Synthesis, Characterization, and Evaluation of Castor Oil-Based Acylated Derivatives as Potential Lubricant Base Stocks

Synthesis, characterization, and evaluation of a series of novel acylated derivatives of castor oil as biolubricant base stocks are described. The acylated derivatives of castor oil, castor oil fatty acid methyl and 2-ethylhexyl esters were synthesized using different anhydrides (C₁–C₆) in about 90–95% yield. All the products were structurally characterized using NMR and IR spectral data. The acylated products were evaluated for their physicochemical and lubricant properties. Although these products belong to group V, based on viscosity index (130–156), acylated derivatives of castor fatty acid alkyl esters belong to group III, the category of base fluids as per API classification. The acylated products exhibited excellent pour point (−21 to −39 °C) and flash point (174–280 °C). The hexanoylated and butanoylated esters of castor oil exhibited excellent flash points of 280 and 272 °C, respectively. The air release value was found to be excellent in the range of 0.38–0.99 min, and NOACK volatilities in the range of 3.25–3.92%. The other lubrication properties such as load carrying capacity, and emulsion stability were found to be good. Therefore, these derivatives will have utility in hydraulic and metal working fluids and other industrial fluids with their wide range of properties