Self-photosensitized [2 + 2] cycloaddition for synthesis of high-energy-density fuels
Self-photosensitized [2 + 2] cycloaddition for synthesis of high-energy-density fuels
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DOI：
10.1039/c9se00863b
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发表时间：
2020-02
影响因子：
5.6
通讯作者：
Junjian Xie;Xiangwen Zhang;Chengxiang Shi;Lun Pan;Fang Hou;Genkuo Nie;Jiawei Xie;Qing Liu;Jijun Zou
中科院分区：
文献类型：
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作者：
Junjian Xie;Xiangwen Zhang;Chengxiang Shi;Lun Pan;Fang Hou;Genkuo Nie;Jiawei Xie;Qing Liu;Jijun Zou
以环己烯和异佛尔酮为原料，通过自光敏[2+2]环加成和加氢脱氧合成高张力四元环烃，具有高密度和高热值。以异佛尔酮作为自敏剂和反应物可以选择性地发生光反应。异佛尔酮/环己烯共环加成的反应速率比异佛尔酮自环加成快得多，并且DFT计算和光化学动力学都表明前者的能垒远低于后者。在最佳条件下，共环加成和自环加成选择性分别可达93.3%和94.9%，异佛尔酮转化率分别为95.4%和68.8%。此外，一系列烯烃可以与异佛尔酮顺利、高选择性地进行自光敏[2+2]环加成反应。加氢脱氧后，由异佛尔酮/环己烯混合物和纯异佛尔酮（总收率分别为82.1%和61.3%）衍生的碳氢化合物分别具有0.903 g mL−1和0.892 g mL−1的高密度，并具有良好的低温性能。特别是，通过光敏环加成合成的碳氢化合物与通过常见的 C-C 偶联途径合成的碳氢化合物相比，显示出相当高的密度和热值，这归因于所构建的应变环状结构。该工作为高能量密度碳氢化合物的光合作用提供了新途径。
Hydrocarbons with a highly strained four-membered ring are synthesized via self-photosensitized [2 + 2] cycloaddition and hydrodeoxygenation using cyclohexene and isophorone as feedstocks, which show high density and high heat values. Photoreaction can take place selectively with isophorone as a self-sensitizer and a reactant. Isophorone/cyclohexene co-cycloaddition has a much faster reaction rate than self-cycloaddition of isophorone, and both DFT calculations and photochemical kinetics show that the energy barrier for the former is much lower than that for the latter. Under optimal conditions, the selectivity of co-cycloaddition and self-cycloaddition can reach 93.3% and 94.9%, with isophorone conversion of 95.4% and 68.8%, respectively. In addition, a series of olefins can undergo self-photosensitized [2 + 2] cycloaddition with isophorone smoothly in high selectivity. After hydrodeoxygenation, hydrocarbons derived from isophorone/cyclohexene mixture and pure isophorone (with an overall yield of 82.1% and 61.3%) have high densities of 0.903 g mL−1 and 0.892 g mL−1, respectively, along with good cryogenic properties. Especially, the hydrocarbons synthesized through photosensitized cycloaddition show considerably higher density and heat values compared with those derived from a common C–C coupling route, which is attributed to the constructed strained cyclic structures. This work provides a new way for photosynthesis of high-energy-density hydrocarbons.