addition-elimination
What addition-elimination means in Chemistry A-Level, as defined for AQA.
Definitions of addition-elimination
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Reference: AQA
A mechanism in which the nitrogen lone pair attacks the carbonyl carbon while the C=O electrons move onto the oxygen, giving a tetrahedral intermediate, then the oxygen's pair reforms C=O and pushes out Cl⁻.
A two-stage mechanism in which a lone pair on the attacking atom adds to the δ⁺ carbonyl carbon, then the C=O reforms and the chlorine leaves as Cl⁻.
Topics that use addition-elimination
- Acylation (A-level only) (AQA A-Level)
- Nucleophilic properties (A-level only) (AQA A-Level)
Related terms
- tetrahedral intermediate
- acid anhydride
- amide
- amide formation
- ammonium salt formation
- anhydride versus acyl chloride
- atom economy
- attack at a δ⁺ carbon
Using addition-elimination in the exam
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