diels-alder reaction
LowTechnical/Scientific
Definition
Meaning
A chemical reaction in which a conjugated diene reacts with a substituted alkene (called a dienophile) to form a substituted cyclohexene system.
A [4+2] cycloaddition reaction that is a cornerstone of synthetic organic chemistry for constructing six-membered rings. It is a pericyclic reaction involving the suprafacial addition of a 4π electron diene and a 2π electron dienophile.
Linguistics
Semantic Notes
The term is hyphenated (Diels–Alder). It refers specifically to a single, well-defined type of cycloaddition. Not a general class but a specific reaction named for its discoverers.
Dialectal Variation
British vs American Usage
Differences
No significant differences in usage, spelling, or meaning. Both regions use the identical hyphenated form and technical definition.
Connotations
Identical technical connotations in both British and American scientific literature.
Frequency
Usage frequency is equally low and confined to chemistry contexts in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
[Diene] undergoes a Diels–Alder reaction with [dienophile].The Diels–Alder reaction of [diene] and [dienophile] yields [product].[Catalyst] facilitates the Diels–Alder reaction.Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[No idioms exist for this highly technical term]”
Usage
Context Usage
Business
Virtually never used.
Academic
Exclusively used in higher education chemistry textbooks, research papers, and lectures.
Everyday
Never used in everyday conversation.
Technical
Core term in synthetic organic chemistry, materials science, and natural product synthesis.
Examples
By Part of Speech
verb
British English
- The diene will Diels–Alder react with the maleimide under these conditions.
- We attempted to Diels–Alder the furan onto the quinone.
American English
- The diene Diels–Alder reacted with the maleimide under these conditions.
- We Diels–Aldered the furan onto the quinone.
adverb
British English
- [This term is not used adverbially.]
American English
- [This term is not used adverbially.]
adjective
British English
- The Diels–Alder-active dienophile was synthesised beforehand.
- They studied the Diels–Alder reactivity of the series.
American English
- The Diels–Alder-active dienophile was synthesized beforehand.
- They studied the Diels–Alder reactivity of the series.
Examples
By CEFR Level
- [This word is far above A2 level.]
- [This word is far above B1 level.]
- [This word is far above B2 level.]
- The synthesis relied on a key Diels–Alder reaction to construct the complex ring system.
- Understanding the regioselectivity of the Diels–Alder reaction is crucial for planning the retrosynthesis.
- Lewis acid catalysts can dramatically accelerate Diels–Alder reactions by lowering the LUMO of the dienophile.
Learning
Memory Aids
Mnemonic
Think Diels–Alder = 'Deals a Ladder' – the reaction builds a six-runged (carbon) ring ladder from two pieces.
Conceptual Metaphor
A molecular handshake (diene and dienophile) that forms a ring.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- The hyphen is crucial and often omitted in transliteration: «реакция Дильса–Альдера». Translating it descriptively (e.g., «циклоприсоединение») loses the specific, named-reaction meaning.
Common Mistakes
- Writing 'Diels Alder' without the hyphen or en dash.
- Incorrectly calling it a 'Diels–Alder synthesis' instead of 'reaction'.
- Confusing it with other cycloadditions like 1,3-dipolar cycloadditions.
Practice
Quiz
What is the primary product ring size formed in a standard Diels–Alder reaction?
FAQ
Frequently Asked Questions
It was discovered by the German chemists Otto Diels and Kurt Alder in 1928, for which they received the Nobel Prize in Chemistry in 1950.
Yes, under certain conditions (often high temperature), the Diels–Alder adduct can undergo a retro-Diels–Alder reaction, cleaving back into the diene and dienophile.
Normal-electron-demand Diels–Alder reactions are typically exothermic (release heat). Inverse-electron-demand variants may have different thermodynamic profiles.
It is an atom-economical, one-step method to form two carbon-carbon bonds and create six-membered rings with high stereoselectivity, making it invaluable for synthesising complex natural products, pharmaceuticals, and polymers.