Synthesis and Characterization of Novel Polyol Esters of Undecylenic Acid As Ecofriendly Lubricants

Abstract

AbstractThree novel esters of undecylenic acid (UA) were synthesized using the following polyols: linear diglycerol (DG), pentaerythritol monomethylether (PEME), and trimethyloltoluene (TMT). They were characterized through density, viscosity, thermo‐oxidative stability, melting point (m.p.), miscibility with mineral oils, and toxicity to evaluate their potential as ecofriendly lubricants. Trimethylolpropane (TMP) triundecylenate was also synthesized and characterized as a reference ester. Esters’ densities were in the range 0.93–0.97 g cm−3. The PEME ester showed a kinematic viscosity of 25.2 cSt at 40°C, only slightly higher than that of TMP ester (24.7 cSt), both of them near the ISO VG 22 class, while DG and TMT esters were near the ISO VG 32 class, with viscosities of 28.3 and 37.1 cSt, respectively. PEME and TMT esters were similar in thermo‐oxidative stability and more stable than their corresponding oleate esters. The m.p. of TMT ester was remarkedly low (−54°C), showing its potential for very cold temperature applications. TMT ester was found to be nontoxic against Artemia salina (LC50 > 1000 μg mL−1), an initial indication of nontoxicity of UA esters in aquatic media. The synthesized esters showed potential to be applied as ecofriendly lubricants.