کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1323748 1499950 2006 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
New selectivities from old catalysts. Occlusion of Grubbs’ catalysts in PDMS to change their reactions
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
New selectivities from old catalysts. Occlusion of Grubbs’ catalysts in PDMS to change their reactions
چکیده انگلیسی

This article describes new selectivities for Grubbs’ first and second generation catalysts when occluded in a hydrophobic matrix of polydimethylsiloxane (PDMS). Occlusion of catalysts in mm-sized slabs of PDMS is accomplished by swelling with methylene chloride then removing the solvent under vacuum. The catalysts are homogenously dissolved in PDMS yet remain catalytically active. Many substrates that react by olefin metathesis with Grubbs’ catalysts freely dissolved in methylene chloride also react by olefin isomerization with occluded catalysts. Eleven examples of substrates that exhibit dual reactivity by undergoing olefin isomerization with occluded catalysts and olefin metathesis with catalysts dissolved in methylene chloride are reported. Most of these substrates have olefins with allylic phosphine oxides, carbonyls, or ethers. Control experiments demonstrate that isomerization is occurring in the solvent by decomposition of the catalyst from a ruthenium carbene to a proposed ruthenium hydride. This work was extended by heating occluded Grubbs’ first generation catalyst to 100 °C in 90% MeOH in H2O in the presence of various alkenes to transform the Grubbs’ catalyst into an isomerization catalyst for unfunctionalized olefins. This work demonstrates that occlusion of organometallic catalysts in PDMS has important implications for their reactions and can be used as a method to control which reactions they catalyze.

We describe how Grubbs’ catalysts occluded in mm-slabs of polydimethylsiloxane are active isomerization catalysts for a variety of substrates that undergo metathesis with these catalysts in methylene chloride. This selectivity allows one to choose whether to react by metathesis or isomerization for a wide range of substrates.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Organometallic Chemistry - Volume 691, Issues 24–25, 1 December 2006, Pages 5278–5288
نویسندگان
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