title: Theoretical model of internal rotation in monosubstituted derivatives of furfural.
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.
authors.affiliation: Laboratorio de Química Computacional y Teórica, Facultad de Química, Universidad de La Habana, La Habana 10400, Cuba.
authors.forename: Rachel
authors.initials: R
authors.lastname: Crespo-Otero
authors.forename: Luis A
authors.initials: LA
authors.lastname: Montero
authors.forename: Giselle
authors.initials: G
authors.lastname: Rosquete
authors.forename: J Alexander
authors.initials: JA
authors.lastname: Padrón-García
authors.forename: Raúl H
authors.initials: RH
authors.lastname: González-Jonte