Craig A. Obafemi, Olatomide A. Fadare, Jerry P. Jasinski, Sean P. Millikan, Efere M. Obuotor, Ezekiel O. Iwalewa, Samson O. Famuyiwa, Kayode Sanusi, Yusuf Yilmaz, Ümit Ceylan. : Alternatively, the above species is a hybrid of an oxonium ion and a carbocation. Tandem mass spectra of ammonium adducts of monosaccharides: differentiation of diastereomers. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Proton solvation in ternary clusters of water—methanol—acetonitrile. On the other hand, when the two types of sites are varied independently (e.g., in Sn-BEA and HCl), the HMF formation rate increases and then approaches a plateau with increasing Brønsted acid site density. Ping-An Wang, Sheng-Yong Zhang, Henri B Kagan. H. Jürgen Kreuzer, Richard L. C. Wang, and Michael Grunze . Advances in Carbohydrate Chemistry and Biochemistry Volume 62. the Altmetric Attention Score and how the score is calculated. Calvert, Ch. Extreme acidity, heat, and dehydrati… Extreme oxatriquinanes and a record C–O bond length. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. 2019, Microporous and Mesoporous Materials, Journal of Catalysis, Volume 279, Issue 1, 2011, pp. Please note: If you switch to a different device, you may be asked to login again with only your ACS ID. The marked differences in selectivity among aluminosilicates frameworks reflect instead diffusional enhancements of secondary transformations. Shin-ichi Takekuma, Ippei Miyamoto, Akio Hamasaki, Toshie Minematsu. $\ce{H3O+ + H2O <=> H3O+ + H2O}$ H+ Hydrogen Bond: Toward a Tetracoordinate Oxadionium(2+) Ion. David V. Dearden,, Chadin Dejsupa,, Yongjiang Liang,, Jerald S. Bradshaw, and. Rapid Communications in Mass Spectrometry. Your Mendeley pairing has expired. resulted oxonium ion-crown ether complexes extract the oxanions containing hexavalent chromium ions from acid aqueous phase through the liquid membrane into the ... parameters i.e. These data show that void structures affect selectivity, but not because of preferential stabilization of some transition states or of acid sites that vary in strength among aluminosilicate framework, as proposed previously to account for such effects. Experimental and computational evidence for C=O π-bonding in [CH. Jeffrey P. Kiplinger, Maurice M. Bursey. Ionic Hydrogen Bonds in Bioenergetics. This interpretation provides a rigorous thermochemical foundation for detailed microkinetic analysis, which we employ to regress elementary interaction energies and kinetic parameters—moving the field toward a fundamental description of reactivity in acid-catalyzed upgrading of γ-valerolactone. Such voids also impose diffusional hurdles that can strongly influence selectivities. Update 1 of: Strong Ionic Hydrogen Bonds. Probing the Structure and Reactivity Of Hydrogen-Bonded Clusters of the Type {M}n{H2O}H+, via the Observation of Magic Numbers. 213-219, Inorganic Chemistry Communications, Volume 99, 2019, pp. International Journal of Mass Spectrometry. We conduct a combined experimental and computational study to reveal the kinetics of tandem glucose isomerization and fructose dehydration to 5-hydroxymethylfurfural (HMF) over a bifunctional zeolite H-BEA-25 in water. In the unimolecular dehydration of alcohols in acidic zeolites, reaction proceeds through a carbenium ion before desorbing as an olefin and water.Clearly, the energy of the transition states between species formed along the reaction pathway must be determined by rigorous calculations [12]; however, the stabilities of species along the reaction pathway can be estimated from these kinds of proton-affinity correlations [21,28].In another example, proton-affinity correlations were shown to be useful for estimating barriers to H-D exchange between aromatic compounds and deuterated zeolites [29]. and you may need to create a new Wiley Online Library account. When both the epoxide carbons are either primary or secondary the halogen anion will attack the less substituted carbon and an S N 2 like reaction. