Ammonolysis solvent efFect

Ionization of liquid ammonia and water solutions.—Solutions of certain salts in liquid ammonia are good conductors of electricity so that liquid ammonia approaches water in its ionizing power. The effect, however, is largely due to the high speed at which the ions are supposed to travel in the solvent. For example, E. C. Franklin and H. P. Cady1 find that univalent ions travel, at —33°, nearly three lames as fast as in aq. soln. at 18°. Just as the solvent water, in the ionization theory of hydrolysis, is supposed to be ionized H20=0H -f-H, so in ammonolysis, the solvent ammonia is supposed to be ionized NH3==NH2-j-H . Sodamide, NaNH, furnishes sodium ions Na and amide ions NH 2 when dissolved in liquid ammonia, and it is to be considered as a base. It reddens phenolphthalein. The neutralization of this solution results in the union of H ions with NH2 ions to form ammonia molecules, just as the neutralization of bases is regarded as an effect of the union of H and OH ions. Acetamide, CH3.CO.NH2, ionizes in liquid ammonia in an analogous manner CH3.CO.NH2 CH3.CO.NH -f-H, and it thus behaves as an acid. 

DFT was employed to study the mechanism of ammonolysis of phenyl formate in the gas phase, and the effect of various solvents on the title reaction was assessed by the polarizable continuum model (PCM). The calculated results show that the neutral concerted pathway is the most favourable one in the gas phase and in solution.24 The structure and stability of putative zwitterionic complexes in the ammonolysis of phenyl acetate were examined using DFT and ab initio methods by applying the explicit, up to 7H20, and implicit PCM solvation models. The stability of the zwitterionic tetrahedral intermediate required an explicit solvation by at least five water molecules with stabilization energy of approximately 35 kcalmol-1 25... 

PSZs without pendent carbon bearing groups, which are precursors to silicon nitride ceramics, can be obtained by ammonolysis of dichlorosilane, H2SiCl2, or a stable complex, with a tertiary amine [18]. A stable H2SiCl2/2-pyridine complex has been used to produce Si-N fibers (Equations 5a, 5b). Pyridine acts as a catalyst in the condensation/crosslinking reaction, whereas other solvents, such as xylene, have the reverse effect [4-5]. The end product Is a clear solution of perhydropolysilazane (PHPSZ). 

By the reaction of iodine and small amounts of liquid ammonia at -75° a black brown solid is formed. A tensimetric deammonation shows that this solid is an addition compound of iodine and ammonia with 2 moles of ammonia per mole of iodine. Further deammonation effects formation of a compound Ij.NH finally, I remains. Ammonolysis of iodine takes place only to a small extent. These brown addition compounds of iodine correspond to the well known brown addition compounds of iodine and ether, alcohol, pyridine or liquid hydrogen sulfide respectively and are looked upon as charge-transfer complexes with iodine as electron acceptor and the solvents as electron donors. This view was proved by the measurement of the charge transfer band of iodine-ammonia in heptane at 229 m i (2). 

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