The purpose of this study is to investigate the acid corrosion inhibition efficiency on carbon steel (CS) by utilizing two novel quinoxaline derivatives obtained from the reaction of recently synthesized d-mannose (MR and MR) nucleophilic substitution (SN). The synthesized compounds were recently characterized by C-NMR and H-NMR spectroscopy. Electrochemistry testing was employed to evaluate their protective efficiency, whereas the surface was investigated using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results indicate that the two inhibitors MR and MR exhibit inhibition efficiencies of 95.3% and 94.8% at 10 M for MR and MR, respectively. The impedance results indicated that the incorporation of MR and MR into the corrosive medium reduces charge capacitance, hence systematically enhancing the interface charge/discharge function and creating an adsorbed layer on the metal surface. Moreover, SEM, water contact angle, and XPS techniques corroborated the formation of a protective coating on the carbon steel substrate surface following the incorporation of MR and MR. The chemical interaction mechanisms at the atomic scale were analysed using theoretical calculations, DFT calculations and MD simulations.