Enzymic deacylation of esterified mono- and disaccharides. 3. The location of acetylated positions in partially acetylated sugars

1969 ◽  
Vol 47 (5) ◽  
pp. 845-853 ◽  
Author(s):  
A. L. Fink ◽  
G. W. Hay
Keyword(s):  
Nitric Acid ◽  
Hydroxyl Groups ◽  
Partition Chromatography ◽  
Reaction Sequence ◽  
Initial Product ◽  
Nitrate Ester ◽  
Product Identification ◽  
Free Hydroxyl ◽  
Fuming Nitric Acid ◽  
Acetyl Migration

The nitrate ester, formed by reaction with fuming nitric acid in acetic anhydride at 0 °C, was suitable to block free hydroxyl groups in partially acetylated sugars without acetyl migration. This allowed the acetylated positions in partially acetylated mono- and disaccharides to be located by the reaction sequence: nitration, deacetylation, methylation, de-nitration, disaccharide hydrolysis and methyl glycosylation (initial product identification by paper partition chromatography), acetylation, and analysis of the products by gas-liquid partition chromatography. D-Glucose, penta-O-acetyl-D-glucopyranose, and 2,3-di-O-acetyl-β-D-glucopyranose were used as test compounds in the evaluation of this scheme.

THE GAS–LIQUID PARTITION CHROMATOGRAPHY OF CARBOHYDRATE DERIVATIVES: PART III. THE SEPARATION OF AMINO GLYCOSE DERIVATIVES AND OF CARBOHYDRATE ACETAL AND KETAL DERIVATIVES

1962 ◽  
Vol 40 (8) ◽  
pp. 1559-1563 ◽  
Author(s):  
H. G. Jones ◽  
J. K. N. Jones ◽  
M. B. Perry
Keyword(s):  
Chromatographic Method ◽  
Hydroxyl Groups ◽  
Partition Chromatography ◽  
Free Hydroxyl

Gas–liquid partition chromatography has been used to separate the anomeric acetates of 2-amino-2-deoxy-D-glucopyranose (D-glucosamine) and of 2-amino-2-deoxy-D-galactopyranose (D-galactosamine) and also their fully acetylated reduction products, 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-glucitol and 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-galactitol. The gas–liquid partition chromatographic method has also been successfully applied to the separation of unsubstituted carbohydrate acetal and ketal derivatives and to those derivatives in which the free hydroxyl groups have been substituted by O-acetyl, O-benzoyl, O-benzyl, carbonate, O-methanesulphonyl, O-methyl, and O-toluene-p-sulphonyl groups.

Gallium Arsenide Integrated Circuits Decapsulation Technique Using Mixed Acid Chemistry For Die-Level Failure Analysis

2018 ◽  
Author(s):  
Harold Jeffrey M. Consigo ◽  
Ricardo S. Calanog ◽  
Melissa O. Caseria
Keyword(s):  
Gallium Arsenide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
Mixed Acid ◽  
Optimum Parameters ◽  
Plastic Package ◽  
Fuming Nitric Acid ◽  
Concentrated Sulfuric Acid

Abstract Gallium Arsenide (GaAs) integrated circuits have become popular these days with superior speed/power products that permit the development of systems that otherwise would have made it impossible or impractical to construct using silicon semiconductors. However, failure analysis remains to be very challenging as GaAs material is easily dissolved when it is reacted with fuming nitric acid used during standard decapsulation process. By utilizing enhanced chemical decapsulation technique with mixture of fuming nitric acid and concentrated sulfuric acid at a low temperature backed with statistical analysis, successful plastic package decapsulation happens to be reproducible mainly for die level failure analysis purposes. The paper aims to develop a chemical decapsulation process with optimum parameters needed to successfully decapsulate plastic molded GaAs integrated circuits for die level failure analysis.

The synthesis and structure of silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complexes

1986 ◽  
Vol 51 (7) ◽  
pp. 1430-1438 ◽  
Author(s):  
Alena Reissová ◽  
Zdeněk Bastl ◽  
Martin Čapka
Keyword(s):  
Free Surface ◽  
Hydroxyl Groups ◽  
Titanium Complex ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Cyclopentadienyl Anion

The title complexes have been obtained by functionalization of silica with cyclopentadienylsilanes of the type Rx(CH3)3 - xSi(CH2)nC5H5 (x = 1-3, n = 0, 1, 3), trimethylsilylation of free surface hydroxyl groups, transformation of the bonded cyclopentadienyl group to the cyclopentadienyl anion, followed by coordination of (h5-cyclopentadienyl)trichlorotitanium. The effects of single steps of the above immobilization on texture of the support, the number of free hydroxyl groups, the coverage of the surface by cyclopentadienyl groups and the degree of their utilization in anchoring the titanium complex have been investigated. ESCA study has shown that the above anchoring leads to formation of the silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complex.

