Unsymmetrical dimethylhydrazine

The determination of organic compounds by their direct catalytic effect on indicator reaction rates is a relatively unexplored ai ea promising valuable analytical chai acteristics, as we have recently shown in the determination of traces of unsymmetrical dimethylhydrazine (UDMH) by the oxidation of 3,3, 5,5 -tetramethylbenzidine (TMB) by atmospheric oxygen initiated with persulfate [1]. 

Until recently the atmospheric chemistry of nitrogen-containing compounds such as the hydrazines, which are widely used as fuels in military and space vehicles, has received comparatively little attention. N,N-dimethyIhydrazine (also UDMH = unsymmetrical dimethylhydrazine) is used in liquid-fueled rockets, and thus there Is a possibility that its use, storage, and handling could result in its release in the atmosphere. 

Hydrazine, methylhydrazine, and unsymmetrical dimethylhydrazine, (CH3)2N-NH2, have been used as rocket fuels that are oxidized by liquid N204. The structure of the hydrazine molecule (//, = 1.75 D) can be shown as... 

Species Hydrazine (ppm) Monomethylhydrazine (ppm) Symmetrical dimethylhydrazine (ppm) Unsymmetrical dimethylhydrazine (ppm)... 

Dost, F.N., D.J.Reed, and C.H.Wang. 1966. The metabolic fate of monomethylhydrazine and unsymmetrical dimethylhydrazine. Biochem. Pharmacol. 15 1325- 1332. 

House, W.B. 1964. Tolerance criteria for continuous exposure inhalation exposure to toxic materials. III. Effects on animals of 90-d exposure to hydrazine, unsymmetrical dimethylhydrazine (UMDH), decaborane, and nitrogen dioxide. ASD-TR-61-519 (iii). Wright-Patterson AFB, OH. 84 pp. 

MacEwen, J.D., and E.H.Vemot. 1975. Acute inhalation toxicity of hydrazine, monomethylhydrazine and unsymmetrical dimethylhydrazine in golden Syrian hamsters. Toxic Hazards Research Unit Annual Report. AMRL-TR-75-57. Aerospace Medical Research Laboratory, Wright-Patterson AFB, OH. 

Shook, B.S., Sr., and O.H.Cowart. 1957. Health hazards associated with unsymmetrical dimethylhydrazine. Ind. Med Surg. 26 333-336. 

Dimethylhydrazine, N,N Unsymmetrical Dimethylhydrazine Hydrazine Derivatives Methylhydrazine Monomethylhydrazine Iodine... 

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... 

A recent publication [71] suggests mixtures of oxygen difluoride as an oxidizer. This substance can give an 7S as high as ca. 400 sec when mixed with hydrogen. The mixture of oxygen difluoride and unsymmetrical dimethylhydrazine has a theoretical specific impulse of ca. 330 sec. 

They remain liquid under normal, ambient operating conditions (moderate temperature, atmospheric pressure). Safety in storage and handling should also be considered. A storable liquid propellant should not have an excessively high vapour pressure at ambient temperature. The leading storable propellant uses dinitrogen tetroxide as oxidizer and a 50/50 mixture of hydrazine-unsymmetrical dimethylhydrazine (UDMH) as fuel [71], Nitrogen tetroxide and UDMH is another storable propellant mixture in use [73],... 

Storable. Together with liquid hydrocarbons, hydrazine-type fuels are the most important storable liquid propellants. They include hydrazine (N2H4), MMH, unsymmetrical dimethylhydrazine (UDMH), Aerozine-50 (50% N2H4 and 50% UDMH), and various blends of these fuels with other amine-based components. All hydrazine-type fuels are toxic to some degree, as are their breakdown products in the environment (especially, as in the case of dilute UDMH with nitrates and nitrites, forming carcinogenic and highly water soluble nitrosodimethylamine, or NDMA). The most notable hydrocarbon storable fuels include kerosene-based liquid propellants (RP-1, JP-8, and others). 

HAN, ADN, AN, HNF, HTP Monopropellants (and oxidizer) Alphabet Soup Studies of hydrazine-family replacements, in this context including hydrazine, methylhydrazine, and unsymmetrical dimethylhydrazine, are increasingly justified based on decreasing toxic limit exposures and associated higher cost for storage and deployments of these... 

Fig. 37.23. A four-sequence 1960s demonstration of liquid Aerozine 50 fuel (50 50 hydrazine unsymmetrical dimethylhydrazine) eyedropper quantities falling onto nitrogen tetroxide liquid oxidizer. Reaction is not dramatic in this testing, but is almost explosively violent when combined in typical liquid rocket engine combustion chambers. 

Trimethylamlne methacrylamide copolymerises well with most standard monomers. The extensive technical literature of the Ashland Co., including patent specifications, gives fiarther details of applications of these conpounds, which should have an interesting future. Unfortunately it is understood (1975) that there has been a setback in commercialisation due to restrictions in the supply of unsymmetrical dimethylhydrazine, a key raw... 

The preparation of unsymmetrical dimethylhydrazine by reduction of nitrosodimethylamine was described by Fischer and by Renouf It has also been prepared by methylation of hydrazine, by reduction of nitrodimethylamine, and by the action of aminopersulfuric acid on dimethylamine. ... 

Finally, we note that propellants for rockets and the like are often explosive mixtures of liquids 100% hydrogen peroxide (H2O2), liquid oxygen, and even liquid fluorine have been used as oxidants in rockets for light substances such as hydrazine (N2H4) or unsymmetrical dimethylhydrazine [(CH3)2N—NH2], while torpedoes and submarines have been powered with diesel fuel oxidized by hydrogen peroxide. Indeed, had the fast Walter H2 02-turbine U-boats come into service earlier than December 1944, the Second World War might have taken a rather different turn. 

Haun CC, Kinkead ER, Vemot EH, et al. 1984. Chronic inhalation toxicity of unsymmetrical dimethylhydrazine Oncogenic effects. AFAMRL-TR-85-020. 

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