Design and preparation of liquid polycyclic norbornanes as potential high performance fuels for aerospace propulsion

Abstract High-energy-density (HED) liquid fuels are required for modern and perspective volume-limited aircrafts to extend the flight distance and to increase the speed. In this work, we report on the synthesis of a new set of HED liquid polycyclic norbornane-containing hydrocarbons and on the study of their key physico-chemical characteristics. A facile route to the desired hydrocarbons was developed through modifications of a cheap commercial diene, 5-vinyl-2-norbornene, using [2 + 2]- and [4 + 2]-cycloaddition reactions. Physico-chemical properties of the obtained hydrocarbons, such as density, freezing point, viscosity and heat of combustion, were systematically studied. Some of the hydrocarbons exhibited an enhanced combination of the properties: high heats of combustions, densities up to 1.0799 g/mL, freezing points in the range of +15 °C to below −60 °C and kinematic viscosities up to 1.89 mm2·s−1. The successive modifications of 5-vinyl-2-norbornene significantly improved the energy density (≤45.38 MJ/L) of the produced hydrocarbons over the widely used related fuel, JP-10. Thus, the developed norbornane-containing hydrocarbons can be considered as new promising HED liquid fuels for advanced propulsion.