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1,1-Dimethylhydrazine, frequently called unsymmetrical dimethylhydrazine (UDMH), is the third member of the hydrazine family to appear in Molecule of the Week. The first two were the parent molecule hydrazine in 2010 and methylhydrazine earlier this year. All these highly toxic hydrazines are used in rocket fuels.
Australian chemist Henry H. Hatt reported a synthesis of the hydrochloride salt1 of UDMH in the 1936 edition of Organic Syntheses. Hatt treated dimethylamine with nitric acid to produce the N-nitroso derivative, which was then reduced with zinc to form UDMH, isolated as the salt. Hatt later made UDMH by treating dimethylamine with chloramine; this is one of two current industrial production processes. In the other, acetylhydrazine is treated with formaldehyde and hydrogen to form a dimethyl derivative, which is then hydrolyzed to produce UDMH.
UDMH is a hypergolic rocket fuel, which means that it ignites when it is mixed with another component of the fuel. The second component is usually dinitrogen tetroxide. UDMH is generally preferred to hydrazine in rocket fuels because it autoignites at a higher temperature and is thus more stable in storage.
1. CAS Reg. No. 593-82-8.
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