- CATALYTIC PRODUCTION OF 1,2,5,6-HEXANETETROL FROM LEVOGLUCOSENONE
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A method of making of 1,2,5,6-hexanetetrol ("tetrol"). The method includes the steps of contacting a reaction solution containing water as well as levoglucosenone, dihydrolevoglucosenone, and/or levoglucosanol, with a catalyst ontaining metal and acid functionalities, at temperature of from about 100 °C to about 175 °C, and a hydrogen partial pressure of from about 1 bar to about 50 bar (about 0.1 MPa to about 5 MPa), and for a time wherein at least a portion of the reactant is converted into 1,2,5,6-hexanetetrol.
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Paragraph 10
(2019/11/12)
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- Mechanistic study on -C-O- and -C-C- hydrogenolysis over Cu catalysts: Identification of reaction pathways and key intermediates
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Important petro-based polyol compounds with a longer carbon chain, such as oligohydroxy hexanes (e.g. 1,2- and 1,6-hexanediol or 1,2,6-hexanetriol), require at least three to four synthesis steps. Replacing this complex chemistry by a one-pot reaction via -C-O- bond cleavage from sugars would be a significant breakthrough for the use of renewable feedstocks. Cu is known for its dehydroxylation (deoxygenation) properties, yielding the desired products from sugars. In this joint research between academic and industrial chemistry, we have identified so far unknown intermediate products and present the first mechanism that explains the selective cleavage of OH-groups over copper. Strong interactions between polyols, unsaturated species and the copper surface are observed. Stable five-membered rings are formed with Cu via two vicinal OH-groups of the polyol reactant that makes these OH-groups inert to -C-O- bond cleavage. Adjacent free OH-groups in close proximity to the catalyst are dehydroxylated (deoxygenated). We further show that degradation of polyols not only occurs via commonly cited retro-aldol reactions. The formation of acid intermediates with subsequent decarboxylation is validated as a new pathway for -C-C- bond cleavage to short-chain polyols and CO2. The proposed mechanisms for -C-O- and -C-C- bond cleavage elucidate why hydrogenolysis reactions require high hydrogen pressure (up to 200 bar) to suppress the degradation of sugars and obtain high yields of deoxy C6 products. With this knowledge, the improvement of a standard commercial Cu-RANEY catalyst under optimized reaction conditions was shown. In contrast to alumina-supported Cu, the Cu-Al alloy in a RANEY-type catalyst shows selective -C-O- bond cleavage properties while maintaining the C6 carbon chain. These new insights into the transformation of sugars to value added commodities show the potential for new approaches in future biorefinery concepts.
- Kühne, Benjamin,Vogel, Herbert,Meusinger, Reinhard,Kunz, Sebastian,Kunz, Markwart
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p. 755 - 767
(2018/02/14)
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- SYNTHESIS OF R-GLUCOSIDES, SUGAR ALCOHOLS, REDUCED SUGAR ALCOHOLS, AND FURAN DERIVATIVES OF REDUCED SUGAR ALCOHOLS
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Disclosed herein are methods for synthesizing 1,2,5,6-hexanetetrol (HTO), 1,6 hexanediol (HDO) and other reduced polyols from C5 and C6 sugar alcohols or R glycosides. The methods include contacting the sugar alcohol or R-glycoside with a copper catalyst, most desirably a Raney copper catalyst with hydrogen for a time, temperature and pressure sufficient to form reduced polyols having 2 to 3 fewer hydoxy groups than the starting material. When the starting compound is a C6 sugar alcohol such as sorbitol or R-glycoside of a C6 sugar such as methyl glucoside, the predominant product is HTO. The same catalyst can be used to further reduce the HTO to HDO.
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- The selective hydrogenation of biomass-derived 5-hydroxymethylfurfural using heterogeneous catalysts
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The products produced by hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) are potential sustainable substitutes for petroleum-based building blocks used in the production of chemicals. We have studied the hydrogenation of HMF over supported Ru, Pd, and Pt catalysts in monophasic and biphasic reactor systems to determine the effects of the metal, support, solution phase acidity, and the solvent to elucidate the factors that determine the selectivity for hydrogenation of HMF to its fully hydrogenated form of 2,5-di-hydroxy-methyl-tetrahydrofuran (DHMTHF). We show that the selectivity to DHMTHF is affected by the acidity of the aqueous solution containing HMF. The major by-products observed are C6-polyols formed from the acid-catalyzed degradation and subsequent hydrogenation of 2,5-dihydroxymethylfuran (DHMF), an intermediate hydrogenation product of HMF to DHMTHF. The highest yields (88-91%) to DHMTHF are achieved using Ru supported on materials with high isoelectric points, such as ceria, magnesia-zirconia, and γ-alumina. Supported catalysts containing Pt and Pd at the same weight percent as Ru are not as active for the selective hydrogenation to DHMTHF.
