Détails Publication
Synthesis, Experimental Characterizations and Theoretical Study of the Chemical Reactivity of Coumarin-6-yl Acetate in Gas and Solvent Phases,
Discipline: Chimie
Auteur(s): Honoré Kouadio Yao, Zakaria Koulabiga, Akoun Abou, Abdoulaye Djandé, Stéphane Coussan, Olivier Ouari
Auteur(s) tagués:
Renseignée par : DJANDE Abdoulaye
Résumé

The first objective of the study is based on experimental characterization of the studied compound. The synthetization process of
C11H8O4 (I) involved the O-acetylation of 6-hydroxycoumarin with acetic anhydride, utilizing diethyl ether as a solvent and
pyridine as a base. The obtained structure was characterized by both spectroscopic analyses such as ESI-MS, FT-IR, 1H and 13C
NMR analysis and by single-crystal X-ray diffraction studies. In the latter case, we employed direct methods to solve the
structure of (I) and subsequently refined to a final R value of 0.054 for 1896 independent reflections. In the structure, C—H···O
hydrogen bonds connect the molecules into R2
2 (8) dimers, which are linked together by C—H···O interactions, forming layers
parallel to the bc crystallographic plane. Similarly, the crystal structure is sustained by π–π interactions between neighboring
rings, with inter-centroid distances lower than 3.8 Å. The second objective of the study is to use theoretical calculation methods
to analyze the effect of solvent polarity on the energy gap of the boundary molecular orbitals and the overall chemical reactivity
of coumarin-6-yl acetate in order to provide a better understanding of stability and reactivity. A series of density functional
theory computations were achieved with B3LYP/6-311++G(d,p) basis set in both gas and solvent phases. In addition to the dipole
moment, the natural bond orbital charge distribution was estimated in toluene, tetrahydrofuran (THF) and benzene solvents. The
calculations were conducted utilizing the Gaussian 09 software, and the outcomes exhibited that the solvents have an influence
on the optimized parameters. Furthermore, dual and local reactivity indices as Fukui functions from the natural bond orbital
(NBO) charges were estimated in order to have a better comprehension of the electrophilic and nucleophilic regions, as well as
the chemical activity of (I). The obtained dipole moment in the gas phase is 6.03 Debye and those in the presence of the solvents
are 7.89, 6.87, 7.51 and 6.83 Debye for water, toluene, THF and benzene, respectively. Additionally, the global chemical
reactivity parameters exhibit variation contingent on the molecular compound and polarity of the solvents, making this an
important consideration in the selection of appropriate solvents for a given chemical reaction. The studied compound shows
higher stability in the benzene solvent evidenced by an EHOMO-ELUMO energy gap of 9.48 eV, while its low stability is observed in
the gas phase with an EHOMO-ELUMO energy gap of 6.64 eV.

Mots-clés

Coumarin Ester, Crystal Structure, Spectroscopic Analysis, Quantum Chemical Calculations, Fukui Functions

936
Enseignants
7719
Publications
49
Laboratoires
101
Projets