Controllable Carbon-Carbon Bond Formation On The Ring For The Production Of High-Density Fuels

The formation reaction of carbon-carbon bonds is an important way to achieve organic synthesis.The controllable formation of carbon-carbon bonds on the ring is an important method to increase the density and calorific value of hydrocarbon fuels.High-density liquid hydrocarbon fuel is an important component of liquid propellant,which can effectively improve the flight performance of aircraft.In this paper,we explored the controllable carbon-carbon bond formation on the ring to prepare high-density fuels.“One-pot”reaction can reduce equipments,save energy,and improve atomic economy.In this paper,cyclopentyl cyclopentane was synthesized from cyclopentanone via aldol condensation and subsequent hydrodeoxygenation in one pot.A series of solid base-palladium bifunctional catalysts were prepared to investigate the effects of support types,support interface regulation,alkali metal types and the amount of two active sites on the reaction network.The activity and selectivity of"one-pot"condensation-hydrogenation were regulated by the coupling of two different active sites in space and activity.The results showed that a catalyst with the spatial order from inside to outside of the support,polydopamine,active sites of hydrogenation,and the active sites of condensation can achieve the optimal spatial coupling of the two active sites,and the yield of cyclopentyl cyclopentane was increased.As a reductant and an interface regulator between support and active site,polydopamine plays a key role in promoting the coupling of two active sites.Cyclopentanone firstly contacts the active sites of condensation to generate 2-cyclopentyl cyclopentanone.The condensation product can immediately diffuse onto the hydrogenation active sites to reduce the ketone groups,which prevents further condensation.We explored the effects of the types of support and solid base on the"one-pot"reaction network.When the support is polydopamine-coated carbon nanotubes,the activity of supported zirconium dioxide can mathch well with the activity of supported palladium nanoparticles.When the amounts of palladium and zirconium dioxide were 7%and 67%,respectively,the two active sites can achieve optimal coupling.The yield of cyclopentyl cyclopentane was increased to 79%.When the support is polydopamine-coated SBA-15,the hydrodeoxygenation activity was increased by the improved dispersion of palladium nanoparticles.A strong base,magnesium oxide,was needed to achieve better coupling with the supported palladium nanoparticles.When the amount of palladium is 5%and the amount of magnesium oxide is 22%,the two active sites can achieve optimal active coupling.The yield of cyclopentyl cyclopentane was increased to 81%.Cyclopropanation of a hydrocarbon compound containing double bonds is an effective way to increase the density and energy of hydrocarbon fuels.In this paper,dichlorocarbene is used for the cyclopropanation of double bonds.A series of experiments were conducted to investigate the effects of alkali type,phase-transfer agent,and olefin structure on the liquid-liquid two-phase cyclopropanation.It has been found that the volume of the aqueous phase has a great influence on the cyclopropanation reaction.Without the addition of extra deionized water,the reaction kinetics can be changed from one order to zero order.The trace-water system not only effectively increased the reaction rate,but also keep the reaction rate stable with the decrease of the reactant concentration.Then,we conducted a scale-up experiment based on the trace-water system,and synthesized hundred grams of product（7,7-dichlorobicyclo[4.1.0]heptane）.Furthermore,the product was dechlorinated by sodium metal to obtain a polycyclic mixture mainly containing tricyclo[4.1.0.0^2,7]heptane and pentacyclotetradecane.The product has a calorific value of 43.64 kJ/g.