Synthesis of Glycoside Derivatives Employing the Ferrier Rearrangement 1

Abstract

Various glycals underwent smooth Lewis acid-catalysed allylic rearrangement reactions with O-nucleophiles to yield 2,3-unsaturated glycoside derivatives. In the hexose series predominantly α-D-, and in the pentose series β-D-anomers resulted. Among others Ω-cyano- as well as Ω-benzyloxycarbonylamino functionalised alcohols could be used successfully. With diols the corresponding 1,1′-bridged disaccharides could be obtained.

     

Micro‐ and Nanoemulsions in Cosmetic and Pharmaceutical Products

This article presents a model of droplet disruption in an ultrasonic field. It describes the experiments with preparing fine emulsions in the ultrasonic field.     

Testing of microorganisms for ω-transaminase activity

Various bacterial cells were tested to identify ω-transaminase activity. For this purpose, the kinetic resolution of a rac-amine was chosen as an assay reaction transforming, in the ideal case, one enantiomer into the corresponding ketone and leaving the other enantiomer untouched. Sodium pyruvate was employed as an amino acceptor. To test also for the amination of the prochiral ketone various amino donors were investigated. Alanine proved to be the most suitable amino donor especially when coupled with a pyruvate decarboxylase to shift the reaction equilibrium; however, much lower conversions were achieved compared to the kinetic resolution. Janibacter terrae DSM 13953 was identified as the most suitable microorganism to possess ω-transaminase activity.     

Formation of hydrated titanium dioxide from seeded titanyl sulphate solution

The paper analyses the influence of various kinds and amounts of titanium dioxide nuclei addition to a solution of titanyl sulphate on the conversion degree of TiOSO₄ to hydrated titanium dioxide and sulphuric acid. An industrial solution of titanyl sulphate used to produce titanium white was used in the present investigations. It was found that the course of hydrolysis clearly depended on the investigated parameters. The anatase nuclei calcined at 373 K and 333 K and rutile nuclei increased the degree of titanyl sulphate hydrolysis as compared to non-nucleation hydrolysis. The final degree of hydrolysis was by 1–2 % higher than that achieved without any nuclei addition. The constant rates of both colloidal intermediate and final crystalline products formation were higher in the hydrolysis process with both anatase nuclei after heat treatment at lower temperature and rutile nuclei in comparison to the same processes conducted in the absence of these nuclei. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

Proton‐conducting electrolytes based on silylated and sulfonated polyetheretherketone: Synthesis and characterization

A derivative of polyetheretherketone (PEEK) having sulfonic acid groups and silicon‐containing substituents covalently bound to the aromatic backbone has been prepared as proton‐exchange membrane material. The polymer 4 (PhSiSPEEK) has been synthesized via (i) sulfonation of PEEK up to 0.9 degree of sulfonation (DS, the number of sulfonic groups per repeat unit), (ii) conversion of sulfonated PEEK 1 (SPEEK09) into sulfonyl chlorinated derivative 2 (PEEKSO₂Cl), (iii) lithiation of 2 and subsequent addition of PhSiCl₃, followed by hydrolysis. The chemical structure of the synthesized polymers has been investigated by ¹H NMR and ¹³C NMR and ATR/FTIR spectroscopy and their thermal stability has been evaluated by thermogravimetric analysis. The presence of inorganic moieties increases the thermal stability of 4 with respect to the sulfonated and not silylated product. Despite its very high DS, PhSiSPEEK is insoluble in water but does not possess the plastic properties needed to be used as an electrolyte membrane. Blend membranes made of SPEEK05 (DS = 0.5) and containing 10 and 25 wt % of 4 (DS = 0.9, degree of silylation DSi = 0.1) have been prepared and characterized by water uptake measurements and electrochemical impedance spectroscopy. The combination of the two functionalized polymers having different properties allows to obtain proton‐conducting electrolytes that are potential candidates for fuel cells applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2178–2186, 2010