Chlorine perchlorate

Chlorine perchlorate is a chemical compound with the formula Cl2O4. This chlorine oxide is an asymmetric oxide, with one chlorine atom in +1 oxidation state and the other +7, with proper formula ClOClO3. It is produced by the photodimerization of chlorine dioxide (ClO2) at room temperature by 436 nm ultraviolet light:[2][3][4]

2 ClO2 → ClOClO3
Chlorine perchlorate
Names
IUPAC name
Chloro perchlorate[1]
Systematic IUPAC name
Chloro perchlorate[1]
Other names
Chlorine (I,VII) oxide
Dichlorine tetroxide
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/Cl2O4/c1-6-2(3,4)5 ☒N
    Key: JRONPIZRZBBOBR-UHFFFAOYSA-N ☒N
  • ClO[Cl](=O)(=O)=O
Properties
Cl2O4
Molar mass 134.90 g·mol−1
Appearance Pale green liquid
Density 1.81 g·cm−3
Melting point −117 °C (−179 °F; 156 K)
Boiling point 20 °C (68 °F; 293 K) (decomposes)
Reacts
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 oxidizer
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Chlorine perchlorate can also be made by the following reaction at −45 °C.

CsClO4 + ClOSO2F → Cs(SO3)F + ClOClO3

Properties

Chlorine perchlorate is a pale greenish liquid. It is less stable than ClO2 (chlorine dioxide) and decomposes at room temperature to give O2 (oxygen), Cl2 (chlorine) and Cl2O6 (dichlorine hexoxide):

2 ClOClO3 → O2 + Cl2 + Cl2O6

Chlorine perchlorate reacts with metal chlorides to form chlorine and the corresponding anhydrous perchlorate:

CrO2Cl2 + 2 ClOClO3 → 2 Cl2 + CrO2(ClO4)2
TiCl4 + 4 ClOClO3 → 4 Cl2 + Ti(ClO4)4
2 AgCl + 2 ClOClO3 → 2 AgClO4 + Cl2

Reactions
ReactantConditionsProducts
—Heatdichlorine hexoxide (80%), chlorine dioxide, chlorine, oxygen
—Ultraviolet lightdichlorine heptoxide, chlorine, oxygen[4]
caesium iodide−45 °CCs[I(OClO3)4][note 1]
ClOSO2F or ClF—MClO4(M = Cs or NO2)[note 2]
bromine−45 °Cbromine perchlorate (BrOClO3)[note 2]
iodine(0.33 mol)−50 °CI(OClO3)3[note 3][5]

Notes
  1. Cs[I(OClO3)4] is a pale yellow salt which is stable at room temperature. It has a square IO4 unit.
  2. MClO4 (M = Cs or NO2) reacts with BrOSO2F at −20 °C and produces bromine perchlorate (BrOClO3). Bromine perchlorate then reacts with hydrogen bromide (HBr) at −70 °C and produces elemental bromine (Br2) and perchloric acid (HClO4).
  3. So far, all attempts to form iodine perchlorate (IOClO3) have failed, because the iodine atom oxidizes to +3 oxidation state immediately.

References
  1. "Chloro Perchlorate - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information.
  2. A. J. Schell-Sorokin; D. S. Bethune; J. R. Lankard; M. M. T. Loy; P. P. Sorokin (1982). "Chlorine perchlorate a major photolysis product of chlorine dioxide". J. Phys. Chem. 86 (24): 4653–4655. doi:10.1021/j100221a001.
  3. M. I. Lopez; J. E. Sicre (1988). "Ultraviolet spectrum of chlorine perchlorate". J. Phys. Chem. 92 (2): 563–564. doi:10.1021/j100313a062.
  4. Rao, Balaji; Anderson, Todd A.; Redder, Aaron; Jackson, W. Andrew (2010-04-15). "Perchlorate Formation by Ozone Oxidation of Aqueous Chlorine/Oxy-Chlorine Species: Role of ClxOy Radicals". Environmental Science & Technology. 44 (8): 2961–2967. Bibcode:2010EnST...44.2961R. doi:10.1021/es903065f. ISSN 0013-936X. PMID 20345093.
  5. Gomberg, M. (1923-02-01). "The Reaction Between Silver Perchlorate and Iodine. Chlorine Tetra-Oxide". Journal of the American Chemical Society. 45 (2): 398–421. doi:10.1021/ja01655a017. ISSN 0002-7863.
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