Dichlorine heptoxide


Dichlorine heptoxide is the chemical compound with the formula. 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:
can be distilled off from the mixture.
It may also be formed by illumination of mixtures of chlorine and ozone with blue light. It slowly hydrolyzes back to perchloric acid.

Structure

is an endergonic molecule, meaning it is intrinsically unstable, decomposing to its constituent elements with release of energy:
Dichlorine heptoxide is a covalent compound consisting of two groups linked by an oxygen atom. It has an overall bent molecular geometry, with a Cl−O−Cl angle of 118.6°. The chlorine–oxygen bond lengths are 1.709 Å in the central region and 1.405 Å within each cluster. 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:
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.
Dichlorine heptoxide reacts with alcohols 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, is a strong oxidizer as well as an explosive that can be set off with flame or mechanical shock, or by contact with iodine. Nevertheless, it is less strongly oxidising than the other chlorine oxides, and does not attack sulfur, phosphorus, or paper when cold. It has the same effects on the human body as elemental chlorine, and requires the same precautions.