Hydrazine Raschig

Hydrazine was isolated first as a sulfate salt by Curtius in 1887. Earlier, in 1875, Fischer prepared and identified the organic derivatives of hydrazine. Raschig in 1906 prepared hydrazine by hypochlorite oxidation of ammonia. 

Raschig process See hydrazine, rasorite See kernite, borax. 

Hydrazine [302-01-2] (diamide), N2H4, a colorless liquid having an ammoniacal odor, is the simplest diamine and unique in its class because of the N—N bond. It was first prepared in 1887 by Curtius as the sulfate salt from diazoacetic ester. Thiele (1893) suggested that the oxidation of ammonia (qv) with hypochlorite should yield hydrazine and in 1906 Raschig demonstrated this process, variations of which constitute the chief commercial methods of manufacture in the 1990s. 

In a variation of the Raschig process for making hydrazine, amines rather than ammonia ate reacted with chloramine to give the corresponding alkyl hydrazine ... 

MMHa.nd UDMH. MonomethyUiydrazine and yyz -dimethylhydrazine are manufactured by Olin Corp. using the same Raschig process and equipment employed for anhydrous hydrazine. Chloramine, prepared as described above, reacts with methylamine or dimethylamine instead of with... 

Urea Process. In a further modification of the fundamental Raschig process, urea (qv) can be used in place of ammonia as the nitrogen source (114—116). This process has been operated commercially. Its principal advantage is low investment because the equipment is relatively simple. For low production levels, this process could be the most economical one. With the rapid growth in hydrazine production and increasing plant size, the urea process has lost importance, although it is reportedly being used, for example, in the People s RepubHc of China (PRC). 

The estimated world production capacity for hydrazine solutions is 44,100 t on a N2H4 basis (Table 6). About 60% is made by the hypochlorite—ketazine process, 25% by the peroxide—ketazine route, and the remainder by the Raschig and urea processes. In addition there is anhydrous hydrazine capacity for propellant appHcations. In the United States, one plant dedicated to fuels production (Olin Corp., Raschig process), has a nominal capacity of 3200 t. This facihty also produces the two other hydrazine fuels, monomethyUiydrazine and unsymmetrical dimethyUiydrazine. Other hydrazine fuels capacity includes AH in the PRC, Japan, and Russia MMH in France and Japan and UDMH in France, Russia, and the PRC. 

The most effective preparative routes to hydrazine are still based on the process introduced by F. Raschig in 1907 this involves the reaction of ammonia with an alkaline solution of sodium hypochlorite in the presence of gelatin or glue. The overall reaction can be written as... 

A final statement on the mechanism of the diaziridine formation cannot yet be made. The obvious formulation [Eq. (36) ] as a reaction of the CN double bond with the imen 39 (with an electron sextet) is almost certainly excluded. The formation of 39 as an intermediate has been jiroposed for the Raschig hydrazine synthesis, but has been disjmted. The following facts are against a diaziridine formation corresjionding to Eq. (36) ... 

In contrast to the Raschig hydrazine synthesis, diaziridine formation occurs in solvents of low polarity such as ether and in the absence of strong bases. An ionization of chloramine and the formation of 39 is thus unlikely. 

Hydrazine is prepared by the Raschig process, the first step of which involves the production of chloramine, NH2C1. The process can be summarized by the equations... 

Bayer ketazine A process for making hydrazine by the reaction of sodium hypochlorite with ammonia in the presence of acetone. Acetone azine is an intermediate. Never commercialized. See also Raschig (1). 

Hydrazine may he produced by several methods. The most common commercial process is the Raschig process, involving partial oxidation of ammonia or urea with hypochlorite. Other oxidizing agents, such as chlorine or hydrogen peroxide may he used instead of hypochlorite. The reaction steps are as follows. 

Hydrazine forms numerous salts and derivatives, some of which are expl or used as ingredients of expls or for their prepn. Several of them are described below Refs 1) V. Meyer M.T. Lecco, ChemBer 16, 2976 (1883) 2)Th.Curtius H. Franzen, ChemBer 35, 323S> (1902) 3) F. Raschig, ZAngewChem 20, 2065-2067 (1907) 4) F. Raschig, ChemZtg 31, 926 (1907) 5) F. 

In the Raschig process (prior to 1924), NaOH, chlorine and ammonia react in aq soln to form dil soln of hydrazine, with Na chloride as a by-product also by oxidation of urea by Na hypochlorite. For its purification can be used fractional distillation, flash distillation or conversion to the slightly sol sulfate, followed by treatment of the latter with coned NaOH soln. 

In the modified Raschig process , used by Bayer A.G. and by Mobay Chem. Co. for large scale production of hydrazine, the intermediacy of an oxaziridine could be clearly evidenced (81MI50800). In this process ammonia and hypochlorite are reacted in the presence of acetone to form ketazine (302). Nitrogen-nitrogen bond formation is faster by a factor of about 1000 in the presence of acetone than in its absence. Thus acetone does not merely trap hydrazine after formation, but participates in the N—N bond forming reaction. Very fast formation of oxaziridine (301), which is isolable, is followed by its likewise fast reaction with ammonia. 

Raschig process -for hydrazine [HYDRAZINE AND ITS DERIVATIVES] (Vol 13) -for hydrazine [HYDRAZINE AND ITS DERIVATIVES] (Vol 13)... 

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