Ternary adducts with carboxylic acids

Abstract

When carboxylic acids function as donor molecules their acidity is influenced by adduct formation. The detailed nature of this interaction will be discussed more fully later and for present purposes it is sufficient to say that the acceptor atom attracts electrons first from the oxygen atom of the C = O bond in the carboxyl group , then from the carbon atom, and finally from the bridging oxygen. The extent of this electron attraction is increased by delocalization effects (see discussion on p. 90) and the net result of adduct formation is an increase in the acidity of the carboxylic acid. This was clearly understood and interpreted by Meerwein (1927: 2) in his studies of adducts between acetic acid and ZnC1₂ or BF₃. He found that the adduct formed with ZnC1₂ was an acid with a strength similar to that of sulfuric acid, and many other examples of this effect have since been studied.