- The solvent-free thermal dehydration of tetritols on zeolites
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A new alditol dehydration method at high temperatures, in the presence of molecular sieves without solvent in an argon atmosphere, is described. Investigations on tetritols have been carried out. Products arising after the intramolecular and intermolecular elimination of water, with retention or inversion of the configuration of asymmetric carbon atoms, were observed. Complete analytical separation of reaction products was achieved by means of GLC. The chemical structures of the compounds obtained were assigned using co-injection with standards, GLC-CIMS and GLC-EIMS analyses. Two intermolecular dehydration products of tetritols were isolated by HPLC and identified by 1H and 13C NMR spectroscopy. Copyright (C) 2000 Elsevier Science Ltd.
- Kurszewska, Maria,Skorupa, Eugenia,Kasprzykowska, Regina,Sowinski, Pawel,Wisniewski, Andrzej
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- Nonlinear Regression Models of Multicomponent Interactions of Anhydropolyols with Aqueous Ammonium Ion by Carbon-13 Nuclear Magnetic Resonance
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The anhydropolyhydric alcohols 1,4-anhydroerythritol and 1,4- anhydrothreitol were synthesized from the corresponding tetratols via acid-catalyzed dehydration, under vacuum, using H+ ion exchange resin.Comparison of temperature-dependent 13C NMR chemical shifts i aqueous and nonaqueous solvents demonstrated a significant molecular association interaction between 1,4-anhydroerythritol and water.The chemical shifts of C(1) and C(2) of 1,4-anhydrothreitol and C(1) of 1,4-anhydroerythritol showed a linear increase with temperature but C(2) of 1,4-anhydroerythritol showed a decrease between ca. 0 and ca. 55 deg C followed by an increase from ca. 55 to ca. 100 deg C.A multiligand complex was shown between 1,4-anhydroerythritol, water, and ammonium ion.The stoichiometry of the interaction between 1,4-anhydroerythritol, water, and aqueous ammonium ion was determined by nonlinear regression analysis applied to data obtained from 13C NMR chemical shifts through variation of temperature, solvent activity, aH2O(c,T), and solute activity, aNH4Cl(c,T).A general model was constructed for the dependence of the 13C NMR chemical shifts upon temperature and the activities of the two ligand species.
- Naugler, David G.,Cushley Robert J.
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- N,N,O-Coordinated tricarbonylrhenium precatalysts for the aerobic deoxydehydration of diols and polyols
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Rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using L4Re(CO)3as precatalyst (L4Re(CO)3= tricarbonylrhenium 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)phenolate). The DODH reaction was optimized using 2 mol% of L4Re(CO)3as precatalyst and 3-octanol as both reductant and solvent under aerobic conditions, generating the active high-valent rhenium speciesin situ. Both diol and biomass-based polyol substrates could be applied in this system to form the corresponding olefins with moderate to high yield. Typical features of this aerobic DODH system include a low tendency for the isomerization of aliphatic external olefin products to internal olefins, a high butadiene selectivity in the DODH of erythritol, the preferential formation of 2-vinylfuran from sugar substrates, and an overall low precatalyst loading. Several of these features indicate the formation of an active species that is different from the species formed in DODH by rhenium-trioxo catalysts. Overall, the bench-top stable and synthetically easily accessible, low-valent NNO-rhenium complex L4Re(CO)3represents an interesting alternative to high-valent rhenium catalysts in DODH chemistry.
- Klein Gebbink, Robertus J. M.,Li, Jing,Lutz, Martin
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p. 3782 - 3788
(2020/06/22)
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- Preparation of 2,3,4-trihydroxybutylarsonic acid: A starting compound for novel arsonolipids
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Possible routes for the preparation of 2,3,4-trihydroxybutylarsonic acid, a key compound for the synthesis of novel arsonolipids, were experimentally evaluated. The best substrate was found to be 3,4-epoxybutane-1,2-diol. Its reaction with alkaline sodium arsenite, "Na3AsO3," gave the arsonic acid in 50% yield, as two pairs of diastereoisomers, each pair being a racemic mixture. Copyright Taylor & Francis Group, LLC.
- Lala, Maria A.,Tsivgoulis, Gerasimos M.,Ioannou, Panayiotis V.
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p. 2747 - 2760
(2008/12/22)
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- Epoxide hydrolase-catalyzed enantioselective synthesis of chiral 1,2-diols via desymmetrization of meso-epoxides
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The discovery, from nature, of a diverse set of microbial epoxide hydrolases is reported. The utility of a library of epoxide hydrolases in the synthesis of chiral 1,2-diols via desymmetrization of a wide range of meso-epoxides, including cyclic as well as acyclic alkyl- and aryl-substituted substrates, is demonstrated. The chiral (R,R)-diols were furnished with high ee's and yields. The discovery of the first microbial epoxide hydrolases providing access to complementary (S,S)-diols is also described. Copyright
- Zhao, Lishan,Han, Bin,Huang, Zilin,Miller, Mark,Huang, Hongjun,Malashock, Dan S.,Zhu, Zuolin,Milan, Aileen,Robertson, Dan E.,Weiner, David P.,Burk, Mark J.
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p. 11156 - 11157
(2007/10/03)
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- DIRECT REGIOSELECTIVE FORMATION OF POLYSUBSTITUTED TETRAHYDROFURANS FROM UNPROTECTED POLYOLS
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The reaction of unprotected polyols (tetraols, pentitol and hexitol) with trimethyl orthobenzoate in CH2Cl2-MeOH afforded polysubstituted tetrahydrofurans in a one-pot synthesis.
- Fujioka, Hiromichi,Kitagawa, Hidetoshi,Kondo, Michinori,Kita, Yasuyuki
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p. 743 - 746
(2007/10/02)
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