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On a New Complex Copper Cyanogen" Compound. 



By A. R. Mjddleton. 



(Preliminary Note.) 



When a cold concentrated solution of KCN is added to a cold con- 

 centrated solution of cupric chloride or sulphate, but not nitrate, greenish 

 brown cupric cyanide is precipitated; the precipitate dissolves on fur- 

 ther addition of KCN with formation of a claret red to violet red com- 

 pound, much resembling potassium permanganate solution. Further addi- 

 tion of KCN destroys the color, with precipitation of white cuprous cyan- 

 ide (presumably), which then dissolves in excess of KCN. First addition 

 of concentrated cupric salt solution, or the solid salt, to concentrated 

 KCN solution produces a brilliant violet color, instantly destroyed by fur- 

 ther addition and quickly disappearing on standing. Further additions 

 of copper salt give the red compound, provided the solution is kept nearly 

 at 0° ; otherwise cyanogen is evolved and the red compound is not formed. 

 If the solutions are too concentrated or too dilute, the red compound is 

 not formed. Solutions about one-half saturated appear to give the com- 

 pound most readily and in largest amount. 



Search through the available literature has revealed no reference to 

 such a compound. It is quite unstable, decomposing to a brown solution 

 on standing in a warm room over night; is instantly decomposed by 

 strong and weak acids and bases and by pyridine ; soluble in alcohol, but 

 insoluble in chloroform, ether, benzene, toluene and carbon tetrachloride. 

 Attempts to crystallize out the compound are in progress, and at the time 

 of writing appear promising. The method pursued is as follows: Solid 

 CuCl 2 .2H 2 was added in small amounts to KCN solution about one-half 

 saturated, with constant shaking in ice water. After the red color reached 

 a maximum, the solution was filtered, three volumes of 95% alcohol added 

 and placed in the icebox in an exhausted desiccator. After 24 hours white 

 opalescent scales separated, which, after washing with alcohol and ether 

 and drying, present a metallic appearance somewhat resembling tinfoil. 

 These contain copper and may be cuprous cyanide. The solution retained 

 its red color unchanged and it is hoped that the compound can be crystal- 

 lized out in form suitable for analysis. 



Purdue University, 

 Lafayette, Ind. 



