Hydrazine

Hydrazine is an inorganic compound with the chemical formula H
2NNH
2 (also written N
2H
4). It is a colorless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. As of 2000, approximately 120,000 tons of hydrazine hydrate (corresponding to a 64% solution of hydrazine in water by weight) were manufactured worldwide per year. Hydrazine is mainly used as a foaming agent in preparing polymer foams, but significant applications also include its uses as a precursor to polymerization catalysts and pharmaceuticals. Additionally, hydrazine is used in various rocket fuels and to prepare the gas precursors used in air bags. Hydrazine is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion.

Molecular structure

Each H₂N-N subunit is pyramidal in shape. The N-N single bond distance is 1.45 Å (145 pm), and the molecule adopts a gauche conformation. The rotational barrier is twice that of ethane. These structural properties resemble those of gaseous hydrogen peroxide, which adopts a "skewed" anticlinal conformation, and also experiences a strong rotational barrier.

Hydrazine (antidepressant)

The hydrazine antidepressants are a group of non-selective, irreversible monoamine oxidase inhibitors (MAOIs) which were discovered and initially marketed in the 1950s and 1960s. Most have been withdrawn due to toxicity, namely hepatotoxicity, but a few still remain in clinical use.

Tranylcypromine, a structurally unrelated MAOI introduced around the same time as the hydrazines, was originally advertised as non-hydrazine as a result of its diminished propensity for causing hepatotoxicity.

List of hydrazine antidepressants

Marketed

Legend: ^‡ = Withdrawn from the market; ^† = Partially discontinued; Bolded names indicate major drugs.

Never marketed