High-Energy-Density Liquid Spiro-Norbornanes from Methylenenorbornane

Abstract

We report a synthetic scheme for obtaining new spiro-hydrocarbons from a versatile norbornane derivative, methylenenorbornane. As a result, four new spiro-hydrocarbons and the isomeric-related norbornanes for the comparison have been obtained in moderate or good yields through [4π + 2π] and cyclopropanation reactions. The effect of introducing a spiro-center is dependent on the nature of carbocycles at a spiro-carbon atom. There is no obvious advantage in properties for spirocycloalkenes consisting of norbornane and cyclopropane rings at the spiro-carbon atom compared to isomeric hydrocarbons. At the same time, spirocycloalkenes with two norbornane motifs at a spiro-center have exhibited much higher values of densities and energy densities (0.992–1.023 g/mL, 41.79–43.28 MJ/L) than the related hydrocarbons without a spiro-center and JP-10. The obtained results can provide insight and an opportunity to further expand this work to bring new high-performance jet fuels to market.

Pd/C catalytic cyclopropanation of polycyclic olefins for synthesis of high‐energy‐density strained fuels

“…The low conversion of MCPDNB may be due to the presence of methyl substituents around the NB double bonds, which increases steric hindrance and hinders the coordination of Pd/C with the substrate. Interestingly, the ethylidene group of CPDEN was cyclopropanated in this work, while the methylene‐norbornane could not be cyclopropanated in literature, 12 probably because the ethylidene group in this work has greater strain and higher reactivity attributed to the two norbornane rings substitution.…”

“…Interestingly, the ethylidene group of CPDEN was cyclopropanated in this work, while the methylene-norbornane could not be cyclopropanated in literature, 12 probably because the ethylidene group in this work has greater strain and higher reactivity attributed to the two norbornane rings substitution.…”

“…7 The cyclopropanation products of derivates such as norbornene and dicyclopentadiene (DCPD) have density of 0.891-1.080 g/cm 3 and VHOC of 37.94-45.38 kJ/cm 3 . [8][9][10][11][12] Additionally, the strained biofuels produced from cyclopropanation of biobased monoterpenes and sesquiterpenes exhibit good properties with the density of 0.855-0.965 g/cm 3 and VHOC of 37.10-41.51 kJ/cm 3 . [13][14][15][16] To construct the smallest carbocycle, several methodologies have been established, such as Simmons-Smith cyclopropanation, diazoderived carbenoids, free carbenes, cycloisomerization, nucleophilic displacement reactions, and so on.…”

“…For intense, quadricyclane (QC) with two cyclopropane rings has the density and volumetric net heat of combustion (VHOC) of 0.982 g/cm 3 and 43.55 kJ/cm 3 , respectively 7 . The cyclopropanation products of derivates such as norbornene and dicyclopentadiene (DCPD) have density of 0.891–1.080 g/cm 3 and VHOC of 37.94–45.38 kJ/cm 3 8–12 . Additionally, the strained biofuels produced from cyclopropanation of bio‐based monoterpenes and sesquiterpenes exhibit good properties with the density of 0.855–0.965 g/cm 3 and VHOC of 37.10–41.51 kJ/cm 3 13–16 …”

Making accessible soluble silicon-containing polynorbornenes: hydrosilylation of vinyl-addition poly(5-vinyl-2-norbornene)

“…Materials 5-Ethylidene-2-norbornene, 5-vinyl-2-norbornene, Karstedt's catalyst, Rh(acac)(CO) 2 , triethylsilane (Et 3 SiH), 1,1,1,3,5,5,5heptamethyltrisiloxane (HMTS-H), 1,1,3,3,3-pentamethyldisiloxane (PMDS-H) as well as all solvents were purchased from ABCR and Aldrich, and used without additional purification. Vinyl-addition poly(5-vinyl-2-norbornene) (PVNB), 35 2-vinyl-norbornane, 40 and 2-ethylidene-norbornane 46 were syn- Table 6 Solubility coefficients of various gases within the modified vinyl-addition polynorbornenes in comparison with vinyl-addition polynorbornene (PNB) 44 and PVNB Polymer Solubility coefficient (S), S × 10 3 , cm 3 (STP) cm −3 cm (Hg) Fig. 11 The dependences of diffusion (a) and solubility (b) coefficients on the squared cross-section diameter and critical temperature of penetrants, respectively, for the modified vinyl-addition polynorbornenes.…”