Tetrafluorohydrazine

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

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

Synthesis

Tetrafluorohydrazine was originally prepared from nitrogen trifluoride using a copper as a fluorine atom acceptor:^[3]

2NF₃ + Cu → N₂F₄ + CuF₂

A number of F-atom acceptors can be used, including carbon, other metals, and nitric oxide. These reactions exploit the relatively weak N-F bond in NF₃.^[4]

Properties

Tetrafluorohydrazine is in equilibrium with its radical monomer nitrogen difluoride.^[5]

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.^[6]

The energy needed to break the N−N bond in N₂F₄ is 20.8 kcal/mol, with an entropy change of 38.6 eu.^[6] 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.^[7]

Uses

Tetrafluorohydrazine is used in organic synthesis and some rocket propellant formulations.^[2] It adds across double bonds to give vicinal di(difluoroamine)s.^[8] 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.^[9]

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. It 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

^ ^a ^b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ ^a ^b ^c ^d ^e ^f ^g ^h "Tetrafluorohydrazine". pubchem.ncbi.nlm.nih.gov. National Library of Medicine. Retrieved 26 March 2023. This article incorporates text from this source, which is in the public domain.
^ Ruff, John K. (1967). "Derivatives of Nitrogen Fluorides". Chemical Reviews. 67 (6): 665–680. doi:10.1021/cr60250a004.
^ Clark, John Drury (1972). Ignition!. New Brunswick, NJ: Rutgers UP. p. 82. ISBN 0-8135-0725-1. LCCN 72-185390.
^ Jäger, Susanne; von Jouanne, Jörn; Keller-Rudek, Hannelore; Koschel, Dieter; Kuhn, Peter; Merlet, Peter; Rupecht, Sigrid; Vanecek, Hans; Wagner, Joachim (1986). Koschel, Dieter; Kuhn, Peter; Merlet, Peter; Ruprecht, Sigrid; Wagner, Joachim (eds.). F Fluorine: Compounds with Oxygen and Nitrogen. Gmelin Handbook of Inorganic Chemistry. Vol. 4. Berlin: Springer. p. 162. doi:10.1007/978-3-662-06339-2. ISBN 978-3-662-06341-5. Retrieved 29 August 2015.
^ ^a ^b Bohn, Robert K.; Bauer, Simon Harvey (February 1967). "An electron diffraction study of the structures of NF₂ and N₂F₄". Inorganic Chemistry. 6 (2): 304–309. doi:10.1021/ic50048a024. molecule dimensions and angles
^ "Nitrogen difluoride NF₂(g)". www.chem.msu.su.
^ Clark 1972, pp. 167–168.
^ Tetrafluorohydrazine at DTIC.mil archived March 12, 2007

[Greenwood&Earnshaw-1] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[pubchem-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h "Tetrafluorohydrazine". pubchem.ncbi.nlm.nih.gov. National Library of Medicine. Retrieved 26 March 2023. This article incorporates text from this source, which is in the public domain.

[Ruff-3] Ruff, John K. (1967). "Derivatives of Nitrogen Fluorides". Chemical Reviews. 67 (6): 665–680. doi:10.1021/cr60250a004.

[4] Clark, John Drury (1972). Ignition!. New Brunswick, NJ: Rutgers UP. p. 82. ISBN 0-8135-0725-1. LCCN 72-185390.

[5] Jäger, Susanne; von Jouanne, Jörn; Keller-Rudek, Hannelore; Koschel, Dieter; Kuhn, Peter; Merlet, Peter; Rupecht, Sigrid; Vanecek, Hans; Wagner, Joachim (1986). Koschel, Dieter; Kuhn, Peter; Merlet, Peter; Ruprecht, Sigrid; Wagner, Joachim (eds.). F Fluorine: Compounds with Oxygen and Nitrogen. Gmelin Handbook of Inorganic Chemistry. Vol. 4. Berlin: Springer. p. 162. doi:10.1007/978-3-662-06339-2. ISBN 978-3-662-06341-5. Retrieved 29 August 2015.

[bohn67-6] Bohn, Robert K.; Bauer, Simon Harvey (February 1967). "An electron diffraction study of the structures of NF₂ and N₂F₄". Inorganic Chemistry. 6 (2): 304–309. doi:10.1021/ic50048a024. molecule dimensions and angles

[7] "Nitrogen difluoride NF₂(g)". www.chem.msu.su.

[FOOTNOTEClark1972167–168-8] Clark 1972, pp. 167–168.

[9] Tetrafluorohydrazine at DTIC.mil archived March 12, 2007

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