Catalyzed Acylation of Phenols and Aromatic Amines with TFAC

Abstract

Selective elimination of various hydrogen bonding functionalities in coal liquids is possible because there is a definite difference in catalyzed acylation of phenols and aromatic amines with trifluoroacetyl chloride (TFAC). Our study of model compound mixtures showed that when pyridine was added as a base catalyst, typical basic aromatic amino compounds were quantitatively derivatized as trifluoroacetyl amides; however, the phenols remained underivatized. When an alkanoic acid was added to the model compounds in the presence of IFAC. the aromatic amino compounds were again derivatized as trifluoroacetyl amides. The phenolic compounds, which might be expected to be converted to trifluoroacetyl esters, were instead derivatized as alkyl esters. No phenolic derivatization was observed when alkanoic acid alone (no TFAC present) was added to the model compounds. It appears that TFAC behaves as a catalyst in the acylation of phenols using alkanoic acid. Some azaarenes (e.g., carbazole) which are very difficult to derivatize in TFAC/pyridine are also readily converted to alkyl amides in the presence of alkanoic acids.