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Updated: Jul 11, 2026

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions
10:22

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Published on: June 16, 2014

什么时候一个纳米粒子成为一个集群? 一个操作式的EXAFS研究,通过Rh(4-6) 集群对胺脱水合

John L Fulton1, John C Linehan, Tom Autrey

  • 1Fundamental Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA. john.fulton@pnl.gov

Journal of the American Chemical Society
|September 11, 2007
PubMed
概括

X射线吸收细结构 (XAFS) 揭示了同质的催化剂驱动氨基脱水合. 活性物种是Rh(4-6) 集群,而不是金属,在后期阶段形成聚合物链.

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Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
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¹H NMR: Long-Range Coupling

The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.