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Hydrazine is an inorganic compound with the chemical formula N 2 H 4.It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour.Hydrazine is highly hazardous unless handled in solution as, for example, hydrazine hydrate (N 2 H 4 ·xH 2 O).
Hydrazines (R 2 N−NR 2) are a class of chemical compounds with two nitrogen atoms linked via a covalent bond and which carry from one up to four alkyl or aryl substituents. . Hydrazines can be considered as derivatives of the inorganic hydrazine (H 2 N−NH 2), in which one or more hydrogen atoms have been replaced by hydrocarbon grou
Alkyl hydrazones are 10 2 - to 10 3-fold more sensitive to hydrolysis than analogous oximes. [10] When derived from hydrazine itself, hydrazones condense with a second equivalent of a carbonyl to give azines: [11] R 2 C=N−NH 2 + R 2 C=O → R 2 C=N−N=CR 2 + H 2 O. Hydrazones are intermediates in the Wolff–Kishner reduction.
Ketazines are also important intermediates in the industrial production of hydrazine hydrate by the peroxide process. [3] In the presence of an oxidant, ammonia and ketones react to give hydrazine via ketazine: 2 Me(Et)C=O + 2 NH 3 + H 2 O 2 → Me(Et)C=NN=C(Et)Me + 2 H 2 O. The ketazine can be hydrolyzed to the hydrazine and regenerate the ketone:
Selected parameters: C=N, 128 pm; N-N, 1.38 pm, N-N-C(Ar), 119 [4] When 3-heptanone is added to a solution of 2,4-DNPH and heated, an orange-red precipitate forms. DNP-derived hydrazones have characteristic melting points, facilitating identification of the carbonyl. In particular, the use of DNPH was developed by Brady and Elsmie. [5]
An applied example is a synthesis of sunitinib begins by mixing 5-fluoroisatin slowly into hydrazine hydrate. [9] After 4 hours at 110 °C, the indole ring structure has been broken into (2-amino-5-fluoro-phenyl)-acetic acid hydrazide with reduction of the ketone at the 3-position.
N-Hydroxyphthalimide ethers, on the other hand, are colorless and provide O-alkylhydroxylamines by alkaline hydrolysis or cleavage through hydrazine hydrate. The "phthalylhydroxylamine" reported by Cohn was known to have a molecular formula of C 8 H 5 NO 3, but the exact structure was not known. [4]
A two-step synthesis starts from hydrazine, first by alkylation with ethyl chloroformate, followed by treating the resulting diethyl hydrazodicarboxylate with chlorine (bubbling through the solution), hypochlorous acid, concentrated nitric acid or red fuming nitric acid. The reaction is carried out in an ice bath, and the reagents are added ...