Hydrazine monohydrate is used as a reducing agent. It is also used in water treatment, especially effluents and industrial boilers, metal treatment and mine extraction process, and synthesis of active ingredients in the pharmaceutical industry like 3-amino-1,2,4-triazole cefazolin, rizatriptan, anastrozole, fluconazole, metazachlor metamitron pyrazole, metribuzin, paclobutrazol, diclobutrazole, propiconazole, and triadimefon. It is involved in the preparation of heterocycles like pyrazoles and pyridazines. It is actively involved in the Wolff-Kishner reduction, which converts the carbonyl group of a ketone into a methylene bridge through a hydrazone intermediate. Further, it is used to cleave N-alkylated phthalimide derivatives. In the Einhorn-Brunner reaction, it reacts with imides to get triazoles.
Forms stable, water-free solid complexes consisting of one hydrazine molecule associated with one molecule of hydroquinone or two molecules of 4-methoxyphenol. These have potential as replacements for the very hazardous anhydrous hydrazine, e.g. in the solid state reaction with esters to give pure hydrazides: J. Chem. Soc., Chem. Commun., 1531, (1995).
Diimide precursor: for generation of diimide by oxidation with O2, and use in selective reduction of a double bond in the presence of a cyclopropane ring, see: J. Chem. Soc., Chem. Commun., 525 (1973). Review of diimide reductions: Org. React., 40, 91 (1991). See also Hydroxylamine-O-sulfonic acid, A12560 .
In the Wolff-Kishner carbonyl to methylene reduction (heating with hydrazine and alkali hydroxide), diethylene glycol is now the usual solvent (the Huang Minlon modification): J. Am. Chem. Soc., 68, 2487 (1946); Org. Synth. Coll., 4, 510 (1963). The reduction has also been performed at ambient temperature by the use of KO-t-Bu in DMSO: J. Am. Chem. Soc., 84, 1734 (1962). See also Isatin, A12468 for an analogous reduction.
In the presence of Rh on carbon, nitrobenzene is selectively reduced to phenylhydroxylamine: Org. Synth. Coll., 8, 16 (1993).
For a brief feature on uses of the reagent in synthesis, see: Synlett, 2445 (2004).
Shiraishi, Y.; Hirakawa, H.; Hirai, T. Photocatalytic Hydrogenation of Nitroaromatics to Anilines on Silica-Supported Iron Oxides with Hydrazine Monohydrate as a Reductant. J. Chem. Eng. Jpn. 2015, 48 (2), 141-146.
Sun, J. K.; Xu, Q. Metal Nanoparticles Immobilized on Carbon Nanodots as Highly Active Catalysts for Hydrogen Generation from Hydrazine in Aqueous Solution. Chem. Cat. Chem. 2015, 7 (3), 526-531.
Gefahrenhinweise (EU): H227-H301-H310-H330-H314-H318-H317-H350
Combustible liquid. Toxic if swallowed. Fatal in contact with skin. Fatal if inhaled. Causes severe skin burns and eye damage. Causes serious eye damage. May cause an allergic skin reaction. May cause cancer.
IF SWALLOWED: IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower. IF INHALED: Remove to fresh air and keep at rest in a position comfortable for breathing. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Specific treatment is urgent (see label). Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.