Dichlorine heptoxide

Dichlorine heptoxide

Names
IUPAC name Dichlorine heptoxide
Other names Chlorine heptoxide Chlorine(VII) oxide Perchloric anhydride (Perchloryloxy)chlorane trioxide
Identifiers
Jmol-3D images	Image
SMILES O=Cl(=O)(=O)OCl(=O)(=O)=O
Properties
Chemical formula	Cl2O7
Molar mass	182.901 g/mol
Appearance	Colorless liquid
Odor	Odorless
Density	1.811 g/cm3 (20 °C)
Melting point	−91.57 °C (−132.83 °F; 181.58 K)
Boiling point	82 °C (180 °F; 355 K)
Solubility in water	Hydrolyzes to form perchloric acid
Solubility	Reacts with organic solvents Miscible with carbon tetrachloride Soluble in benzene, phosphoryl chloride
Vapor pressure	72 mmHg (20 °C)
Thermochemistry
Std enthalpy of formation (ΔfHo298)	251 kJ/mol
Hazards
Safety data sheet	None
Flash point	Non-flammable
Related compounds
Related compounds	Chlorine dioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dichlorine heptoxide is a chemical compound, a clear, oily liquid. It is a strong oxidizing agent. The compound has the chemical formula Cl₂O₇.

Properties

Chemical

Dichlorine heptoxide reacts exothermically with water to yield perchloric acid.

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

2 RNH₂ + Cl₂O₇ → 2 RNHClO₃ + H₂O

2 R₂NH + Cl₂O₇ → 2 R₂NClO₃ + H₂O

Unlike other chlorine oxides, dichlorine heptoxide does not attack sulfur, phosphorus, or paper at standard conditions.

Physical

Dichlorine heptoxide is a clear, oily, very volatile liquid. It reacts with water and organic compounds, but dissolves in halocarbons.

Availability

Dichlorine heptoxide is not available due to its hazards, but can be made in situ.

Preparation

This preparation is extremely dangerous because of the explosive and very oxidizing nature of Cl₂O₇.

Dichlorine heptoxide can be obtained by dehydrating perchloric acid with phosphorus pentoxide.

12 HClO₄ + P₄O₁₀ → 4 H₃PO₄ + 6 Cl₂O₇

The reaction has to be performed under 0 °C, optimally between -70 °C to -10 °C. The resulting product has to be distilled very carefully under vacuum to safely obtain pure dichlorine heptoxide.

Other routes involve oxidizing chlorine or chlorine oxides with ozone, under UV light.

Projects

• Make pure perchloric acid

Handling

Safety

Dichlorine heptoxide is explosive and a strong oxidizer, that can be set off in contact with flame or mechanical shock, or in presence of iodine. It is very corrosive and toxic in contact with skin, mouth or eyes.

Storage

Best to use it as quickly as possible.

Disposal

Dichlorine heptoxide can be safely neutralized by slowly adding it in cold water or ice, followed by neutralization with a base.