Hydrazines specials

This method cannot be applied to polynitro amines, since these are so weakly basic that they can be diazotised only under special conditions in strongly acidic solutions. In such cases use may, however, be made of the mobility oonfared upon halogen atoms by the presence of nitro groups in the orlko and para positions. Thus the valuable reagent 2 4-dinitrophenylhydrazine is readily prepared by the condensation of 2 4-dinitrochlorobenzene with hydrazine ... 

Hydrazine in air Lab method using sampling either onto acid-coated glass-fibre filters followed by solvent desorption or into specially constructed impingers. Linal analysis by derivatization and high performance liquid chromatography 86... 

There is nothing particularly special about the product except its feed rate, which is fairly low in comparison to some of the other novel oxygen scavengers. It exhibits passivation characteristics (forming magnetite in a way similar to hydrazine), coupled with good corrosion and iron transport control. 

Plumbanes with particular or bulky substituents can be prepared by several special procedures. For example, tetra-p-nitrophenyllead can be prepared by a disproportionation reaction, induced by hydrazine, of Ar2PbX2, where Ar = p-N(OCgFE, X = Cl, Br, I190 ... 

Kocevar et al. investigated the reactivity of 3-hydrazinopyridazines 386 in the presence of the oxazolone compound 387 <2001H(54)1011 >. In some special cases (mostly when R8 = Me), formation of 388 in high yields was observed, while in other cases an entirely different transformation (formation of a pyrazolone ring as a substituent instead of the hydrazine group) was experienced. 

Hydrazine compounds are widely used as fuels, corrosion inhibitors, catalysts, and dyes. However, such compounds are recognized as toxic agents consequently, their detection and processing are of much concern. Only a few recent papers pertain to the catalytic oxidation of hydrazine [148-150], with special emphasis... 

Chemical Stability of Fuels. Although the principal problem associated with the development of a gelled heterogeneous fuel is the mechanical stabilization of the suspended solids, the solid phase must be chemically compatible with the carrier fuel. The hydrazine-type carriers utilized in these fuels are thermodynamically unstable and decompose to produce gaseous products by mechanisms that are sensitive to catalysts. Special attention must therefore be given to the problem of decomposi-... 

A series of special linkers and cleavage strategies has been developed for the release of amines from insoluble supports (Table 3.23). These include the attachment of amines as triazenes, enamines, aminals, amidines, sulfonamides, sulfinamides, hydrazines, or amides. 

Sometimes, anion radicals are formed indirectly, by means of special chemical reactions. Photoionization of hydrazine in a mixture of liquid ammonia with THF in the presence of potassium l-butoxide leads to the formation of the diazene anion radical by the sequence of the following reactions (Brand et al. 1985) ... 

Dihydropyrimidines 296 react very easily with water, forming 6-oxy derivatives 297 even during storage of 296 in solvents containing water and special catalysts [248]. There are examples of other addition reactions with water [326, 327, 328, 329, 330, 331], alcohols [82, 332], hydrazine and hydroxylamine [333]. 

The only satisfactory method for synthesizing hydrazine was devised by Raschig1 and involves the oxidation of ammonia by sodium hypochlorite in the presence of some such catalyst as glue or gelatin. The purpose of the catalyst is to raise the viscosity of the solution and to inhibit the effect, by adsorption, of traces of metallic ions which cause decomposition of the hydrazine formed.2 It is therefore advisable to use distilled water. Since free chlorine, if present in the hypochlorite solution, oxidizes ammonia to nitrogen, special care must be taken in the preparation of the oxidizing solution. The hypochlorite solution should be distinctly alkaline. %... 

Higginson, W. C. E. The Oxidation of Hydrazine in Aqueous Solution. The Chemical Society, London. Special Publication No. 10, p. 95 (1957). (Recent Aspects of the Inorganic Chemistry of Nitrogen.)... 

The scope aromatic C-N bond formation extends beyond simple amine substrates. For example, selected imines, sulfoximines, hydrazines, lactams, azoles, and carbamates give useful products from intermolecular aromatic C-N bond formation. Intramolecular formation of aryl amides has been reported. In addition, allylamine undergoes arylation, providing a readily cleaved amine alternative to the ammonia surrogates benzylamine, t-butylcarbamate, or benzophenone imine. Although it is an amine substrate, the reaction of this reagent is included here because of its special purpose. 

Under special conditions a number of hydrazine derivatives can be transformed to enlarged ring compounds. A selection of such reactions is collected in Scheme 11/22. 

Hydrazine and alkylhydrazines are important propellants in rocket engines, especially for flight control rockets which are actuated only for short periods of time during space travel. In the presence of special catalysts, hydrazine can be made to decompose within milliseconds -+ also Dimethylhydrazine. 

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