JPH0825951B2 - Method for producing perfluoroketone - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to the following general formula (1) R ¹ _f COR ² _f (1) (wherein R ¹ _f and R ² _f are perfluoroalkyl groups each having 1 to 30 carbon atoms). And may contain one or more oxygen atoms as an ether bond.).

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a method for producing the perfluoroketone as described above, the following general formula (4) R ³ _f —COOM ² (4) (wherein R ³ _f is a perfluoroalkyl group having 2 to 50 carbon atoms, It may contain at least one oxygen atom as an ether bond. M ² is a metal atom selected from Li, Na, K, Rb, Cs and Ag. Formula (5) R ⁴ _f —COF (5) (wherein R ⁴ _f is a perfluoroalkyl group having 1 to 50 carbon atoms and may contain one or more oxygen atoms as an ether bond). There is known a method of reacting a perfluorocarboxylic acid fluoride represented by the following in a polar aprotic solvent (US Pat. No. 4,136,121). However, since this method includes a decarboxylation process, it requires a reaction temperature of substantially 100 ° C. or higher, and has a problem that the reaction temperature is high.

As another method for producing perfluoroketone, a fluoroalkyl ether having an unsaturated bond represented by the following general formula (6) and a perfluorocarboxylic acid fluoride R ⁵ _{f represented by the following} general formula (7). OCF = CF ₂ (6) R ⁶ _f COF (7) (However, in both formulas, R ⁵ _f and R ⁶ _f are each a perfluoroalkyl group, and R ⁵ _f and R ⁶ _f are 10 in total. Which has a carbon number of up to 80 and may be linear, branched or cyclic.) In the presence of CsF at a temperature of about 40 ° C. to give a perfluoroketone of the following general formula (8): A method for obtaining the same has been reported (US Pat. No. 4,067,884).

[0004]

Embedded image (However, R ⁵ _f and R ⁶ _f have the same meaning as above.)

However, the compound of the formula (6) used as one raw material in this method needs to be produced by thermally decomposing the perfluorocarboxylic acid metal salt of the formula (9) at a high temperature.

[0006]

Embedded image (However, R ⁵ _f has the same meaning as above, and M ³ is a monovalent metal atom.)

For this reason, there has been a demand for a method capable of producing not only perfluoroketone but also its raw material under mild conditions.

[0008]

Means and Actions for Solving the Problems As a result of extensive studies conducted by the present inventor in order to meet the above demands, the following general formula (2) R ¹ _f M ¹ X (2) (where R ¹ _f is It is a perfluoroalkyl group having 1 to 30 carbon atoms and may contain one or more oxygen atoms as an ether bond, and M ¹ is a metal atom selected from Zn and Cd, preferably Zn. Is R ¹ _f , or
It is a halogen atom selected from Cl, Br and I, preferably I. ) And a perfluorocarboxylic acid fluoride represented by the following general formula (3) R ² _f COF (3) (wherein R ² _f has the same meaning as R ¹ _f above). When the and are reacted in an aprotic polar solvent, the following general formula (1) R ^{1 can be} efficiently obtained under a temperature condition lower than the conventional one, specifically 90 ° C. or lower, preferably 50 ° C. or lower. _f COR ² _f (1) (wherein R ¹ _f and R ² _f have the same meanings as described above), the perfluoroketone can be easily produced, and in this case, the above-mentioned general formula used for this reaction is used. R ¹ _{f of} (2)
They have found that M ¹ X can also be synthesized under low temperature conditions, and have completed the present invention.

Therefore, the present invention is characterized in that the perfluoroalkyl metal compound represented by the formula (2) and the perfluorocarboxylic acid fluoride represented by the formula (3) are reacted in an aprotic polar solvent. Provided is a novel method for producing a perfluoroketone represented by the formula (1).

