JPS58222038A - Preparation of 1,1-dichloro-2,2,2-trifluoroethane - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as a refrigerant, etc. in high yield, by reducing an easily preparably 1,1,1-trichloro-2,2,2-trifluoroethane as a starting raw material with zinc in a protonic solvent. CONSTITUTION:1,1,1,-Trichloro-2,2,2-trifluoroethane obtained by isomerizing CCl2FCClF2 with an aluminum halide catalyst or photochlorinating CH3CF3 is reduced with zinc in protonic solvent, e.g. water or acetic acid, preferably about 50-150 deg.C, particularly about 70-90 deg.C, under about 0-10kg/cm<2>.G, preferably about 2-4kg/cm<2>.G, to give 1,1-dichloro-2,2,2-trifluoroethane. USE:An intermediate for ''Flon 124'' which is a working fluid and trifluoroacetic acid.

Description

Detailed Description of the Invention The present invention relates to 1,1-dichloro-2,2,2-trifluoroethane (Freon 123, hereinafter referred to as CHCl2CF3)
Concerning the manufacturing method.

CHCl□CF3 itself is useful as a refrigerant, and by fluorination with anhydrous hydrogen fluoride, it can be derived into CHCIFCF3 (Freon 124), which is useful as a working fluid. It is known that fluoroacetic acid can be produced and is an industrially useful compound.

It is known that CHCl2CF3 can be obtained by fluorinating tetrachloroethylene with anhydrous hydrogen fluoride in the presence of a fluorination catalyst.
eChem, 13 (1979) 7-18),
D Yield (d) is extremely low and cannot be called a cheap and easy industrial production method.

On the other hand, when zinc dust is generally applied to 1,2-halogen-substituted ethane, intramolecular elimination easily occurs to produce an ethylene derivative. For example, when zinc dust is applied to CCl2FCCIF2 (Freon 113), the main acid produced is chlorotrifluoroethylene even in a protic solvent such as water or methanol, and the chlorine atoms in the raw material molecules are replaced by hydrogen atoms. Compounds produced by this process are rarely produced.

However, according to the research of the present inventors, the above CCl2F
Chemically similar to CCl F2 (Freon 113) cc
l, cF":, (7o)113 a) as a starting material, and when zinc is reacted with it in the presence of a protonosolvent, unexpectedly a reduction product is produced in which the chlorine atoms in the raw material molecules are replaced by hydrogen atoms. The present invention was completed based on the discovery that , can be obtained as the main product in high yield.

That is, the present invention is characterized in that CCl30F3 is reduced with in<lead in the presence of a proton solvent.
Concerning the manufacturing method of CI□CF3.

CCl3CF used as starting material in the present invention
3] - by isomerizing commercially produced CCI□FCCIF2 using an aluminum halide catalyst, or CH3CF3 ()onl 4.8
8) It is a compound that can be easily produced by photochlorination.

The proton solvent used in the present invention is not particularly limited, but for example, lower alcohols such as methanol and ethanol, water, acetic acid, etc. are preferable, and methanol is particularly preferable.

The zinc used in the present invention may be in any form such as zinc powder, granular zinc, or zinc flakes, and zinc powder is particularly preferred. The amount of zinc used is usually the raw material CC
It is preferred that the amount is equimolar to l30F3. Note that there is no need to subject zinc to any special activation treatment.

The reaction of the present invention is usually carried out at a temperature of about 50 to 150°C, preferably about 70 to 90°C, and the reaction pressure is not particularly limited, but is usually about 0 to 10 kg, 4JG: preferably about 2 to 4 It is best to choose from the range of kg/JG.

The target compound of the present invention obtained by the above method is usually separated and purified by a known method such as distillation.

be able to.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 C in a 100 ml glass-lined autoclave 1
Cl30F'35 f'! , 3 (0.3 mol), zinc dust 19.6 r (0.3 mol) and methanol 40 ml
at a temperature of 75-85°C, 2-4 kg/J
The reaction mixture was stirred for 9 hours under the pressure of G. Thereafter, the product was distilled under normal pressure, and the distillate was analyzed using gas chromatography. As a result, the reaction rate was 94.8%, and the CHC
12CF3 was produced at a yield of 89.1%. Furthermore, other products! : Then CF2=CHC1, (3,1),
CF3CH2Cl (0.8%), CF2=CC12
(0-5%) were produced respectively.

Examples 2 to 7 Reactions were carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1. The results are shown in the table. In the same table, (1) is C
HCl20F3, (2) is CF2=CC12, (8)
indicates CF3CI-I□C1, and (4) indicates CF2-CC1□.

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Claims (4)

[Claims] (1) 1,1-dichloro-2,2゜2 characterized by reducing 1,1.1-trichloro-2,2,2-trifluoroene/ with zinc in the presence of a proton solvent
-1. Method for producing refluoroethane. (2) The production method according to claim 1, wherein the proton solvent is a lower alcohol such as methanol or ethanol, water, or acetic acid. (3) Claim 1 in which the reaction is carried out at about 50 to 150°C.
Manufacturing method described in Section. (4) The production method according to claim 1, wherein the reaction is carried out under a pressure of about 0 to IOkg/r, JG.