382 PRACTICAL ORGANIC CHEMISTRY HCl. The derivative crystallises out immediately: filter off, wash with cold water and recrystailise from boiling water. Long colourless silky needles, m.p. 179°. 5. Copper salt, (a) Add aqueous copper acetate solution to an aqueous solution of glycine. Note the formation of a blue colour which is considerably deeper than the colour of the original copper acetate solution. On heating the solution, blue needles of the copper salt usually separate. (b) Dissolve about 0-5 g. of glycine in about 40 ml. of water and add an excess of freshly precipitated well-washed cupric hydroxide. Boil for 5 minutes and filter while hot into a small evaporating-basin. Concentrate to about half-bulk on a boiling water-bath and then allow to cool: fine blue needles of the copper salt, (NH 2 CH 2 COO) 2 Cu, crystallise out (cf. p. 130). Prepare the cupric hydroxide by dissolving 2 g. of copper sulphate in about ioo ml. of water, and adding with stirring 16 ml. of TV.NaOH solution.
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