JP2000169404A - Bromination of fluorine-containing olefins - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which the bromination of a fluorine-containing olefin is performed without using light while suppressing byproduct. SOLUTION: Fluorine-containing olefins of the formula [R1 is F, CF3, CHF2, CH2F, CF2R5 or CHFR5; R2, R3 and R4 are each the same or different F, H or R6; R5 and R6 are each the same or different lower alkyl group (having a substituent)], [e.g. 3,3,3-trifluoropropene] is brominated to produce a fluorine- containing brominated hydrocarbons. A metal powder such as antimony or a Lewis acid is allowed to coexist with the reaction system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to pharmaceuticals, agricultural chemicals, dyes,
The present invention relates to a method for producing a fluorinated brominated hydrocarbon useful as a perfume or other organic synthesis raw material.

[0002]

2. Description of the Related Art Generally, bromination of fluorine-containing olefins is slow only by mixing and heating with bromine due to the electron-attracting property of fluorine atoms. Therefore, bromination is conventionally performed using light as a catalyst.

For example, (1) a method of brominating 3,3,3-trifluoropropene using light as a catalyst (G
oetzoe, Stephan P. et al. ; Seebac
h, Dieter, Chimia, 50 <1996>
1-2, 20-23. , Dolbier, William
mR. Burkholder, Conrad;
R. Piedrahita, Carlos A .; ,
J. Fluorine Chem. , 20 <1982
>, 637-647. (2) A method of brominating 1,1-difluoroethylene (vinylidene fluoride) using light as a catalyst (Drak
esmit, F.E. G. FIG. et al. , J. et al. Org. C
hem. , 33 <1968>, 286-291. ) and so on.

[0004]

However, these conventional methods have the following disadvantages and are not industrially suitable.

(1) The method using light as a catalyst cannot be manufactured unless equipment having a photoreactor is used.

(2) Due to the light absorption of bromine, light is not transmitted on an industrial scale, and the reaction speed is reduced.

(3) By using strong light, by-products increase.

Accordingly, an object of the present invention is to provide a method for brominating fluorine-containing olefins without using light and suppressing by-products.

[0009]

In order to solve this problem, the present inventors have developed an industrial bromination method of fluorine-containing olefins using metal powder or Lewis acid having catalytic activity for electrophilic reaction. investigated. As a result, they found that the bromination rate was increased by the presence of a metal powder or a Lewis acid in the reaction system, and found that industrially simple synthesis was possible, and the present invention was completed.

That is, the present invention provides a compound represented by the general formula (1):

[0011]

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(Wherein R ¹ is F, CF ₃ , CHF ₂ , CH ₂
F, CF ₂ R ⁵ or CHFR ⁵ ; R ² , R ³ , R ⁴
Represents the same or different F, H, and R ⁶ . R ⁵ , R
⁶ represents a lower alkyl group which may be the same or different and may have a substituent. )) Is obtained by brominating a fluorine-containing olefin represented by the general formula (2)

[0013]

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(Wherein, R ^{1 to} R ⁶ represent the same groups as described above). In the method for producing a fluorinated brominated hydrocarbon represented by the formula ( ¹ ), metal powder or Lewis acid coexists in the reaction system. This is a method for brominating fluorine-containing olefins. Hereinafter, the present invention will be described in detail.

In the present invention, the term "lower alkyl group" means a linear or branched lower alkyl group, preferably having 1 to 6 carbon atoms. In the general formula (1) or (2), R
^{1 to} R ⁶ are as described above, and among them, R ¹ is preferably CF ₃ or F. R ² , R ³ and R ⁴ are the same or different and are preferably F, H and a lower alkyl group.

The fluorinated olefins represented by the general formula (1) are not particularly limited, but the following compounds are preferred as specific examples. For example, fluoroethylene, 1,1-difluoroethylene (vinylidene fluoride), 1,1,2-trifluoroethylene, tetrafluoroethylene, 3,3,3-trifluoropropene,
2,3,3,3-tetrafluoropropene, 1,2,2
3,3,3-pentafluoropropene, 1,1,3
3,3-pentafluoropropene, hexafluoropropene, 2- (trifluoromethyl) propene, 1,1,
Examples thereof include 1-trifluoro-2-butene and 1,1,1,2,3-pentafluoro-2-butene.

The metal powder or Lewis acid used in the present invention includes metal powder such as iron powder, aluminum powder and antimony powder, iron-based Lewis acids such as iron (III) chloride and iron (III) bromide, and aluminum chloride ( III), aluminum-based Lewis acids such as aluminum (III) bromide,
Examples include antimony-based Lewis acids such as antimony (III) chloride, antimony (V) chloride, and antimony (III) bromide, and other Lewis acids such as boron trifluoride, titanium tetrachloride, and tin tetrachloride. Of these, iron powder or iron-based Lewis acid is preferable, and iron (III) chloride is more preferable.