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Theoretical Foundation for the Presence of Oxacarbenium Ions in Chemical Glycoside Synthesis. Design and synthesis of polycyclic bisindoles via Fischer indolization and ring-closing metathesis as key steps. Mechanisms for nucleophilic aliphatic substitution at glycosides. The reaction was conducted over ZSM-35 zeolites with different concentrations of Brönsted acid, which were prepared by the sodium ion-exchange process with H-form zeolite. Application of Fischer Indolization under Green Conditions using Deep Eutectic Solvents. Selectivities reflect instead diffusional effects that become more severe as the number and strength of acid sites and the size and diffusive resistances increase within these acid domains, which shift, in turn, the products formed from relative abundances dictated by kinetics to those prescribed by thermodynamics. https://doi.org/10.1524/ract.2006.94.3.123, https://doi.org/10.1016/S1387-3806(01)00504-8, https://doi.org/10.1016/S1387-3806(99)00243-2, https://doi.org/10.1016/S1387-3806(98)14052-6, https://doi.org/10.1016/S0168-1176(96)04462-X, https://doi.org/10.1016/0021-9673(94)80417-6, https://doi.org/10.1007/978-94-011-1058-7_2, https://doi.org/10.1016/0009-2614(93)80175-O, https://doi.org/10.1016/S0009-2614(91)85046-Y, https://doi.org/10.1016/S0020-1693(00)83010-8, https://doi.org/10.1016/S0277-5387(00)80911-0, https://doi.org/10.1016/S0040-4039(00)84011-3. Andreas J Kesel, Zhuhui Huang, Michael G Murray, Mark N Prichard, Laura Caboni, Daniel K Nevin, Darren Fayne, David G Lloyd, Mervi A Detorio, Raymond F Schinazi. Solution vs. gas phase relative stability of the choline/acetylcholine cavitand complexes. Singh, Martin. Influence of Linkage Stereochemistry and Protecting Groups on Glycosidic Bond Stability of Sodium Cationized Glycosyl Phosphates. Dilrukshi M. Peiris, Yarjing Yang, Ragulan Ramanathan, Kathryn R. Williams, Clifford H. Watson, John R. Eyler. Find more information about Crossref citation counts. The product is an alkene. 1–S The Quest for Tetracoordinated Halonium Ions: A Theoretical Investigation. The production of CO-free H2 was achieved only on supported Ir at 383–473 K. Similarly, as regards the H2 yield the outstanding catalyst was Ir/Norit, followed by Pt/Norit. . The dependence of deprotonation energies of zeolitic Brønsted acid sites on the dielectric constants of these materials is investigated using quantum chemical calculations. unstable oxonium ion + acetal Oxonium ions have three bonds to a positively charged oxygen atom. Oxatriquinanes are tricyclic oxonium ions which are known to possess remarkable solvolytic stability compared to simple alkyl oxonium salts. Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. Modeling Proton-Bound Methanol, Ammonia, and Amine Complexes of 12-Crown-4-Ether and Dimethoxyethane (“Glyme”) Using Density Functional Theory. Through microkinetic analysis, macroscopically observed production rates and product distributions are reconciled with a mechanistic description of all chemistries. We reveal that tandem reactions exhibit multiple kinetic regimes. Please reconnect. triple-coordinated oxygen. Number of times cited according to CrossRef: Gas phase dynamics, conformational transitions and spectroscopy of charged saccharides: the oxocarbenium ion, protonated anhydrogalactose and protonated methyl galactopyranoside. You can support us by purchasing something. Unexpected IR Characteristics of Hydrogen Bonds in the 18-Crown-6-Ether Complex of the H3O+ Hydronium Ion. http://pubs.acs.org/page/copyright/permissions.html, https://doi.org/10.1021/acs.accounts.9b00554, https://doi.org/10.1016/B978-0-12-409547-2.14960-1, https://doi.org/10.1038/s41467-019-12537-3, https://doi.org/10.1016/j.comptc.2018.12.002, https://doi.org/10.1016/j.molstruc.2017.11.018, https://doi.org/10.1016/j.tetlet.2016.10.112, https://doi.org/10.1016/bs.aiq.2014.07.005, https://doi.org/10.1016/j.tet.2011.09.148, https://doi.org/10.1002/9780470979525.ch7, https://doi.org/10.1016/j.tetlet.2011.06.058, https://doi.org/10.1016/j.tetlet.2010.12.063. Hydronium Ion Complex of 18-Crown-6: Where Are the Protons? Although dehydrogenation was the predominant process at lower temperatures, CO-free H2 was not produced on any catalyst. 38 publications. One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes. The catalytic reactions were effected at relatively lower temperatures (170–190 °C) yielding the alkenes in moderate yields.