Understanding the Chemical Reactivity of Dihydroxyfumaric Acid and its Derivatives through Conceptual DFT

Gheorghe Duca,Natalia Bolocan

doi:10.37358/rc.21.4.8465

Abstract

The chemical reactivity descriptors have been calculated through Molecular Electron Density Theory encompassing Conceptual DFT. The validity of �Koopmans� theorem in DFT� (KID) has been assessed by a comparison between the global descriptors (electronegativity, total hardness, and global electrophilicity) calculated through vertical energy values and those arising from the HOMO and LUMO values. These results suggest that the KID procedure is valid and may be used, in conjunction with the B3LYP/3-611G(d, p) level of theory in further studies of related compounds in the aqueous medium. The active sites for nucleophilic and electrophilic attacks have been identified and verified using the local reactivity descriptors: the dual descriptor, the electrophilic and nucleophilic Parr functions, the local reactivity difference index Rk and MEP maps. Obtained results suggest that the antioxidant/antiradical power of investigated compounds may be explained by the highest ambiphilic activation of the oxygen atoms of the hydroxyl groups in the ene-diol moiety.

Highlights

Dihydroxyfumaric acid (DHF4) has recently attracted attention in the context of the “glyoxylate scenario”, which suggested that it might have been one of the central building blocks in the synthesis of complex organic macromolecular structures, such as sugars and nucleosides [1].The chemical reactivity of dihydroxyfumaric acid is mainly due to its ene-diol moiety, which is readily oxidized or reduced, depending on the environment
Conceptual Density Functional Theory (DFT) descriptors that predict and explain the chemical reactivity of molecular systems may be calculated with accuracy directly from the energies of the frontier orbitals only if the validity of the Koopman’s theorem is ensured
The present research investigated the goodness of the B3LYP density functional together with the 3-611G(d,p) basis set in predicting and explaining the chemical reactivity of DHF4 and its three derivatives, by checking how well it follows the KID procedure

Summary

Introduction

The chemical reactivity of dihydroxyfumaric acid is mainly due to its ene-diol moiety, which is readily oxidized or reduced, depending on the environment. The ene-diol fragment has the ability to efficiently capture electrons from free radicals, making DHF4 a good radical scavenger, similar to ascorbic acid. DHF4 is prone to autooxidation and decarboxylation, but its dimethyl ester is stable in solution for days, making it a good starting point for further synthesis. The chemical structure of the DHF4 and its dimethyl ester give two possible types of bond forming reactivity: through the C atom in the carboxylic acid fragment, which favors interactions with nucleophilic reagents, or through the ene-diol moiety, susceptible to electrophiles

Methods

Results

Conclusion