Chapter23 - Chapter 23. Carbonyl Condensation Reactions...

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Chapter 23. Carbonyl Condensation Reactions Based on McMurry’s Organic Chemistry , 6 th edition ©2003 Ronald Kluger Department of Chemistry University of Toronto
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 2 Condensation Reactions Carbonyl compounds are both the electrophile and nucleophile in carbonyl condensation reactions
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 3 23.1 Mechanism of Carbonyl Condensation Reactions Carbonyl condensation reactions utilize α -substitution steps An enolate ion adds as a nucleophile to the electrophilic acceptor
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 4 23.2 Condensations of Aldehydes and Ketones: The Aldol Reaction Acetaldehyde reacts in basic solution (NaOEt, NaOH) with another molecule of acetaldhyde The β -hydroxy aldehyde product is aldol ( ald ehyde + alcoh ol ) This is a general reaction of aldehydes and ketones
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 5 The Equilibrium of the Aldol The aldol reaction is reversible, favoring the condensation product only for aldehydes with no α substituent Steric factors are increased in the aldol product
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 6 Aldehydes and the Aldol Equilibrium
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 7 Ketones and the Aldol Equilibrium
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 8 Mechanism of Aldol Reactions Aldol reactions, like all carbonyl condensations, occur by nucleophilic addition of the enolate ion of the donor molecule to the carbonyl group of the acceptor molecule The addition intermediate is protonated to give an alcohol product
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 9 23.3 Carbonyl Condensation Reactions versus Alpha-Substitution Reactions Carbonyl condensations and α substitutions both involve formation of enolate ion intermediates Alpha-substitution reactions are accomplished by converting all of the carbonyl compound to enolate form so it is not an electrophile Immediate addition of an alkyl halide to completes the alkylation reaction
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 10 Conditions for Condensations A small amount of base is used to generate a small amount of enolate in the presence of unreacted carbonyl compound After the condensation, the basic catalyst is regenerated
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Based on McMurry, Organic Chemistry, Chapter 23, 6th 11 23.4 Dehydration of Aldol Products:
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Chapter23 - Chapter 23. Carbonyl Condensation Reactions...

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