Synthesis of Novel Polycyclic Alkylated Tetralin Base Oils Catalyzed by Ionic Liquids and Its Lubricating Properties

Graphical At low temperatures, an efficient synthesis of polycyclic alkylated compounds by tetralin and 1,7-octadiene using Et 3 NHCl−AlCl 3 ionic liquid has been developed. The polycyclic alkylated tetralin with high viscosity has excellent tribological properties, which provides a new route for the production of high viscosity lubricating base oils from coal-based feedstocks. A novel polycyclic alkylated tetralin (PAT) similar to the naphthenic oil was successfully synthesized through Friedel-Crafts alkylation. This was accomplished by reacting coal-based chemical tetralin with 1,7-octadiene, using Et 3 NHCl−AlCl 3 ionic liquid as a catalyst. To enhance the selectivity towards dialkylated products (C28−2THN), the reaction conditions were systematically studied. Interestingly, the reaction could proceed well even at a low temperature of 0 °C and the selectivity for C28−2THN products could reach 54.0 %. The primary physicochemical properties of PAT were investigated in detail, it was found that the existence of polycyclic structures contributes to high viscosity, better thermal-oxidative stability and good polarity. Compared with octyltetralins- and commercial alkylnaphthalene-based oil (AN30), the PAT exhibited superior friction-reducing and anti-wear properties under the load of 100 N at 50 °C due to its rigid cycle structures and flexible chain.