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

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 Et3NHCl-AlCl3 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 degrees 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 degrees C due to its rigid cycle structures and flexible chain. At low temperatures, an efficient synthesis of polycyclic alkylated compounds by tetralin and 1,7-octadiene using Et3NHCl-AlCl3 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.image