Estudo computacional das reações SN2 e E2: efeito do impedimento estérico do substrato e nucleófilo

Abstract

Reactions SN2 and E2 are typical reactions of organic chemistry and there are a multitude of reactions in this segment, these are presented as fundamental in the synthesis, both in industry and in nature. And based on these utilities, we will show here the influence of some variables such as substrate, nucleophile and solvent will favor one of the two reactions, although they occur simultaneously, but with predominance of one over the other in all cases. Thus, in the present work two theoretical computational methods were developed with the aid of the GAUSSIAN 5.0.8 programfor the kinetic and thermodynamic study of these reactions, as well as the ideal conditions for their occurrence. In the first part of the study, there was a relative comparison between the two reactions at the semiempirical level AM1 and PM6, in the two methods the E2 reactions did not have expected behavior for the primary alkyl halides, whereas SN2 in the AM1 method also caused anomalous results, but In the PM6 method was presented as expected. Thus the study of the E2 reactions was terminated. The second part of the study was focused only on the SN2 reactions, in which several experiments were performed with different electrophiles and nucleophiles simulating an implicit methanol solvate medium (IEFPCM) at semiempirical PM6 level. The results were optimistic and corresponded to the expectations of the study, where factors such as steric effects on the electrophile, nucleophile and reactive medium had positive influences on the final result, following a tendency of reactivity imposed by experimental analyzes.