Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
Dalton Trans. 2018 Jun 25;47(25):8193-8198. doi: 10.1039/c8dt00866c.
The effect of microwave and mechanochemical ball milling energy inputs was studied for the peroxidative oxidation (with aqueous H2O2) of cyclohexane to cyclohexanol and cyclohexanone, over CoCl2 and/or V2O5 dispersed (μm scale) catalysts. A maximum total yield of cyclohexanol and cyclohexanone of 43% after 1 h of reaction at 30 °C, in acetonitrile and under microwave irradiation (5 W), was achieved over the CoCl2-V2O5 (3 : 1) catalyst prepared by ball milling. Cyclohexanol is the main final product with a selectivity of up to 93% over cyclohexanone. Conducting the oxidation reaction under microwave irradiation under the same conditions but without any mechanochemical treatment of the catalyst prior to use resulted in a lower total yield of 30% with a lower selectivity (69%) towards cyclohexanol over cyclohexanone. The sole application of mechanochemical treatment for the catalyst preparation and the catalytic oxidation of cyclohexane allowed to reach yields of 29% after 1 h of reaction, at room temperature, without microwave irradiation and any additive and in the absence of any organic solvent. Ball milling is shown to provide a convenient, solvent-free method to disperse these solid catalysts and to promote the above cyclohexane oxidation, although, in the latter case, not so effectively as microwave irradiation.
研究了微波和机械化学球磨能量输入对环己烷过氧化（用过氧化氢水溶液）生成环己醇和环己酮的影响，使用 CoCl2 和/或 V2O5 分散（μm 级）催化剂。在 30°C、乙腈中并在微波辐射（5 W）下，通过球磨制备的 CoCl2-V2O5（3:1）催化剂在 1 小时内反应，可获得最高总收率为 43%的环己醇和环己酮。环己醇是主要的最终产物，环己酮的选择性高达 93%。在相同条件下，在使用前不对催化剂进行任何机械化学处理而进行微波辐射下的氧化反应，导致总收率降低至 30%，环己醇对环己酮的选择性降低至 69%。仅对催化剂进行机械化学处理并用于环己烷的催化氧化，可在无微波辐射、无任何添加剂且无有机溶剂的情况下，在室温下反应 1 小时，达到 29%的收率。球磨被证明是一种方便的、无溶剂的方法，可以分散这些固体催化剂，并促进上述环己烷氧化，尽管在后一种情况下，效果不如微波辐射。
