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Rainer Ludwig Claisen (1851-1930) Developed the Claisen Condensation in 1887.

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Presentation on theme: "Rainer Ludwig Claisen (1851-1930) Developed the Claisen Condensation in 1887."— Presentation transcript:

1 Rainer Ludwig Claisen ( ) Developed the Claisen Condensation in 1887

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3 What are the building blocks?

4 sp 2 orbitals p orbitals π bond sp 3 orbitals α hydrogens

5 Sites for nucleophilic attacks High Electronegativity of Oxygen

6 Resonance Energy Stabilization energy

7 Ethyl propanoate Formation of the enolate Condensation with ethyl benzoate to form β-keto ester Et -O - C - CH 2 – CH 3 O || Loss of 2 nd alpha hydrogen on β- keto ester Et -O - C - CH – CH 3 O || -

8 Ethyl Propanoate 0.04 pK a of alpha hydrogens 24 or K a

9 Bond Angles 120 o sp 2 orbitals o sp 3 orbitals 180 o sp orbitals 90 o p orbitals

10 Overview of the Claisen Condensation Reaction Ethyl Propanoate Ethoxide ion Ethyl Benzoate 1. Ethoxide ion acting as a strong base deprotonates ethyl propanoate. 2. The enolate of ethyl propanoate is formed. 3. The enolate of ethyl propanoate is a strong nucleophile that attacks the partially positive carbon of the carbonyl group on ethyl benzoate. 4. The alpha substitution makes this a carbonyl condensation reaction. 5. A β-keto ester is formed The driving force for this reaction is the transfer of the second alpha hydrogen to the ethoxide ion. This is exothermic.

11 Deprotonation of Ethyl Propanoate Resonance The enolate ion is a strong nucleophile and will attack the partially positive carbon of a carbonyl group. + Ethyl Propanoate Ethyl Benzoate Enolate of

12 Self condensation of ethyl propanoate

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15 Rainer Ludwig Claisen ( ) Developed the Claisen Condensation in 1887


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