Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia,ChemSusChem

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Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia
ChemSusChem ( IF 7.5 ) Pub Date : 2018-08-23 , DOI: 10.1002/cssc.201801067
Julie Rorrer _{1,

2} , Suresh Pindi _{1,

3} , F. Dean Toste _{1,

3} , Alexis T. Bell _{1,

2}

Affiliation

Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass‐derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct etherification of primary alcohols in the liquid phase, achieving ether selectivities of >94 % for C₆–C₁₂ linear alcohol coupling at 393 K. The length of linear primary alcohols (C₆–C₁₂) was shown to have a negligible effect on apparent activation energies for etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C₆ alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β‐carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the ‐OH group are highly selective to ether. A novel model compound, 4‐hexyl‐1dodecanol, was synthesized and tested to further demonstrate this structure–activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass‐derived alcohols.

中文翻译：

醇结构对钨酸二氧化锆醚化和脱水动力学的影响

线性和支链醚分子作为可从生物质衍生的醇生产的柴油添加剂和润滑剂，最近引起了人们的兴趣。在这项研究中，钨酸锆被鉴定为是一种选择性的绿色固体酸催化剂，用于液相中伯醇的直接醚化，在393 K下对C ₆ -C ₁₂线性醇偶联的醚选择性达到> 94％。线性伯醇（C ₆ –C ₁₂）对醚化和脱水的表观活化能的影响可忽略不计，证明了同时生产对称和不对称线性醚的可能性。在一系列C _6上的反应甲基支链位置变化的醇表明，取代的醇（2°，3°）和在β-碳上具有支链的醇容易脱水，但是在支链上离OH基团至少三个碳的醇对醚具有高度选择性。合成并测试了一种新型的模型化合物4-己基-1-十二烷醇，以进一步证明这种结构-活性关系。醇结构对选择性的影响趋势与先前提出的醚化和脱水机理相一致，并有助于定义可能的途径，以从生物质衍生的醇中选择性地形成醚。

更新日期：2018-08-23

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