. TITLE FLUORINATED BENZENE MANUFACTURING PROCESS FIELD OF THE INVENTION
This invention relates to a process for the manufacture of fmorobenzene by contacting chlorobenzene with argentous fluoride.
BACKGROUND
Fluorobenzene, an agricultural chemicals intermediate, is typically. produced by the reaction of aniline and sodium nitrite hi the presence of hydrogen fluoride. A diazonium salt intermediate is formed during this process which because of its instability adds to the cost of manufacture. U.S. Patent No. 4.394,527 discloses a process for monoiiuorinating a benzene nucleus comprising reacting a benzene compound in the liquid phase with argentic fluoride which is reduced to argentous fluoride during the reaction.
There is still a need for an efficient commercial process for preparing fluorobenzene using less expensive materials.
SUMMARY OF THE INVENTION
A process is provided for producing fiuorinated benzene. The process comprises (a) contacting chlorobenzene starting material with a metal fluoride composition of the formula (AgF)(MF2)x where M is selected from the group consisting of Mm Fe. Co, Ni. Cu, Zn and mixtures thereof and wherein x is a number between 0 and 1. at a temperature above 175°C sufficient to remove the chlorine substiment from the starting material and to transfer F from the metal fluoride composition to the starting material, thereby producing a reduced metal fluoride composition comprising a silver component of the formula AgF1-y where y is a number from 0.01 to 1; (b) oxidizing the reduced metal fluoride composition from (a) in the presence of HF to regenerate the metal fluoride mixture composition-of the formula (AgF)(MF2)x; and (c) recycling regenerated metal fluoride composition of (b) to (a).
DETAILED DESCRIPTION
An important aspect of this invention involves the reaction of a metal fluoride composition of the formula (AgF)(MF2)x. where M and x are as defined above, with chlorobenzene to produce fluorobenzene. In an embodiment of this invention chlorobenzene is passed over the regenerable reagent, argentous fluoride (AgF), at reaction conditions until the conversion rate to fluorobenzene is reduced to an economically insufficient level. The contacting of chlorobenzene (CH5C1) with argentous fluoride is done in the vapor phase at a temperature from about 175=C to about 220°C, preferably from about 200°C to about 220°C. As the reaction temperature is raised above 220CC, the fluorobenzene (C6H5F) is further
iiuormated and difluorobenzene (C6H4F2), trifluorobenzene (C6H3F3) and tetrafluorobenzene (C6K2F4) are produced.
In a second embodiment, chlorobenzene is passed over the regenerable reagent, (AgF)(MF2)x. at reaction conditions until the conversion rate to fluorobenzene is reduced to an economically insufficient level. With this second reagent the contacting vvitii chlorobenzene is also done in the vapor phase, but at a temperature of from about 250°C to 450°C. preferably from about 275°C to about 325°C. As the reaction temperature is raised above 300°C, the fluorobenzene (C6H5F) is further fiuorinated and difluorobenzene (C6H4F2), trifluorobenzene (C6H3F3) and tetrafluorobenzene (C6H2F4) are produced.
The (AgF)(MF2)x functions as a regenerate fluorinaiing reagent (i.e., the reduced metal fluoride composition comprising a reduced form of silver such as metallic stiver can be oxidized back to (AgF)(MF2.)x). The argentous fluoride (AgF) can be used by itself or as part of a mixture. The metal fluoride mixtures of this invention, (AgF)(Mr2)x where M is selected from the group consisting of Mn, Fe. Co. Ni, Cu, Zn and/or mixtures thereof and wherein x is a number between 0 and 1 can be prepared by conventional engineering mixing techniques using the metal fluoride powder(s). Mixed metal compounds such as AgMnF-, AgFeF3, AgCoF3, AgNiF3, AgCuF3 and AgZnF3 can be prepared by heating a 1:1 molar mixture of AgF and MF2. where M is as defined above, to between from about 400°C to about 450°C for about at least one hour in an inert atmosphere (e.g., nitrogen or argon). The powders may be made into granules or pellets.
The contact time is typically from about 1 to about 120 seconds (e.g., from about 5 to 60 seconds).
The reaction can also be done in the presence of inert gases which are stable under the reaction conditions such as nitrogen and argon.
tinreactea chlorobenzene can be recycled to the reactor for the production of additional fluorobenzene. The fluorobenzene may be recovered from the reaction product and any unreacted benzene by conventional procedures such as distillation.
Argentous fluoride can be regenerated from me fluoride-decletea reagent either by reacting with oxygen and HF at a temperature between about 250oC to about 500°C or by convening the fluoride-depleted reagent to a stable salt (e,2. AgNO3.) and reacting said salt with HF. The oxygen may be diluted with men gases such nitrogen and argon.
The reaction zone and its associated feed lines, effluent lines and associated units should be constmcted of materials resistant to hydrogen fluoride. Typical materials of construction, well-known to the fiuorinaiion art, include
stainless steels, in particular of me austenitic type, the well-known high nickel alloys, such as Monel® nickel-copper alloys, Hastelloy® nickel-based alloys and, Inconel® nickel-chromium alloys, and copper-clad steel. Silicon carbide is also suitable for reactor fabrication.
Without further elaboration, it is believed that one skilled in the art can, using the description herein, utilize the present invention to its fullest extent The following embodiments are to be construed as illustrative, and not as constraining the remainder of the disclosure in any way whatsoever.
EXAMPLES
EXAMPLE 1
Preparation of Pluorobenzene
An Inconel® nickel alloy tube reactor was packed with argentous fluoride (AgF, 5 g). The catalyst was heated co reaction temperature under a nitrogen flow. The nitrogen flow was adjusted to 30 cc/min. passed through chlorobenzene over the catalyst. Reaction products were analyzed using a Hewlett Packard 6890 Gas Chromatograph/5973Mass Spectrometer. All analyses are reported in area% and are shown in Table 1.
(Table removed)

EXAMPLE 2 An Inconel® nickel alloy tube reactor was packed with AgCuFs (5 g). The catalyst was heated to reaction temperature under a nitrogen flow. The nitrogen flow was adjusted to 30 cc/mic, and passed through chlorobenzene over the catalyst. Reaction products were analyzed using a Hewlett Packard 6890 Gas
Chromatograph/5973Mass Spectrometer. All analyses are reported in area% and are shown in Table 2.
(Table removed)

. CLAIMS
1. A process for producing fiuorinated benzene, comprising:
(a) contacting chlorobenzene starting material with a metal fluoride composition of the formula (AgF)(MF2)x where M is selected from the group consisting of Mm Fe, Co. Ni, Cu. Zn and mixtures thereof and wherein x is a number between 0 and 1. at a temperature above i 75°C sufficient to remove the chlorine substituenc from the starting material and to transfer F from the metal fluoride composition to the starting material, thereby producing a reduced metal fluoride composition comprising a silver component of the formula AgF;_v where y is a number from 0.01 to 1;
(bi oxidizing ihe reduced metal fluoride composition from ia; in the oresence of HF to regenerate the metal fluoride mixture composition of the formula (AgF)(MF2)x; and
(c) recycling regenerated metal fluoride composition of (b.) to (a).
2. The process of Claim 1-wherein iraorobenzene is produced by
contacting chicrcbenzene with argentous fluoride.
3. A process for producing fluorinated benzene substantially as herein described with reference to the foregoing description, examples, and the accompanying
table.