Pyrolysis of D-Glucose to Acrolein

Despite of its great importance, the detailed molecular mechanism for carbohydrate pyrolysis remains poorly understood. We perform a density functional study with a newly developed XYG3 functional on the processes for D-glucose pyrolysis to acrolein. The most feasible reaction pathway starts from an isomerization from D-glucose to D-fructose, which then undergoes a cyclic Grob fragmentation, followed by a concerted electrocyclic dehydration to yield acrolein. This mechanism can account for the known experimental results.

Optical Rotatory Dispersion Measurement of D-Glucose with Fixed Polarizer Analyzer Accessory in Conventional Spectrophotometer

In the sample compartment of a conventional spectrophotometer, mounting of a polarizer before sample and an analyzer behind sample allows the determination of the optical rotatory dispersion of optical active media by measurement of the transmission ratio of crossed and parallel arranged polarizer and analyzer. A formula for the determination of the angle of rotation is derived from the transmission ratio. The arrangement is applied to determine the molar optical rotation of D-glucose in water in the wavelength range from 220 nm to 820 nm.

Theoretical and Electrochemical Characterization of δ-RuCl2(Nazpy)2: Application to Oxidation of D-Glucose

The heterogenized δ-RuCl2(Nazpy)2 deposited on carbon toray (CT) was studied for the first time as electrochemical catalyst. Before, it was characterized by visible-ultraviolet spectra and theoretically by TDDFT method at B3LYP/Lanl2DZ level. It displayed an MLCT t2geg → π* transition where t2geg due to the structure of Nazpy that considerably reduces energy between d AOs of Ru represents the HOMO of the complex and π* is identified as the LUMO. Electrochemistry study shows two redox ranges in both negative and positive sides of the potential. The positive side that corresponds to the couple RuIV/RuIII of catalyst appears to be active for oxidation of D-glucose in carbonate buffer with a high turnover. Therefore, Keto-2-gluconic and gluconic acids were the two main products obtained with respectively 80% and 17.6% of selectivity. Moreover, a small amount of tartaric and glycol acids coming from the c-c bond cleavage due to non-protection of the anomeric carbon of D-glucose were also observed.

Densities and Viscosities of the Quaternary System Mannitol-Sorbitol- D-Glucose-H2O and Its Ternary Subsystems at 298.15K

To check the applicabilities of the simple density equation and viscosity equation in the semi-ideal solution theory to nonelectrolyte solutions, the densities and viscosities were measured for the quaternary system mannitol-sorbitol-D-glucose-HzO and its ternary subsystems mannitol-D-glucose-H2O and sorbitol-D-glucose-H2O at 298.15K. The results were used to test the applicability of the simple equations for the density and viscosity of the multicomponent nonelectrolyte solution. The agreements between the predicted and measured results are good.

Anomeric specificity of D-glucose metabolism study in rat and human erythrocytes

The anomeric specificity of D-glucose metabolism in erythrocytes has been since 1985 the matter of extensive investigations reported in about ten publications. The present report aims at providing an integrated review of the major findings on this issue.

A BINOL Based Fluorescence Sensor for Distinction of D-Glucose

A saccharide fluorescent receptor based on 1,1'-binaphthol was developed.The boronic acids groups are di-rectly attached to the 3,3'-positions of BINOL which acted as probes to saccharides.The methyl protected receptor R1 showed better response to D-fructose compared to other saccharides in the fluorescence quenching experiment.To improve the selectivity of D-glucose,the triethylene glycol protected receptor R2 was developed.Receptor R2 has a better water-solubility than R1 that can be applied in completely aqueous environment.With receptor R2,D-glucose has a different response to other saccharides that can be useful for the distinction of D-glucose.

