Scope of the DMC mediated glycosylation of unprotected sugars with phenols in aqueous solution

2020 ◽  
Vol 18 (37) ◽  
pp. 7355-7365 ◽  
Author(s):  
Xin Qiu ◽  
Antony J. Fairbanks
Keyword(s):  
Aqueous Solution ◽  
Reducing Sugars ◽  
Protecting Groups ◽  
Aryl Glycosides

Activation of reducing sugars in aqueous solution using DMC and triethylamine in the presence of phenols allows direct stereoselective conversion to the corresponding 1,2-trans aryl glycosides without the need for any protecting groups.

scholarly journals Nopalea cochenillifera Biomass as Bioadsorbent in Water Purification

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2012
Author(s):  
Vitória Régia do Nascimento Lima ◽  
Álvaro Gustavo Ferreira da Silva ◽  
Renata Ranielly Pedroza Cruz ◽  
Luana da Silva Barbosa ◽  
Neilier Rodrigues da Silva Junior ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Water Purification ◽  
Reducing Sugars ◽  
Northeastern Brazil ◽  
Human Consumption ◽  
Contaminated Water ◽  
Water Safety ◽  
Total Coliforms ◽  
Exchange Matrix ◽  
Nopalea Cochenillifera

Contaminated water consumption is one of the greatest risks to human health, especially in underdeveloped and developing countries. Water is a universal right, but millions of people worldwide consume untreated surface water. The objective in this study is to evaluate water purification with Nopalea cochenillifera var. Miúda biomass. Fragments (1, 2, and 3 g) of N. cochenillifera were added to the aqueous solution containing red-yellow Chromic and Podzolic Luvisol simulating turbid water sources in Northeastern Brazil. The total, non-structural (i.e., reducing and non-reducing sugars, alcohol insoluble solids), and structural (i.e., pectin) carbohydrates, adsorption kinetics, turbidity, electrical conductivity, pH, zeta potential, and total coliforms presence were evaluated. Findings show that the Nopalea cochenillifera biomass adsorbed the suspended particles in the aqueous solution, making it more translucent due to the complex and heterogeneous adsorbents’ ion exchange matrix, but the biomass addition did not eliminate total coliforms from the aqueous solution. We concluded that the Nopalea cochenillifera biomass water treatment reduces suspended dissolved particles and turbidity, but it needs to be associated with other treatments to eliminate total coliforms and ensure water safety for human consumption.

scholarly journals The kinetics of mutarotation in solution

1940 ◽  
Vol 176 (966) ◽  
pp. 352-367 ◽  
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Reducing Sugars ◽  
Arrhenius Equation ◽  
Energy Of Activation ◽  
A Value ◽  
Temperature Ranges ◽  
Velocity Coefficient ◽  
Kinetics Of ◽  
True Energy

The kinetics of the mutarotation of representative reducing sugars from the pentose, hexose and disaccharide series have been investigated polarimetrically over wide temperature ranges in aqueous solution. The dependence of the velocity coefficient, k , upon temperature is fairly well reproduced by an equation of the form ln k = C + ( J/R ) ln T - E/RT . The true energy of activation, E , is found to be some 6000 calories greater than the apparent value afforded by the Arrhenius equation at room temperature. J/R has a value of — 10, which is identified as the number of oscillators contributing to the activation. The constants C, J and E of this equation are discussed, with reference to many reactions, in terms of a theory of unimolecular reactions in solution.

Direct aqueous synthesis of cyanomethyl thioglycosides from reducing sugars; ready access to reagents for protein glycosylation

2016 ◽  
Vol 14 (28) ◽  
pp. 6679-6682 ◽  
Author(s):  
Stewart R. Alexander ◽  
Antony J. Fairbanks
Keyword(s):  
Aqueous Solution ◽  
Reducing Sugars ◽  
Protein Glycosylation ◽  
Aqueous Synthesis ◽  
Ready Access

Unprotected carbohydrates can be directly converted into cyanooethyl thioglycosides, which in turn may be used for protein glycosylation, in a completely stereoselective manner by reaction with 2-chloro-1,3-dimethylimidazolinium chloride (DMC) and mercaptoacetonitrile in aqueous solution.

scholarly journals Protecting group free synthesis of glycosyl thiols from reducing sugars in water; application to the production of N-glycan glycoconjugates

2017 ◽  
Vol 15 (10) ◽  
pp. 2152-2156 ◽  
Author(s):  
S. R. Alexander ◽  
D. Lim ◽  
Z. Amso ◽  
M. A. Brimble ◽  
A. J. Fairbanks
Keyword(s):  
Reducing Sugars ◽  
Click Reaction ◽  
Protecting Groups ◽  
Water Application ◽  
Protecting Group

Un-protected 2-acetamido terminated reducing sugars may be converted into the corresponding glycosyl thiols in water, and conjugated to peptides using the thiol–ene click reaction without recourse to any protecting groups.

scholarly journals The photosynthesis of naturally occurring compounds. I.—The action of ultra-violet light on carbonic acid

