DE1187595B - Process for the preparation of 1, 1, 1-trifluoro-2-bromo-2-chloroethane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

JLJLJk

GERMAN JMWSSSSl PATENT OFFICE

EDITORIAL

Int. CL:

C07c

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German class: 12 ο-2/01

1187595
J19097IVb / 12ö
2nd December 1960
February 25, 1965

The process for the preparation of 1,1,1-trifluoro-2-bromo-2-chloroethane is characterized in that a compound of the formula

CHQBr CO-X

wherein X denotes a hydroxy or a halogen radical or the group —OR, where R is an alkyl radical is, which has no more than 4 carbon atoms, with sulfur tetrafluoride at 100 to 200 ° C in the closed The vessel.

It should be noted that the bromochloroacetic acid in the form of a salt, for example an alkali metal or alkaline earth metal salt of bromochloroacetic acid, can be applied.

The process can be carried out using hydrogen fluoride or boron trifluoride as a catalyst will.

The process is preferably carried out using between 1 and 6 moles of sulfur tetrafluoride and preferably carried out under superatmospheric pressure.

l, l, l-trifluoro-2-bromo-2-chloroethane is useful as a respiratory anesthetic.

From the United States patent specification 2859 245 it is known that certain aliphatic carboxylic acids, namely formic acid, enanthic acid and acrylic acid, under conditions similar to those of the process are similar to the present invention react to give analogous trifluoromethyl derivatives. However, none of these acids has a halogen substituent on the carbon atom. Farther is indicated in Example 14 of the patent mentioned that trichloroacetic acid also with sulfur tetrafluoride would react. However, no practical details are given about it.

However, it is well known that sulfur tetrafluoride is used because of its high fluorinating power other halogen atoms, for example bromine or chlorine atoms, can be replaced by in their place Fluorine atoms occur. This is what it says in an article in J. Amer. former Soc, 82, S 5107 (1960) that a or more of the halogen atoms, for example of carbon tetrabromide, carbon tetrachloride, Tetrachlorethylene, trichlorethylene or 2,4-dichloropyrimidine, under the action of sulfur tetrafluoride be replaced.

It is also known that the halogen atoms of an α-halogen-substituted carboxylic acid are particularly reactive Are halogen atoms. In this regard, M. Hudlicky, “Chemistry of Organic Fluorine Compounds ", Pergamon Press, 1961, p. 87, lines 9 to 11, stated:

Method of manufacture
vonl, l, l-TriflüQr = 2-bromo ~ 2-chloroethane

Applicant:

Imperial Chemical Industries Limited, London

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr
and Dipl.-Ing. S. Staeger, patent attorneys,
Munich 5, Müllerstr. 31

Named as inventor:

Albert Frederick Crowther,

Macclesfield, Cheshire;

Hugh Leithead Roberts,

Northwich, Cheshire (UK)

Claimed priority:

Great Britain dated December 4, 1959 (41 379), November 9, 1960

»The replacement of halogen atoms by fluorine atoms in reactive halogen derivatives,

such as B. ... acid halides, ce-halocarbonyl compounds, a-halo acids or esters ..., is easy to carry out ... «
It was therefore not to be expected that neither the α-bromine nor the α-chlorine atom would be replaced by fluorine under the reaction conditions used in the process according to the invention.

The invention is illustrated in the following examples, in which parts are by weight.

example 1

13.5 parts of bromochloroacetic acid are placed in a nickel autoclave, and 21 parts of sulfur tetrafluoride are distilled into the autoclave. The reaction mixture is initially for 4 hours heated to 100 ° C and then 200 ° C for 6 hours and then allowed to cool. The content of the The autoclave is then blown down through a template that is cooled with solid carbon dioxide, until the internal pressure of the autoclave equals that of the atmosphere. In this way, mainly

509 510/417

borrowed TManyl fluoride and hydrogen fluoride collected. The autoclave is then evacuated through a receiver carbonized with liquid air. The volatile products are collected in this receiver and then washed with dilute aqueous sodium bicarbonate solution. The heavy water-immiscible liquid obtained in this way is separated off and dried over calcium chloride. This gives 1,1,1-trifluoro-2-bromo-2-chlorofane, boiling point 50.2 ° C./760 mm . The ratio of the starting materials in this example is 2.5 mol sulfur tetrafluoride to 1 mol bromochloroacetic acid. The yield is 34%.

Example 2

2.4 parts of bromochloroacetyl chloride are placed in a nickel autoclave and 10 parts of sulfur tetrafluoride are distilled into the autoclave. The reaction mixture is heated to about 200 ° C for 10 hours and then allowed to cool. The pressure in the autoclave is then released and the liquid product is washed with aqueous sodium bicarbonate and then with water. The product is dried over C ^ cmmchlqrid and filtered. The filtrate obtained in this way consists of 1,1,1-trifluoro-2 ^ bromo-2-chloroethane and has a boiling point of 50.2 ⁰ C hm 760 mm. In this example, the ratio of the starting materials is 7.4 mol of sulfur tetrafluoride to 1 mol of bromochloroacetic acid.

Example 3

30 parts of bromochloroacetic acid are placed in a nickel autoclave, and 50 parts of sulfur tetrafluoride and 1 part of boron trifluoride are distilled into the autoclave. The mixture is then 6 hours warmed to about 100 ° C for a long time and then allowed to cool. The pressure in the autoclave is drained, and the liquid product is made with dilute aqueous sodium bicarbonate and then with Water washed. It is dried over calcium chloride and filtered, and the filtrate obtained in this way exists from!, ljl-trifluoro ^ -bromo ^ -chloroethane, boiling point 50.2 ° C at 760 mm. The ratio of the starting materials in this example is 2.7 mol Sulfur tetrafluoride to 1 mole of bromochloroacetic acid.

Claims (4)

Patent claims: 1. Process for the production of 1,1,1-trifluoro-2-bromo-2-chloroethane, characterized in that a compound of the formula ¹ S CHClBr -CO-X wherein X denotes a hydroxy or a halogen radical or the group - OR, where R is a An alkyl radical that has no more than 4 carbon atoms has, reacted with sulfur tetrafluoride at 100 to 200 ° C in a closed vessel. 2. The method according to claim 1, characterized in that the bromochloroacetic acid in Form of a salt is used. 3. The method according to claim 1, characterized in that the reaction is in the presence is carried out by hydrogen fluoride or boron trifluoride as a catalyst. 4. The method according to any one of claims 1 to 3, characterized in that between 1 and 6 moles of sulfur tetrafluoride are used. Considered publications:
U.S. Patent No. 2,859,245;
J. Amer. former Soc, 81 (1959), pp. 3165 to 3166. 509 510/417 2.65 © Bundesdruckerei Berlin