Search results for "Acid–base titration"
showing 3 items of 3 documents
An efficient acetylation of dextran using in situ activated acetic anhydride with iodine
2010
A facile, efficient, cost-effective and solvent-free acetylation method has been developed for the acetylation of dextran. Dextran acetates were successfully synthesized using different molar ratios of acetic anhydride in the presence of iodine as a catalyst without the use of any solvent. The reactions were realized at 50?C for 3 h under stirring and nitrogen. This efficient method yielded highly pure and organosoluble dextran esters. The reaction appears highly effective for obtaining higher degrees of substitution (DS) with great efficiency. Under solvent-free conditions, dextran triacetates were efficiently synthesized. It was also observed that the molar ratio can easily control the DS…
Synthesis, characterisation and properties of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide-graft-maleic anhydride precursors and their stimuli-responsiv…
2009
Abstract A family of poly(amino acid)-maleic anhydride hydrogels were designed and synthesized. Water soluble polymeric precursors were prepared by partially substituting the hydroxyl groups of the α,β-poly( N -2-hydroxyethyl)- dl -aspartamide backbone with maleic anhydride, so as to provide double bonds for crosslinking and carboxylic acid groups for pH and electric field responsiveness. Reaction conditions (reactive mixture composition and catalysis) were systematically varied in order to obtain PHEA–MA precursors with different and reliable graft-maleic anhydride levels. PHEA–MA precursors were characterised by titration, Nuclear Magnetic Resonance ( 1 H NMR), Fourier-Transformed Infrare…
Binding of acrylic and sulphonic polyanions by open-chain polyammonium cations
2000
Abstract The interactions between some acrylic and sulphonic polyanions and some protonated amines (diamines NH 2 -(CH 2 ) x -NH 2 , x =2,…,10; linear tri-, tetra-, penta- and hexa-amines) were studied potentiometrically in aqueous solution, at 25°C. For both types of polyanions AL 2 H i (L − , monomer of polyanion, A, amine) species are formed, with i =1,…, n ( n =number of amino groups in the amine). The stability of these species is strictly dependent on the polyammonium cation charge, and fairly independent of the type of amine (in diamine species maximum stability is observed for x =4, 5). Acrylic and sulphonic polyanion complexes are considerably stronger than analogous species formed…