Density functional theory study on isomerization reactions of pyridazine derivatives bearing N,N-dialkylaminoethyl group

The isomerization reactions of four pyridazine derivatives, i.e., 6‐chloro‐3‐hydroxy‐pyridazine, 1,2‐dihydrogen‐1‐methyl‐3,6‐pyridazindione, 6‐chloro‐3‐diethylamino‐ethoxy‐pyridazine, and 1‐methyl‐2‐diethylaminoethyl‐3,6(2H)‐pyridazindione, have been studied using density functional theory (DFT) B3LYP method at the 6‐311+G** basis set. The geometric structures of reactants, transition states and products have been optimized. The transition states have been explored and proved by vibration analysis as well as intrinsic reaction coordination (IRC) analysis. The activation energies of four reactions were calculated, and the corresponding isomerization mechanisms were also elucidated in theory. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004