Methylenealkane-based low-viscosity ester oils: Synthesis and outlook

Both Group 4 poly-α-olefin (PAO) and Group 5 ester oil basestocks are used in formulations of synthetic engine oils, transmission fluids, and lubricants with leading characteristics such as low viscosity (providing fuel saving), high stability, and environmental safety. The modern technologies of the production of PAOs use catalytic oligomerization of α-olefins, which is complicated by the formation of low-molecular-weight α-olefin dimers (methylenealkanes) as imminent side products. The use of methylenealkanes as raw materials for the synthesis of Group 5 base stocks appears to be highly promising. In the present work, we report the use of methyl 3-butylnonanoate and methyl 3-hexylundecanoate, the products of catalytic methoxycarbonylation of hex-1-ene and oct-1-ene dimers, in the synthesis of two series of branched isomeric esters. These esters demonstrated excellent rheological behavior and may be considered as low-viscosity engine oils with leading characteristics.