Dichlorine heptoxide

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Dichlorine heptoxide
Dichlorine heptoxide.svg
Dichlorine-heptoxide-3D-balls.png
Names
IUPAC name
Dichlorine heptoxide
Other names
Chlorine(VII) oxide; Perchloric anhydride; (Perchloryloxy)chlorane trioxide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
PubChem CID
UNII
  • InChI=1S/Cl2O7/c3-1(4,5)9-2(6,7)8 Yes check.svgY
    Key: SCDFUIZLRPEIIH-UHFFFAOYSA-N Yes check.svgY
  • InChI=1.001/Cl2O7/c3-1(4,5)9-2(6,7)8
    Key: SCDFUIZLRPEIIH-UHFFFAOYAG
  • O=Cl(=O)(=O)OCl(=O)(=O)=O
Properties
Cl2O7
Molar mass 182.901 g/mol
Appearancecolorless liquid, colorless gas
Density 1.9 g/cm3
Melting point −91.57 °C (−132.83 °F; 181.58 K)
Boiling point 82.07 °C (179.73 °F; 355.22 K)
hydrolyzes to form perchloric acid
Thermochemistry
275.7 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
oxidizer, contact explosive [1]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
3
0
3
OX
Related compounds
Related compounds
 Manganese heptoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Dichlorine heptoxide is the chemical compound with the formula Cl2O7. This chlorine oxide is the anhydride of perchloric acid. It is produced by the careful distillation of perchloric acid in the presence of the dehydrating agent phosphorus pentoxide: [1]

Contents

2 HClO4 + P4O10 → Cl2O7 + H2P4O11

The chlorine(VII) oxide can be distilled off from the mixture.

It may also be formed by illumination of mixtures of chlorine and ozone with blue light. [2] It slowly hydrolyzes back to perchloric acid.

Structure

Cl2O7 is an endergonic molecule, meaning it is intrinsically unstable, decomposing to its constituent elements with release of energy: [3]

2 Cl2O7 → 2 Cl2 + 7 O2 (ΔH° = –132 kcal/mol)

Dichlorine heptoxide is a covalent compound consisting of two ClO3 portions linked by an oxygen atom. It has an overall bent molecular geometry (C2 symmetry), with a Cl−O−Cl angle of 118.6°. The carbon–oxygen bond lengths are 1.709 Å in the central region and 1.405 Å within each ClO3 cluster. [1] In this compound, chlorine exists in its highest formal oxidation state of +7.

Chemistry

Dichlorine heptoxide reacts with primary and secondary amines in carbon tetrachloride solution to yield perchloric amides: [4]

2 RNH
2 + Cl
2O
7 → 2 RNHClO
3 + H
2O
2 R
2NH + Cl
2O
7 → 2 R
2NClO
3 + H
2O

It also reacts with alkenes to give alkyl perchlorates. For example, it reacts with propene in carbon tetrachloride solution to yield isopropyl perchlorate and 1-chloro-2-propyl perchlorate. [5]

Dichlorine heptoxide reacts with alcohols to form alkyl perchlorates. [6]

Dichlorine heptoxide is a strongly acidic oxide, and in solution it forms an equilibrium with perchloric acid.

Safety

Although it is the most stable chlorine oxide, Cl2O7 is a strong oxidizer as well as an explosive that can be set off with flame or mechanical shock, or by contact with iodine. [7] Nevertheless, it is less strongly oxidising than the other chlorine oxides, and does not attack sulfur, phosphorus, or paper when cold. [1] It has the same effects on the human body as elemental chlorine, and requires the same precautions. [8]

Related Research Articles

<span class="mw-page-title-main">Chlorine</span> Chemical element, symbol Cl and atomic number 17

Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.

<span class="mw-page-title-main">Perchloric acid</span> Chemical compound

Perchloric acid is a mineral acid with the formula HClO4. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid, nitric acid and hydrochloric acid. It is a powerful oxidizer when hot, but aqueous solutions up to approximately 70% by weight at room temperature are generally safe, only showing strong acid features and no oxidizing properties. Perchloric acid is useful for preparing perchlorate salts, especially ammonium perchlorate, an important rocket fuel component. Perchloric acid is dangerously corrosive and readily forms potentially explosive mixtures.

