Epoxidation
A peroxyacid transfers oxygen across the alkene in a concerted step, forming two C-O bonds while breaking the C=C pi bond. Both bonds form from one face, retaining the alkene substituents’ relative stereochemistry in the epoxide.
- Reagents
- Peroxyacid, e.g. mCPBA
- Conditions
- Controlled peroxyacid oxidation
- Reaction class
- Epoxidation
- Equation
- alkene + RCO3H -> epoxide + RCO2H
Overview
A peroxyacid transfers oxygen across the alkene in a concerted step, forming two C-O bonds while breaking the C=C pi bond. Both bonds form from one face, retaining the alkene substituents’ relative stereochemistry in the epoxide.
Transformation
- Equation
- alkene + RCO3H -> epoxide + RCO2H
- Reagents
- Peroxyacid, e.g. mCPBA
- Environment
- Controlled peroxyacid oxidation
- Reaction class
- Epoxidation
- Mechanism
- concerted oxygen transfer
- Evidence level
- textbook extension
Scope and limitations
- Scope
- Oxygen transfer across an isolated C=C bond.
- Limitations
- Alkene stereochemistry is retained in the epoxide relationship; other oxidisable groups can affect selectivity.
Related reactions
- Hydrochlorination: Alkenes → Chloroalkanes
Addition of hydrogen chloride across an alkene can form a chloroalkane.
- Hydrobromination: Alkenes → Bromoalkanes
Addition of hydrogen bromide across an alkene can form a bromoalkane.
- Hydroiodination: Alkenes → Iodoalkanes
Addition of hydrogen iodide across an alkene can form an iodoalkane.
- Elimination: Chloroalkanes → Alkenes
Base-promoted elimination removes HCl to form an alkene.
- Elimination: Bromoalkanes → Alkenes
Base-promoted elimination removes HBr to form an alkene.
- Elimination: Iodoalkanes → Alkenes
Base-promoted elimination removes HI to form an alkene.
- Cracking: Alkanes → Alkenes
Thermal or catalytic cracking converts long-chain alkanes into shorter molecules including alkenes.
- Hydrogenation: Alkenes → Alkanes
Hydrogenation reduces alkenes to alkanes.
- Halogen addition: Alkenes → Dihalogenoalkanes
Bromine addition converts alkenes into vicinal dibromoalkanes.
- Dihydroxylation: Alkenes → Diols
Cold, dilute manganate(VII) oxidises an alkene to a vicinal diol without the oxidative cleavage associated with stronger conditions.
- Addition polymerisation: Alkenes → Addition polymers
Alkenes can form addition polymers by chain-growth addition.
- Hydration: Alkenes → Alcohols
Catalytic hydration converts alkenes into alcohols.
- Dehydration: Alcohols → Alkenes
Dehydration converts alcohols into alkenes.
- Epoxide hydrolysis: Epoxides → Diols
Protonation activates the strained ring toward attack by water. Backside attack breaks one C-O bond; proton transfer leaves hydroxyl groups on adjacent carbons, with an anti relationship when ring geometry makes that distinction meaningful.
References
- Organic Chemistry: Oxidation of Alkenes: Epoxidation and HydroxylationJohn McMurry · OpenStax Organic Chemistry · 2023
Supports functional-group chemistry used to curate the linked examples. Checked 2026-09-16; named examples are applications of textbook scope, without claimed experimental yields.