Synthesis and Characterization of Iso-Undecenoic and Iso-Undecanoic Acids Based Polyol Esters

The polymerization of 10-undecenoic acid (UDA) was carried out in the presence of montmorillonite K10 clay catalyst (5% of UDA) and deionized water (2.5% of UDA) at a temperature of 250 °C in an autoclave. The UDA polymerized product is a mixture of monomer acids (47–51%), dimer acids (30–32%), and higher polymeric acids (17–23%). The present study describes the isolation of less valuable monomer acids fraction (iso-undecenoic acid) through distillation from polymerization reaction product. This monomer acids fraction was found to be a mixture of iso-undecenoic acid (93–96%) and γ-undecalactone (4–7%) when analyzed by GC-MS. Monomer acids fraction was hydrogenated to also give hydrogenated monomer acids (iso undecanoic acids). Finally, the esterification of monomer and hydrogenated monomer acids fractions were done by the reaction with different polyols like neopentyl glycol (NPG), trimethylol propane (TMP), trimethylolhexane (TMH), and pentaerythritol (PE). Physicochemical and lubricant properties of all the synthesized polyol esters were evaluated including density, kinematic viscosity, pour point, flash point, thermal stability (TGA), oxidation stability (DSC), copper corrosion, weld load, and wear. All the synthesized polyol esters were found to be suitable as hydraulic fluids and automotive lubricants base stocks. Comparatively the iso-undecenoic acid based polyol esters were showed excellent pour point, viscosity-temperature properties, and good thermal stabilities, while the iso-undecanoic acid polyol esters showed good oxidation stability.