Propionic acid as a very valuable chemical is in high demand, and it is industrially produced via the oxo-synthesis of ethylene or ethyl alcohol and via the oxidation of propionaldehyde with oxygen. It is urgent to discover a new preparation method for propionic acid via a green route. Recyclable amino-acid-based organic–inorganic heteropolyoxometalates were first used to high-efficiently catalyse the selective oxidation of 1-propanol to propionic acid with H2O2 as an oxidant. A series of amino-acid-based heteropoly catalysts using different types of amino acids and heteropoly acids were synthesized, and the experimental results showed proline-based heteropolyphosphatotungstate (ProH)3[PW12O40] exhibited excellent catalytic activity for the selective catalytic oxidation of 1-propanol to propionic acid owing to its high capacity as an oxygen transfer agent and suitable acidity. Under optimized reaction conditions, the conversion of 1-propanol and the selectivity of propionic acid reached 88% and 75%, respectively. Over four cycles, the conversion remained at >80%, and the selectivity was >60%. (ProH)3[PW12O40] was also used to catalyse the oxidations of 1-butanol, 1-pentanol, 1-hexanol, and benzyl alcohol. All the reactions had high conversions, with the corresponding acids being the primary oxidation product. Proline-based heteropolyoxometalate (ProH)3[PW12O40] has been successfully used to catalyse the selective oxidation of primary alcohols to the corresponding carboxylic acids with H2O2 as the oxidant. The new developed catalytic oxidation system is mild, high-efficient, and reliable. This study provides a potential green route for the preparation propionic acid.

中文翻译：

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杂多金属氧酸盐催化过氧化氢将1-丙醇氧化为丙酸

对丙酸作为非常有价值的化学品有很高的需求，并且它是通过乙烯或乙醇的羰基合成以及通过丙醛与氧气的氧化而在工业上生产的。迫切需要通过绿色途径发现一种新的丙酸制备方法。可循环使用的基于氨基酸的有机-无机杂多金属氧酸盐首先被用来以H2O2为氧化剂高效催化1-丙醇选择性氧化为丙酸。合成了一系列使用不同类型氨基酸和杂多氨基酸的氨基酸杂多催化剂，实验结果表明，脯氨酸基杂多磷钨酸盐（ProH）3 [PW12O40]由于其作为氧转移剂的高容量和合适的酸度，对1-丙醇选择性催化氧化为丙酸具有优异的催化活性。在优化的反应条件下，1-丙醇的转化率和丙酸的选择性分别达到88％和75％。在四个循环中，转化率保持在> 80％，选择性为> 60％。（ProH）3 [PW12O40]也用于催化1-丁醇，1-戊醇，1-己醇和苯甲醇的氧化。所有反应都具有高转化率，相应的酸是主要的氧化产物。脯氨酸基杂多金属氧酸盐（ProH）3 [PW12O40]已成功用于以H2O2为氧化剂催化伯醇选择性氧化为相应的羧酸。新开发的催化氧化系统温和，高效且可靠。这项研究为制备丙酸提供了一条潜在的绿色途径。