Abstract: High-energy-density fuels are important for volume-limited aerospace vehicles, but the increase in fuel energy density always leads to poor cryogenic performance. Herein, we investigated the transposed Paternò-Büchi reaction of biomass cyclic ketone and cyclic alkene to synthesize a new kind of alkyl-substituted polycyclic hydrocarbon fuel with high energy density and good cryogenic performance. The triplet-energy-quenching results and phosphorescent emission spectra reveal the sensitization mechanism of the reaction, including photosensitizer excitation, triplettriplet energy transfer, cyclization, and relaxation, and the possible reaction path was revealed by the density functional theory (DFT) calculations. The reaction conditions of photosensitizer type and addition, molar ratio of substrates, reaction temperature, and incident light intensity were optimized, with the target product yield achieving 65.5%. Moreover, the reaction dynamics of the reaction rate versus the light intensity are established. After the hydrogenation-deoxygenation reaction, three fuels with a high density of≥0.864-0.938 g·ml^-1 and a low freezing point of < 55 ℃ are obtained. This work provides a benign and effective approach to synthesize high-performance fuels.

Key words: High-energy-density fuel, Transposed Paternò-Büchi reaction, Kinetics, Bioenergy, Photochemistry

摘要： High-energy-density fuels are important for volume-limited aerospace vehicles, but the increase in fuel energy density always leads to poor cryogenic performance. Herein, we investigated the transposed Paternò-Büchi reaction of biomass cyclic ketone and cyclic alkene to synthesize a new kind of alkyl-substituted polycyclic hydrocarbon fuel with high energy density and good cryogenic performance. The triplet-energy-quenching results and phosphorescent emission spectra reveal the sensitization mechanism of the reaction, including photosensitizer excitation, triplettriplet energy transfer, cyclization, and relaxation, and the possible reaction path was revealed by the density functional theory (DFT) calculations. The reaction conditions of photosensitizer type and addition, molar ratio of substrates, reaction temperature, and incident light intensity were optimized, with the target product yield achieving 65.5%. Moreover, the reaction dynamics of the reaction rate versus the light intensity are established. After the hydrogenation-deoxygenation reaction, three fuels with a high density of≥0.864-0.938 g·ml^-1 and a low freezing point of < 55 ℃ are obtained. This work provides a benign and effective approach to synthesize high-performance fuels.

关键词: High-energy-density fuel, Transposed Paternò-Büchi reaction, Kinetics, Bioenergy, Photochemistry