A new ketal cyclic from ethyl 9,10-dihydroxyoctadecanoate with acetone had been synthesized by reflux and sonochemical method. The synthesis was performed via several steps of reaction, i.e.: transesterification, hydrolysis, oxidation with 1% KMnO4 in basic condition, esterification, and ketalization. The structures of the products were confirmed by FTIR, GC-MS, 1H- and 13C-NMR spectrometers. Direct transesterification of used cooking oil produced a mixture of ethyl ester in 82.94% yield meanwhile hydrolysis of this mixture gave free fatty acids mixture in 88.46% yield. Hydroxylation reaction of free fatty acids mixture yielded a white powder of 9,10-dihydroxyoctadecanoic acid in 46.52% yield. Esterification of 9,10-dihydroxyoctadecanoic acid and ethanol catalyzed by sulfuric acid with reflux condition for 4 hours and sonochemical method, respectively yielded 90% and 93.8% of ethyl 9,10-dihydroxystearate. In the other side, the utilization of KSF montmorillonite as catalyst conducted with reflux gave 52% in yield of ester. Furthermore, the use of acetone in 45 minutes sonochemical method with montmorillonite KSF catalyst gave cyclic ketal (ethyl 8-(2,2-dimethyl-5-octyl-1,3-dioxolan-4-yl)octanoate) as a yellow viscous liquid in 53.30% yield. From physicochemical properties –density, kinematic viscosity, viscosity index, total acid number, total base number and iodine value- gave the conclusion that this novel compound is potential biolubricant candidates to be developed.
Definition of oil change intervals based on the analysis of selected physicochemical properties of used engine oils
