Synthesis of Functionalised Cyclohexanes from Carbohydrates

10.26686/wgtn.16934992 ◽

2021 ◽

Author(s):

◽

Regine Blattner

Keyword(s):

Hydrogen Cyanide ◽

Reductive Elimination ◽

Hydroxyl Groups ◽

Reaction Sequence ◽

Tertiary Alcohols ◽

Carbocyclic Compounds ◽

Branched Chain ◽

By Products ◽

Tertiary Hydroxyl ◽

Bromo Compound

Beta-D-glucopyranose pentaacetate was photobrominated to give the 5-baromide from which 6-deoxy-Beta-D-xylo-hex-5-enopyranose tetraacetate was obtained by reductive elimination. This reaction sequence represents an efficient new route to the 5-ene. A detailed investigation into the photobromination of Beta-D-glucopyranose pentaacetate with bromine and with NBS led to the isolation of several by-products containing bromine substituents at C-1 and/or C-5; their reactions with zinc-acetic acid were studied, and the conformations. in solution of four alkenes derived from the 5-bromo compound were determined. 2,3,4-Triacylated 2,3,4,5-tetrahydroxycyclohexanones were Obtained by mercury (II) catalysed rearrangement of 5-deoxyhex-5-enopyranose esters. The mechanism of this rearrangement, and some enopyranose esters The mechanism of this rearrangement, reactions of the products were examined. The use of these new carbocyclic compounds in the synthesis of branched-chain cyclitol derivatives was explored. By means of diazomethane or, alternatively, hydrogen cyanide, substituted cyclohexanes with one-carbon branches and tertiary hydroxyl groups at the site of chain-branching were preared. Attempts to eliminate water from these tertiary alcohols to give substituted cyclohexene-carbonitriles or -carbaldehydes were unsuccessful.

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Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

International Astronomical Union Colloquium ◽

10.1017/s025292110001469x ◽

1997 ◽

Vol 161 ◽

pp. 179-187

Author(s):

Clifford N. Matthews ◽

Rose A. Pesce-Rodriguez ◽

Shirley A. Liebman

Keyword(s):

Amino Acids ◽

Solar System ◽

Hydrogen Cyanide ◽

Nitrogen Heterocycles ◽

Laboratory Studies ◽

Heterogeneous Solids ◽

The Many ◽

Comet Halley ◽

The Impact ◽

By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

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Improvement of l-Leucine Production in Corynebacterium glutamicum by Altering the Redox Flux

International Journal of Molecular Sciences ◽

10.3390/ijms20082020 ◽

2019 ◽

Vol 20 (8) ◽

pp. 2020 ◽

Cited By ~ 1

Author(s):

Ying-Yu Wang ◽

Feng Zhang ◽

Jian-Zhong Xu ◽

Wei-Guo Zhang ◽

Xiu-Lai Chen ◽

...

Keyword(s):

Corynebacterium Glutamicum ◽

Glutamate Dehydrogenase ◽

Redox State ◽

Leucine Biosynthesis ◽

Lysinibacillus Sphaericus ◽

Coenzyme Binding ◽

Binding Domains ◽

Branched Chain Amino Acid ◽

Branched Chain ◽

By Products

The production of l-leucine was improved by the disruption of ltbR encoding transcriptional regulator and overexpression of the key genes (leuAilvBNCE) of the l-leucine biosynthesis pathway in Corynebacterium glutamicum XQ-9. In order to improve l-leucine production, we rationally engineered C. glutamicum to enhance l-leucine production, by improving the redox flux. On the basis of this, we manipulated the redox state of the cells by mutating the coenzyme-binding domains of acetohydroxyacid isomeroreductase encoded by ilvC, inserting NAD-specific leucine dehydrogenase, encoded by leuDH from Lysinibacillus sphaericus, and glutamate dehydrogenase encoded by rocG from Bacillus subtilis, instead of endogenous branched-chain amino acid transaminase and glutamate dehydrogenase, respectively. The yield of l-leucine reached 22.62 ± 0.17 g·L−1 by strain ΔLtbR-acetohydroxyacid isomeroreductase (AHAIR)M/ABNCME, and the concentrations of the by-products (l-valine and l-alanine) increased, compared to the strain ΔLtbR/ABNCE. Strain ΔLtbR-AHAIRMLeuDH/ABNCMLDH accumulated 22.87±0.31 g·L−1 l-leucine, but showed a drastically low l-valine accumulation (from 8.06 ± 0.35 g·L−1 to 2.72 ± 0.11 g·L−1), in comparison to strain ΔLtbR-AHAIRM/ABNCME, which indicated that LeuDH has much specificity for l-leucine synthesis but not for l-valine synthesis. Subsequently, the resultant strain ΔLtbR-AHAIRMLeuDHRocG/ABNCMLDH accumulated 23.31 ± 0.24 g·L−1 l-leucine with a glucose conversion efficiency of 0.191 g·g−1.

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Kinetics Study of the Acidic Catalyzed Polymerization of Tetraethoxysilane by 29Si NMR.

