Synthesis, Characterization, and Effectiveness of Pyranopyrimidine Derivatives as Multi-function Additive for Lubricating Oils

In the lubricating oil industry, multifunction additives have garnered considerable interest because of their ability to significantly enhance and add different functions. This study details the two-step synthesis of pyranopyrimidine derivatives. The initial step entails a three-component, one-pot reaction of pyrrole-2-carboxaldehyde, malononitrile, and 3-methyl-1-phenyl-2-pyrazoline-5-one, or dimedone, or barbituric acid, to produce compounds (1-3) using nanoparticles magnesium oxide (MgO-Nps) as the catalyst. In the second step, these products are cyclized with isothiocyanatobenzene to form the desired pyranopyrimidine derivatives (4, 5, and 6). The structures of synthesized compounds were confirmed using FTIR and 1H-NMR spectroscopies. The pyranopyrimidine derivatives were blended with the base lubricating oil, and then evaluated as effective antioxidants, corrosion inhibitors, and anti-rust agents using the IP-280 test (Institute of Petroleum's testing method), ASTM-D-130 and ASTM-D-665 tests (American Society of Testing and Materials methods), respectively. Furthermore, pyranopyrimidine derivatives were investigated for antimicrobially induced corrosion (MIC) by molecular docking on the rubredoxin (2DSX) protein from Desulfovibrio gigas bacteria and the cytochrome-c3 (2CTH) protein from Desulfovibrio vulgaris bacteria