaction temperature is preferably in the range of 150°C to 260°C. If the reaction temperature is less than 150°C, the reaction will be slow and require a long reaction time, and if it exceeds 260°C, side reactions will increase and the quality of the solvent will change. Next, the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited by the following examples. The conversion rate % shown in the following examples and comparative examples is calculated by the following formula: (Charged CF ₃ CH ₂ Clmol - Unreacted
CF ₃ CH ₂ Clmol)/Preparation CF ₃ CH ₂ Clmol
The yield of ester is calculated by the following formula: mol of ester produced/
(Charge CF ₃ CH ₂ Clmol - Unreacted CF ₃ CH ₂ Clmol) Example 1 5 autoclave equipped with a magnetic stirrer (material
SUS316), 28.5mol of sulfolane, potassium acetate
After charging 6.68 mol of potassium fluoride and 1.33 mol of potassium fluoride and sealing the container, 6.67 mol of CF ₃ CH ₂ Cl in the pressure-resistant container was forced into the autoclave using N ₂ gas pressure, and the autoclave was heated in an electric furnace.
The mixture was heated to 210°C and reacted for 1.5 hours with stirring. After the reaction is complete, volatile components in the system are extracted at 210℃, the first stage is cooled with water to collect the fluorinated ester, and the second stage is cooled with dry ice-methanol to collect unreacted components. did. When the collected material was analyzed and quantified using gas chromatography,
Unreacted CF ₃ CH ₂ Cl 0.061 mol (conversion rate 99.1%),
6.23 mol of CF ₃ CH ₂ OCOCH ₃ (yield 94.2%) was obtained. Comparative Example 1 In order to clarify the effect of adding a fluorine compound that generates fluorine anions, Comparative Example 1 shows the results obtained without adding potassium fluoride. Sulfolane was placed in the same autoclave as in Example 1.
28.3mol, potassium acetate 6.67mol,
The same procedure as in Example 1 was conducted except that 6.69 mol of CF ₃ CH ₂ Cl was charged and potassium fluoride was not added.
After the reaction was completed, the same operation as in Example 1 was performed, and analysis and quantification using gas chromatography revealed that
Unreacted CF ₃ CH ₂ Cl 0.619 mol (conversion rate 90.7%),
The amount of CF ₃ CH ₂ OCOCH ₃ was 5.67 mol (yield 93.7%). Example 2 27.3 mol of N-methylpyrrolidone, 6.64 mol of potassium acetate, and 1.36 mol of potassium fluoride were placed in the same autoclave as in Example 1, and 6.64 mol of CF ₃ CH ₂ Cl was introduced into the autoclave in the same manner as in Example 1. After that, the container was sealed and reacted at a temperature of 200°C for 1 hour.
After the reaction was completed, volatile components were extracted in the same manner as in Example 1, except that they were cooled to 180°C and extracted.
When analyzed and quantified by gas chromatography, unreacted CF ₃ CH ₂ Cl0.092 mol (conversion rate 98.6%),
6.17 mol of CF ₃ CH ₂ OCOCH ₃ (yield 94.2%) was obtained. Comparative Example 2 In this comparative example, the reaction was carried out without adding potassium fluoride. That is, N-methylpyrrolidone was placed in the same autoclave as in Example 1.
27.3mol, potassium acetate 6.66mol,
The same procedure as in Example 2 was conducted except that 6.64 mol of CF ₃ CH ₂ Cl was charged and potassium fluoride was not added. The operation after the reaction was completed was the same as in Example 1, except that it was cooled to 180°C and extracted. When analyzed and quantified by gas chromatography, it was found that no reaction occurred.
CF ₃ CH ₂ Cl0.636mol (conversion rate 90.4%),
The amount of CF ₃ CH ₂ OCOCH ₃ was 5.64 mol (yield 94.0%). Example 3 N,N-dimethylacetamide was placed in a 300ml autoclave (material: SUS316) equipped with a magnetic stirrer.
After introducing 1.28 mol of potassium benzoate, 0.421 mol of potassium benzoate, and 0.077 mol of cesium fluoride, and introducing 0.405 mol of CF ₃ CH ₂ Cl, which had been collected in a pressure-resistant glass container in advance, into the autoclave, the autoclave was sealed and allowed to react at 210°C for 2 hours. Ta. After the reaction was completed, the reaction mixture was cooled to 50°C, and volatile components were collected in a trap cooled with dry ice-methanol. Next, the lid of the autoclave was opened, and the contents were quickly filtered through a glass filter to separate the produced potassium chloride, unreacted potassium benzoate, and cesium fluoride from the reaction solution. The collected potassium chloride, potassium benzoate, and cesium fluoride were washed repeatedly with a solvent, and the washing solution was combined with the reaction solution. The volatile components and reaction liquid recovered in these operations were analyzed and quantified by gas chromatography, and it was found that unreacted CF ₃ CH ₂ Cl0.0073 mol (conversion rate 98.2
%), 0.359 mol of C ₆ H ₅ COOCH ₂ CF ₃ (yield 90.3%) was obtained. Comparative Example 3 In this comparative example, the reaction was carried out without adding cesium fluoride. In an autoclave similar to Example 3, add 1.28 mol of N,N-dimethylacetamide and potassium benzoate.
The same procedure as in Example 3 was conducted except that 0.421 mol of CF ₃ CH ₂ Cl and 0.405 mol of CF 3 CH 2 Cl were added and cesium fluoride was not added. When the recovered volatile components and reaction liquid were analyzed and quantified by gas chromatography, no reaction was detected.
CF ₃ CH ₂ Cl0.048mol (conversion rate 88.1%),
The amount of C ₆ H ₅ COOCH ₂ CF ₃ was 0.321 mol (yield 90.0%). Example 4 In an autoclave similar to Example 3, 1.82 mol of N-methylpyrrolidone, 0.447 mol of sodium acetate,
After charging 0.144 mol of potassium fluoride and introducing 0.443 mol of CF ₃ CH ₂ Cl into the autoclave in the same manner as in Example 3, the autoclave was sealed and reacted at a temperature of 230° C. for 3 hours. The operation after the completion of the reaction was carried out in the same manner as in Example 1 except that it was cooled to 180°C and extracted. When analyzed and quantified by gas chromatography, it was found that no reaction occurred.
CF ₃ CH ₂ Cl 0.026 mol (conversion rate 94.1%),
0.352 mol of CF ₃ CH ₂ OCOCH ₃ (yield 84.4%) was obtained. Comparative Example 4 In the same autoclave as in Example 3, 1.82 mol of N-methylpyrrolidone, 0.447 mol of sodium acetate,
The same procedure as in Example 4 was conducted except that 0.445 mol of CF ₃ CH ₂ Cl was charged and potassium fluoride was not added. The operation after the reaction was completed was the same as in Example 1, except that it was cooled to 180°C and then extracted. When analyzed and quantified by gas chromatography, no reaction was detected.
CF ₃ CH ₂ Cl 0.075 mol (conversion rate 83.2%),
The amount of CF ₃ CH ₂ OCOCH ₃ was 0.311 mol (yield 84.0%). Example 5 Using potassium succinate and potassium fluoride in dimethyl sulfoxide as a solvent, 4
Allowed time to react. The operations after completion of the reaction were carried out in the same manner as in Example 3, and the results are shown in Table 1. Example 6 Mixed solvent of N-methylpyrrolidone and dimethylacetamide (53.3% by weight of N-methylpyrrolidone)
The mixture was reacted with potassium oleate and potassium fluoride at 230°C for 2 hours. The operations after the completion of the reaction were carried out in the same manner as in Example 3, and the results were as follows.

