کد مقاله کد نشریه سال انتشار مقاله انگلیسی ترجمه فارسی نسخه تمام متن
60487 47534 2016 10 صفحه PDF سفارش دهید دانلود کنید
عنوان انگلیسی مقاله ISI
Methyl-ligated tin silsesquioxane catalyzed reactions of glucose
ترجمه فارسی عنوان
واکنش کاتالیزوری silsesquioxane قلع مسدود شده با متیل گلوکز
کلمات کلیدی
silsesquioxanes قلع؛ تبدیل گلوکز؛ Epimerization؛ ایزومریزاسیون؛ اسید لوئیس
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
چکیده انگلیسی


• A methyl tin silsesquioxane is studied as a model for the closed site in Sn-Beta.
• Glucose is catalyzed through equivalent pathways to the heterogeneous open site.
• The closed site is catalytically active, but less so than the open site.

Tin-containing zeolite Beta (Sn-Beta) has been investigated as a catalyst for isomerizing aldohexoses into ketohexoses through a Lewis acid mediated hydride shift. Recent studies on the reactivities of Lewis base-doped and alkali-exchanged Sn-Beta samples have conclusively demonstrated that the “open” tin site performs the glucose isomerization reaction. With Lewis base doped Sn-Beta, glucose conversion is almost completely eliminated and product selectivity is shifted predominantly to mannose. These data suggest that glucose reactions may occur through pathways that do not involve the “open” site in Sn-Beta; albeit at significantly lower rates. To examine this possibility, reactions of glucose catalyzed by a homogeneous model of Sn-Beta that does not contain “open” sites, methyl-ligated tin silsesquioxane 1a, is experimentally and theoretically examined. 1a is an active glucose conversion catalyst selectively producing mannose, although the rates of reaction are far below those obtained from Sn-Beta. A hybrid quantum mechanical/molecular mechanics model is constructed, and the complete catalytic cycle is computationally examined, considering ring-opening, three distinct pathways for each hydride- and carbon-shift reaction, and ring-closing. The combined experimental and computational results suggest that there could be reaction pathways that involve Si–O–Sn cleavage that give much slower reaction rates than the open tin site in Sn-Beta.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 341, September 2016, Pages 62–71
نویسندگان
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