کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
66917 48457 2009 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Synthesis of titanium–triazine based MCM-41 hybrid materials as catalyst for the asymmetric epoxidation of cinammyl alcohol
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Synthesis of titanium–triazine based MCM-41 hybrid materials as catalyst for the asymmetric epoxidation of cinammyl alcohol
چکیده انگلیسی

A molecular precursor approach involving tethering procedures was used to produce site isolated titanium-supported asymmetric epoxidation catalysts. This was done by first modifying the support in one step with a mixture of silanes: the synthesized triazine propyl triethoxysilane as functional linker and hexamethyldisilizane as capped agent, to increase the hydrophobicity of the support and mask the remaining silanol groups. In addition, [Ti(OPri)4] and [{Ti(OPri)3(OMent)}2] (MentO = 1R,2S,5R-(−)-menthoxo) complexes were heterogenized by reaction with the modified MCM-41. Finally, after [Ti(OPri)4] immobilization on to the organomodified support the reaction with the chiral auxiliary (+)-diethyl-l-tartrate was accomplished. All the materials were characterized by elemental analysis, X-ray diffraction, nitrogen adsorption techniques, FT-IR, ICP-MS, DR-UV–vis, 29Si and 13C MAS NMR and TGA. The different systems were tested in the asymmetric epoxidation of cinnamyl alcohol in order to evaluate their catalytic activity and enantioselectivity.

A molecular precursor approach involving tethering procedures was used to produce site isolated titanium-supported asymmetric epoxidation catalysts. This was done by first modifying the support in one step with a mixture of silanes: the synthesized triazine propyl triethoxysilane as functional linker and hexamethyldisilizane as capped agent, to increase the hydrophobicity of the support and mask the remaining silanol groups. In addition, [Ti(OPri)4] and [{Ti(OPri)3(OMent)}2] (MentO = 1R,2S,5R-(−)-menthoxo) complexes were heterogenized by reaction with the modified MCM-41. Finally, after [Ti(OPri)4] immobilization on to the organomodified support the reaction with the chiral auxiliar (+)-diethyl-l-tartrate was accomplished. The different systems were tested in the asymmetric epoxidation of cinnamyl alcohol in order to evaluate their catalytic activity and enantioselectivity.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis A: Chemical - Volume 310, Issues 1–2, 1 September 2009, Pages 83–92
نویسندگان
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