No abstract

The present work explores the effect of substitution in all free positions of furfural on conformational preferences of formyl group by using ab-initio calculations at the MP2/6-31G(p,d) level of theory. Theoretical modeling was made in vacuo. The selected substituents were -CH(3), NH(2), NO(2) and F groups in 3, 4, 5 and ipso carbonyl positions. Geometries of all derivatives were analyzed and it is ascertained that substitution has not important consequences on furan ring geometry. Differences of energy between OO-cis and trans conformers and energy barriers between them are described and extreme cases are explained. Interesting features appear in the cases of -NH(2) and -NO(2) groups, and particularly when the 3 and ipso carbonyl positions are substituted. Variations in energy barriers are correlated with variations in C2-C6 distances for the transition states and planar forms. Substitution effect on Mülliken charges are analyzed and related with internal rotation energy barriers and differences between conformers.

Surfactants have been applied in diverse practical situations mostly related to adsorption phenomena. Also, micelles are quite important to electrocatalytic processes, namely in reactions with nonpolar substrates in aqueous environments. The Critical Micellar Concentration (CMC) and Surface Packing Parameter (G) are parameters that facilitate characterization of the micellization process. In this research work, we have calculated through Quantum Mechanics methods (DFT) a group of nine anionic surfactants. Thus, a model has been built of an hemimicelle fragment optimized by means of a semiempirical method AM1, which allowed us to obtain new geometric parameters with the aim to assess G in conditions where the surfactant molecule is not considered in isolation. A multiple lineal regression analysis was used employing the CMC as the dependent variable, to propose a Quantitative Structure- Property Relationship (QSPR)