Green synthesis of trimethylolpropane triisostearate and triisooleate for usage as bio-lubricants

Abstract

Two methyl-branched triesters, trimethylolpropane-triisostearate (TMP-ISA) and trimethylolpropane-triisooleate (TMP-IOA) have been synthesized via esterification of trimethylolpropane with isostearic-acid and isooleic-acid, respectively. Isostearic-acid and isooleic-acid have been previously produced through the skeletal-isomerization reaction of naturally derived oleic acid using a reusable zeolite catalyst. TMP-ISA and TMP-IOA are characterized by FTIR NMR, GC-MS, and LC-MS. Physicochemical and tribological analysis reveal that TMP-ISA and TMP-IOA exhibit higher oxidative stability, viscosity index, anti-wear property, and better cold flow properties when compared to high-oleic sunflower oil or polyalphaolefin, a common lubricant base oil. Lubricant property analysis of blends of TMP-ISA or TMP-IOA with high-oleic sunflower oil or polyalphaolefin demonstrates their miscibility and potential applications as biolubricants. Upon commercialization, these developed bio-based esters have the potential to reduce the existing reliance on non-renewable petroleum based lubricants. Practical application: Methyl-branched triesters with trimethylolpropane backbone exhibit promising physicochemical and tribological properties to be used as bioingredients in bioproducts.