Hydrazines hydrogen bonding

In liquid hydrazine, hydrogen bonding occurs between the hydrazine molecules similar to the hydrogen bonding in liquid water. In solid hydrazine, the hydrogen bonds have NH-N distances between 319 and 367 pm. In hydrazine hydrate, each hydrazine molecule is linked via six hydrogen bonds to surrounding water molecules so that the hydrazine molecules are separated from each other by water molecules. Some physical properties of hydrazine and hydrazine hydrate are shown in Table 16. 

Factor b above is discussed in Sections II, B, 1 II, B, 4 and II, C. A hydrogen-bonded structure such as 221 can account for the facile reaction of 5-bromouracil or for the unique, so-called hydrolyzability of carboxymethylthio-azines (237). The latter may also react via the intramolecular mechanism indicated in 136. The hydrogen-bonded transition state 238 seems a reasonable explanation of the fact that 3,4,6- and 3,4,5-trichloropyridazines react with glacial acetic acid selectively to give 3-pyridazinones while other nucleophiles (alkoxides, hydrazine, ammonia, or sulfanilamide anion) react at the 4- and 5-positions. In this connection, 4-amino-3,5-dichloro-pyridazine in liquid hydrazine gives (95°, 3hr, 60%yield)the isomer-... 

Reality Check In acetic acid, the H atom bonded to oxygen in one molecule forms a hydrogen bond with an oxygen in an adjacent molecule. The same situation applies in hydrazine if you substitute nitrogen for oxygen. 

When hot, ammonia and compounds, which contain nitrogen-hydrogen bonds eg ammonium salts and cyanides react violently with chlorates and alkaline perchlorates. Diammonlum sulphate, ammonium chloride, hydroxyl-amine, hydrazine, sodamide, sodium cyanide and ammonium thiocyanate have been cited. So far as hydrazine is concerned, the danger comes from the formation of a complex with sodium or lithium perchlorate, which is explosive when ground. Many of these interactions are explosive but the factors which determine the seriousness of the accident are not known. 

With the compounds that contain nitrogen-hydrogen bonds there are highly reactive or unstable metal compounds formed. Thus with hydrazine ... 

The polarity of hydrazine (34.0 g/mol) might explain its high boiling point. But HC1 (36.5 g/mol) also is polar, and it is a gas at room temperature. The distinction between the two substances is that hydrazine can form strong hydrogen bonds, while HC1 cannot. This... 

Scheme 6.13 Mechanistic proposal for the catalytic effect of hydrogen-bonding thiourea 9 and the product formation resulting from an equilibrium between the hydrazone and its nucleophilic ene-hydrazine form.

Most linear ceilulosics may be dissolved in solvents capable of breaking the strong hydrogen bonds. These solvents include aqueous solutions of inorganic acids, zinc chloride, lithium chloride, dimethyl dibenzyl ammonium hydroxide, and cadmium or copper ammonia hydroxide (Schweizer s reagent). Cellulose is also soluble in hydrazine, dimethyl sulfoxide in the presence of formaldehyde, and dimethylformamide in the presence of lithium chloride. The product precipitated by the addition of nonsolvents to these solutions is highly amorphous and is called regenerated cellulose. 

Even though ammonia, hydrazine, and hydrazoic acid have nitrogen-hydrogen bonds, their photochemistry is very different. In hydrazoic acid the photochemistry is dominated by the weak HN-N bond while in ammonia and hydrazine the fragmentation of the N-H bond appears to be the most important process. 

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