INVESTIGADORES
SANCHO Matias Israel
artículos
Título:
Mechanism of the complexation reaction of aluminum chloride with o-hidroxy-benzophenone
Autor/es:
M. I. SANCHO; M.C. ALMANDOZ; S.E. BLANCO; F.H. FERRETTI
Revista:
JOURNAL OF MOLECULAR STRUCTURE THEOCHEM
Editorial:
Elsevier
Referencias:
Año: 2003 vol. 634 p. 107 - 120
ISSN:
0166-1280
Resumen:
A theoretical and experimental study on the formation reaction of the complex between AlCl3 and 2-hydroxy-benzophenone
in primary alcohols was performed. The influence of the temperature, the ionic strength and the solvent on the reaction rate were
investigated. Under the adopted experimental conditions the stoichiometric composition of the formed complex is 1:1. In the
theoretical study, thermodynamic magnitudes, torsional angles, length bonds, energy and reactivity indices were used. The
calculations were performed at the RHF/3-21G and RHF/6-31G(d) levels of theory, using the Onsagers and COSMO methods.
To explain the kinetic results obtained we proposed a reaction mechanism that includes the acidbase dissociation of 2-
hydroxy-benzophenone, the reaction between AlCl3 and a solvated proton to form the AlCl2+ cation, and the formation of the
metal complex by an ionic reaction between the 2-hydroxy-benzophenonate anion and the metal cation. This reaction between
two ions of opposite charges is the rate-determining step of the complexation reaction analyzed. On the other hand, the
theoretical conclusion on the greater planarity of the molecules of the complex with respect to the free molecules of 2-hydroxybenzophenone
is in agreement with the batochromic shift experimentally observed. Also, the proposed mechanism
satisfactorily explains the global rate of the second order reaction, and the dependence of the rate constant with the temperature,
ionic strength and permittivity of the reaction medium.