Computational investigations, Hirshfeld surface analysis, interaction energy calculations, and energy framework crystal structure of methyl 2-amino-5-hydroxybenzoate

Abstract

The title compound with the molecular formula C8H9NO3 is synthesized by refluxing 2-amino-5-hydroxybenzoic acid in methanol. The molecular structure of the compound is determined by single crystal X-ray diffraction. Methyl 2-amino-5-hydroxybenzoate crystallizes in the orthorhombic space group P212121 with a = 4.973(2) Å, b = 10.923(5) Å, c = 14.074(6) Å, Z = 4 and V = 764.4(6) Å3. DFT is used to compute HOMO—LUMO energy levels, to predict the reactivity of substituents (NH2 and OH), and to determine the nucleophilic character of these two groups. The orientation and nature of substituents on benzene favors the formation of a stable six-membered ring via hydrogen bonding which plays a key role in the properties of the investigated compound. The natural bond orbital (NBO) population analysis demonstrates that the hyperconjugative effect between the donor lone pairs located on the carbonyl oxygen atom and the N—H group, via the lp O → σ*(N—H) 1,6-remote interaction, is responsible for the preferred conformation. The molecular electrostatic potential (MEP) surface shows the electrical neutrality in the molecule. To get an insight to the intermolecular interactions in the crystal a Hirshfeld surface analysis is also carried out.