Epoxides
Strained three-membered cyclic ethers that open to new functional groups.
- Functional group
- three-membered C-O-C ring
- Also known as
- epoxide, oxiranes, oxirane rings, alkene oxides
Overview
Strained three-membered cyclic ethers that open to new functional groups.
An epoxide is a three-membered ring containing oxygen. Ring strain makes it more susceptible to nucleophilic opening than ordinary ethers. Epoxide opening connects alkene oxidation to diols and other functionalised molecules; a monoepoxide is not automatically an epoxy resin.
Identifiers
- Functional group
- three-membered C-O-C ring
- Also known as
- epoxide, oxiranes, oxirane rings, alkene oxides
Properties
- Ring boundary
- Tetrahydrofuran and 1,4-dioxane are cyclic ethers, but their larger rings are not epoxides.
- Ring opening
- Under basic conditions nucleophiles usually attack the less hindered carbon; acid-promoted regioselectivity depends on substitution.
Related compounds
- Oxirane
The smallest epoxide, with two carbon atoms and one oxygen in a three-membered ring.
- Propylene oxide
A methyl-substituted epoxide with two nonequivalent ring carbons.
Connected reactions
- Epoxidation: Alkenes → Epoxides
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.
- 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: Cyclic Ethers: EpoxidesJohn 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.
- Organic Chemistry: Reactions of Epoxides: Ring-OpeningJohn 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.
- PubChem Compound Summary: Oxirane (CID 6354)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and selected English aliases retrieved via PUG REST on 2026-09-16. Chinese search names are curated nomenclature translations. Unspecified stereochemistry remains unspecified.
- PubChem Compound Summary: Propylene oxide (CID 6378)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and selected English aliases retrieved via PUG REST on 2026-09-16. Chinese search names are curated nomenclature translations. Unspecified stereochemistry remains unspecified.