A theoretical study of the reactivity of quinoline-4-one derivatives is undertaken in order to understand the involved mechanisms. The calculations were carried out in gas phase and in N, N-Dimethylformamide (DMF) solution. The Density Functional Theory (DFT) with B3LYP functional associated to 6-311G (d) and 6-311+G (d) bases is used to perform these calculations. The results of the thermodynamic parameters showed that there is an equilibrium relation between the different tautomers. This equilibrium can be used to explain the failure to obtain tetrahydroquinoline from 5,8-dimethoxy-quinolin-4-one. Reactivity analysis from Frontier Molecular Orbitals theory and Fukui function calculations revealed that ketone forms are less reactive than enol ones. The methoxyl substituent decreases the acidity of the nitrogen and oxygen atoms of quinolin-4-one while the bromine increases the acidity of the same sites. These results foresee that nitrogen deprotonation in the case of the brominated compound is easier than in the case of methoxylated ones.

This work is a contribution of theoretical chemistry to the knowledge of 2-thioxanthine's properties. Its aim first consists in checking the chemistry's results related to the exploitation of semi-empirical methods; it provides theoretical data on the acidity of 2-thioxanthine tautomers. To do this, the DFT method with the B3LYP functional, associated with the 6-311+G(d, p) basis set was used. The aqueous phase was modelled with the Polarizable Continuum Model (PCM). The results show that in gas and aqueous phases 2-thioxanthine can exist as a mixture of four tautomers 2TX(

No abstract