Dichlorine heptoxide is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

Cl₂O₇. This chlorine oxide is the anhydride of

perchloric acid Perchloric acid is a mineral acid with the formula H Cl O4. 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 sol ...

. It is produced by the careful distillation of perchloric acid in the presence of the dehydrating agent phosphorus pentoxide: :2 HClO₄ + P₄O₁₀ → Cl₂O₇ + H₂P₄O₁₁ The chlorine(VII) oxide can be distilled off from the mixture. It may also be formed by illumination on mixtures of chlorine and

ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...

. It slowly

hydrolyzes Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

back to

Structure

Cl₂O₇ is an endergonic molecule, meaning it is intrinsically unstable, decomposing to its constituent elements with release of energy: :2 Cl₂O₇ → 2 Cl₂ + 7 O₂ (Δ''H°'' = –132 kcal/mol) Cl₂O₇ is bent with Cl−O−Cl angle of 118.6° giving the molecule C₂

symmetry Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

. The terminal Cl−O distances are 1.709 Å and the Cl=O distances are 1.405 Å. In this compound, chlorine exists in its highest formal

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of +7, although the bonding in this molecule is significantly covalent.

Chemistry

Dichlorine heptoxide reacts with primary and secondary

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...

s in

carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also IUPAC nomenclature of inorganic chemistry, recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVAC ...

solution to yield perchloric amides: :2 + → 2 + :2 + → 2 + It also reacts with

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s to give alkyl perchlorates. For example, it reacts with

propene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petrole ...

in carbon tetrachloride solution to yield isopropyl perchlorate and 1-chloro-2-propyl perchlorate. Dichlorine heptoxide reacts with

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

s to form alkyl perchlorates. 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 Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

. Nevertheless, it is less strongly oxidising than the other chlorine oxides, and does not attack

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

, or

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...

when cold. It has the same effects on the human body as elemental

chlorine Chlorine is a chemical element with the Symbol (chemistry), 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 betwee ...

, and requires the same precautions.

References

{{oxygen compounds Chlorine oxides Oxidizing agents Acid anhydrides Acidic oxides Chlorine(VII) compounds