RESUMO
The aim of this work is to present results derived from experimental IR and UV spectra and theoretical studies of DPCH, in order to get a more deeper insight on the physicochemical properties of this compound to gain a more deep knowledge of its action, helping in the design of new compounds with antimalaric effects. Experimental results are analyzed on the basis of theoretical calculations, which allow to derive suitable interpretations of spectral data.
Assuntos
Cicloexanonas/química , Oxigênio/química , Peróxidos/química , Compostos de Espiro/química , Modelos Moleculares , Conformação Molecular , Espectrofotometria Infravermelho , Eletricidade Estática , VibraçãoRESUMO
The influence of temperature and solvent effects on the stability of the complex formed by two molecules of 1,2-dihydroxybenzene and one molecule of AlCl3 were experimentally and theoretically studied, by means of UV spectroscopic methods and Density Functional Theory methods. The changes of the stability constant with the temperature were analyzed using the van't Hoff equation, while the variations with the permittivity of the reaction medium were explained with an equation proposed by us. The experimental and theoretical data obtained allowed proving that the increase in the hydrogen-bond donor ability of the solvents favors a higher thermodynamic stability of the reactants with respect to the complex and, therefore a decrease in the corresponding stability constant. The non-planar structure proposed for the 2:1 ligand-metal complex is coherent with the small batochromic shift experimentally observed. In the complex molecule, the planes containing the phenyl rings are tilted by approximately 89 degrees with each other. It was concluded that the complexation reaction is an endothermic process in which the solvent-solute interactions play an essential role.
Assuntos
Alumínio/química , Catecóis/química , Compostos Organometálicos/química , Estabilidade de Medicamentos , Solventes , Espectrofotometria Ultravioleta , Temperatura , TermodinâmicaRESUMO
We report the experimental preparation of the 1,3-butanal-1,2,4,5-tetroxane by oxidation of glutataldehyde with oxygen peroxide in presence of concentrated sulfuric acid, following the Bayer and Viller method modified by Jorge et al. The UV and IR spectra are studied from the experimental and theoretical standpoint. A rather complete vibrational assignment was performed and the nature of the electronic transitions was discussed in detail.
Assuntos
Aldeídos/química , Tetraoxanos/química , Tetraoxanos/síntese química , Espectrofotometria Infravermelho , Espectrofotometria UltravioletaRESUMO
A thermochemical a rather simple experimental technique method, is used to determine the enthalpy of the formation of 3,6-dibutanoic-1,2,4,5-tetroxane. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6-311G basis set level. Some possible extensions of the present procedure are pointed out.
