JPH03181430A - Production of 1-bromo-1-chloro-2,2,2-trifluoroethane - Google Patents

Abstract

PURPOSE:To obtain in high efficiency at low cost the title compound useful for e.g. anesthetics through a process suitable for mass production by reaction of 1,2-bromo-1,1,2-trichloroethane with hydrogen fluoride in a liquid phase in the presence of antimony pentachloride. CONSTITUTION:1,2-Bromo-1,1,2-trichloroethane is reacted with pref. 3-9 molar times of HF in a liquid phase in the presence of antimony pentachloride pref. at 50-150 deg.C under a pressure of 0-25kg/cm<2>G, thus obtaining the objective compound in high efficiency from inexpensive raw materials using an inexpensive catalyst through a process suitable for mass production and applicable to both batch and continuous processes. The present compound is expected to be used as an alternative to conventional CFCs, as a kind of CFC causing no ozone layer depletion and, in addition, useful as an intermediate for CHClFCF3 useful as a working fluid, etc., and trifluoroacetic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing l-bromo-1-chloro-2°2,2-trifluoroethane.

[Prior Art] 1-Bromo-1-chloro-2,2,2-trifluoroethane (hereinafter referred to as R123B1) is itself useful as an anesthetic and has been used as a fluorocarbon that does not destroy the ozone layer. It can be used as a substitute for fluorocarbons. Furthermore, by fluorination using anhydrous hydrogen fluoride, CHCIFCF3 (R1
24) can be induced and also oxidized.

Since trifluoroacetic acid can be produced by hydrolysis, it is considered to be an industrially useful compound.

A conventionally known method for producing R 123Bl is, for example, a method of adding ethanol to trichlorethylene and then deoxidizing the resulting ethoxyethylene derivative, which is then brominated and fluorinated (PL 96979). However, the yield is low and two steps are required, so
There is no cheap and easy industrial manufacturing method.

Moreover, R 123Bl is chlorotrifluoroethylene (
It is known that it can be obtained by adding HBr to CTFE) and then isomerizing it (JP 48/42
609 [73/42609]), but CTFE is expensive, and this method cannot be called a cheap and easy industrial manufacturing method.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned problems that the conventional R123B1 manufacturing method had.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems.
R120aB2) is reacted with HF in the liquid phase in the presence of antimony pentachloride.
1-chloro-2,2,2-trifluoroethane (R12
, 3B1).

In the present invention, R120aB2 can be used as a starting material. R120aB2 can also be obtained, for example, by photo- or thermal bromination of trichlorethylene.

R120aB2 may be fed to the reactor as a raw material, but since it is relatively thermally unstable as a single product, it may be produced within the reaction system without being isolated. Operationally, the latter method is more advantageous because it does not require isolation, but the reaction results tend to be slightly lower, so which method to select can be decided based on a comprehensive judgment.

In the present invention, R120aB2 is reacted with HF in the liquid phase as described above, but R120aB2 to R123B
Since the fluorination to l proceeds sequentially, it is desirable to proceed with these reactions as a series of reactions.

If the amount of HF used in the reaction is less than the stoichiometric ratio, R123B
1 cannot be obtained efficiently, but if the amount is too large, the production amount of R123B1 will be lowered due to a side reaction producing R124, which is not preferable. Therefore,
It is preferable to use HF in a molar amount 3 to 9 times that of R120aB2.

Antimony pentachloride as a catalyst was partially fluorinated in the presence of HF, giving 5bCIX F.

(, X+Y=5, O<X<5, O<Y<5), and it is said that the fluorinated product functions as a catalyst. Therefore, it is preferable to supply sufficient HF to fluorinate antimony pentachloride before or during the reaction.

If the amount of catalyst is too small, the effect as a catalyst will be small, and if it is too large, the catalyst will be wasted, which is not economically preferable.

Therefore, the amount of catalyst is between 2 and 100% based on the compound to be fluorinated.
Mol% is generally preferred.

The reaction temperature is preferably as high as possible because it improves the reaction rate of the compound to be fluorinated, but if it is too high, there are problems such as a decrease in selectivity and decomposition of raw materials and catalysts, so the reaction pressure is Although it depends, the temperature is preferably 50 to 150°C.

The higher the reaction pressure, the higher the reaction rate and productivity.
If it is too high, there will be problems such as the need for the equipment to have a pressure-resistant structure, so 0 to 25 Kg/cm
It is preferable to perform this in the range of 2G.

Furthermore, in order to prevent decomposition of the catalyst, the reaction may be carried out in the coexistence of C1□ and Brz.

[Example] Examples of the present invention are shown below.

Example 1 In a 4-liter stainless steel pressure-resistant container, 4.5 kg of antimony pentachloride was charged, and 3 kg of HF was heated at 50°C at Okg/c.
It was fed and fluorinated at m2G. While heating to 100℃, 360g/hr of HF and 1 hour of R120aB2 were added.
Supply at a rate of 330 g/hr (residence time: 4 hours),
By passing the product gas through a caustic soda wash bottle, an oily product could be obtained at the bottom of the wash bottle. A 10 minute sampling yielded 118 g of oily product. When this was analyzed by gas chromatography, the following results were obtained in terms of area ratio.

・Result Conv, 100%R1
23BI Se1. 65%R1
24Se1. 25%R122BI
Se1. 5% Other high boiling substances
Se1. ．． 5% Example 2 Using the same reactor as Example 1, feeding R 120
aB2 was not isolated, but was added to trichloroethane 600 g/hr in the feed line, and B r a 730 g/h.
r was added to the reactor and sampled for 10 minutes in the same manner as in Example 1 to obtain 112 g of oily product. Analysis by gas chromatography gave the following results.

Results Conv, 100%R123
BI Se1. 63%R124Se1.
22% R122BI Se1. 6%R113
Se1. 6% Other high boiling substances Se1. 3% [Effects of the Invention] As shown in the Examples, the present invention is a manufacturing method that can efficiently manufacture R123Bl. Further, the manufacturing method of the present invention can be applied to both a batch method and a continuous method, and is a method suitable for mass production.

Furthermore, since the raw materials and catalysts used are inexpensive, R12
It is possible to manufacture 3B1 at low cost.

Claims (1)

[Claims] 1,1,2-dibromo-1,1,2-trichloroethane (R120aB2) in the presence of antimony pentachloride,
A method for producing 1-bromo-1-chloro-2,2,2-trifluoroethane (R123B1), which comprises reacting with HF in a liquid phase. 2. The production method according to claim 1, wherein HF is used in a molar amount 3 to 9 times that of R120aB2. 3. The production method according to any one of claims 1 and 2, wherein the reaction is carried out at 50 to 15°C. 4. The production method according to any one of claims 1 to 3, wherein the reaction is carried out at 0 to 25 Kg/cm^2G.