Study of Antioxidant Activity of a Phenyl Phosphorylated Compound Derived from Hydrogenated Cardol by Thermogravimetric Analysis

Aims: Use a natural compound derived from cashew nut shell liquid to the production of an additive inhibitor of the oxidation of lubricants oils.
Study Design: This article describes the syntheses, characterization and evaluation of the antioxidant action of a phosphorylated compound derivate from hydrogenated cardol (diphenyl phosphorylated-cardol).
Place and Duration of Study: Department of organic and inorganic chemistry (Universidade Federal do Ceará), between June 2009 and July 2010.
Methodology: Cardol was isolated from hydrogenated cashew nut shell liquid through column chromatography eluted with a stepwise gradient of n-hexane/ethyl acetate. Diphenyl phosphorylated compound was synthesized through of reaction between cardol and diphenyl chloro-phosphate in basic medium. After purification and characterization the performance this compound was evaluated in minerals oils by thermal analyses, monitoring parameters as T(onset), T(endset), T(max) and IPDT, using samples doped in 1 %.
Results: The cardol was isolated with 10 % of the yield and the diphenyl phosphorylated compound was synthesized with a yield of 61,4 %. The techniques of characterization (GC/MS, FT-IR and NMR) showed that the product was efficiently synthesized with a good degree of purity. The Thermo-gravimetric analysis showed that the addition of the new compound promoted a significant increase in thermal stability of mineral naphthenic oils, which confirms its action in inhibition of oxidative process.
Conclusion: According to the experimental data a new phosphorylated antioxidant derived from hydrogenated cardol was efficiently synthesized and characterized. This compound presented excellent performance as inhibitor of oxidation of mineral oils, become these oils more resistant to thermal degradation process.