1 Carbonyl Condensation Reactions

2 Very General Reaction. What is needed? –A Ketone or aldehyde – ONE reactant must have  -Hydrogens –Base (NaOH)

3 Very General Reaction. NO α-HYDROGENS αα α α α α 1. An α-carbon is the carbon directly attached to the C=O 2. Hydrogens attached to these C are called α-hydrogens

4 Aldol Condensation Reaction CH 3 C O H Acetaldehyde HO - CH 3 C O H CH 3 C O - H CH 2 C O H H 2 O CH 3 C OH H CH 2 C O H H 2 O CH 3 C O - H CH 2 C O H HO - Aldol α α α a β-hydroxy aldehyde β

5 Predict the Products Aldol reactions

6 Possible Crossed Aldols One carbonyl has no  -hydrogens C O H HO - Slowly add O H Can not form enolate C O H C OH H O H O H

7 Practice making mixed products Aldol reactions with CH 3 CH 2 C O H dilu. HO - CH 2 C O H dilu. HO - O + + CH 3 CH 2 C O H There are two products for each reaction

8 Intramolecular Aldol OO HH HO - O - O H O - O OH O A beta hydroxy ketone

9 What would happen? or

10 What would happen? Consider carefully or Remember, five and six membered rings are most stable

11 Recognizing Aldol Products 1.Product is a  -hydroxy aldehyde or ketone 2.Removing the bond between the C α – C β reveals the carbon units that were joined in the aldol condensation

12 Recognizing Aldol Products 3.The hydroxy becomes a carbonyl OHO H

13 a  -hydroxy How would you make these Compounds by an Aldol Condensation reaction? β β a β-hydroxy These are: aldehyde and ketone

14 3.Change the C-OH β β α α 1.Identify the bond between the α- and  -carbon atoms 2.Delete the bond between the α- and  -carbon atoms into a C=O

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