کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
66807 48451 2010 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dependence of the Heck coupling in aqueous microemulsion by supported palladium acetate on the surfactant and on the hydrophobicity of the support
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Dependence of the Heck coupling in aqueous microemulsion by supported palladium acetate on the surfactant and on the hydrophobicity of the support
چکیده انگلیسی

Heck coupling of aqueous microemulsions of bromobenzene and styrene by palladium acetate entrapped within hydrophobicitized silica sol–gel is associated with the formation of supported Pd(0) nanoparticles that catalyze the process. The efficiency of the coupling strongly depends on the hydrophobicity of the sol–gel matrix. In a series of experiments in which the support was prepared by co-condensation of tetramethoxysilane [Si(OMe)4] and ca. 5% of either alkyl or aryl alkoxysilanes [Rn(OR′)4−n] the activity of the immobilized catalyst increased along with the increasing length of the hydrophobic alkyl chain R in the alkylalkoxysilane as well as with the increase of n. Hydrophobic aryl groups are superior to alkyl ones but electron-withdrawing substituents on the aryl moieties lower the reactivity. The rate of the coupling process depends also on the nature of the surfactant used to solubilize the reactants. The order of rates is anionic < non-ionic < cationic surfactants. The metallic nanoparticles can be recycled and reused for at least 4–6 further catalytic runs without any loss of catalytic activity.

Heck coupling of bromobenzene and styrene in water by sol–gel entrapped palladium acetate depends on the hydrophobicity of the ceramic support and on the electronic nature of the surfactant.Figure optionsDownload high-quality image (41 K)Download as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis A: Chemical - Volume 323, Issues 1–2, 17 May 2010, Pages 65–69
نویسندگان
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