“Metafining” of nerolidol with a Grubbs-Hoveyda catalyst to generate high-performance sustainable aviation fuels

Abstract

trans-Nerolidol was quantitatively converted into a stoichiometric mixture of 2-methyl-cyclopentene-1-ol and 2,6-dimethyl-1,5-heptadiene via ring-closing metathesis with a 2nd generation Grubbs-Hoveyda catalyst at 0.03 mol% loading. The alcohol was then converted into tetrahydrodimethyldicyclopentadiene isomers (THDMDCPD) by dehydration, Diels–Alder cycloaddition, and hydrogenation. In parallel, 2,6-dimethyl-1,5-heptadiene was hydrogenated to generate 2,6-dimethylheptane (DMH). A stoichiometric mixture of THDMDCPD and DMH, designated as F1, exhibited outstanding fuel properties including density, gravimetric heat of combustion, and viscosity measurements that met the requirements for Jet-A. In addition, hydrogenation of 2,6-dimethyl-1,5-heptadiene in the presence of a heterogeneous acid catalyst resulted in partial cyclization followed by hydrogenation to yield a mixture containing 70% 2,6-dimethylheptane and 30% 1,1,3-trimethylcyclohexane (F2). F2 exhibited a gravimetric net heat of combustion of 43.69 MJ kg⁻¹ and a kinematic viscosity of only 1.75 mm² s⁻¹ at −20 °C. The remarkable fuel properties of F1 and F2 suggest that they have applications as sustainable aviation fuels or blendstocks with conventional jet fuel.