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Methyl-ligated tin silsesquioxane catalyzed reactions of glucose

Brand, Stephen K. and Josephson, Tyler R. and Labinger, Jay A. and Caratzoulas, Stavros and Vlachos, Dionisios G. and Davis, Mark E. (2016) Methyl-ligated tin silsesquioxane catalyzed reactions of glucose. Journal of Catalysis, 341 . pp. 62-71. ISSN 0021-9517. https://resolver.caltech.edu/CaltechAUTHORS:20160714-110754013

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Abstract

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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.jcat.2016.06.013DOIArticle
http://www.sciencedirect.com/science/article/pii/S0021951716300938PublisherArticle
ORCID:
AuthorORCID
Labinger, Jay A.0000-0002-1942-9232
Additional Information:© 2016 Elsevier Inc. Received 28 April 2016; Revised 6 June 2016; Accepted 19 June 2016. Research was supported as part of the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award number DE-SC0001004. S.K. B. wishes to acknowledge funding from the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1144469. T.R.J. also wishes to acknowledge funding from the National Science Foundation Graduate Research Fellowship Program under Grant No. 0750966, as well as the George W. Laird Merit Fellowship. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author (s) and do not necessarily reflect the views of the National Science Foundation. The authors would like to thank Marat Orazov and Jeff Christianson for numerous useful conversations.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0001004
NSF Graduate Research FellowshipDGE-1144469
NSF Graduate Research FellowshipDGE-0750966
George W. Laird Merit FellowshipUNSPECIFIED
Subject Keywords:Tin silsesquioxanes; Glucose conversion; Epimerization; Isomerization; Lewis acid
Record Number:CaltechAUTHORS:20160714-110754013
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160714-110754013
Official Citation:Stephen K. Brand, Tyler R. Josephson, Jay A. Labinger, Stavros Caratzoulas, Dionisios G. Vlachos, Mark E. Davis, Methyl-ligated tin silsesquioxane catalyzed reactions of glucose, Journal of Catalysis, Volume 341, September 2016, Pages 62-71, ISSN 0021-9517, http://dx.doi.org/10.1016/j.jcat.2016.06.013. (http://www.sciencedirect.com/science/article/pii/S0021951716300938)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69028
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 Jul 2016 22:47
Last Modified:03 Oct 2019 10:18

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