The present invention will be described in detail below. In the production method of the present invention, a perfluoroalkyl metal compound represented by the following formula (2) R ¹ _f M ¹ X ... (2) is used as a starting material. Here, in the above formula (2), R ¹ _f
Is a perfluoroalkyl group having 1 to 30 carbon atoms, more preferably 2 to 15, and is 1 or more, more preferably 1
The oxygen atom of 4 may be contained as an ether bond. M ¹ is Zn or Cd, preferably Zn. X is the same as R ¹ _f or a halogen atom selected from Cl, Br and I, and is preferably I.

The perfluoroalkyl metal compound of the formula (2) can be prepared by a known method, for example, as described in J. Chem. Soc. 19
53 , 3607; Am. Chem. Soc. 79 ,
4159 (1957) (a method of producing a perfluoroalkylzinc compound by reacting a perfluoroalkyl iodide with metallic zinc in an aprotic polar solvent). it can. That is, according to this method, the par represented by the formula R ¹ _f Y (wherein R ¹ _f has the same meaning as described above, and Y is a halogen atom selected from Cl, Br and I, preferably I). A fluoroalkyl halide and a metal represented by the formula M ¹ (wherein M ¹ has the same meaning as described above) are added to dimethylformamide (DMF), dimethylacetamide (DM).
Ac), dimethyl sulfoxide (DMSO), glyme, diglyme, triglyme, tetraglyme, dioxane, tetrahydrofuran (THF), hexamethylphosphoric triamide (HMPA) and the like in an aprotic polar solvent at a temperature of 0 to 30 ° C. The perfluoroalkyl metal compound represented by the formula (2) can be obtained by reacting for 0.5 to 24 hours, preferably 1 to 3 hours. In this case, it is desirable that the metal M ¹ be activated by previously treating it with dilute hydrochloric acid in an organic solvent such as acetone, washing with water, washing with acetone, and drying. Further, it is desirable that the solvent used is dehydrated in advance by an appropriate method.

As described above, the perfluoroalkyl metal compound which is one of the starting materials of the present invention can be synthesized under low temperature conditions. The perfluoroalkyl halide represented by the formula R ¹ _f Y which is the precursor of this starting material is, for example, Y = I, Japanese Patent Application Nos. 2-222809 and 2-22209 of the present applicant
According to the method described in No. 0, a perfluorocarboxylic acid fluoride represented by the formula R ¹ _f COF and a formula M ³ I _a (provided that
M ³ is a metal atom such as an alkali metal, an alkaline earth metal or Al, and a is a valence number of the metal atom. ), A perfluorocarboxylic acid iodide represented by the formula R ¹ _f COI is obtained, which is then irradiated with ultraviolet rays to carry out a decarbonylation reaction.
It can be easily synthesized under low temperature conditions of ℃ or below.

On the other hand, in the production method of the present invention, perfluorocarboxylic acid fluoride represented by the following formula (3) R ² _f COF (3) is used as another starting material. Here, R ² _f has the same meaning as R ¹ _f in formula (2).

Perfluorocarboxylic acid fluorides of formula (3) are also known methods, for example US Pat. No. 3,250,808.
It can be easily manufactured according to the method described in Japanese Patent Publication No. 3322826.

According to the method of the present invention, R ¹ _f M ¹ of the above formula (2) is used.
The perfluoroalkyl metal compound represented by X and the perfluorocarboxylic acid fluoride represented by R ² _f COF of the formula (3) are reacted in the aprotic polar solvent as described above to obtain R ^{1 of the} formula (1). _f COR ² _f for producing a perfluoroketone. In this case, since the perfluoroalkyl metal compound raw material is obtained as a solution of the aprotic polar solvent by the method described above, the perfluorocarboxylic acid is added to this solution at room temperature to 90 ° C, preferably room temperature to 50 ° C. Acid fluoride may be added dropwise and reacted for 0.5 to 24 hours, preferably 2 to 10 hours. In this case, if the reaction temperature is lower than room temperature, the reaction time is too long, which is disadvantageous in the process, and if it exceeds 90 ° C., the perfluoroalkyl metal compound represented by R ¹ _f M ¹ X of the formula (2) is decomposed. There is a risk.