An acidic oxide is an oxide that either produces an acidic solution upon addition to water, or acts as an acceptor of hydroxide ions effectively functioning as a Lewis acid. Acidic oxides will typically have a low pKa and may be inorganic or organic. A commonly encountered acidic oxide, carbon dioxide produces an acidic solution when dissolved.

<span class="mw-page-title-main">Chlorine oxide</span> Index of chemical compounds with the same name

Chlorine and oxygen can bond in many ways:

<span class="mw-page-title-main">Sodium perchlorate</span> Chemical compound

Sodium perchlorate is an inorganic compound with the chemical formula NaClO4. It consists of sodium cations Na+ and perchlorate anions ClO−4. It is a white crystalline, hygroscopic solid that is highly soluble in water and ethanol. It is usually encountered as sodium perchlorate monohydrate NaClO4·H2O. The compound is noteworthy as the most water-soluble of the common perchlorate salts.

An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.

<span class="mw-page-title-main">Manganese heptoxide</span> Chemical compound

Manganese(VII) oxide (manganese heptoxide) is an inorganic compound with the formula Mn2O7. Manganese heptoxide is a volatile liquid with an oily consistency. It is a highly reactive and powerful oxidizer that reacts explosively with nearly any organic compound. It was first described in 1860. It is the acid anhydride of permanganic acid.

<span class="mw-page-title-main">Fluorine perchlorate</span> Chemical compound

Fluorine perchlorate, also called perchloryl hypofluorite is the rarely encountered chemical compound of fluorine, chlorine, and oxygen with the chemical formula ClO
4F or FOClO
3. It is an extremely unstable gas that explodes spontaneously and has a penetrating odor.

<span class="mw-page-title-main">Dichlorine hexoxide</span> Chemical compound

Dichlorine hexoxide is the chemical compound with the molecular formula Cl
2O
6, which is correct for its gaseous state. However, in liquid or solid form, this chlorine oxide ionizes into the dark red ionic compound chloryl perchlorate [ClO
2]+
[ClO
4]−
, which may be thought of as the mixed anhydride of chloric and perchloric acids.

<span class="mw-page-title-main">Chlorine perchlorate</span> Chemical compound

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:

Chlorine tetroxide is an unstable chlorine oxide with the chemical formula ClO4.

Perchloratoborate is an anion of the form [B(ClO4)4]−. It can form partly stable solid salts with heavy alkali metals. They are more stable than nitratoborate salts. K[B(ClO4)4] decomposes at 35 °C, Rb[B(ClO4)4] is stable to 50 °C, and Cs[B(ClO4)4] can exist up to 80 °C.

<span class="mw-page-title-main">Titanium perchlorate</span> Chemical compound

Titanium perchlorate is a molecular compound of titanium and perchlorate groups with formula Ti(ClO4)4. Anhydrous titanium perchlorate decomposes explosively at 130 °C and melts at 85 °C with a slight decomposition. It can sublime in a vacuum as low as 70 °C, and can form vapour at up to 120°. Titanium perchlorate is quite volatile. It has density 2.35. It decomposes to TiO2, ClO2 and dioxygen O2 Also TiO(ClO4)2 is formed during decomposition.

<span class="mw-page-title-main">Vanadyl perchlorate</span> Chemical compound

Vanadyl perchlorate or vanadyl triperchlorate is a golden yellow coloured liquid or crystalline compound of vanadium, oxygen and perchlorate group. The substance consists of molecules covalently bound and is quite volatile; it ignites organic solvents on contact and explodes at temperatures above 80 °C.

