Amides, nitrides from

Lithium Amide. Lithium amide [7782-89-0], LiNH2, is produced from the reaction of anhydrous ammonia and lithium hydride. The compound can also be prepared by the removal of ammonia from solutions of lithium metal in the presence of catalysts (54). Lithium amide starts to decompose at 320°C and melts at 375°C. Decomposition of the amide above 400°C results first in lithium imide, Li2NH, and eventually in lithium nitride, Li N. Lithium amide is used in the production of antioxidants (qv) and antihistamines (see HiSTAMlNE AND HISTAMINE ANTAGONISTS). 

The cubic 2inc blende form of boron nitride is usually prepared from the hexagonal or rhombohedral form at high (4—6 GPa (40—60 kbar)) pressures and temperatures (1400—1700°C). The reaction is accelerated by lithium or alkaline-earth nitrides or amides, which are the best catalysts, and form intermediate Hquid compounds with BN, which are molten under synthesis conditions (11,16). Many other substances can aid the transformation. At higher pressures (6—13 GPa) the cubic or wurt2itic forms are obtained without catalysts (17). 

The heavier alkaline earth metals Ca, Sr, Ba (and Ra) react even more readily with non-metals, and again the direct formation of nitrides M3N2 is notable. Other products are similar though the hydrides are more stable (p. 65) and the carbides less stable than for Be and Mg. There is also a tendency, previously noted for the alkali metals (p. 84), to form peroxides MO2 of increasing stability in addition to the normal oxides MO. Calcium, Sr and Ba dissolve in liquid NH3 to give deep blue-black solutions from which lustrous, coppery, ammoniates M(NH3)g can be recovered on evaporation these ammoniates gradually decompose to the corresponding amides, especially in the presence of catalysts ... 

Exposure of ammoniacal silver chloride solutions to air or heat produces a black crystalline deposit of fulminating silver , mainly silver nitride, with silver diimide and silver amide also possibly present [1], Attention is drawn [2] to the possible explosion hazard in a method of recovering silver from the chloride by passing an ammoniacal solution of the chloride through an ion exchange column to separate the Ag(NH3)+ ion, prior to elution as the nitrate [3], It is essential to avoid letting the ammoniacal solution stand for several hours, either alone or on the column [2], See Silver nitride... 

The thermal desorption of hydrogen from lithium nitride (LiNHa) was investigated by Chen et al. [92,93]. The thermal desorption of pure lithium amide mainly evolves NH3 at elevated temperatures following the reaction (Figure 5.54)... 

Metallic amides and imides can be pptd from liq ammonia solns of certain metallic salts by the action of potassium amide, KNH2 Some amides and imides are explosive, eg, silver amide and lead imide (Compare with Nitrides) (See also Polyamides)... 

Arsenic Amide, As(NH2)3, is formed by the action of ammonia on arsenic trichloride, tribromide or triiodide at -35° to —40° C., the ammonium halide being removed from the residue by washing with liquid ammonia, in which the amide is insoluble.3 It is a greyish-white powder, stable in dry air below 0° C., but above this temperature it begins to decompose, yielding the imide and, at higher temperatures, the nitride. It may be kept at ordinary temperatures in an atmosphere of ammonia without decomposition. Water readily converts it into arsenious oxide and ammonia. 

Recent developments in the synthesis, structures, and properties of ionic/covalent ternary nitrides are reviewed. A description, including synthetic conditions, is given of preparative methods reported in the literature. Solid state synthetic reactions from binary nitrides as well as novel synthetic approaches such as amide synthesis and ammonolysis of ternary oxides are described. Examples of common structure types as well as electronic and magnetic properties are discussed. 

The isostructural compounds Na3WN3 and Na3MoN3 can be synthesized from the metal nitride and sodium amide either at 673 K under high-pressure ammonia38 or from the metal nitride and sodium amide under... 

Nitrogen-rich nitrides are produced by the thermal decomposition of amides prepared by precipitation from liquid ammonia. Examples are CoN from Co(NH2)361 and Ni3N2 from Ni(NH2)2.62 The products are not crystalline. 

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