Coordination equilibria in transition metal based cellulose solvents

Abstract

AbstractTaking into account the coordination chemistry of divalent palladium and nickel, two new cellulose solvents have been developed. Pd‐en is an aqueous solution of the ethylenediamine palladium complex [(en)Pd(OH)2]. Low molecular diols are deprotonated twice in Pd‐en and form a five membered chelate ring with the transition metal. Cellulose dissolves in Pd‐en to give a yellow solution, which allows light scattering analysis. NMR investigation of the solutions are simplified due to the diamagnetism of palladium(II) complexes. — The analysis of solution equilibria is essential in the development of complexing polysaccharide solvents. This feature is demonstrated by means of the new cellulose solvent Ni‐tren, which is an aqueous solution containing tris(2‐aminoethyl)amine, nickel salt and hydroxide in a molar ratio of ≥1:1:2. The difference in the cellulose solving mechanism between Ni‐tren and the long known solvents ‘nioxen’ and ‘nioxam’ developed by Jayme in the 1950ths is outlined. The question, wether or not the dissolution of cellulose in a complexing solvent is a derivatization, is discussed.