Zirconium perchlorate is a molecular substance containing zirconium and perchlorate groups with formula Zr(ClO4)4. Zr(ClO4)4 is a volatile crystalline product. It can be formed by reacting zirconium tetrachloride with dry perchloric acid at liquid nitrogen temperatures. Zr(ClO4)4 sublimes slowly in a vacuum at 70°C showing that the molecule is covalently bound rather than being ionic. The reaction also forms some zirconyl perchlorate (or zirconium oxyperchlorate) ZrO(ClO4)2 as even apparently pure perchloric acid is in equilibrium with dichlorine heptoxide, hydronium ions and perchlorate ions. This side product can be minimised by adding more dichlorine heptoxide or doing the reaction as cold as possible.

Silver hyponitrite is an ionic compound with formula Ag2N2O2 or (Ag+
)2[ON=NO]2−, containing monovalent silver cations and hyponitrite anions. It is a bright canary yellow solid practically insoluble in water and most organic solvents, including DMF and DMSO.

<span class="mw-page-title-main">Acetyl hypochlorite</span> Chemical compound

Acetyl hypochlorite, also known as chlorine acetate, is a chemical compound with the formula CH3COOCl. It is a photosensitive colorless liquid that is a short lived intermediate in the Hunsdiecker reaction.

<span class="mw-page-title-main">Lead(II) perchlorate</span> Chemical compound

Lead(II) perchlorate is a chemical compound with the formula Pb(ClO4)2·xH2O, where is x is 0,1, or 3. It is an extremely hygroscopic white solid that is very soluble in water.

<span class="mw-page-title-main">Nitrosyl perchlorate</span> Chemical compound

Nitrosyl perchlorate is the inorganic compound with the formula NO(ClO4). A hygroscopic white solid, it is the salt of the nitrosonium cation with the perchlorate anion. It is an oxidant and strong electrophile, but has fallen out of use with the availability of the closely related salt nitrosonium tetrafluoroborate NO(BF4).

Niobium perchlorate is a chemical compound with the formula Nb(ClO4)5. It is a hygroscopic, white crystalline solid that readily reacts with moist air or water to produce niobium(V) oxide.

References

  1. 1 2 3 4 Holleman, Arnold F.; Wiberg, Egon (2001). Inorganic chemistry. Translated by Mary Eagleson; William Brewer. San Diego: Academic Press. p. 464. ISBN   0-12-352651-5.
  2. ↑ Byrns, A. C.; Rollefson, G. K. (1934). "The Formation of Chlorine Heptoxide on Illumination of Mixtures of Chlorine and Ozone". Journal of the American Chemical Society. 56 (5): 1250–1251. doi:10.1021/ja01320a506.
  3. ↑ Martin, Jan M. L (2006-10-12). "Heats of formation of perchloric acid, HClO4, and perchloric anhydride, Cl2O7. Probing the limits of W1 and W2 theory". Journal of Molecular Structure: THEOCHEM. Modelling Structure and Reactivity: the 7th triennial conference of the World Association of Theoritical and Computational Chemists (WATOC 2005). 771 (1): 19–26. arXiv: physics/0508076 . doi:10.1016/j.theochem.2006.03.035. ISSN   0166-1280. S2CID   98385268.
  4. ↑ Beard, C. D.; Baum, K. (1974). "Reactions of dichlorine heptoxide with amines". Journal of the American Chemical Society. 96 (10): 3237–3239. doi:10.1021/ja00817a034.
  5. ↑ Baum, K. . (1976). "Reactions of dichlorine heptoxide with olefins". The Journal of Organic Chemistry. 41 (9): 1663–1665. doi:10.1021/jo00871a048.
  6. ↑ Baum, Kurt; Beard, Charles D. (1974-05-01). "Reactions of dichlorine heptoxide with alcohols". Journal of the American Chemical Society. 96 (10): 3233–3237. doi:10.1021/ja00817a033. ISSN   0002-7863.
  7. ↑ Lewis, Robert Alan (1998). Lewis' dictionary of toxicology . CRC Press. p.  260. ISBN   1-56670-223-2.
  8. ↑ Jeanne Mager Stellman, ed. (1998). "Halogens and their compounds". Encyclopaedia of occupational health and safety (4th ed.). International Labour Organization. p.  104.210. ISBN   92-2-109817-6.
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