Antioxidant Additives for Lubricating Oils. Synthesis and Evaluation of some Polyfunctionalized Phenols Linked to Heterocycles

The polyfunctionalized phenols linked to heterocyclic derivatives, 6-amino-3-ethyl-4-(4- hydroxy-3-methoxyphenyl)-1-phenyl-4h-pyrano[3,2-d]pyrazole-5-carbonitrile (3), methyl-6- amino-5-cyano-2-ethyl-4-(4-hydroxy-3-methylphenyl)-4h-pyran-3-carboxylate (4), 5-amino-7-(4- hydroxy-3-methoxyphenyl)-2-methyyl-4,7,7a-trihydropyrazolo[1,5-a]pyrimidine-6-carbonitrile (5) and 3-amino-1-(4-hydroxy-3-methoxyphenyl)-4h-benzo[f]chromene-2-carbonitrile (6) were synthesized. the antioxidants activities of different dosages of these compounds 3-6, using the turbine base oil with viscosity grade iso 46, were evaluated. oxidation test (rbot) according to ip 229 was applied and the optimum dosage of the promising compound was determined. the formulated blend containing 1.6 % wt. of compound 3 gave higher oxidation stability than a blend containing 0.8 % wt. of international commercial antioxidant additive (ia).