Synthesis of Sulfated Polysaccharides and Oligosaccharide Derivatives with Potent Anti-Aids Virus Activity

Abstract

Sulfated synthetic polysaccharides (with both high anti-AIDS virus activity and high anticoagulant activity) were prepared by sulfating such synthetic polysaccharides as ribopyranan, ribofuranans, and dextrans. Sulfated natural polysaccharides with high anti-AIDS virus activity but low anticoagulant activity were synthesized from lentinan and curdlan. It is assumed that curdlan sulfate will be helpful as an AIDS drug. In addition, sulfated alkyl oligosaccharides with high anti-AIDS virus activity were prepared.     

3,14‐Bis(p‐nitrophenyl)‐17,17‐dipentyltetrabenzo[a,c,g,i]‐fluorene: A New Fluorophore Displaying Both Remarkable Solvatochromism and Crystalline‐Induced Emission

A series of 17,17‐dialkyl‐3,14‐diaryltetrabenzofluorenes were efficiently prepared by using Suzuki–Miyaura cross‐coupling reactions of the corresponding 3,14‐dibromo derivatives. Studies of the unique fluorescence properties of these compounds showed that they display intense blue to yellow fluorescence with high quantum yields in the solution state and blue to orange fluorescence with moderate quantum yields in the solid state. In addition, the fluorescence wavelength of the bis(p‐nitrophenyl) derivative is remarkably solvent‐dependent in a manner that correlates with the solvent polarity parameter E_T(30). The results of density function theory calculations suggest that the intramolecular charge‐transfer character of the HOMO–LUMO transition is responsible for the large solvent effect. Moreover, addition of water to a tetrahydrofuran (THF) solution of this compound leads to quenching of the yellow fluorescence owing to an increase in the solvent polarity. However, when the amount of water fraction exceeds 70 %, a new fluorescence band appears at the same orange‐red emission wavelength as that of the solid‐state fluorescence. This observation suggests the occurrence of a crystallization‐induced emission (CIE) phenomenon in highly aqueous THF.     

A Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite

There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template. The aluminosilicate ITH zeolite has very high crystallinity, nanosheet‐like crystal morphology, large surface area, fully four‐coordinated Al species, and abundant acidic sites. Methanol‐to‐propylene (MTP) tests reveal that the Al‐ITH zeolite shows much higher selectivity for propylene and longer lifetime than commercial ZSM‐5. FCC tests show that Al‐ITH zeolite is a good candidate as a shape‐selective FCC additive for enhancing propylene and butylene selectivity.     

Synthesis of 5-ethoxymethylfurfural from saccharides using combined metal–surfactant catalyst in ethanol/dimethyl sulfoxide

Research on Chemical Intermediates - The synthesis of 5-ethoxymethylfurfural (EMF) from glucose using metal chlorides or combined metal–surfactant catalysts as Lewis acids in a solution of...     

Intermolecular interactions,ion solvation,and association in mixtures of 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate and γ‐butyrolactone: insights from Raman spectroscopy

By means of Raman spectroscopy coupled with density functional theory (DFT) calculations and perturbation correlation moving window two‐dimensional correlation spectroscopy intermolecular interactions were assessed in mixtures of ionic liquid (IL) 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate (BmimPF₆) with polar aprotic solvent γ‐butyrolactone (γ‐BL) over the entire range of compositions. The symmetrical P―F stretching vibration of the IL anion was found to be insensitive to the changes in mixture concentration in contrast to the CO stretching vibration of the γ‐BL and the imidazolium ring C―H stretching vibrations of the IL cation. Each of these vibrational profiles was decomposed in various spectral contributions, and their number was rationalized by the results of quantum‐chemical calculations and/or previous controversial published data. Progressive redshift of the ring C―H stretching wavenumbers was referred to pronounced solvation of the cation at the imidazolium ring site accompanied with H‐bond formation. This was especially pronounced at IL mole fraction less than 0.18. Complicated variations in the intensities of the individual contributions of the CO profile were treated as a manifestation of the changing with concentration pattern of the intermolecular interactions. The self‐association of γ‐BL molecules and distinct cation solvation as dominant intermolecular interactions at low IL content are replaced with weaker cation solvation and ion association at high concentrations of IL. Possible representative molecular structures were proposed on the basis of DFT calculations. Copyright © 2015 John Wiley & Sons, Ltd.     

