Criegee Reaction
The term "Criegee Reaction" can refer to several different reactions named after the German chemist Rudolf Criegee. These include the formation of Criegee intermediates, the Criegee rearrangement, and the Criegee oxidation.
- Criegee Intermediates: Criegee intermediates are carbonyl oxides with two charge centers. They are formed during the ozonolysis of alkenes, a process where unsaturated bonds are cleaved with ozone. These intermediates can react with sulfur dioxide and nitrogen oxides in the Earth's atmosphere, contributing to the formation of aerosols, which play a significant role in controlling global climate. They are also an important source of hydroxyl radicals (OH), which are crucial in controlling air quality and pollution[1][6].
- Criegee Rearrangement: This is an organic reaction where a tertiary alcohol is cleaved in an organic oxidation by a peroxyacid to a ketone. The reaction mechanism has similarities with the Baeyer-Villiger oxidation, where the intermediate hydroxyperacid is called a Criegee intermediate. The reaction involves the migration of an alkyl substituent from carbon to the adjacent oxygen atom, replacing the carboxylic acid and leaving behind a carbocation. A subsequent hydrolysis step forms the ketone together with the alcohol[2].
- Criegee Oxidation: This is a glycol cleavage reaction in which vicinal diols are oxidized to form ketones and aldehydes using lead tetraacetate. The rate of the reaction is highly dependent on the relative geometric position of the two hydroxyl groups. Two mechanisms are proposed for the Criegee oxidation, depending on the configuration of the diol. If the oxygen atoms of the two hydroxy groups are conformationally close enough to form a five-membered ring, the reaction occurs via a cyclic intermediate. If the structure cannot adopt such a conformation, an alternate mechanism is possible, but is slower[5].
In summary, Criegee reactions play a significant role in atmospheric chemistry, organic synthesis, and the formation of various organic compounds.
Citations:
[1] https://en.wikipedia.org/wiki/Criegee_intermediate
[2] https://en.wikipedia.org/wiki/Criegee_rearrangement
[3] https://www.sciencedirect.com/science/article/pii/S2667325823000614
[4] https://onlinelibrary.wiley.com/doi/full/10.1002/anie.202014974
[5] https://en.wikipedia.org/wiki/Criegee_oxidation
[6] https://publikationen.bibliothek.kit.edu/1000130939/107231606
[7] https://www.osti.gov/biblio/1329620
[8] https://www.sciencedirect.com/topics/chemistry/criegee-rearrangement
[9] https://www.annualreviews.org/doi/abs/10.1146/annurev-physchem-052516-050739
[10] https://www.youtube.com/watch?v=YVWCu_x0KvQ
[11] https://pubs.acs.org/doi/10.1021/acsearthspacechem.7b00108
[12] https://pubs.rsc.org/en/content/articlelanding/2017/cp/c7cp05132h
[13] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6494847/
[14] https://pubmed.ncbi.nlm.nih.gov/34523463/
[15] https://en.wikipedia.org/wiki/Ozonolysis