US2007208A - Manufacture of halo-fluoro derivative of aliphatic hydrocarbons - Google Patents

Description

y 1935- T. MIDGLEY, JR., ET AL 2,007,208

MANUFACTURE OF HALO-FLUORO DERIVATIVE OF ALIPHATIC HYDROCARBQNS Filed Feb. 24, 1951 IN VENT QR S AITORNEB Patented July 9, 1935 UNITED STATES PATENT oFncE I MANUFACTURE OF HALO-FLUORO DERIVA- TIVE OF ALIPHATIC HYDROCARBONS Thomas Midgley, Jr., Worthington, Albert L. Henne, Columbus, and Robert Reed McNary, Dayton, Ohio, assignors, by mesne assignments, to General Motors Corporation, a. corporation of Delaware Application February 24, 1931, Serial No. 517,854

5 Claims.

other than fluorine, which are desired in the final product are already present in the molecule before fluoration.

Our present invention differs from the former methods in that its objects are to fluorate an allphatic hydrocarbon derivative in which all the halogen atoms desired in the final product are not present before fluoration, and to add the missing halogen atoms, during or after fluoration.

As a specific example, CC12F2, can be obtained, according to our present invention by fluorating dichloromethane, CHzCl-z to difluoromethane, CHzFz and by subsequently or at the same time chlorinating the CHzFz to dichlorodifiuoromethane CClzFz. The latter operation may be modified to form CHClFz or a mixture of CClzFz and CHClFa. A partial fluoration of CHzCl: to CHzCIF could be subsequently or simultaneously chlorinated toCHClzF and/or CChF.

In carrying out this invention, an apparatus similar to that diagrammatically shown on the drawing may be used.

A fluorating' substance, such as antimony trifluoride, SbF3, together with a catalytic agent, such as antimony pentachloride, SbCl5, are introduced into the autoclave 20 through the opening 2|. After the autoclave 20 is closed, a hydrocarbon derivative, such as dichloromethane, CHzClz, which, for convenience, is stored in the tanklZ, is introduce'd'into the autoclave 20 by means-of the pump 23. The reaction then proceeds and may, if desired, be promoted by warming the autoclave 20 with a steam jacket 24. One method of obtaining a good yield of CHzFz is to maintain the pressure at about 130 pounds gauge and the temperature at about F. The CH2F2 is then admitted into chamber 26 where it is chlorinated by chlorine fed through conduit 28. The chlorination in the reaction chamber 26 is promoted by the iron filings 21. The amounts of chlorine and difluorometh ane entering the reaction chamber 26 may be proportionally regulated by means of the valves 29 and 25 respectively. The reaction product CC12F2 is led through the conduit 30 into the washer 3| containing a solution of sodium hydroxide indicated at 32. where HCl and any excess chlorine are removed. Thereafter the dichloro- 'difluoromethane may be compressed into and stored in the container 33 by means of the pump 34.

The above method of manufacture, and the steps involved therein are set forth in the following equation:

The above specific example has been set forth to illustrate the production of CClzFz. However it is possible to also produce a less fluorated substance in chamber 20, for example monochloromonofluoromethane by varying the pressure temperature conditions within this apparatus. In the reaction chamber 26 this monochloromonofluoromethane will be halogenated by the chlorine to produce dichloromonofiuoro or trichloromonofluoromethane according to the amount of chlorine introduced. The reactions involving the production and chlorination of monofluoro compound are as follows:

In the above description, the hologenation takes place after the fiuoration. It is possible, however, to vary the process to carry out both the fluoration and the halogenation simultaneously. For example, the chlorine may be fed directly into the autoclave 20 and the reaction chamber 26 eliminated. In this manner both the fiuoration and chlorination will be carried out in the autoclave 20. Or, if desired, both processes may be combined. That is, chlorine may be fed into both the reaction chamber 26 and into the autoclave 20 so as to start the chlorination during fluoration within the autoclave 20 and to bring it to completion in the chamber 26.

Derivatives of methane have been used for illustrative purposes but it is likewise possible to fluorate and subsequently or at the same time halogenate derivatives of the methane liomologs. Such fiuoro compounds include CHClFz. CClzFz, C2C12F4 illustrative of the ethane series and C3H3F2Bl3 illustrative of the propane series.

In the specific examples, SbFs has been named as the fluorating agent and SbCl5 as the catalytic agent, other fiuorating agents such as lead fluoride and zinc fluoride may be used in place of antimony trifiuoride and other. catalytic agents such as Br, titaniumtetrachloride may be used in place oi. SbCls when an. antimony salt is present.

What is claimed is as follows:

1. The process comprising simultaneously reacting an aliphatic hydrocarbon derivative containing hydrogen and halogen other than fluorine with a fluorating agent and with chlorine, the amount of fluorinating agent being insufllcient to cause fluorine substitution on all of the carbon bonds, substituting one or more. fluorine atoms for the halogen atoms other than fluorine and simultaneously therewith substituting one or more chlorine atoms for one of more hydrogen atoms to thereby obtain a halo-fluoro derivative of an aliphatic hydrocarbon.

2. The process which comprises simultaneously reacting the derivative of methane containing hydrogen atoms and halogen atoms other than fluorine with a metal fluoride and with chlorine, the amount of fluorating agen't being insumcient to cause fluorine substitution on all oi the carbon bonds, substituting one or more fluorine atoms for one or more of the halogen atoms other than fluorine and substituting simultaneously one or more chlorine atoms for one or more of the hydrogen atoms substantially as described to thereby form a halo-fluoro derivative of methane.

3. The process which comprises simultaneously reacting a derivative oi. methane containing hydrogen atoms and halogen atoms other than fluorine with a fluorating agent and with chlorine, the amount of fluorating agent being insuflicient to cause fluorine substitution on all 0! the carbon bonds, substituting one or more fluorine atoms for the halogen atoms other than fluorine and simultaneously therewith substituting one or more chlorine atoms for one or more hydrogen atoms to thereby form a halo-fluoro derivative of methane.

all of the carbon bonds, to obtain a halo-fluoro ll hydrocarbon derivative.

THOMAS MIDGLEY, Ja.

ALBERT L. HENNE. ROBERT REED McNARY.

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