142 PROCEEDINGS OF THE AMERICAN ACADEMY. 



III. The Action of Alkyliodides on Silver Dinitroethane, 



CHg - C = NOAg. 



I II 

 NOo O 



Preparation of Dinitroethane. — After many experiments, the fol- 

 lowing method of preparing dinitroethane was found to give the best 

 results.* 50 grams bromnitroethane (bpt. 140-145°, prepared accord- 

 ing to the directions of Tscherniak f), 50 c.cm. alcohol, and a solution 

 of 56 grams potassic nitrite in 56 grams water, were kept shaken up 

 very thoroughly in a shaking apparatus for 24 hours. The potassium 

 salt of dinitroethane separates out slowly in yellow crystals, which, 

 when filtered off and well washed with alcohol, are sufficiently pure. 

 The yield is from 13 to 14 grams. The salt is dissolved in warm 

 water and treated directly with silver nitrate (one molecule), and 

 the silver salt obtained in glistening heavy yellow leaflets, which are 

 filtered off and dried in a vacuum. 



Ter Meer J has already studied the behavior of this salt towards 

 methyliodide and obtained thereby an oil, which, on treatment with 

 alcoholic potash, is partially converted back again into potassic dini- 

 troethane. Very recently Duden has studied the behavior of silver 

 dinitromethane towards alkyliodides, § and shown that, for example, it 

 is converted by means of methyliodide into dinitroethane. 



The reaction which takes place, however, on treating the silver salt 

 of dinitromethane and of dinitroethane with alkyliodides, is far more 

 complicated than either ter Meer or Duden have surmised ; the very 

 remarkable and peculiar reaction is cleared up fully by the following 

 experiments. 



50 grams silver dinitroethane are added slowly to 100 grams methyl- 

 iodide, taking care to cool well with water. Reaction quickly takes 

 place, with formation of silveriodide, and, towards the end, a strong 

 smell of formaldehyde is noticed. After standing one hour, ether is 

 added and the excess of methyliodide as well as the ether is removed 

 from the filtrate by heating in a distilling flask at 50 mm. pressure to a 

 temperature of 50°. The residual oil is taken up with ether, and treated 

 with cold dilute sodic hydrate and the deep red colored alkaline solu- 



* Ter Meer, Ann Chem. (Liebig), CLXXXI. 6; Chancel, Jahresber,, 1883, 

 p. 1039. 



t Ann. Chem. (Liebig), CLXXX. 126. t Ibid., CLXXXI. 16. 



§ Ber. d. cliem. Ges., XXVL 3003. 



