Reinvestigating Catalytic Alcohol Dehydrogenation with an Iridium Dihydroxybipyridine Catalyst
Reinvestigating Catalytic Alcohol Dehydrogenation with an Iridium Dihydroxybipyridine Catalyst
复制标题
重新研究铱二羟基联吡啶催化剂催化酒精脱氢
DOI：
10.1021/acs.organomet.0c00398
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发表时间：
2020
期刊：
影响因子：
2.8
通讯作者：
Papish, Elizabeth T.
中科院分区：
文献类型：
--
作者：
Yao, Wenzhi;DeRegnaucourt, Alexa R.;Shrewsbury, Emily D.;Loadholt, Kylie H.;Silprakob, Weerachai;Qu, Fengrui;Brewster, Timothy P.;Papish, Elizabeth T.
2012年，研究的催化剂[Cp*Ir（H2O）（6，6 ′-dhbp）]2+（1; 6，6 ′-dhbp = 6，6 ′-二羟基-2，2 ′-联吡啶）被报道为一种高效（92%转化率）和选择性催化剂，用于通过无受体脱氢将苯甲醇转化为苯甲醛作为唯一产物。我们在此报告，观察到的转化率和选择性数据是不准确的，但可能是由于，在一定程度上，从其他产品正在生产，不容易检测。具体而言，苯甲酸是通过苯甲醛的反硝化作为副产物形成的，但在高温下，产生的大部分苯甲酸就地转化为苯和二氧化碳。虽然我们可以解释观察到的选择性，但我们无法解释观察到的产物转化率。在我们手中，我们观察到在原始条件下15%转化为产物。其他醇底物也进行了检查，并给出较低的转化率的产品和降低的选择性与原始报告相比。无受体醇脱氢生成醛是一种潜在的变革性技术，它可以让化学家用仅生成H2气体作为副产物的高效催化剂取代产生废物的化学计量氧化剂。因此，澄清2012年的报告，指出什么条件可以导致高效率和高选择性是一个值得讨论的主题。
The examined catalyst [Cp*Ir(H2O)(6,6′-dhbp)]2+(1; 6,6′-dhbp = 6,6′-dihydroxy-2,2′-bipyridine) was reported in 2012 as a highly efficient (92% conversion) and selective catalyst for the conversion of benzyl alcohol to benzaldehyde as the sole product via acceptorless dehydrogenation. We report herein that the observed conversion and selectivity data are not accurate but may have resulted, in part, from other products being produced that are not easily detected. Specifically, benzoic acid is formed as a byproduct via the disproportionation of benzaldehyde, but at high temperatures, most of the benzoic acid produced is convertedin situto benzene and carbon dioxide. While we can explain the observed selectivity, we cannot explain the observed conversion to products. In our hands, we observed 15% conversion to products under the original conditions. Other alcohol substrates were also examined and gave lower conversion to products and decreased selectivity in comparison with the original report. Acceptorless alcohol dehydrogenation to generate aldehydes is a potentially transformative technology which can allow chemists to replace stoichiometric oxidants that produce waste with efficient catalysts that only generate H2gas as a byproduct. Thus, clarification of the 2012 report to indicate what conditions can lead to high efficiency and selectivity is a worthy topic of discussion in the literature.