Recovery of hexafluoroacetone from a hexafluoroacetone-HF control

#The present invention relates to a process for the recovery of hexafluoroacetone from a complex of hexafluoroacetone-HF. Both chemical and electrochemical processes are known by which hexafluoroacetone can be produced. Generally, however, hydrofluoric acid (HF) is the reagent in these processes and when it is, a hexafluoroacetone-HF complex is formed to some degree. This complex is particularly stable and it is difficult to separate and recover the hexafluoroacetone from the complex. A number of procedures to effect the separation have been devised, one of which employs the use of liquified sulfur trioxide, for example. The present invention provides an alternative process for recovering the hexafluoroacetone from the hexafluoroacetone-HF complex.

#The principal object of the present invention is to provide a process for recovering hexafluoroacetone from a hexafluoroacetone-HF complex and to provide such a process wherein certain reaction products can be further reacted so that the total process can be made a cyclic type of process.

#Other objects and advantages of the present invention will become apparent from the following detailed description wherein are set forth by way of illustration and example certain embodiments of the present invention.

#FIG. 1 is a diagrammatic illustration of the process for recovering hexafluoroacetone from a hexafluoroacetone-HF complex.

#As required, detailed embodiments of the present invention are disclosed herein, however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner.

#Hexafluoroacetone can be produced in any suitable manner such as by a chemical process or an electrochemical process wherein hydrofluoric acid is a reagent and in the process of producing hexafluoroacetone, a complex of hexafluoroacetone-HF is formed. The HF-containing complex can be contacted under reaction conditions with acetic anhydride to form liberated hexafluoroacetone and by-products, acetic acid and acetyl fluoride. Preferably, the reaction by-products, acetic acid and acetyl fluoride, can be further reacted to form acetic anhydride which can be recycled and hydrogen fluoride which can be used, e.g., in electrochemical fluorination.

#Generally, the steps of the cyclic process include reacting the hexafluoroacetone-HF complex with acetic anhydride to liberate hexafluoroacetone in separable form and to produce acetyl fluoride and acetic acid as by-products. The products of the first reaction are separated as hexafluoroacetone, acetyl fluoride and acetic acid. The separated acetyl fluoride can then be reacted with an alkali metal or alkaline earth metal acetate (hereinafter referred to as a metal acetate) such as potassium acetate, to regenerate acetic anhydride for use in the first reaction. The second reaction also produces an alkali metal or alkaline earth metal fluoride (hereinafter referred to as a metal fluoride) such as preferably potassium fluoride which is then used in a third reaction. The third reaction includes the reaction of the acetic acid with the metal fluoride which will then liberate recoverable HF and produce metal acetate which can be recycled for use in the second reaction.