JPS60158137A - Preparation of fluorine-containing acrylic acid derivative - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an intermediate for medicines and materials for sheath materials of optical fibers, etc. safely in high yield without using highly toxic compounds, etc., by dehalogenating a fluorine-containing propionic acid as a raw material. CONSTITUTION:A halogen compound expressed by the formula XF (X is halogen) is eliminated from a fluorine-containing propionic acid derivative expressed by formula I (X is halogen; Y is halogen or lower alkoxyl) to afford the aimed compound expressed by formula II. A well-known dehalogenating agent, e.g. zinc, sodium or magnesium, is used as the dehalogenating agent. The reaction temperature is within 0-150 deg.C, preferably 40-60 deg.C range. The reaction may be carried out under ordinary pressure, but under <=200mm.Hg, preferably 20-50mm. Hg. The starting material compound expressed by formula I is synthesized by treating for example 2,2,3,3-tetrafluorooxetane with sodium iodide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fluorine-containing acrylic acid derivative, and more particularly to a method for producing a fluorine-containing acrylic acid derivative, which comprises dehalogenating fluorine-containing propionic acid.

The fluorine-containing acrylic acid derivative represented by the general formula: CH2=CFCOY (1) (in the formula, Y represents a halogen or a lower alkoxy group) is used as an intermediate for pharmaceuticals (for example, antibiotics) and as a sheath material for optical fibers. It is useful as an intermediate for industrial materials, paint materials, and semiconductor renost materials.

Conventionally, the compound (1), for example, α-fluoroacrylic acid ester, is obtained by converting α, α, β-tribromopropionate with 7-mercuric nitride.

A method for obtaining β-shifted α-fluoropropionic acid and debrominating it (Journal of the Chemical Society, Vol. 75, pp. 479-481, published in 1954), Fluorination with potassium chloride to obtain monofluoroacetic acid, which is then reacted with dimethyl oxalate in ether, and further reacted with paraformaldehyde and sodium methoxy (Macromolecules, Vol. 13, Nos. 1031-1036,
(published in 1980).

However, the former method requires the use of a highly toxic mercury compound and the yield is as low as 10%, while the latter method also requires the use of highly toxic monofluoroacetic acid and has a low yield. 30%, and there are problems such as the use of highly flammable ether as a solvent.

The present inventors conducted research on the method for producing the compound (1) and found that the compound (1) can be easily obtained by dehalogenating the corresponding fluorine-containing propionic acid derivative. This led to the completion of the present invention.

That is, the gist of the present invention is the general formula: % formula % (2) (In the formula, Y has the same meaning as above. X represents) 10 gen.

) From the fluorine-containing propionic acid derivative represented by the general formula:
XF (3) (In the formula, X has the same meaning as above.) By eliminating the halogen compound represented by: The present invention relates to a method for producing a heptad-containing acrylic acid derivative, characterized in that it obtains the following.

The starting material, fluorine-containing propiolic acid derivative (2), is
For example, it can be easily obtained by treating 2,2,3,3-tetrafluorooxecune with sodium iodide.

Known dehalogenating agents such as zinc,
Sodium, magnesium, tin, copper, iron, etc. are used.

The reaction temperature is generally ()~150°C, preferably 30~150°C.
81) 'C1 is more preferably 40 to 60°C.

The reaction pressure may be normal pressure, but 2 (10 mmHg or less,
Preferably, when the reaction is carried out under a reduced pressure of 20 to 50+ nmHH, polymerization of the product fluorine-containing acrylic acid derivative, which tends to self-polymerize, is prevented and the yield thereof is improved.

Further, the reaction is preferably carried out in a solvent, and the solvent is a polar solvent such as dimethylformamide (DM
F), acetonitrile, acetone, etc.

In the present invention, the reaction may be carried out under reflux and the product may be recovered by distillation under reduced pressure after the completion of the reaction. It is desirable to collect continuously.

Next, the manufacturing method of the present invention will be specifically explained with reference to Examples.

Example 1 373 g of zinc in 250 DMF in a 51 four-neck flask
0g suspension at 50-60℃ lCH2CF2C0F 1
After adding 042 g (4,378 mol) dropwise, the mixture was stirred for 1 hour. The reaction mixture was then heated to 42-45°C 150C1
Crude CH2 = CF COF”16 by simple distillation under reduced pressure at 5O
2g was obtained. Yield 37.6%. Purity analysis by chromatography was 93.5%.

Example 2 The same charge amount as in Example 1 was used, but IC-12C
F2COF was added dropwise at 50 to 60° C. under a reduced pressure of 20 mm HH while refluxing. After completion of the dropwise addition, the mixture was distilled in the same manner as in Example 1 to obtain 274 g of crude CH2=CFCOF.

Yield 62.0%. Purity analysis by chromatography was 91.2%.

Example 3 Reduced pressure: 40 + nm Hg, reaction temperature: 50-60°C
The procedure of Example 2 was repeated except that the product was continuously recovered at a distillation overhead temperature of 38-40°C.
(343 g of 2=CFco F was obtained. Yield: 80°6%
. Purity analysis by chromatography was 94.8%.

Example 4 Acetonitrile 5% of zinc 938% in 114 D7 flask
01.1 Add BrCH2 to gljJ suspension at 50-613℃
After dropping CF2C00C1 (3194 g (o, 956 mol)), it was stirred for 1 hour.Then, the reaction mixture was subjected to simple distillation under reduced pressure to obtain crude CH2=CF COOCH340,7[
I got 1. C; C-MS: 104 (M”), 59 (
COOC143), 45 (CH22CF).

Example 5 11 In a four-roof flask, 210 g of lCH2CF2COCl was added to a suspension of 70 g of zinc in 500 g of DMF at 50-60°C.
(0,825 mol) was added dropwise, and the mixture was stirred for 1 hour. Then, the reaction mixture was subjected to simple distillation under reduced pressure to obtain crude CH2=CFCO.
5 g of C149 was obtained. GC-Yari S: 1108 (”)
, 63 (COCI), 45 (CH2CF2 de

Claims (1)

[Claims] 1. From a fluorine-containing propionic acid derivative represented by the general formula: % formula % (wherein, X represents a halogen and Y represents a halogen or a lower alkoxy group)
It is characterized by eliminating the halogen compound represented by F (in the formula or the same meaning as above) to obtain a compound represented by the general formula: %Formula% (in the formula, Y has the same meaning as above) A method for producing a fluorine-containing acrylic acid derivative. 2. The production method according to claim 1, wherein the elimination reaction is carried out under reduced pressure of 200 mmHg or less. 3. The production method according to claim 1 or 2, wherein the elimination reaction is carried out under reduced pressure of 20 to 50+++n+Hg. 4. The production method according to any one of claims 1 to 3, wherein the fluorine-containing acrylic acid derivative is continuously recovered and obtained during the elimination reaction. 5. The production method according to any one of claims 1 to 4, wherein the elimination reaction is carried out at a temperature of 0 to 150°C. 6. The production method according to claim 5, wherein the elimination reaction is carried out at a temperature of 40 to 60°C. 7. The manufacturing method according to any one of claims 1 to 6, wherein Y is halogen.