Synthesis and some sorption properties of the anion-exchangers with biguanidyl groups

Effect of silica precursor transformation on diclofenac sodium release

The present paper describes the preparation of a new type of ternary composites where pure silica gel or polysilsesquioxane was deposited on a polymer carrier loaded with a high dose of diclofenac sodium.

Synthesis of a Thermostable Polymer-supported Strongly Basic Catalyst and its Catalytic Activity

A novel strongly basic polymer-supported catalyst with guanidine groups has been synthesized and its thermal stability has been investigated. To obtain a thermally stable, cross-linked structure, guanidine groups bound to a polystyrene matrix were allowed to react in a nucleophilic manner with p-xylylene dichloride. Compared with the conventional strongly basic anion-exchange resin 201, it possesses higher thermal stability when placed in deionized water at 95°C for 60 h. This was confirmed by thermogravimetric analysis. The excellent thermal stability can be attributed to the unique structure of guanidine and the cross-linking connection mode between this base and the polymeric matrix. The obtained resin was found to efficiently catalyze Knoevenagel condensation reactions with remarkably high yields. Furthermore, the catalytic efficiency of the resin was found to remain unaffected for seven cycles, whereas that of 201 resin was reduced by 25 % owing to degradation of the strongly basic groups.