Estudio de la Influencia de la polarizabilidad del grupo vecino C=X, en la cinética de eliminación de cloruro de hidrógeno a partir de cloruros de alquilos β- sustituidos (X = CH2 , S, NH, PH), usando la teoría del funcional de la densidad
Study of the Influence of the polarization of the neighboring group C = X, in the kinetics of hydrogen chloride removal from b- (substituted) alkyl chlorides (X = CH2 , S, NH, PH), using the density functional theory
Date
2018
2018
Author
Márquez Brazón, E. A.
Flores-Sumoza, M. C.
Cortes Gómez, E.
Puello-Polo, E.
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Abstract
The elimination kinetics of the compounds 5-chloro 2-methylpentene, 5-chloropentan-2-imine, (5-chloropentan-2-ylidene) phosphine and 5-chloropenta2-thione compounds were studied using the electron structure methods: B3LYP, MW1PW91 and PBEPBE with the basis set 6-31++G(2d,p), respectively, belonging to the computational package G09W. According to the elimination products, two possible reaction mechanisms were proposed: a discrete path through a four-member transition state and a intime ion-par via a 5-membered cyclic transition state, where the C = X group assists, anchimerically, the HCl elimination. With the exception of the group X = CH2, the favorable mechanism occurs through an intimate Ion-Pair type 5-membered TS, where the breaking of the C2 - Cl1 bond is the determining step of the reaction. The concept of stabilization energy by anchimeric assistance was proposed and used to determine the following order of reactivity: S> PH> NH> O; A linear relationship between the free activation energy and the molecular polarizability of the transition states was found, suggesting that this parameter plays a pivotal role in the anchimerical assistance observed in these systems.
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