Nucleofilicidad relativa intrínseca de pirroles
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Fecha
2020
Autores
Profesor/a Guía
Facultad/escuela
Idioma
es
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Editor
Universidad Andrés Bello
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Este trabajo de investigación se enmarca en el contexto de la búsqueda y
caracterización de escalas relativas de reactividad (electrofilicidad y nucleofilicidad)
orientadas a racionalizar procesos químicos. En particular, el foco de los esfuerzos del
estudio que se plantea es la extensión de la aplicación de modelos teóricos de
reactividad propuestos como un análogo electrónico a la relación de Mayr-Patz, log
kAB = SN,B(NB+EA), que racionaliza la cinética (log kAB) entre pares de electrófilos (A)
y nucleófilos (B) en función de parámetros de reactividad absolutas exclusivamente
asociados a las especies reaccionantes (SN,B y NB al nucleófilo; y EA al electrófilo),i.e.,
∆EAB(∆N
∗
B→A) = SB(A)(ωA + ωB(A)). En esta expresión, ΔEAB(ΔN*B→A) corresponde a la máxima estabilización esperada
para la interacción entre los pares de reacción como consecuencia de una
transferencia de electrones desde el nucleófilo al electrófilo; ωA mide la electrofilicidad
global de A; ωB(A) es la nucleofilicidad de B en presencia del electrófilo A, y SB(A) es
una constante de selectividad electrónica para el par de especies que interaccionan.
Continuando estudios sobre aminas e indoles, la exploración teórica planteada aquí
se centró en reacciones de acoplamiento de pirroles con cationes benzhidrilos con el
fin de cuantificar las respuestas químicas relativas de nucleófilos y de electrófilos que
permiten aumentar nuestra comprensión sobre la reactividad global y selectividad
local de las especies que interactúan. Los resultados computacionales obtenidos
resultan útiles para establecer los efectos electrónicos dominantes en los indicadores
de reactividad conocidos a nivel experimental. Dichos estudios permiten extender la
utilidad de modelos pertubativos de reactividad electrofílica y nucleofílica en procesos
de reacciones orgánicas asociadas a combinaciones polares de reactivos.
This research work is framed within the context of the search and characterization of relative scales of reactivity (electrophilicity and nucleophilicity) oriented to rationalize chemical processes. In particular, the focus of the study is the extension of the application of theoretical models of reactivity proposed as an electronic analogue to the Mayr-Patz equation, log kAB = SN,B(NB+EA), that rationalizes the kinetics (log kAB) between pairs of electrophiles (A) and nucleophiles (B) as a function of absolute reactivity parameters exclusively associated to the reacting species (i.e., SN,B and NB to the nucleophile; and EA to the electrophilic), i.e., ∆EAB(∆N ∗ B→A) = SB(A)(ωA + ωB(A)). In this equation, ∆EAB(∆N ∗ B→A) measures the maximum expected stabilization for the interaction between the reaction pairs as a result of a transfer of electrons from the nucleophile to the electrophilic; ωA measures the overall electrophilicity of A; ωB(A) is the nucleophilicity of B in the presence of the electrophilic A, and SB(A) is a constant of electronic selectivity for the pair of interacting species. Continuing studies on amines and indoles, the theoretical exploration here focuses on pyrrole coupling reactions with benzhydrylium cations in order to quantify the relative chemical responses of nucleophiles and electrophiles that allow us to increase our understanding of the global reactivity and local selectivity of the interacting species. The computational results are useful to establish the dominant electronic effects on the indicators of reactivity known at the experimental level. These studies extend the usefulness of perturbative models of electrophilic and nucleophilic reactivity in organic reaction processes associated to polar combinations of reagents
This research work is framed within the context of the search and characterization of relative scales of reactivity (electrophilicity and nucleophilicity) oriented to rationalize chemical processes. In particular, the focus of the study is the extension of the application of theoretical models of reactivity proposed as an electronic analogue to the Mayr-Patz equation, log kAB = SN,B(NB+EA), that rationalizes the kinetics (log kAB) between pairs of electrophiles (A) and nucleophiles (B) as a function of absolute reactivity parameters exclusively associated to the reacting species (i.e., SN,B and NB to the nucleophile; and EA to the electrophilic), i.e., ∆EAB(∆N ∗ B→A) = SB(A)(ωA + ωB(A)). In this equation, ∆EAB(∆N ∗ B→A) measures the maximum expected stabilization for the interaction between the reaction pairs as a result of a transfer of electrons from the nucleophile to the electrophilic; ωA measures the overall electrophilicity of A; ωB(A) is the nucleophilicity of B in the presence of the electrophilic A, and SB(A) is a constant of electronic selectivity for the pair of interacting species. Continuing studies on amines and indoles, the theoretical exploration here focuses on pyrrole coupling reactions with benzhydrylium cations in order to quantify the relative chemical responses of nucleophiles and electrophiles that allow us to increase our understanding of the global reactivity and local selectivity of the interacting species. The computational results are useful to establish the dominant electronic effects on the indicators of reactivity known at the experimental level. These studies extend the usefulness of perturbative models of electrophilic and nucleophilic reactivity in organic reaction processes associated to polar combinations of reagents
Notas
Tesis (Licenciado en Química)
Palabras clave
Reactividad (Química), Pirrol