Alkyl-adamantane fuels have drawn tremendous attention for aerospace vehicles due to their high density and high oxidation stability. Here, we reported a regioselective route to synthesize methyl-substituted adamantanes including 1,3,5-trimethyl-adamantane and 1,3,5,7-tetramethyl-adamantane with single configuration via alkylation of 1,3-dimethyl-adamantane, with yields of ∼60 and ∼80%, respectively. The reaction kinetics of alkylation has been investigated, and the reaction rate constants and apparent activation energies were calculated based on the experimental kinetic data. The oxidation stability of methyl-substituted adamantane family were first evaluated via pressure differential scanning calorimetry and rapid small-scale oxidation test, and the results indicate that the oxidation stability is correlated to the carbon type available on the molecule in the order of 1,3,5,7-tetramethyl-adamantane > 1,3,5-trimethyl-adamantane > 1,3-dimethyl-adamantane > 1-methyl-adamantane. Notably, 1,3,5,7-tetramethyl-adamantane with four quaternary carbons and no tertiary carbon presents supreme oxidation stability than JP-10 and decalin. Finally, we used 1,3,5,7-tetramethyl-adamantane as an additive and achieved in improving the oxidation stability of JP-10. This work presents methyl-substituted adamantanes as good high-density and high-oxidation-stability fuel components and suggests that methyl groups substituted on tertiary carbon of adamantane has a beneficial effect on improving oxidation stability.

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区域选择性合成甲基取代的金刚烷，以促进高密度燃料的氧化稳定性

烷基-金刚烷类燃料因其高密度和高氧化稳定性而受到航空航天业的极大关注。在这里，我们报道了一种区域选择性路线，可通过1,3-二甲基金刚烷的烷基化反应，合成具有单个构型的包括1,3,5-三甲基金刚烷和1,3,5,7-四甲基金刚烷在内的甲基取代的金刚烷。产率分别为〜60％和〜80％。研究了烷基化反应的动力学，并根据实验动力学数据计算了反应速率常数和表观活化能。甲基取代的金刚烷家族的氧化稳定性首先通过差示扫描量热法和快速小规模氧化试验，结果表明，氧化稳定性与分子上可用的碳类型相关，顺序为1,3,5,7-四甲基-金刚烷> 1,3， 5-三甲基金刚烷> 1,3-二甲基金刚烷> 1-甲基金刚烷。值得注意的是，具有四个季碳且没有叔碳的1,3,5,7-四甲基金刚烷比JP-10和十氢化萘具有最高的氧化稳定性。最后，我们使用了1,3,5,7-四甲基金刚烷作为添加剂，并提高了JP-10的氧化稳定性。这项工作提出了甲基取代的金刚烷类作为良好的高密度和高氧化稳定性的燃料组分，并表明在金刚烷的叔碳上取代的甲基对改善氧化稳定性具有有益的作用。