Theoretical study of reactivity based on the hard-soft/acid-base (HSAB) in isatoic anhydride and some derivatives

In order to utilize the great chemical potential of isatoic anhidryde (ISA) as a precursor of several derived products, it was most important to determine its molecular reactivity. To this end, we have carried out theoretical calculations on ISA and some of its derivatives by using density functional theory (DFT), MP2, HF levels of theory with a correlated augmented basis set aug-cc-pvDZ. The B3LYP/aug-cc-pvDZ level yielded theoretical results that correlated very well with the experimental work. We used this method to get the global and local descriptors with Koopman's approximation, taking into account two main ISA structural components: the aromatic and heterocyclic systems. The Fukui functions were calculated on the formalism of the quantum theory of atoms in molecules (QTAIM) which is a method for condensation. These theoretical calculations allow to study the electron-withdrawing or donating substituent of the aromatic ring. The results showed that, globally, the most reactive compound is ISA with the OCH₃ substituent. Locally, it is confirmed that C2 is the molecular region most susceptible to suffer a nucleophilic attack against ISA.