Bf3 catalyzed acylation of aromatic compounds

Abstract

In accordance with the present invention, aromatic ketones are prepared by the acylation of aromatic reactants using boron trifluoride as a catalyst and in a solvent medium comprising anhydrous liquid sulfur dioxide. The acylation proceeds in accordance with the equation I: ##STR1## wherein n ranges from 5 to 9, Ar is phenylene and n is 5, naphthalene and n is 7, or a bis phenylene radical having the structure: ##STR2## and n is 9; wherein Z is selected from the group consisting of a covalent carbon to carbon bond, O, S, SO.sub.2, C.dbd.O and C.sub.1 to C.sub.3 alkylene or alkylidene, X is selected from the group consisting of H, OH, halogen, C.sub.1 to C.sub.6 alkyl C.sub.1 to C.sub.6 alkoxy and combinations thereof, R is an alkyl group containing from 1 to about 16 carbon atoms and Y is selected from the group consisting of hydroxy, acyloxy and halogen. The acylation process of this invention gives rise to aromatic ketones which are highly selectively acylated at the activated ring carbon and also yields a high ratio of conversion of the aromatic starting material. The process also provides a faster rate of reaction than analogous processes and affords the opportunity to recover large quantities of the BF.sub.3 catalyst as well as the SO.sub.2 solvent for recycle, thus offering improved economy and efficiencies.