Reactivity and stability of aromatic carbonyl compounds using density functional theory-based local and global reactivity descriptors

The reactivity of acetaldehyde and some aromatic aldehydes towards acid-cat alysed oxygen-18 exchange reactions with H2O18 was studied using the densit y functional theory (DFT)-based reactivity descriptors local softness and l ocal hardness. Local softness is used to predict the preferable reactive si tes within a given molecule, whereas local hardness reproduces the experime ntal intermolecular reactivity trends. A new concept, intrinsic global hard ness, obtained via filtering out the volume effect of the global softness, shows an excellent correlation with the degree of aromaticity of the compou nds. Copyright (C) 1999 John Wiley & Sons, Ltd.