1927 ◽  
Vol 116 (773) ◽  
pp. 197-211 ◽  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Reducing Sugars ◽  
Carbonic Acid ◽  
Ultra Violet ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Naturally Occurring ◽  
Two Stages

In a preliminary paper one of us, in conjunction with Prof. Heilbron and Prof. Barker, described some observations on the action of ultra-violet light on pure aqueous solutions of carbonic acid. It was found that traces of formaldehyde were present in these solutions after insolation, provided that a stream of the gas were passed through the water during the exposure to the light. These results differed from those which had previously been recorded by Moore and Webster, who had stated that the presence of a catalyst such as colloidal ferric or uranium hydroxide was necessary. The observation by Moore and Webster that formaldehyde in aqueous solution is converted by ultra-violet light into reducing sugars was fully confirmed, and the view was put forward that the mechanism of the photosynthesis of carbohydrates from carbonic acid consisted of two stages, first, the formation of formaldehyde, and, second, the conversion of this substance into hexoses.

A Simple Conversion of Creatinine to Creatol via Creatinine Chloroamine

2015 ◽  
Vol 68 (2) ◽  
pp. 248 ◽  
Author(s):  
Kazuharu Ienaga ◽  
Yoshiaki Toya ◽  
Kiyohiko Nakajima ◽  
Mariko Tachikawa
Keyword(s):  
Aqueous Solution ◽  
Solid State ◽  
Protecting Groups ◽  
X Ray ◽  
Simple Conversion

Creatinine (2-amino-1,5-dihydro-l-methylimidazol-4-one) (1a) was converted in a simple way to creatol (2-amino-1,5-dihydro-5-hydroxy-l-methylimidazol-4-one) (1b) via creatinine chloramine (2-N-chloroamino-1,5-dihydro-l-methylimidazol-4-one) (3a), without using protecting groups. The creatinine chloroamine exists in the 2-N-chloroamino form (3a) in aqueous solution, but in the solid state, X-ray crystal analysis shows that it has the 2-N-chloroimino structure (2-N-chloroimino-1,5-dihydro-1-methylimidazol-4-one) (4a). Related imidazolones have also been prepared and are discussed.

The composition of reducing sugars in aqueous solution : glyceraldehyde, erythrose, threose

1980 ◽  
Vol 33 (5) ◽  
pp. 1001 ◽  
Author(s):  
SJ Angyal ◽  
RG Wheen
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Reducing Sugars

In the syrupy state, DL-glyceraldehyde, D-erythrose and D-threose consist mainly of mixtures of dimeric forms. Their aqueous solutions also contain some dimers; glyceraldehyde is present mainly as the aldehydrol, and the tetroses as mixtures of the furanoses and the aldehydrol. All the solutions contain some (> 1 %) of the aldehydo form. The proportion of the monomeric forms has been determined, from the 1H n.m.r. spectra, at various temperatures.

Structures Formed by Cryoprotective Agents Used in Freezc-Etching

1971 ◽  
Vol 29 ◽  
pp. 448-449
Author(s):  
G. G. Cocks ◽  
C. E. Cluthe
Keyword(s):  
Aqueous Solution ◽  
Polyethylene Oxide ◽  
Liquid Nitrogen Temperature ◽  
Ice Crystals ◽  
Etching Technique ◽  
Structural Constituent ◽  
Cryoprotective Agents ◽  
Quick Freezing ◽  
Freeze Etching ◽  
Fractured Surface

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

TEM observation of iron oxide pillars in montmorillonite

1990 ◽  
Vol 48 (4) ◽  
pp. 882-883
Author(s):  
H. Mori ◽  
Y. Murata ◽  
H. Yoneyama ◽  
H. Fujita
Keyword(s):  
Aqueous Solution ◽  
Iron Oxide ◽  
Fine Particles ◽  
Aqueous Suspension ◽  
Volume Ratio ◽  
Exchange Capacity ◽  
Nano Composites ◽  
Pillared Montmorillonite ◽  
Topographic Features ◽  
Transmission Electron

Recently, a new sort of nano-composites has been prepared by incorporating such fine particles as metal oxide microcrystallites and organic polymers into the interlayer space of montmorillonite. Owing to their extremely large specific surface area, the nano-composites are finding wide application[1∼3]. However, the topographic features of the microstructures have not been elucidated as yet In the present work, the microstructures of iron oxide-pillared montmorillonite have been investigated by high-resolution transmission electron microscopy.Iron oxide-pillared montmorillonite was prepared through the procedure essentially the same as that reported by Yamanaka et al. Firstly, 0.125 M aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate, [Fe3(OCOCH3)7 OH.2H2O]NO3, was prepared and then the solution was mixed with an aqueous suspension of 1 wt% clay by continuously stirring at 308 K. The final volume ratio of the latter aqueous solution to the former was 0.4. The clay used was sodium montmorillonite (Kunimine Industrial Co.), having a cation exchange capacity of 100 mequiv/100g. The montmorillonite in the mixed suspension was then centrifuged, followed by washing with deionized water. The washed samples were spread on glass plates, air dried, and then annealed at 673 K for 72 ks in air. The resultant film products were approximately 20 μm in thickness and brown in color.

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