Chapter 18: Enols and Enolates |
Summary
Study Tip: Try to recognise the two units that came together and identify the nucleophilic (enolate) portion and the electrophilic (carbonyl) portion. Recognise the enone that arises from dehydration. |
Related Reactions
MECHANISM OF THE ALDOL CONDENSATION OF A KETONE
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1. MECHANISM OF THE ALDOL
REACTION OF A KETONE
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Step 1: First, an acid-base reaction. Hydroxide functions as a base and removes the acidic α-hydrogen giving the reactive enolate. |
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Step 2: The nucleophilic enolate attacks the ketone at the electrophilic carbonyl C in a nucleophilic addition type process giving an intermediate alkoxide. |
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Step 3: An acid-base reaction. The alkoxide deprotonates a water molecule creating hydroxide and the β-hydroxyketone, the aldol product. |
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2. MECHANISM OF THE DEHYDRATION
OF THE ALDOL PRODUCT
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Step 1: |
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Step 2: The electrons associated with the negative charge of the enolate are used to form the C=C and displace the leaving group, regenerating hydroxide giving the conjugated ketone. |
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© Dr. Ian Hunt, Department of Chemistry |