Ozonolysis (reductive work-up): practice and mechanism
Ozone cleaves the C=C bond completely; each former double-bond carbon gets an =O (aldehyde or ketone).
Example
Ozone cleaves the C=C double bond completely. With a reductive work-up (dimethyl sulfide), each former double-bond carbon becomes a carbonyl group (aldehyde or ketone), not a carboxylic acid.
Mechanism step by step
- 1
O₃ adds to the double bond: primary ozonide (molozonide).
- 2
It breaks into a carbonyl compound and a carbonyl oxide, which recombine to the ozonide.
- 3
Dimethyl sulfide reduces the ozonide: two carbonyl compounds; (CH₃)₂S becomes DMSO.
Practice tasks
Which product forms, which reagent is needed? After each answer you see the explanation.
Which main product forms?
Typical mistakes
- Carboxylic acids only form with an oxidative work-up (e.g. H₂O₂). With dimethyl sulfide (reductive) you get aldehydes and ketones.
Often confused with: syn dihydroxylation · Epoxidation
Frequently asked questions
What is ozonolysis used for?
To locate double bonds (structure determination) and to make aldehydes/ketones from alkenes on purpose.
What happens with a ring?
The ring opens: cyclohexene becomes a chain with two aldehyde groups (hexanedial).