MRS Proceedings ◽

10.1557/proc-121-37 ◽

1988 ◽

Vol 121 ◽

Cited By ~ 9

Author(s):

Jean-Claude Pouxviel ◽

J. P. Boilot

Keyword(s):

Significant Contribution ◽

Hydrolysis Rate ◽

Hydroxyl Groups ◽

29Si Nmr ◽

Condensation Reactions ◽

Levels Of Detail ◽

Degree Of Condensation ◽

By Products ◽

Different Levels

ABSTRACTTEOS has been hydrolysed under acidic condition with stoichiome-tric or excess amount of water. Evolution of the silicon species is followed by 29Si NMR. The data are analyzed at different levels of detail; first, analysis of the by products of polymerization reactions, second determination of the extents and overall rate constants of hydrolysis and condensation reactions and finally kinetics simulations of the evolution taking into account all the present silicon species. We have shown that the hydrolysis rate increases with the number of hydroxyl groups, and the reesterification reactions have a significant contribution. We also found that condensation reactions preferentially occur with loss of water between the more hydrolyzed monomers; their rates rapidly decrease with the degree of condensation. We compare the two compositions as a function of their water content and pH.

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Lyotropic Phase Behaviour and Structural Parameters of Monosaccharide and Disaccharide Guerbet Branched-Chain β-D-Glycosides

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.895.111 ◽

2014 ◽

Vol 895 ◽

pp. 111-115 ◽

Cited By ~ 2

Author(s):

Hairul A.A. Hamid ◽

Rauzah Hashim ◽

John M. Seddon ◽

Nicholas J. Brooks

Keyword(s):

Self Assembly ◽

Room Temperature ◽

Structural Parameters ◽

Phase Behaviour ◽

Hydroxyl Groups ◽

X Ray Diffraction ◽

X Ray ◽

Branched Chain ◽

Optical Polarizing Microscopy ◽

Water Contents

The phase behaviour and self-assembly structural parameters of a pair of monosaccharide and disaccharide Guerbet branched-chain β-D-glycosides, namely 2-octyldodecyl β-D-glucoside (β-Glc-C12C8) and 2-octyldodecyl β-D-maltoside (β-Mal-C12C8), have been studied by means of optical polarizing microscopy (OPM) and small-angle X-ray diffraction at room temperature (25°C). These compounds are sugar-based glycolipid surfactants having a total chain length of C20, and differ based on the increasing number of hydroxyl groups of the sugar headgroup (glucose and maltose). The repeat spacings obtained by X-ray diffraction as a function of water content have been used to determine the limiting hydration for the two glycosides. At room temperature, β-Glc-C12C8 and β-Mal-C12C8 have limiting hydrations of 22 wt% and 25 wt%, corresponding to 8 10 and 10 12 water molecules per glycoside, respectively. At all water contents between 5 and 29 wt % water, these compounds adopt inverse hexagonal (HII) or fluid lamellar (Lα) phases. The structural parameters of these phases have been determined from the diffraction data, from the X-ray repeat spacings, densities and concentration of the glycosides.

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ChemInform Abstract: ACTION OF DIPHOSPHORUS TETRAIODIDE UPON SOME SECONDARY AND TERTIARY ALCOHOLS BEARING HYDROXYL GROUPS AT ACTIVATED POSITIONS

Chemischer Informationsdienst ◽

10.1002/chin.197808171 ◽

1978 ◽

Vol 9 (8) ◽

Author(s):

H. SUZUKI ◽

T. FUCHITA

Keyword(s):

Hydroxyl Groups ◽

Tertiary Alcohols

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Zur Chemie des Phorbols, V

Zeitschrift für Naturforschung B ◽

10.1515/znb-1968-1107 ◽

1968 ◽

Vol 23 (11) ◽

pp. 1444-1452 ◽

Cited By ~ 11

Author(s):

Gert Kreibich ◽

Erich Hecker

Keyword(s):

Methyl Iodide ◽

Natural Compound ◽

Cyclopropane Ring ◽

Hydroxyl Groups ◽

Tertiary Hydroxyl ◽

Reducing Properties

In phorbol and partial acetates of phorbol the hydroxyl groups in the 20-, 13-, 12- and 4-positions can be etherified with one of the following methods: diazoalkane/Al-i-propylate, tritylchloride/pyridine and methyl-iodide/silveroxide. The investigation of suitable phorbol ethers with Fehling's and Tollens' reagent proves that the tertiary hydroxyl at the cyclopropane ring is solely responsible for the reducing properties of phorbol. Thus, phorbol is the first natural compound in which this reaction of tertiary cyclopropanols was detected.

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ChemInform Abstract: PROTECTION OF TERTIARY HYDROXYL GROUPS AS METHYLTHIOMETHYL ETHERS

Chemischer Informationsdienst ◽

10.1002/chin.197612172 ◽

1976 ◽

Vol 7 (12) ◽

pp. no-no

Author(s):

K. YAMADA ◽

K. KATO ◽

H. NAGASE ◽

Y. HIRATA

Keyword(s):

Hydroxyl Groups ◽

Methylthiomethyl Ethers ◽

Tertiary Hydroxyl

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First Principles Mechanistic Study of Self-Limiting Oxidative Adsorption of Remote Oxygen Plasma During the Atomic Layer Deposition of Alumina

10.26434/chemrxiv.6377372 ◽

2018 ◽

Author(s):

Glen N. Fomengia ◽

Michael Nolan ◽

Simon D. Elliott

Keyword(s):

Atomic Layer Deposition ◽

First Principles ◽

Density Functional ◽

Atomic Layer ◽

Molecular Water ◽

Mechanistic Study ◽

Hydroxyl Groups ◽

Layer Deposition ◽

Surface Intermediates ◽

By Products

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O2-plasma or O3 adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH3 ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH2O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH3 group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

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