- Alamillo, Ricardo,Tucker, Mark,Chia, Mei,Pagan-Torres, Yomaira,Dumesic, James
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experimental part
p. 1413 - 1419
(2012/06/15)
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- Symmetry-Assisted Synthesis of C2-Symmetric trans-α,α'-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of αω-Terminal Dienes
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A new strategy has been developed for the synthesis of C2-symmetric trans-α,α'-bis(hydroxymethyl)pyrrolidine and piperidine derivatives 1-3 starting from symmetric αω-terminal dienes 4-6. The double-asymmetric dihydroxylation (AD) reaction of 4-6 gave C2-symmetric tetrols, which were converted in a four-step sequence to C2-symmetric azacycloalkanes 17,9, and 22, respectively. These azacycloalkanes were transformed into 1-3 in high enantiomeric excess (82% → 98%ee). The double AD reaction proved to cause enantiomeric enhancement, even though the asymmetric induction for the first AD reaction is moderate. In addition, it was observed that the chromatography on silica gel of several C2-symmetric azacycloalkanes (17, 20, and 22) of varying ee's resulted in marked enantiomeric fractionation.
- Takahata, Hiroki,Takahashi, Seiki,Kouno, Shin-Ichi,Momose, Takefumi
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p. 2224 - 2231
(2007/10/03)
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- New C2 symmetric bis-aziridines efficient synthesis of (2S,5S)-1,6-di(p-toluenesulfonyloxy)-2,5-hexanediol, and (2S,3E,5S)-1,6-di(p-toluenesulfonyloxy)-2,5-hexenediol
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The regioselective tosylation and functionalization of (S,S)-1,2,5,6-hexanetetrol is reported. The reductive aminocyclization of conformationally flexible diazidodiols by PPh3 leads to C2 symmetric bis-aziridines and to substituted furans.
- Fitremann, Juliette,Dureault, Annie,Depezay, Jean-Claude
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p. 9581 - 9594
(2007/10/02)
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- Optically active isoxazole derivatives and intermediates for preparation thereof
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The present invention relates to novel optically active isoxazole derivatives represented by general formula: STR1 which are useful as intermediates for synthesis of prostaglandin and a process for producing the same as well as novel aldehyde compounds represented by general formula: STR2 which are intermediates for preparing the compounds [XI] described above and a process for preparation thereof. In the compounds shown by these formulae, R1 represents an alkyl group or a cycloalkyl group which may have an alkoxy group or a group shown by --Ra--A--B (wherein Ra is an alkyl group; A is a hetero atom or an single bond; and B is an aromatic or hetero ring which may have a substituent(s)); and R2 and R3, which may be the same or different, each represents an aralkyl group, a silyl group or an acyl group.
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- Process for the production of 3,4-dideoxyhexitol
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A process for the production of 3,4-dideoxyhexitol and for its cyclodehydration to 2,5-bis(hydroxymethyl)tetrahydrofuran. The 3,4-dideoxyhexitol is obtained by hydrogenolysis in the presence of a copper chromite catalyst, of hexitols, or of compound which undergo reaction with hydrogen to give hexitols.
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- Comparison of the Stable Products Formed by Fast Atom Bombardment and γ-Irradiation of Glycerol
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The major end-products formed by fast atom bombardment (FAB) and γ-irradiation of glycerol have been identified using capillary gas chromatography/mass spectrometry.The product distributions differ dramatically.Products resulting from the recombination of either carbon-centered or oxygen-centered radicals are evident for both sources of irradiation.However, the major FAB-generated products are formed by the recombination of carbon-centered . radicals with other carbon-centered radicals while the major γ-radiolysis products result from the recombination of oxygen-centered . radicals with lower-weight carbon-centered species. γ-Radiolysis of an N2O saturated aqueous solution of glycerol, experimental conditions that strongly favor the formation of carbon-centered . radicals at the expense of the oxygen-centered species, yielded some products that were identical to those produced by FAB of neat glycerol.Finally, the free radicals produced by γ-radiolysis of glycerol were investigated by electron spin resonance spectroscopy and spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide.The presence of only the carbon-centered free radical was established by this technique.The implications of these results are discussed.
- Keough, T.,Ezra, F. S.,Russell, A. F.,Pryne, J. D.
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p. 241 - 247
(2007/10/02)
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