Kinetics of Acid Catalysed Cyclisation of some Hydrazones

Abstract

The cyclisation of hydrazones is an interesting subject which worth thorough investigation. In the present work, molecular model calculations using the MM2 force field are applied to study the conformational preferences of the possible confonners of the unprotonated, the aminoprotonated and the iminoprotonated hydrzones.

From the calculation of the potential energy- torsional angle relations, the energy barrier between the most stable conformation, guache synclinal and the synclinal conformer, with w = 0o, which is the most

favourable conformer for the cyclisation was found to be AE = 317.65 kJ/mol for the unprotonated, AE = 110.95 kJ/mol for the arninoprotonated and AE = 25.20 kJ/mol for the iminoprotonated hydrazones.