Thermal Isomerization Kinetics of Azophenols in Isotropic Solvents

Thermal Isomerization Kinetics of Azophenols in Isotropic Solvents 

The operation of a different isomerization mechanism for the cis-to-trans conversion for 1 and 2 is also reflected in the corresponding thermal activation parameters. While the enthalpy and entropy of activation for the thermal isomerization of 1 are 95 and -42 J mol , respectively, completely different 

2 (11 and-186 J mol respectively). Indeed, these latter values reveal a more easily accessible and highly organized transition state for the thermal isomerization of 2, mainly due to the presence of intermolecular hydrogen bonding, which enables, in turn, the operation of the rotational pathway. 

3 displays an additional broad absorption band peaking at about 425 nm, which is ascribable to the azo-hydrazone tautomerism [46]. 

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