Synthesis and Physicochemical Properties of Low Viscosity 2‐Ethylhexyl Alkyl Ethers Made from Palm‐Based Esters as Potential Biolubricant

A series of 2‐ethylhexyl alkyl ethers (EHAE) are synthesized from palm‐based esters via a one‐step reaction under mild reaction conditions for potential usage as biolubricant. In this work, 2‐ethylhexyl esters with varying fatty acid chain lengths are reacted with 1,1,3,3‐tetramethyldisiloxane (TMDS), catalyzed by indium bromide (InBr3) at 40 °C to afford EHAE with lauryl, palmityl, stearyl, and oleyl alkyl chain with 55–68% isolated yield. These compounds are characterized using Fourier‐transform infrared (FTIR) and NMR spectroscopic methods and are evaluated for their viscosity, thermal, cold‐flow, oxidative, and anti‐wear properties. The synthesized EHAEs demonstrate low viscosity (1.65–2.55 cSt at 100 °C) with excellent viscosity indices (130–182). These EHAEs show comparable wear scar diameter (0.6–1.0 mm) in comparison with commercial mineral oil base stock (group I SN150) in the four‐ball wear test. Thermal‐oxidative investigation of the EHAE reveals that the thermal degradation temperatures are in the range of 200–250 °C and oxidation onset temperatures are between 165 and 184 °C. Among the EHAEs, 2‐ethylhexyl lauryl ether with the shortest alkyl chain has the lowest pour point of −27 °C. The physicochemical properties of synthesized EHAEs indicate that they are potential as biolubricant base stocks. Practical Applications: The EHAEs produced from this work exhibit promising physicochemical and lubricity properties, which offer great potential to be used as lubricant base stock especially for internal engine oil application. This work demonstrates that a series of 2‐ethylhexyl alkyl ethers (EHAE) can be synthesized from palm‐based ethers using one‐step reductive etherification process. The EHAE exhibits low viscosity with high viscosity indices and good anti‐wear property, potential to be used as lubricant base oil for internal engine oil application.