Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Electrical conductivity technique has been employed to investigate the molecular interaction of aza-aromatics viz. pyridine, α-pikoline, β-picoline and γ-picoline with haloanils, namely chloranil, bromanil and fluranil. The stoichiometry of the charge transfer (CT) complexes has been established and molar conductivities of the complexes determined employing the method of Gutmann and Keyzer. A model has been proposed for determining the equilibrium constant (K) of 1 : 1 molecular complexes of CT type by conductometric measurements. The model involves the assumption: 1/σ = [(1 + K c⁰_A)/q_dK c⁰_A] (1/c⁰_D) + (1/q_d c⁰_A), where σ is the conductivity of the molecular complex, q_d is the extent of depolarization of the complex, c⁰_A) and c⁰_D) are the initial concentrations of the acceptors and donors, respectively. The values of K and q_d follows the expected trend of the conductometric parameters determined by the method of Gutmann and Keyzer as well as ionization potential of donors, thereby substantiating the validity of the model proposed. The observed and theoretical values of thermodynamic parameters for the aza-aromatic-chloranil systems that the interaction of aza-aromatics with haloanils is occurring through the lone pair of nitrogen ring.