We report the highly remarkable discovery that glucose oxidation catalysed by polyoxometalates (POMs) in methanolic solution enables formation of formic acid and methyl formate in close to 100% combined selectivity, thus with only negligible sugar oxidation to CO₂. In detail, we report oxidation of a methanolic glucose solution using H₈[PV₅Mo₇O₄₀] (HPA-5) as catalyst at 90 °C and 20 bar O₂ pressure. Experiments with ¹³C-labelled glucose confirm unambiguously that glucose is the only source of the observed formic acid and methyl formate formation under the applied oxidation conditions. Our results demonstrate a very astonishing solvent effect for the POM-catalysed glucose oxidation. In comparison to earlier work, a step-change in product yield and selectivity is achieved by applying an alcoholic reaction medium. The extremely high combined yields of formic acid and methyl formate greatly facilitate product isolation as low-boiling methyl formate (bp = 32 °C) can simply be isolated from the reaction mixture by distillation.

中文翻译：

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葡萄糖氧化为甲酸和甲酸甲酯，具有完美的选择性

我们报告了一个非常了不起的发现，即在甲醇溶液中由多金属氧酸盐（POMs）催化的葡萄糖氧化使甲酸和甲酸甲酯的形成具有接近100％的组合选择性，因此糖氧化至CO _2的作用微不足道。详细地，我们报道了在90°C和20 bar O ₂压力下使用H ₈ [PV ₅ Mo ₇ O ₄₀ ]（HPA-5）作为催化剂氧化甲醇葡萄糖溶液的情况。实验¹³C标记的葡萄糖明确证实，葡萄糖是在所施加的氧化条件下观察到的甲酸和甲酸甲酯形成的唯一来源。我们的结果表明，POM催化的葡萄糖氧化具有非常惊人的溶剂作用。与以前的工作相比，通过使用醇类反应介质可以实现产品收率和选择性的逐步变化。甲酸和甲酸甲酯的合并收率极高，极大地促进了产物的分离，因为低沸点的甲酸甲酯（沸点= 32°C）可以通过蒸馏简单地从反应混合物中分离出来。