METHOD FOR REMOVING HYDROGEN FLUORIDE FROM MIXTURES COMPRISING AROMATIC KETONES

• Main Authors: CURTIS, THOMAS A, LINDLEY, DANIEL D, RYAN, TIMOTHY R
• Format: Patent
• Language: English; French
• Published: 10.09.2002
• Edition: 5
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; APPARATUS THEREFOR; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; GENERAL METHODS OF ORGANIC CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR RELEVANT APPARATUS; TRANSPORTING

A method is provided for separating hydrogen fluoride (HF) from a mixture comprising HF complexed with an aromatic ketone in which the keto carbon atom is directly bonded to an aromatic ring carbon atom, e.g., 4-isobutylacetophenone, by adding a carboxylic acid anhydride, e.g., acetic anhydride, to the mixture while maintaining the mixture at conditions sufficient to sustain a reaction between the anhydride and the HF to form the corresponding acyl fluoride, e.g., acetyl fluoride, and carboxylic acid, e.g., acetic acid, and separating the acyl fluoride from the mixture. The method is conveniently carried out in a stripping column near the top of which the mixture comprising aromatic ketone and HF is fed and below which the anhydride is fed. Between these feed points, the uncomplexed HF is stripped from the mixture, while below the anhydride feed point or points, the anhydride reacts with the complexed HF to form the acyl fluoride which is stripped from the mixture, and the carboxylic acid. The separation method may be integrated with the production of the aromatic ketone by the Friedel-Crafts acylation of an aromatic compound e.g., isobutylbenzene with an acyl fluoride, a carboxylic acid anhydride, a free carboxylic acid, or a mixture of the foregoing reactants, using an excess of HF as catalyst, to produce the mixture comprising aromatic ketone and HF to be separated, and to which the separated HF and in some cases the acyl fluoride may be recycled.