| 摘要 |
<p>Perhaloacetones of the formula C3OCl6-xFx where x is 1 to 6 are made by heating in the vapour phase one or more perhalogenated acetone containing 0 to 5 fluorine atoms and no halogens other than chlorine and fluorine with substantially anhydrous hydrogen fluoride in the presence of a catalyst consisting of chromium trifluoride at a temperature high enough to cause fluorination of the perhaloacetone to give a product of higher fluorine content. Preferably the reactants are heated to a temperature of 250-550 DEG C., and the hydrogen fluoride is used in an amount not more than 25% in excess of that theoretically required for perfluorination. For the production of pentafluorochloroacetone and hexafluoroacetone, the preferred starting materials are perhalogenated acetones containing 0-4 fluorine atoms. The catalysts may be unsupported, or supported on an inert carrier, such as calcium, which is stable at the reaction temperature and resistant to hydrogen fluoride and chloride. Detailed examples are given. Specification 794,075 is referred to.ALSO:A catalyst (for making fluorine-containing perhaloacetones by heating a perhaloacetone in the vapour phase with hydrogen fluoride) consists of chromium trifluoride in unsupported form, or supported on a suitable inert carrier, such as calcium fluoride. The catalyst may be made by pelleting chromium trichloride to 3-14 mesh size and treating with anhydrous HF at 350-600 DEG C. Alternatively the chromium trichloride may be reacted with liquid anhydrous HF in a polar solvent and the product heated to remove unreacted and by-product hydrogen halides.</p> |
