Microwave-assisted oxidative coupling of thiols using polystyrene supported bromoderivatives of 2-oxazolidone

Polymer-supported reagents have become popular in synthetic organic chemistry over the past decades. But the kinetics of polymer-supported reactions is slow compared to solution phase synthesis because of the poor diffusion of the reactants through the macromolecular polymer matrix. This difficulty can be reduced to a great extent by performing polymer-supported reactions under microwave (MW) conditions. The present work is focussed on the design and development of an innovative, powerful, MW stable and recyclable polymeric reagent prepared by attaching bromoderivative of 2-oxazolidone into the macromolecular matrix of polystyrene. 3% cross-linked polystyrene was prepared by free radical aqueous suspension polymerization technique using tetra ethylene glycol diacrylate as the cross-linking agent and the resulting beads were functionalized by chloromethylation followed by reaction with 2-oxazolidone. Bromine functionality is introduced into the polymer by treating with bromine in carbon tetrachloride. The synthetic utility of the prepared polymeric reagent was demonstrated by the oxidative coupling of thiols to disulfides under MW irradiation. No over oxidation was observed in this protocol and the utilization of polystyrene support simplifies work up and product isolation. The synthesised polymeric reagent displayed good cyclic stability up to five cycles without any substantial decrease in bromine content and satisfactory storage stability under normal laboratory condition. Moreover this may be the first report that uses MW energy for the oxidation of thiols to disulfides using polymer-supported reagents. [Formula: see text]

Results of Spectral Analysis of the Effective Flushing Liquid

The article is devoted to the results of spectral analysis of effective flushing liquid with the use of lightweight polymeric reagent (LPR). On the basis of spectral research it is shown that the mechanism of ion exchange of particles of flushing liquid (replacement reaction) at replacement of mineral in the crystal lattice by cat ions of disperse medium is a permanent replacement of organic and inorganic cat ions of flushing liquid with rock particles and whole groups of dispersive medium. The results of the processes of addition of fluids and rock elements to the flushing liquid particles, as well as simultaneously occurring ion-exchange and none change processes determining the mechanisms of inhibition (reduction of hydrophilicity), stabilization and colloidal protection in flushing liquids are obtained.