Anti-oxidant Mechanism of Aminoantipyrines: A Computational Investigation

Abstract

Mechanism for the reaction of aminoantipyrines with OH radical have been studied using M062X/6-31G(d,p) and M08HX/6-311+G(d,p) level of theory. Two types of possible reaction pathways are discussed: Hydrogen atom abstraction and OH addition on the aromatic ring. Further, the Hydrogen abstraction is studied from three different channels. The PESs are computed using the same level of theories. The H-atom abstraction channels possess lower energetics than that of addition and the product is obtained from demethylation reaction. The enthalpies of formation were computed and compared with available experimental results to verify the reliability of the used methods. Thus, it was found that hydrogen atom abstraction mechanism was thermodynamically favorable in comparison with hydroxyl addition mechanism. Our results are also in good agreement with the experimental observation as both the investigations shows that the N-demethylation product is the major product.