Tetrafluorohydrazine

Tetrafluorohydrazine

Names
IUPAC name 1,1,2,2-tetrafluorohydrazine
Other names Tetrafluorohydrazine, perfluorohydrazine, UN 1955
Identifiers
CAS Number	10036-47-2 N
3D model (JSmol)	Interactive image
ChemSpider	23228 Y
ECHA InfoCard	100.030.091
PubChem CID	24845
UNII	RR3J2QP9MG Y
CompTox Dashboard (EPA)	DTXSID9064922
InChI InChI=1S/F4N2/c1-5(2)6(3)4 Y Key: GFADZIUESKAXAK-UHFFFAOYSA-N Y InChI=1/F4N2/c1 InChI=1/F4N2/c1-5(2)6(3)4 Key: GFADZIUESKAXAK-UHFFFAOYAX
SMILES FN(F)N(F)F
Properties
Chemical formula	N2F4
Molar mass	104.008 g·mol−1
Appearance	Colourless gas
Melting point	−164.5 °C (−264.1 °F; 108.6 K)[1]
Boiling point	−73 °C (−99 °F; 200 K)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Explosion
Lethal dose or concentration (LD, LC):
LD50 (median dose)	10 mL/kg (rat, intraperitoneal)[2]
LC50 (median concentration)	440 mg/m3 (mouse, inhalation) 900 ppm/1H (guinea pig, inhalation) [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Tetrafluorohydrazine or perfluorohydrazine, N₂F₄, is a colourless, nonflammable,^[2] reactive inorganic gas. It is a fluorinated analog of hydrazine.

Synthesis

Tetrafluorohydrazine is manufactured from nitrogen trifluoride using an iron catalyst or iron(II) fluoride.^{[citation needed]}

Alternate procedures include the reduction of nitrogen trifluoride with hot arsenic, or oxygen-fluorine exchange between nitrogen trifluoride and nitric oxide.^[3]

Properties

Tetrafluorohydrazine is in equilibrium with its radical monomer nitrogen difluoride.^[4]

N₂F₄ ⇌ 2 •NF₂

At room temperature N₂F₄ is mostly associated with only 0.7% in the form of NF₂ at 5mm Hg pressure. When the temperature rises to 225 °C, it mostly dissociates with 99% in the form of NF₂.^[5]

The energy needed to break the N−N bond in N₂F₄ is 20.8 kcal/mol, with an entropy change of 38.6 eu.^[5] For comparison, the dissociation energy of the N−N bond is 14.6 kcal/mol (61 kJ/mol) in N₂O₄, 10.2 kcal/mol (43 kJ/mol) in N₂O₂, and 60 kcal/mol (250 kJ/mol) in N₂H₄. The enthalpy of formation of N₂F₄ (Δ_fH°) is 34.421 kJ/mol.^[6]

Uses

Tetrafluorohydrazine is used in organic synthesis and some rocket propellant formulations.^[2] It adds across double bonds to give vicinal di(difluoroamine)s.^[7] In chemical syntheses, as a precursor or a catalyst. It was considered for use as a high-energy liquid oxidizer in some never-flown rocket fuel formulas in 1959.^[8]

Safety

Tetrafluorohydrazine is a highly hazardous chemical that explodes in the presence of organic materials.^[2]

It is a toxic chemical which irritates skin, eyes and lungs. It is a neurotoxin and may cause methemoglobinemia. May be fatal if inhaled or absorbed through skin. Vapors may be irritating and corrosive. It is a strong oxidizing agent. Contact with this chemical may cause burns and severe injury. Fire produces irritating, corrosive and toxic gases. Vapors from liquefied gas are initially heavier than air and spread across the ground.^[2]

Tetrafluorohydrazine explodes or ignites on contact with reducing agents at room temperature, including hydrogen, hydrocarbons, alcohols, thiols, amines, ammonia, hydrazines, dicyanogen, nitroalkanes, alkylberylliums, silanes, boranes or powdered metals. Prolonged exposure of the container of tetrafluorohydrazine to high heat may cause it to rupture violently and rocket. Tetrafluorohydrazine itself can explode at high temperatures or with shock or blast when under pressure. When heated to decomposition in air, it emits highly toxic fumes of fluorine and oxides of nitrogen.^[2]

There is a fatal case in which during opening of valves to check the pressure, the cylinder exploded, killing one man and injuring another.^[2]

References