The Criegee rearrangement converts a tertiary alcohol into an alcohol and a ketone by using a peroxy acid and in turn forming peroxide intermediate that breaks down and forms the products. In an ozonolysis, after the [3+2] between an ozone molecule and an alkene, the five membered ring breaks down to a carbonyl and a carbonyl dioxide intermediate, which is called a “Criegee inermediate”.
Craig Taatjes and co-workers from Sandia National Laboratories have reported in Science on the observation of the Criegee intermediate by mass spec in the gas phase by reacting a methyl iodide radical and oxygen.