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首页> 外文期刊>ACS catalysis >Molybdenum-Catalyzed Conversion of Diols and Biomass-Derived Polyols to Alkenes Using Isopropyl Alcohol as Reductant and Solvent
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Molybdenum-Catalyzed Conversion of Diols and Biomass-Derived Polyols to Alkenes Using Isopropyl Alcohol as Reductant and Solvent

机译：异丙醇作为还原剂和溶剂的钼催化将二元醇和生物质衍生的多元醇转化为烯烃

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Chemical processes capable of reducing the high oxygen content of biomass-derived polyols are in demand in order to produce renewable substitutes for chemicals of fossil origin. Deoxydehydration (DODH) is an attractive reaction that in a single step transforms a vicinal diol into an alkene but the reaction requires a homogeneous catalyst, a reductant and a solvent, which are typically expensive, unsustainable, or inefficient Herein, we present the use of molybdenum(VI)-based compounds, in particular the cheap and commercially available (NH4)(6)Mo7O24 center dot 4H(2)O, as catalysts for the DODH of vicinal diols in isopropyl alcohol ((PrOH)-Pr-i), which serves as both the solvent and reductant. The reaction proceeds at 240-250 degrees C in a pressurized autoclave, and the alkene yield from simple aliphatic diols can be as high as 77%. The major byproducts are carbonyl compounds formed by dehydration of the diol and the alcohols formed by transfer hydrogenation of the carbonyl compounds; the total yield of reduced species (i.e, alkene alcohols) can be as high as 92%. The DODH of glycerol yields allyl alcohol, Which undergoes subsequent Mo-catalyzeddeeoxygenation to propylene driven by the oxidation of (PrOH)-Pr-i; a major byproduct is the homocoupled product 1,5-h-exadiene. Further insight in this Mo-catalyzed deoxygenation is gained by an investigation of Model compounds: The allylic alcohol 1-hexen-3-ol is deoxygenated to hexene isomers in a yield of 65%, while benzyl alcohol is deoxygenated to toluene in a yield of 93%. The DODH of erythritol yields 39% 2,5-dihydrofuran, while the DOOR of the proposed intermediate 1,4-anhydroerythritol yields 75%. The mechanism of the DODH of 1,4-anhydroerythritol was investigated by means of density functional theory (DFT), and the rate-determining step (24.1 kcal/mol) was found to be reduction of a,molybdenum(VI) diolate to a molybdenum(IV) diolate.
机译：为了生产化石来源的化学物质的可再生替代品，需要能够降低生物质衍生的多元醇的高氧含量的化学方法。脱氧脱水（DODH）是一种引人注目的反应，只需一步即可将邻位二醇转化为烯烃，但该反应需要均相的催化剂，还原剂和溶剂，它们通常是昂贵的，不可持续的或效率低下的。钼（VI）基化合物，尤其是便宜且可商购的（NH4）（6）Mo7O24中心点4H（2）O，作为异丙醇中邻位二醇DODH的催化剂（（PrOH）-Pr-i） ，它既是溶剂又是还原剂。反应在加压的高压釜中在240-250摄氏度下进行，简单脂肪族二醇的烯烃收率可高达77％。主要的副产物是由二醇脱水形成的羰基化合物和由羰基化合物的转移加氢形成的醇。还原物种（即烯烃醇）的总收率可高达92％。甘油的DODH产生烯丙醇，烯丙醇随后通过（PrOH）-Pr-i的氧化而发生Mo-催化二氧化加氧生成丙烯。主要副产物是1，5-h-己二烯的均偶联产物。通过研究以下模型化合物，可以进一步了解Mo催化的脱氧：将烯丙醇1-己烯-3-醇脱氧为己烯异构体，产率为65％，而苯甲醇则脱氧为甲苯。 93％。赤藓糖醇的DODH产率为39％的2，5-二氢呋喃，而所提出的中间体1，4-脱水赤藓糖醇的DOOR产率为75％。通过密度泛函理论（DFT）研究了1,4-脱水赤藓糖醇的DODH机理，发现速率决定步骤（24.1 kcal / mol）是将羟基乙酸钼（VI）还原为α二醇钼（IV）。

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