COORDINATION EQUILIBRIA IN TRANSITION-METAL BASED CELLULOSE SOLVENTS

Taking 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 farm 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 greater than or equal to 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.