The bromination reaction can be carried out by bringing the fluorine-containing olefin represented by the general formula (1) into contact with bromine in the presence of a metal powder or a Lewis acid. The metal powder or Lewis acid at this time acts as a bromination catalyst by coexisting in the reaction system. The amount of the bromine added is preferably large because the bromination rate is increased by increasing the amount. However, the amount is preferably 0.01 to 10 mol% based on the bromine as the raw material. More preferably, the ratio is 0.1 to 1 mol%.

The bromination reaction is carried out at a reaction temperature of -10.degree.
It is preferable to carry out the reaction in a temperature range of 0 ° C.,
To 60 ° C.

[0020]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. The analysis of reaction products in the following Examples and Comparative Examples was performed by gas chromatography.

Example 1 0.227 g of iron powder was added to 64.2 g of light-shielded bromine, and 4.39 of 3,3,3-trifluoropropene at 30 to 40 ° C. in a dark place and with stirring. I blew it over time. Immediately thereafter, the reaction product was washed with water and analyzed. The yield of 1,2-dibromo-3,3,3-trifluoropropane was 93.8 g (yield: 91.3%, purity: 9).
7.0%).

Example 2 0.41 g of iron (III) chloride was added to 400 g of light-shielded bromine, and the mixture was stirred at 35 to 50 ° C. in a dark place with stirring at 35 to 50 ° C.
291.4 g of trifluoropropene were blown in over 15.3 hours. Immediately thereafter, the reaction product was washed with water, bubbling with nitrogen, and analyzed to find 1,2-dibromo-3,3,3.
The yield of 3-trifluoropropane was 608.7 g (yield: 95.2%, purity: 99.3%).

Example 3 0.65 g of iron (III) chloride was added to 64.0 g of light-shielded bromine, and 35 g of 1,1-difluoroethylene (vinylidene fluoride) was added at 35 to 50 ° C. in a dark place with stirring. 5.5
I blew it over time. Immediately thereafter, the reaction product was washed with water, bubbling with nitrogen and analyzed. The yield of 1,2-dibromo-1,1-difluoroethane was 74.7 g (yield: 84.1%, purity: 97.0%). Was.

COMPARATIVE EXAMPLE 1 Bromine (64.1 g) was shielded from light, and was darkened in a dark place and under stirring conditions.
When 3,3,3-trifluoropropene (103 g) was blown in at 6 ° C. for 19 hours, the reaction rate was low and bromination did not proceed completely. The remaining bromine was reduced with a 5% aqueous hydrazine solution, and the obtained reaction mixture was washed with water and analyzed. As a result, the yield of 1,2-dibromo-3,3,3-trifluoropropane was 64.2 g (yield: 62). 0.6%,
(Purity: 98.7%).

Comparative Example 2 16.0 g of bromine was irradiated with light (100 W high-pressure mercury lamp) under stirring conditions, and 12.7 g of 3,3,3-trifluoropropene was blown at 25-30 ° C. over 1 hour. It is. The reaction mixture obtained immediately thereafter was analyzed,
The purity of -dibromo-3,3,3-trifluoropropane was 93.6%, and the purity was reduced due to the generation of by-products.

[0026]

According to the method of the present invention, fluorine-containing brominated hydrocarbons can be produced simply, in a short time, efficiently and with high purity without photoreaction equipment. It is useful as an industrial production method of chlorinated hydrocarbons.

Continued on the front page F term (reference) 4H006 AA02 AC30 BA09 BA13 BA19 BA67 BE53 EA02 4H039 CA53 CF10

Claims (2)

[Claims] 1. A compound of the general formula (1) (Where R ¹ is F, CF ₃ , CHF ₂ , CH ₂ F, CF
_{2 represents} R ⁵ or CHFR ⁵ , and R ² , R ³ and R ⁴ are the same or different and represent F, H and R ⁶ . R ⁵ and R ⁶ are the same or different and represent a lower alkyl group which may have a substituent. The brominated fluorine-containing olefins represented by the general formula (2) (Wherein, R ^{1 to} R ⁶ represent the same groups as described above.) In the method for producing a fluorinated brominated hydrocarbon represented by the formula:
A method for brominating a fluorine-containing olefin, wherein a metal powder or a Lewis acid coexists in the reaction system. 2. The bromination method according to claim 1, wherein the Lewis acid is an iron Lewis acid, an aluminum Lewis acid, or an antimony Lewis acid.