The amount of the perfluoroalkyl metal compound and the perfluorocarboxylic acid fluoride used is usually the former: the latter = 1: 0.5 to 1: 2, but may be approximately stoichiometric.

The perfluoroketone thus obtained is usually separated from the solvent to form the lower layer, and can be isolated by distillation or the like.

[0018]

As described above, according to the method of the present invention, the perfluoroketone represented by R ¹ _f COR ² _f of the formula (1) can be produced under a mild condition at a lower temperature than before. Moreover, even perfluoroalkyl metallic compound represented by R ¹ _f M ¹ X of the formula (2) which is the raw material, also formula (3) R ² _f
Since perfluorocarboxylic acid fluoride represented by COF can also be synthesized at a low temperature, the whole process is mild,
It has excellent workability and is economical.

[0019]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples.

[Example] Zinc powder 2 previously treated with dilute hydrochloric acid in 300 ml of previously dehydrated dimethylformamide.
9.4 g (0.45 mol) was suspended, and 130.0 g (0.225 mol) of the compound of the following formula (10) was added dropwise under N ₂ atmosphere so that the temperature did not exceed 20 ° C.

[0021]

Embedded image

After the dropping, the mixture was further stirred at room temperature for 1 hour and the excess zinc powder was filtered off to obtain 360 ml of a dimethylformaldehyde solution of the reaction product. When this solution was analyzed by ¹⁹ F-NMR, it was identified as perfluoroalkylzinc represented by the following formula (11).

[0023]

[Chemical 4]

Also, a certain amount of Ph added as an internal standard
From the integral ratio with the peak of CF ₃ (Ph is a phenyl group),
The concentration of the compound was 0.38 mol / l, and the yield was 6
It was recognized to be 0%.

Further, in order to confirm the structure of this zinc compound, dilute hydrochloric acid was added to a small amount of the above solution, shaken well, and again analyzed by ¹⁹ F-NMR. As a result, -59.
Absorption at 8 ppm disappeared and a doublet peak with a coupling constant of 52 Hz appeared at -72.7 ppm. This shows the reaction of the following formula A, and the structure of the zinc compound was more clearly confirmed.

[0026]

Embedded image

Next, 250 ml of a solution of the perfluoroalkylzinc compound thus obtained in dimethylformamide.
(0.38 mol / l, 0.095 mol) at room temperature under N
31.5 g (0.095 mol) of perfluorocarboxylic acid fluoride represented by the following formula (12) was added dropwise in ₂ air streams over 10 hours. Separate the lower layer formed during dropping,
Reaction product 3 having a boiling point of 99 ° C./50 mmHg by distillation
7.7 g was obtained.

[0028]

[Chemical 6]

[0029] ¹⁹ this compound, represented by the following formula (13)
By F-NMR, infrared absorption spectrum and elemental analysis,
It was confirmed to be a perfluoroketone having the structure of the following formula (14). The yield was 52%.

[0030]

[Chemical 7]

[0031]

Embedded image Infrared absorption spectrum 1787cm ^-1 (C = O) Elemental analysis

Claims (1)

[Claims] 1. A compound represented by the following general formula (2): R ¹ _f M ¹ X (2) (wherein R ¹ _f is a perfluoroalkyl group having 1 to 30 carbon atoms and one or more oxygen atoms are ether-bonded. M ¹ is Zn or Cd, X is R ¹ _f or a halogen atom selected from Cl, Br and I.) and a perfluoroalkyl metal compound represented by the following general formula: (3) R ² _f COF (3) (where R ² _f has the same meaning as R ¹ _f above) is reacted with a perfluorocarboxylic acid fluoride in an aprotic polar solvent. A method for producing a perfluoroketone represented by the following general formula (1): R ¹ _f COR ² _f (1) (wherein R ¹ _f and R ² _f have the same meanings as described above).