Hydrogenation of Glucose on a Carbon-Supported Ru Catalyst: Optimization of the Reaction Conditions

The catalytic hydrogenation of D-glucose over a 3 wt% Ru/C catalyst was studied varying the operating conditions in mild conditions range to optimize the obtention of D-sorbitol. The stirring speed, temperature, pressure, and initial glucose concentration were varied between 250 - 700 rpm, 343 - 383 K, 0.5 - 2 MPa, and 0.033 - 0.133 M, respectively. To verify the absence of mass transport limitations, the diffusion of reagents in the gas-liquid interface, the liquid-solid interface, and the internal diffusion in the particles were evaluated. Under the operating conditions studied, the reaction rate showed an order with respect to H2 of 0.586 and with respect to glucose of 0.406. The kinetic data were adjusted using 3 general models and 19 different sub-models based on Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetics. Model 3a was the best one interpreting the aqueous phase hydrogenation of glucose (both reagents competitively adsorbed on the catalyst). The H2 adsorption is dissociative and the rate-limiting step is the surface chemical reaction.

Synthesis, Crystal Structure and Biological Activity of 1-(β-D-Glucopyranosyl)-3-amino-5-methyl-1H-1,2,4-triazole

The title compound 1-（β-D-glucopyranosyl）-3-amino-5-methyl- 1H- 1,2,4-triazole was synthesized and characterized by IR, 1H-NMR and elemental analysis. Its single crystals of 2H2O adduct suitable for X-ray analysis were obtained by the slow evaporation of a H2O solution and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to orthorhombic, space group P212121 with a = 7.7490（15）, b = 10.424（2）, c = 17.447（4） A^°, V = 1409.3（5） A^°^3, Z= 4, C9H20N4O7, Mr = 296.29, Dc = 1.396 g/cm^3,μ = 0.120 mm^-1, S = 1.007, F（000） = 632, R = 0.0686 and wR = 0.1560 for 1217 observed reflections with I 〉 20（I）. The title molecules are linked through intermolecular hydrogen bonds to form two 1-D chain structures, and such adjacent chains are further linked by intermolecular hydrogen bonds and H2O bridges to form a 3-D supramolecular network structure. The preliminary bioassay results showed that the title compound exhibits fungicidal activities against Gibberella zeae and Colletotrichum orbiculare.

Effect of external electric field upon charge distribution, energy and dipole moment of selected monosaccharide molecules

External electric field of 0.001, 0.01 and 0.05 a.u. changes distribution of the electron density in α- and β-D-glucose, α- and β-D-galactose, α- and β-fructopyranoses and α- and β-fructofuranoses, α- and β-D-ribofuranoses and α and β-D-xylo- furanoses. Hyper-Chem 8.0 software was used together with the AM1 method for optimization of the conformation of the molecules of monosaccharides under study. Then polarizability, charge distribution, potential and dipole moment for molecules placed in the external electric field of 0.000, 0.001, 0.01 and 0.05 a.u. were calculated involving DFT 3-21G method. Application of the external field induced polarizability of electrons, atoms and dipoles, the latter resulting in eventual reorientation of the molecules along the applied field of the molecules and the electron density redistribution at particular atoms. Increase in the field strength generated mostly irregular changes of the electron densities at particular atoms of the molecules as well as polarizabilities. Energy of these molecules and their dipole moments also varied with the strength of the field applied. Results of computations imply that saccharides present in the living organisms may participate in the response of the living organisms to the external electric field affecting metabolism of the molecules in the body fluids by fitting molecules to the enzymes. Structural changes of saccharide components of the membranes can influence the membrane permeability.

Physiopathology of parotid cell energetics

Attention was recently drawn to the production of D-glucose by salivary glands and its concentration in the saliva of both normal and diabetic subjects. Likewise, the identity and expression of selected transporters involved in the handling of the hexose by salivary glands were recently investigated in both normal and diabetic rats. In consideration of this information, the present report aims at providing an integrated review on the physiopathology of parotid cell energetics.

Synthesis of melamine-glucose resin adhesive

The synthesis of a novel melamine-glucose adhesive that is similar to urea-formaldehyde adhesive is reported in this paper. The conditions of synthesis, such as the initial pH, the quantity of catalyst, the temperature of reaction, the percentage of each reactant and the time of reaction, were optimized by using the orthogonal experimental method.