1559Tch18323-34311/3/0511:12Page323 EQA 18 Enols,Enolates,and the Aldol Condensation: o,B-Unsaturated Aldehydes and Ketones As the text continues to develop the chemistry of aldehydes and ketones. the nuc ically temed ee them here for aldehydes and ketones:thed additionteof cdpotetcharater. Pay close attention to the structural relationships between starting materials and products.Thesc are the Outline of the Chapter 18-2 Keto-Enol Equilibria 18-3,18-4 Halogenation and Alkylation at the a-Carbon 18-5,18-6,18-7 Aldol Condensation A very important new reaction for synthesis 18-8 through 18-11 a,B-Unsaturated Aldehydes and Ketones The properties of the versatile products of aldol condensation. Keys to the Chapter 18-1.The Acidity of a-Hydrogens:Enolate lons second carbonyl group. 32318 Enols, Enolates, and the Aldol Condensation:
, -Unsaturated Aldehydes and Ketones As the text continues to develop the chemistry of aldehydes and ketones, you will now see how the carbon ad￾jacent to a carbonyl group can become nucleophilic. First, reactions of these new nucleophiles with common electrophiles like haloalkanes will be covered: alkylation reactions. More important are reactions of the nucle￾ophilic
-carbons of one carbonyl compound with electrophilic carbonyl carbons of another. They are gener￾ically termed carbonyl condensation reactions. You see them here for aldehydes and ketones: the aldol con￾densation. (In a later chapter you will be introduced to the analogous reaction of carboxylic esters: the Claisen condensation.) The products of aldol condensations are
, -unsaturated aldehydes and ketones, which contain additional sites of electrophilic and potential nucleophilic character. Pay close attention to the structural relationships between starting materials and products. These are the reactions of real-world organic synthesis, and they are among the most important ones you will see in this course. Outline of the Chapter 18-1 The Acidity of
-Hydrogens: Enolate lons Making a nucleophile at the carbon
to a carbonyl group. 18-2 Keto-Enol Equilibria 18-3, 18-4 Halogenation and Alkylation at the
-Carbon 18-5, 18-6, 18-7 Aldol Condensation A very important new reaction for synthesis. 18-8 through 18-11
, -Unsaturated Aldehydes and Ketones The properties of the versatile products of aldol condensation. Keys to the Chapter 18-1. The Acidity of
-Hydrogens: Enolate lons Hydrogens on carbons adjacent to carbonyl or related functional groups are, as a class, the most acidic of alkanelike hydrogens. A short list of representative pKa values follows. Notice how acidity is enhanced by a second carbonyl group. 323 1559T_ch18_323-343 11/3/05 11:12 Page 323