【table】

[Table] Shown in the table. Example 7 Using N,N-dimethylformamide as a solvent,
₁₆₀ using potassium phthalate and ( _C4H9 ) _4NF
The reaction was carried out at ℃ for 6 hours. The operations after completion of the reaction were carried out in the same manner as in Example 3, and the results are shown in Table 1. Example 8 Using sulfolane as a solvent, potassium salt of bis-(3-carboxyl-propyl)-ether and cesium fluoride were reacted at 210°C for 2 hours. The operations after completion of the reaction were carried out in the same manner as in Example 3, and the results are shown in Table 1. Comparative Examples 5, 6, 7, and 8 Table 1 summarizes the results of Examples 5, 6, 7, and 8 in which no fluoride that generates fluorine anions was added as comparative examples.

Claims (1)

[Claims] 1 1.1.1-trifluoroethyl chloride
In a method for producing a fluorinated ester having a trifluoromethyl group, in which the esterification reaction between CF ₃ CH ₂ Cl and a carboxylic acid salt is carried out in an aprotic polar solvent, a fluorine anion is generated in the reaction system. A method for producing a fluorinated ester, which comprises adding a fluorinated ester. 2. The method according to claim 1, wherein the fluorine compound capable of producing the fluorine anion is an alkali metal fluoride. 3. The method according to claim 1, wherein the fluorine compound capable of producing the fluorine anion is R ₄ NF (R is an alkyl group having 1 to 4 carbon atoms). 4. The method according to claim 1, wherein the amount of the fluorine compound capable of producing the fluorine anion added is 2.0 to 60 mol% based on 1.1.1-trifluoroethyl chloride. 5 The aprotic polar solvent is NN'-dimethylformamide, dimethyl sulfoxide, N.
N'-dimethylacetamide, sulfolane, N-
The method according to claim 1, wherein the methylpyrrolidone is one or a mixture of two or more thereof. 6. The method according to claim 1, wherein the reaction temperature is in the range of 150°C to 260°C.