Enantioselective surface chemistry of R-2-bromobutane on Cu(643)R&S and Cu(531)R&S.
Enantioselective surface chemistry of R-2-bromobutane on Cu(643)R&S and Cu(531)R&S.
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R-2-溴丁烷在 Cu(643)R 上的对映选择性表面化学
DOI：
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发表时间：
2006
影响因子：
3.3
通讯作者：
A. Gellman
中科院分区：
文献类型：
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作者：
D. Rampulla;A. J. Francis;K. Knight;A. Gellman
通过比较程序升温反应的相对产物产率，研究了手性R-2-溴丁烷在天然手性铜(643)R&S和铜(531)R&S表面上的对映选择性表面化学。分子吸附的R-2-溴丁烷可以在分子上解吸或脱溴，在表面形成R-2-丁基。R-2-丁基通过β-氢化物消除进一步反应生成1-或2-丁烯，或通过加氢生成丁烷。程序升温反应光谱被用来定量各种反应产物的相对产率。在R-2-溴丁烷在铜(643)R&S和铜(531)R&S上的低覆盖度下，表面化学不是对映选择性的。然而，在单层覆盖下，产物产率表明R-2-溴丁烷的分解反应速率对两个手性表面的利手性很敏感。通过对R-2-溴丁烷在铜(643)R&S和铜(531)R&S上的化学研究，考察了表面结构对R-2-溴丁烷对映体选择性的影响。R-2-溴丁烷脱附与脱溴的选择性是对映体专一性的，且与铜(643)和铜(531)的选择性有显著差异。β-氢化物消除与加氢反应对R-2-丁基反应的选择性只是弱对映体，在铜(643)和铜(531)表面上的选择性是相似的。这些结果是首次定量观察到反应中的对映体选择性，这些反应具有众所周知的机制，使用天然手性金属表面的简单吸附来探测。
The enantioselective surface chemistry of chiral R-2-bromobutane was studied on the naturally chiral Cu(643)R&S and Cu(531)R&S surfaces by comparing relative product yields during temperature-programmed reaction spectroscopy. Molecularly adsorbed R-2-bromobutane can desorb molecularly or debrominate to form R-2-butyl groups on the surfaces. The R-2-butyl groups react further by beta-hydride elimination to form 1- or 2-butene or by hydrogenation to form butane. Temperature-programmed reaction spectroscopy was used to quantify the relative yields of the various reaction products. At low coverages of R-2-bromobutane on Cu(643)R&S and Cu(531)R&S, the surface chemistry is not enantioselective. At monolayer coverage, however, the product yields indicate that the R-2-bromobutane decomposition reaction rates are sensitive to the handedness of the two chiral surfaces. The impact of surface structure on enantioselectivity was examined by studying the chemistry of R-2-bromobutane on both Cu(643)R&S and Cu(531)R&S. The selectivity of R-2-bromobutane desorption versus debromination is enantiospecific and differs significantly from Cu(643) to Cu(531). The selectivity of the R-2-butyl reaction by beta-hydride elimination versus hydrogenation is only weakly enantiospecific and is similar on both the Cu(643) and Cu(531) surfaces. These results represent the first quantitative observations of enantioselectivity in reactions with well-known mechanisms probed using a simple adsorbate on naturally chiral metal surfaces.