Tetrafluorohydrazine

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Tetrafluorohydrazine
Tetrafluorohydrazine-2D.png
Tetrafluorohydrazine-3D-vdW.png
Names
IUPAC name
1,1,2,2-tetrafluorohydrazine
Other names
Tetrafluorohydrazine, perfluorohydrazine, UN 1955
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.091 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/F4N2/c1-5(2)6(3)4 Yes check.svgY
    Key: GFADZIUESKAXAK-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/F4N2/c1
  • InChI=1/F4N2/c1-5(2)6(3)4
    Key: GFADZIUESKAXAK-UHFFFAOYAX
  • FN(F)N(F)F
Properties
N2F4
Molar mass 104.008 g·mol−1
AppearanceColourless 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):
10 mL/kg (rat, intraperitoneal) [2]
  • 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).
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Tetrafluorohydrazine or perfluorohydrazine, N 2 F 4, is a colourless, nonflammable, [2] reactive inorganic gas. It is a fluorinated analog of hydrazine.

Contents

Synthesis

Tetrafluorohydrazine was originally prepared from nitrogen trifluoride using an 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 N2F4fH°) 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. 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]

Related Research Articles

Chlorine trifluoride is an interhalogen compound with the formula ClF3. It is a colorless, poisonous, corrosive, and extremely reactive gas that condenses to a pale-greenish yellow liquid, the form in which it is most often sold. It is famous for its extreme oxidation properties. The compound is primarily of interest in plasmaless cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, historically as a component in rocket fuels, and various other industrial operations owing to its corrosive nature.

<span class="mw-page-title-main">Oxygen difluoride</span> Chemical compound

Oxygen difluoride is a chemical compound with the formula OF2. As predicted by VSEPR theory, the molecule adopts a bent molecular geometry. It is a strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of −144.75 °C, OF2 is the most volatile (isolable) triatomic compound. The compound is one of many known oxygen fluorides.

<span class="mw-page-title-main">Oxygen fluoride</span> Any binary compound of oxygen and fluorine

Oxygen fluorides are compounds of elements oxygen and fluorine with the general formula OnF2, where n = 1 to 6. Many different oxygen fluorides are known:

Dioxygen difluoride is a compound of fluorine and oxygen with the molecular formula O2F2. It can exist as an orange-colored solid which melts into a red liquid at −163 °C (110 K). It is an extremely strong oxidant and decomposes into oxygen and fluorine even at −160 °C (113 K) at a rate of 4% per dayits lifetime at room temperature is thus extremely short. Dioxygen difluoride reacts vigorously with nearly every chemical it encounters (including ordinary ice) leading to its onomatopoeic nickname FOOF (a play on its chemical structure and its explosive tendencies).

<span class="mw-page-title-main">Bromine pentafluoride</span> Chemical compound

Bromine pentafluoride, BrF5, is an interhalogen compound and a fluoride of bromine. It is a strong fluorinating agent.

Nitryl fluoride, NO2F, is a colourless gas and strong oxidizing agent, which is used as a fluorinating agent and has been proposed as an oxidiser in rocket propellants (though never flown).

<span class="mw-page-title-main">Cadmium fluoride</span> Chemical compound

Cadmium fluoride (CdF2) is a mostly water-insoluble source of cadmium used in oxygen-sensitive applications, such as the production of metallic alloys. In extremely low concentrations (ppm), this and other fluoride compounds are used in limited medical treatment protocols. Fluoride compounds also have significant uses in synthetic organic chemistry. The standard enthalpy has been found to be -167.39 kcal. mole−1 and the Gibbs energy of formation has been found to be -155.4 kcal. mole−1, and the heat of sublimation was determined to be 76 kcal. mole−1.

<span class="mw-page-title-main">Xenon difluoride</span> Chemical compound

Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2
, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.

The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.

Nitrogen fluorides are compounds of chemical elements nitrogen and fluorine. Many different nitrogen fluorides are known:

<span class="mw-page-title-main">Krypton difluoride</span> Chemical compound

Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid at room temperature. The structure of the KrF2 molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF+ and Kr
2
F+
3
cations.

Dinitrogen difluoride is a chemical compound with the formula N2F2. It is a gas at room temperature, and was first identified in 1952 as the thermal decomposition product of the fluorine azide. It has the structure F−N=N−F and exists in both cis and trans isomers, as typical for diimides.

Boron monofluoride or fluoroborylene is a chemical compound with the formula BF, one atom of boron and one of fluorine. It is an unstable gas, but it is a stable ligand on transition metals, in the same way as carbon monoxide. It is a subhalide, containing fewer than the normal number of fluorine atoms, compared with boron trifluoride. It can also be called a borylene, as it contains boron with two unshared electrons. BF is isoelectronic with carbon monoxide and dinitrogen; each molecule has 14 electrons.

Nitrogen pentafluoride (NF5) is a theoretical compound of nitrogen and fluorine that is hypothesized to exist based on the existence of the pentafluorides of the atoms below nitrogen in the periodic table, such as phosphorus pentafluoride. Theoretical models of the nitrogen pentafluoride molecule are either a trigonal bipyramidal covalently bound molecule with symmetry group D3h, or NF+
4
F, which would be an ionic solid.

<span class="mw-page-title-main">Nitrogen monofluoride</span> Chemical compound

Nitrogen monofluoride (fluoroimidogen) is a metastable species that has been observed in laser studies. It is isoelectronic with O2. Like boron monofluoride, it is an instance of the rare multiply-bonded fluorine atom. It is unstable with respect to its formal dimer, dinitrogen difluoride, as well as to its elements, nitrogen and fluorine.

Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.

<span class="mw-page-title-main">Nitrogen difluoride</span> Chemical compound

Nitrogen difluoride, also known as difluoroamino, is a reactive radical molecule with formula NF2. This small molecule is in equilibrium with its dimer tetrafluorohydrazine.

Difluoroamino sulfur pentafluoride is a gaseous chemical compound of fluorine, sulfur, and nitrogen. It is unusual in having a hexa-coordinated sulfur atom with a link to nitrogen. Other names for this substance include difluoro(pentafluorosulfur)amine, pentafluorosulfanyldifluoramine, and pentafluorosulfanyl N,N-difluoramine.

Lucia V. Streng was a Russian Empire-born American chemist. She spent much of her career studying the noble gases and their properties, successfully synthesizing krypton difluoride. She and her husband, Alex G. Streng, both held positions at Temple University.

Diphosphorus tetrafluoride is a gaseous compound of phosphorus and fluorine with formula P2F4. Two fluorine atoms are connected to each phosphorus atom, and there is a bond between the two phosphorus atoms. Phosphorus can be considered to have oxidation state +2, as indicated by the name phosphorus difluoride.

References

  1. 1 2 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  2. 1 2 3 4 5 6 7 8 "Tetrafluorohydrazine". pubchem.ncbi.nlm.nih.gov. National Library of Medicine. Retrieved 26 March 2023.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  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.
  6. 1 2 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.
  8. Clark 1972, pp. 167–168.
  9. Tetrafluorohydrazine at DTIC.mil archived March 12, 2007