Amines hydrates

Ethyleneamines are soluble in water. However, in concentrated aqueous solutions, amine hydrates may form the reaction is mildly exothermic. The hydrates of linear TETA and PIP melt around 50°C (65,66). 

Although the ethyleneamines ate water soluble, soHd amine hydrates may form at certain concentrations that may plug processing equipment, vent lines, and safety devices. Hydrate formation usually can be avoided by insulating and heat tracing equipment to maintain a temperature of at least 50°C. Water cleanup of ethyleneamine equipment can result in hydrate formation even in areas where routine processing is nonaqueous. Use of warm water can reduce the extent of the problem. 

Amine Guard, 4 813 Amine hydrates, 14 171 Amine oxides, 2 463-476 as cellulose solvents, 11 266 chemical reactions, 2 466-469 commercial, 2 464t economic aspects, 2 471 health and safety factors, 2 472 manufacturing and porcessing, 2 469-471... 

The unusual cavities in Jeffrey s structure VI (4454,43596273) and structure VII (4668) have been observed only for single terf-butylamine guests and hexafluoro-phosphoric acid (HPF6-6H20) guests, respectively. tm-Butylamine, Me3CNH2 (Jeffrey and McMullan, 1967), is unique among amine hydrates since it forms a true clathrate rather than a semiclathrate. 

For hydrates, the question is, to what extent does the nitrogen atom lone pair contribute to hydrogen bonding in amine hydrates Hydrogen bonding is expected to explain the difference between gaseous and solid ammonia couplings. 

Some attempts to observe resonances in other amine hydrates were unsuccessful. 

Such symmetry elements are not possible in crystals of cydodextrins, proteins, and nucleic acids, which all contain asymmetric carbon atoms, and therefore cannot be organized into highly symmetrical three-dimensional patterns. Natural product molecules of this sort crystallize in space groups in which the cyclic hydrogen-bonding motifs are formed without symmetry limitations. In this respect they resemble the lower symmetry amine hydrates described in Part IV, Chapter 21. 

Proton exchange can only occur if the hydrogen bond in the amine hydrate, R3N HOH, breaks before the amine hydrate reacts with hydrox-onium ion. The kinetic parameters k and Q are identified as... 

Alum, ammoniacal, 250 potassic, 201 Aluminium, 300 Amines, hydrates of, 225 Aminosuccinic acid, 294 Ammonia, 156 334. 393, 394 Ammonium, bisulpnide, 340 carbonate, 336 chloride, 200, 262, 269 cyanide, 339 nitrate, 105,175 picrate, 105 racemate, 296 sulphate, 262 tartrate, 296 Analcime, 157 Aniline, 318 Anthra ne, 289... 

Rizzo RC, Jorgensen WL (1999) OPLS All-atom model for amines Resolution of the amine hydration problem. J Am Chem Soc 121 4827-4836... 

The imidoyl chloride (10 mmol) and Et,N (1.01 g, 10 mmol) were dissolved in CH2C12 (50 mL). 1/f-Tetrazol-5-amine hydrate (1 g, 10 mmol) was added, and the solution was stirred at rt for 12 h. The solvent was removed in vacuo and the residue was recrystallized (EtOH). 

Further, following up on Jeffrey s early work on amine hydrates (amine semiclathrates), numerous amines remain to be explored for hydrate phases. In particular, since it has also been observed that some amine clathrates as weU as stoichiometric alcohol hydrates show phase transitions to double clathrate hydrates in the presence of helpgases such as xenon, H2S, and methane, it becomes a worthwhile area for exploration. 

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