Cupri-ethylenediamine

T 1) an improved method is recommended. The silk is dissolved in a cupri-ethylenediamine solution which is prepared by shaking together for two hours 70 g of copper hydroxide and one litre of 8 per cent ethylene-diamine which has been adjusted to pH 4-5 by the addition of acid. The undissolved cupric hydroxide is separated by filtering through asbestos mixed with kieselguhr. The copper in the filtrate is determined by titration with thiosulphate of the iodine liberated from potassium iodide, and the necessary adjustment is made to bring it to the equivalent of 5-95 to 6-05 per cent of cupric hydroxide. This solution can be kept for some months in, a dark bottle in a cool place. 

Figure 12. Light micrographs of fibers from diquaternary ammonium cellulose (3.46% N) prepared non-aqueously from DEAE and diiodo-pentane. Fibers immersed in mineral oil, water, and 0.5 M cupri-ethylenediamine are shown in top, middle, and bottom micrographs, respectively.

Cotton is not dissolved by common organic solvents. Cotton is swollen slightly by water because of its hydrophilic nature, but it is soluble only in solvents capable of breaking down the associative forces within the crystalline areas of cotton. Aqueous cupianunonium hydroxide and cupri-ethylenediamine are such solvents. 

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