Advanced Topic 780 of 1102 Organic Chemistry
Ozonolysis
Cleavage of alkenes with ozone to give carbonyl compounds.
In-depth explanation of Ozonolysis
Ozonolysis is the cleavage of carbon-carbon double bonds using ozone, O3, which first adds across the alkene to form an unstable molozonide and then an ozonide. The ozonide is then worked up under reductive conditions, such as zinc with water or dimethyl sulfide, to give aldehydes and ketones, or under oxidative conditions, using hydrogen peroxide, to give carboxylic acids and ketones. Because the products show exactly where the double bond was, ozonolysis is a classic method for locating the position of a C=C bond in an unknown molecule.
Going deeper: Ozonolysis
Key ideas: Alkene plus O3 forms a molozonide then an ozonide, which is cleaved by Zn with water or dimethyl sulfide (reductive) giving aldehydes and ketones, or by H2O2 (oxidative) giving carboxylic acids and ketones. Each C=C is replaced by two C=O. Use the products to find the alkene by joining the carbonyl carbons. Alkynes give diketones or acids.
Common mistakes and connections: Students forget that reductive workup keeps aldehydes while oxidative workup converts them to acids. Another error is pairing the wrong carbonyl carbons when reconstructing the alkene. Links to structure determination, the Baeyer test and hot KMnO4 cleavage, which also converts terminal CH2 to CO2.
Visualization of Ozonolysis
Ozone, a bent O3 molecule, adds across C=C to form an ozonide that is then cleaved into two carbonyl compounds. The interactive lesson shows this as a live animation or chart.
Worked example and use case
2-Butene gives two molecules of acetaldehyde on reductive ozonolysis.
Frequently asked questions about Ozonolysis
What is Ozonolysis?
Cleavage of alkenes with ozone to give carbonyl compounds.
Is Ozonolysis a beginner, intermediate or advanced topic?
Ozonolysis is a advanced topic in Organic Chemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Ozonolysis?
Study these earlier topics in Organic Chemistry first: Anti-Markovnikov Addition, Hydrogenation, Hydration of Alkenes.
What comes after Ozonolysis?
The next topics in Organic Chemistry are Polymerization of Alkenes and Electrophilic Aromatic Substitution.
Can I practise Ozonolysis with quizzes?
Yes. The interactive lesson includes a self-check question on Ozonolysis, and the Organic Chemistry quiz draws on every topic in this area.
Where Ozonolysis fits in Organic Chemistry
Ozonolysis is topic 52 of 148 in Organic Chemistry.