Synthesis and properties of 1,3-bis(4-nitrophenyl)-1-butene

1980 ◽  
Vol 45 (7) ◽  
pp. 2120-2124 ◽  
Author(s):  
Gabriel Čík ◽  
Anton Blažej ◽  
Kamil Antoš ◽  
Igor Hrušovský
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Double Bond ◽  
Fuming Nitric Acid

1,3-Bis(4-nitrophenyl)-1-butene was prepared by nitration of 1,3-diphenyl-1-butene (I) with fuming nitric acid in acetic acid. The double bond in I was protected by addition of bromine which was eliminated after the nitration. The UV, IR and 1H- spectra of the synthesized compounds are interpreted.

scholarly journals Nanocarbon from Rocket Fuel Waste: The Case of Furfuryl Alcohol-Fuming Nitric Acid Hypergolic Pair

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Nikolaos Chalmpes ◽  
Athanasios B. Bourlinos ◽  
Smita Talande ◽  
Aristides Bakandritsos ◽  
Dimitrios Moschovas ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Furfuryl Alcohol ◽  
Materials Science ◽  
Ambient Conditions ◽  
Materials Synthesis ◽  
Rocket Fuel ◽  
Carbon Nanosheets ◽  
New Synthesis ◽  
Fuming Nitric Acid ◽  
Liquid Rocket

In hypergolics two substances ignite spontaneously upon contact without external aid. Although the concept mostly applies to rocket fuels and propellants, it is only recently that hypergolics has been recognized from our group as a radically new methodology towards carbon materials synthesis. Comparatively to other preparative methods, hypergolics allows the rapid and spontaneous formation of carbon at ambient conditions in an exothermic manner (e.g., the method releases both carbon and energy at room temperature and atmospheric pressure). In an effort to further build upon the idea of hypergolic synthesis, herein we exploit a classic liquid rocket bipropellant composed of furfuryl alcohol and fuming nitric acid to prepare carbon nanosheets by simply mixing the two reagents at ambient conditions. Furfuryl alcohol served as the carbon source while fuming nitric acid as a strong oxidizer. On ignition the temperature is raised high enough to induce carbonization in a sort of in-situ pyrolytic process. Simultaneously, the released energy was directly converted into useful work, such as heating a liquid to boiling or placing Crookes radiometer into motion. Apart from its value as a new synthesis approach in materials science, carbon from rocket fuel additionally provides a practical way in processing rocket fuel waste or disposed rocket fuels.

Substitutional and solvation effects on conformational equilibria. Effects on the interaction between opposing axial oxygen atoms

1969 ◽  
Vol 47 (23) ◽  
pp. 4441-4446 ◽  
Author(s):  
R. U. Lemieux ◽  
A. A. Pavia
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Hydroxyl Groups ◽  
Evidence Based ◽  
Electrostatic Repulsion ◽  
Hydrogen Bridge ◽  
Conformational Equilibria ◽  
Free Hydroxyl ◽  
Oxygen Atoms

Evidence based both on nuclear magnetic resonance and rotation data primarily obtained from methyl 3-deoxy-β-L-erythro-pentopyranoside and a number of its derivatives is interpreted to show that the electrostatic repulsion between the oxygen atoms at the 2 and 4 positions is substantially less when these oxygens are linked to acyl groups than when in the form of either methyl ethers or as hydroxyl groups hydrogen bonded to solvent. Also, experimental evidence is presented which requires the hydrogen bridge between two axially disposed hydroxyl groups to be substantially strengthened by hydrogen bonding of the free hydroxyl by solvent.

Light-Mediated Cross-Coupling of Anomeric Trifluoroborates

2021 ◽  
Author(s):  
Eric Miller ◽  
Maciej Walczak
Keyword(s):  
Cross Coupling ◽  
Hydroxyl Groups ◽  
Anomeric Effect ◽  
Computational Studies ◽  
Carbohydrate Chemistry ◽  
New Class ◽  
Free Hydroxyl ◽  
Anomeric Carbon ◽  
Stereoselective Reactions

Stereoselective reactions at the anomeric carbon constitute the cornerstone of preparative carbohydrate chemistry. Here, we report the synthesis of axial C1 trifluoroborates and stereoselective C-arylation and etherification reactions under photoredox conditions. These reactions are characterized by high anomeric selectivities for 2-deoxysugars and broad substrate scope (24 examples), including disaccharides and trifluoroborates with free hydroxyl groups. Computational studies show that high axial selectivities for these reactions originate from a combination of kinetic anomeric effect of the intermediate C1 radical and stereoelectronic stabilization of Ni(III) through the metallo-anomeric effect. Taken together, this new class of carbohydrate reagents adds the palette of anomeric nucleophile reagents suitable for efficient installation C-C and Cheteroatom bonds.

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