Hydrogen bonding in ammonia

Boese, A. D., Chandra, A., Martin, J. M. L., Marx, D. (2003), From ab initio quantum chemistry to molecular dynamics The delicate case of hydrogen bonding in ammonia, J. Chem. Phys. 119, 5965-5980. 

The resulting compound, NH4C1, is an ionic-bonded salt. The salts ammonium cation (NH4+) is held together by covalent bonds, one of which formed when a hydrogen ion united with the pair of unshared electrons on the nitrogen atom. Keep in mind that three of the nitrogen-hydrogen bonds in ammonia formed as ordinary covalent bonds, in which each element contributed one electron,... 

Cook, K. D. and Taylor, J. W., A supersonic molecular beam mass spectrometric study of hydrogen bonding in ammonia, Int. J. Mass Spectr. Ion Phys. 30, 345-357 (1979). 

Example 9-2. The heat of sublimation of ammonia is 29 kJ mole". Using information in Example 9-1, estimate the energy of the hydrogen bonds in ammonia. 

From Ab Initio Quantum Ghemistry to Molecular Dynamics The Delicate Case of Hydrogen Bonding in Ammonia. 

The rate of reaction of a series of nucleophiles with a single substrate is related to the basicity when the nucleophilic atom is the same and the nucleophiles are closely related in chemical type. Thus, although the rates parallel the basicities of anilines (Tables VII and VIII) as a class and of pyridine bases (Tables VII and VIII) as a class, the less basic anilines are much more reactive. This difference in reactivity is based on a lower energy of activation as is the reactivity sequence piperidine > ammonia > aniline. Further relationships among the nucleophiles found in this work are morpholine vs. piperidine (Table III) methoxide vs. 4-nitrophenoxide (Table II) and alkoxides vs. piperidine (Tables II, III, and VIII). Hydrogen bonding in the transition state and acid catalysis increase the rates of reaction of anilines. Reaction rates of the pyridine bases are decreased by steric hindrance between their alpha hydrogens and the substituents or... 

In many of its properties, liquid ammonia resembles water. Both are polar and involve extensive hydrogen bonding in the liquid state. It is interesting to note that hydrogen bonding in liquid... 

Ammonia liquefies at atmospheric pressure only when cooled to -33° but at moderate pressures it can be liquefied at ordinary temperatures. There is considerable intermolecular hydrogen bonding in liquid ammonia, which is a colourless mobile liquid but is troublesome to handle because the fumes are noxious. This is why great care is required in its handling. 

Tertiary Amine an amine in which the nitrogen atom is bonded to three carbon atoms, when three hydrogen atoms in ammonia have been replaced by three organic R groups... 

Nucleophilic addition to C=0 (contd.) ammonia derivs., 219 base catalysis, 204, 207, 212, 216, 226 benzoin condensation, 231 bisulphite anion, 207, 213 Cannizzaro reaction, 216 carbanions, 221-234 Claisen ester condensation, 229 Claisen-Schmidt reaction, 226 conjugate, 200, 213 cyanide ion, 212 Dieckmann reaction, 230 electronic effects in, 205, 208, 226 electrons, 217 Grignard reagents, 221, 235 halide ion, 214 hydration, 207 hydride ion, 214 hydrogen bonding in, 204, 209 in carboxylic derivs., 236-244 intermediates in, 50, 219 intramolecular, 217, 232 irreversible, 215, 222 Knoevenagel reaction, 228 Lewis acids in, 204, 222 Meerwein-Ponndorf reaction, 215 MejSiCN, 213 nitroalkanes, 226 Perkin reaction, 227 pH and, 204, 208, 219 protection, 211... 

The hydrogen bonds in crystalline and liquid ammonia are weaker than those in ice and water for two reasons the small ionic character of the N—H bond gives it only small hydrogen-bond-forming power, and the one unshared electron pair of the NH8 molecule must serve for... 

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