Hydrazine physical properties

Commercial hybrid materials, silicon-based, 73 538—540 Commercial hydrazines, physical properties of, 73 565t Commercial hydrolysis, in vinyl alcohol polymerization, 25 609, 612t Commercial immunoassays, for clinical applications, 74 140 Commercial inks, 74 320 Commercial laundering, detersive systems for, 8 413t... 

The freezing point diagram for the hydrazine—water system (Eig. 1) shows two low melting eutectics and a compound at 64 wt % hydrazine having a melting point of —51.6°C. The latter corresponds to hydrazine hydrate [7803-57-8] which has a 1 1 molar ratio of hydrazine to water. The anomalous behavior of certain physical properties such as viscosity and density at the hydrate composition indicates that the hydrate exists both in the Hquid as well as in the soHd phase. In the vapor phase, hydrazine hydrate partially dissociates. 

Table 1 summarizes some of the physical properties of anhydrous hydrazine, hydrazine hydrate, monomethyUiydrazine, and unsymmetrical dimethyUiydrazine (6—8). A comprehensive review of the physical and thermodynamic properties of the hydrazines is available (9). 

Its physical properties are very similar to those of water for instance, its melting point is f.5°C and its boiling point is 113°C. However, its chemical properties are very different. It is dangerously explosive and is normally stored and used in aqueous solution. Hydrazine is used as a rocket fuel and to eliminate dissolved, corrosive oxygen from the water used in high-pressure, high-temperature steam furnaces ... 

Acetyltransferases catalyze the acetylation of amino, hydroxyl, and thiol functional groups. Acetylation of hydroxy and thiol groups is comparatively rare and of much less importance in alkaloid metabolism than reactions with amino functional groups. The types of amines that are acetylated include arylamines (the major route of metabolism in many species), aliphatic amines, hydrazines, sulfonamides, and the a-amino group of cysteine conjugates. The purification, physical properties, and specificity of the N-acetyltransfereases have been reviewed (116-118). 

Of the many alkyl substituted hydrazines, only two are used as rocket fuels now monomethyl hydrazine (MMH), CH3NHNH2, and unsymmetrical dimethylhydrazine (UDMH), (CH3)2NNH2. (See Hypergolic Fuels in this Vol for combustion properties as rocket fuels). Their physical properties are summarized below... 

The cis-[Pt(PR3 )2Cl2] compounds, where R = alkyl, were converted smoothly to trans-[Pt(PR3 )2HCl] by treating them with hydrazine hydrate in a mixture of ethanol and chloroform. Chloroform must be added since the complexes are insoluble in pure ethanol. The hydride complexes are cream-colored, low-melting, crystalline solids that closely resemble the physical properties of the parent dichloro complexes. 

We can also compare the rate of hydrogen exchange in liquid ammonia and in anhydrous hydrazine, ethylenediamine, and ethanolamine. Some physical properties of these solvents are given below (/jl = dipole moment). 

The preparation of the silylated amines, hydrazines, and hydroxylamines follows conventional synthetic methods established previously for species with fully or partially alkylated silyl groups. The low moleeular masses and the absence of substituent branching lead to new physical properties, however, which make the simple hydrogen-rich molecules attractive for vapour phase technology. 

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. 

Table 16 Physical properties of hydrazine and hydrazine hydrate...

Os(NH3)5(N2)]l2 is air-stable and inert to replacement of N2, except on oxidation. It can be diazotized with HNO2, giving [Os(NH3)4(N2)2]. Other chemical and physical properties have been reported. > > The salt [Os(NH3)e]-I3 appears to be similar to its ruthenium analog but has been investigated only briefly.2,5 [Os(NH3)s(NO)]3+ is reversibly deprotonated to form [Os(NH2)-(NH3)4(NO)]2+, and may be reduced with zinc to [Os(NH3)e] or with hydrazine to [Os(NH3)s(N2)] +. None of the nitrosyls synthesized here is susceptible to nucleophilic attack at the NO+ group. All are diamagnetic, and their other... 

Codeposition of hydrogen during electrolysis often leads to formation of deposits that do not adhere well. These are usually unsatisfactory for analytical purposes. This problem can be resolved by introducing another species that is reduced at a less negative potential than hydrogen ion and does not adversely affect the physical properties of the deposit. One such cathode depolarizer is nitrate ion. Hydrazine and hydroxylamine are also commonly used. 

Very little is known about how hydrazines enter and leave your body. Based on limited studies in animals, hydrazines are probably rapidly absorbed into your blood if you swallow them or if you get them on your skin. Based on their chemical and physical properties, hydrazines are also likely to be well absorbed if you breathe them into your lungs. Once they are in your blood, hydrazines are probably carried to all tissues of your body. Animal studies suggest that soon after you are exposed, the levels of hydrazines in your blood and tissues will fall rapidly. This is because your body changes hydrazines into other compounds called metabolites. Some of these metabolites (or compounds) can react with important molecules in your body and may harm you. Animal studies show that most metabolites and unchanged hydrazines leave your body in urine within 1 day. A small amount can also be found in the air you breathe out. 

CHaCiO + H2N.NH2 = CHaCiN.NHa + H2O The compounds formed, called hydrazoneSj can be hydrolyzed by boiling with a dilute acid. In the identification of aldehydes, the physical properties of the hydrazone prepared from the aldehyde and phenylhydrazine, C6H5HN.NH2, are frequently determined. The reaction in this case is analogous to that with hydrazine —... 

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