HYPONITRITES. 321 



the preparation of hj'ponitrites in this laboratory, pointed to the 

 partial decomposition, by the excess of water present, of the 

 hyponitrite formed by ihe reduction of nitre; hence it was thought 

 that in the absence of water a larger yield of hyponitrite might be 

 obtained. 



The preparation was based on the expectation that the reaction 

 of soilium amalgam with ethyl nitrite would yield sodium hyponi- 

 trite and sodium ethylate. 



The ethyl nitrite was obtained, as the most convenient method 

 of formation, by the action of glyceryl trinitrite on absolute alcohol, 

 glycerol being formed at the same time ; but this apparently does 

 not affect the reaction, and, being soluble in alcohol, is easily 

 separated from the hyponitrite afterwards produced. The glyceryl 

 trinitrite whs prepared by the action of nitrogen trioxide on 

 glycerol (Masson, J.O.S., 1883). The preparation is most con- 

 veniently performed in Varentrapp and Will bulbs— the absorption 

 of the gas being very rapid and complete — the bulbs being kept 

 cooled to about 10° in a current of water. 



'J'he trinitrite was separated as completely as possible from the 

 water produced in a separating funnel, but not further purified. 



About 18c. c. (23grms.) of the ether were thus prepared and 

 intioduced drop by drop into a large flask containing 2,000 grams 

 of 9 2ier cent, sodium amalgam and a large excess (1 litre) of 

 absolute alcohol. The ether sinks to the surface of the amalgam, 

 reacting with the alcohol, forming ethyl nitrite and j^lycerol, and 

 the ethyl nitrite then reacts with the sodium, forming sodium 

 ethylate and sodium hyponitrite. 



C3H5 (N02)3 + 3 EtOH = C3H5 (0H)3 + 3 EtNOi 

 EtN02 4- 2 Na = EtONa + NaNO. 



Heat is evolved during the reaction and the flask was kept cooled 

 in a current of cold water. After the whole of the ether was intro- 

 duced the flask was allowed to stand over night in the water. A 

 voluminous white precipitate is formed and a considerable amount 

 of ammonia evolved, hydroxylamine being, probably, also formed 

 by the further reduction of the nitrite. The precipitate was 

 separated from the mercury, filtered out, and washed with absolute 

 alcohol, in which sodium hyponitrite is quite insoluble, till only 

 slightly alkaline. This removes all the glycerol and sodium 

 ethylate, as well as all reducing substances, such as hydroxylamine, 

 which may be formed, and leaves the sodium hyponitrite only 

 mechanically mixed with a little mercury. Experience showed 

 that very thorough washing with alcohol is necessary to yield the 

 hyponitrite in a pure state. It was then dissolved in w-ater filtered 

 from the mercury present, the filtrate being an almost pure solution 

 of sodium hyponitrite. This was acidified Avith a drop of acetic 

 acid and silver nitrite added, tiiving a bright yellow precipitate of 

 silver hyponitrite, which did not blacken on exposure to light, as 



X 



