Sodamide, NaNH₂

Sodamide, NaNH₂, is formed by the action of liquid ammonia on the metal, or by passing dry ammonia over fused sodium or one of its alloys. An apparatus for its preparation has been described by Wohler and Stang-Lund.

Sodamide is a white substance. According to Wohler and Stang-Lund, it melts at 210° C., and not between 149° and 155° C., as stated by Titherley; but Me Gee found that it melts sharply at 208° C. He was unable to prepare the blue solutions of sodium in the amide described by Titherley, and found no solvent action on glass below 240° C. Contact of the amide with glass for several days at 270° to 300° C. is attended by slight action, probably due to the presence of sodium hydroxide. Sodamide begins to sublime at 400° C. At 500° C. it decomposes with evolution of nitrogen and hydrogen, leaving a residue of sodium and sodium nitride. Between 200° and 300° C. in an atmosphere of hydrogen, it becomes partially converted into sodium hydride and ammonia:

NaNH₂+H₂=NaH+NH₃.

It is employed in organic syntheses, an example being the conversion of phenylglycine into indoxyl in the manufacture of synthetic indigo.

When exposed to the action of air in presence of a small proportion of water, finely divided sodamide undergoes autoxidation, becoming transformed into a yellowish-red peroxide, probably having the formula NaNH₂,O₂. At the ordinary temperature there is no autoxidation in dry air, but between 100° and 110° C. the peroxide is slowly generated. In dry air this substance is stable.