کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1326464 | 977432 | 2009 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: ‘Click’ silica immobilisation of metallo-porphyrin complexes and their application in epoxidation catalysis ‘Click’ silica immobilisation of metallo-porphyrin complexes and their application in epoxidation catalysis](/preview/png/1326464.png)
We present the synthesis, via Adler condensation reactions, of mono- and tetrakis-4-(ethynyl-phenyl)porphyrin ligands and the zinc and manganese complexes thereof. The formed complexes were immobilised on silica by reacting the ethynyl groups with azide-functionalised silica in a copper(I) catalysed Huisgens 1,3-dipolar cycloaddition reaction. The synthesised metallo-porphyrin containing materials were thoroughly characterised using various solid-state techniques (NMR, IR, UV–Vis, elemental content analysis). The manganese containing materials were applied as catalysts in the epoxidation of various alkenes (cyclooctene, cyclohexene, styrene) with various oxidants (iodosylbenzene, tert-butylperoxide). The heterogenised homogeneous catalysts show diminished activity and yields compared to the analogous homogeneous catalysts (71% yield cf. 92% for cyclooctene epoxidation, TOF 82 h−1 cf. 230 h−1). Upon recycling, the heterogenised catalysts become gradually less active over five cycles until they are catalytically inactive. The deactivation process is discussed, with spectroscopy suggesting that the catalysts themselves are intact and thus stable to the reaction conditions and recycling, however there is likely some decomplexation, and also both chemical and mechanical decomposition of the silica support resulting in inaccessibility to the catalytic site.
Copper catalysed ‘Click’ tethering of mono- and tetra- ethynyl functionalised porphyrin complexes to a silica support yields immobilised manganese complexes. The orgamometallic functionalised silica materials are applied in epoxidation catalysis, with multiple recycles of the immobilised catalysts resulting in eventual decomposition of the complex, which is investigated herein.Figure optionsDownload as PowerPoint slide
Journal: Journal of Organometallic Chemistry - Volume 694, Issue 14, 15 June 2009, Pages 2153–2162