α-Fe₂O₃ immobilized benzimidazolium tribromide as novel magnetically retrievable catalyst for one-pot synthesis of highly functionalized piperidines

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• 作者：Bappi Paul^a ; ^{bappipaulnits@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Sethumathavan Vadivel^b ; Siddhartha Sankar Dhar^a ; ^{ssd_iitg@hotmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Nano α-Fe2O3 ; Covalent grafting ; Ionic liquid ; Multicomponent reaction
• 刊名：Chinese Chemical Letters
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：27
• 期：11
• 页码：1725-1730
• 全文大小：2313 K

文摘

Nanostructured α-Fe₂O₃ were prepared by precipitation followed by calcination method. Cetyltrimethylammonium bromide (CTAB) was used as surfactant. The nano α-Fe₂O₃ was then silanized with (3-chloropropyl)-triethoxysilane (CPTES) by room temperature mixing of α-Fe₂O₃ and CPTES to produce silane coated α-Fe₂O₃ (ClPr-Si@Fe₂O₃). As-synthesized ClPr-Si@Fe₂O₃ was functionalized via covalent grafting of benzimidazole to produce 3-(1-benzimidazole)Pr-Si@Fe₂O₃. This was further reacted with bromine to afford α-Fe₂O₃ immobilized benzimidazolium tribromide (α-Fe₂O₃-BIM tribromide). This ionic liquid (IL) α-Fe₂O₃ BIM tribromide was characterized by FT-IR, XRD, TEM, SEM, TGA, VSM, EDX and BET analysis. The as-synthesized IL tribromide was used as catalyst for one-pot synthesis of highly substituted piperidines. The method is greener in terms of solvent selection, recovery of the catalyst and efficiency.