Hydrolysis of Diazonium Salts Using a Two‐Phase System (CPME and Water)

A new method for the hydrolysis of diazonium salts, without the formation of tar, was developed. A two‐phase system consisting of cyclopentyl methyl ether (CPME) and water is very effective for the hydrolysis of diazonium salts. Using this solvent system, the diazonium salt prepared from 3‐(4‐nitrophenoxy)aniline gave 3‐(4‐nitrophenoxy)phenol in high yield (96%) within 20 min. The synthesized phenol is an industrially important raw material in polymer syntheses. Furthermore, the use of the present two‐phase system of CPME and water successfully brought about the efficient conversions of several m‐substituted anilines into the corresponding m‐substituted phenols. This is the first example of hydrolysis of diazonium salts using the two‐phase system (CPME and water).     

Dielectric Barrier Discharge for Ammonia Production

The leading after-treatment technology for NOx removal process in Diesel engines for stationary and mobile applications is the selective catalytic reduction of oxides of nitrogen [NOx] by ammonia [NH₃]. A novel non-thermal plasma electrode with a needle array in a dielectric barrier discharge reactor, powered by a high frequency neon transformer, is used for the thermal decomposition of solid urea [(NH₂)CO(NH₂)] to produce ammonia. The thermolysis of urea produces iso-cyanic acid [HNCO] as a byproduct, besides ammonia, which can react with water in the gas phase, thus giving carbon dioxide and more ammonia. The presence of water fed before and/or after the plasma reactor was studied to assess its effect on the amount of produced ammonia. Results clearly showed that water fed to the entrance of the reactor can efficiently promote the reaction of iso-cyanic acid to produce ammonia and this result can be improved when air is used as carrier gas for 115 V of input voltage to a neon transformer and with a gas flow rate of 4 L/min.     

Hybrid films prepared from latex particles incorporating metal oxide nanoparticles

Metal oxide (ZrO₂) nanoparticle-dispersed polymer films (hybrid latex films) were prepared from polymer particles incorporating ZrO₂ nanoparticles (hybrid latex dispersion). The hybrid latex dispersions were synthesized by miniemulsion polymerization. The resulting films were transparent, and they derived their properties from the ZrO₂ nanoparticles. The refractive indexes of the films increased with the ZrO₂ content. Surface-modified ZrO₂ nanoparticles were dispersed successfully in a polymer matrix containing phosphoric acid groups, which interacts with the surfaces of the ZrO₂ nanoparticles and increases the compatibility between the polymer and ZrO₂.     

Direct and Selective Production of Propene from Bio‐Ethanol on Sc‐Loaded In2O3 Catalysts

Propene, one of key building blocks for manufacturing plastics and chemicals, could be directly and stably produced from ethanol in good yields. The conversion degree of ethanol to propene reached approximately 60 mol % by using a 3 atom % scandium‐loaded indium oxide catalyst at 823 K in the presence of water and hydrogen. The introduction of Sc prevented the reduction of In₂O₃ to In metal during the reaction, and that of water decreased the coke formation. Both additions resulted in longer lifetimes of the catalysts. The hydrogen addition increased the conversion of acetone to propene. The reaction pathways are also suggested on the basis of the product distributions and the pulse experiments, ethanol→acetaldehyde→acetone→propene, which is quite different from the shape‐selective catalysis on zeolites and the dimerization‐metathesis of ethene on nickel ion‐loaded silica catalysts.