Kinetics and Mechanism of Iodination of Naphthalenes

Abstract

The kinetics of iodination of naphthalenes have been investigated with
the iodinating system A: I₂-NaNO₂-HNO₃. The reaction is half order in
[I₂]. It is first order in the substrate. Though there is a dependence of the
reaction kinetics on [HNO₃], no definite order has been observed in
[HNO₃]. With increasing [NaNO₂], the rate constants for each substrate
increase initially and subsequently decrease. It is observed that the reactions
are favoured in media of higher acetic acid content. The activation
parameters have been evaluated using the Arrhenius relationship. The
isokinetic temperature has also been evaluated. A mechanism of iodination
has been suggested. It involves the initial formation of electrophilic
HNO₂I⁺.