CHE 332 Chapter Notes - Chapter 19: Claisen Condensation, Aldol Reaction, Dieckmann Condensation
Document Summary
Chapter 19: condensation and conjugate addition reactions of carbonyl compounds notes (more enolates: condensation reactions of carbonyls: enolate or enol reacts with carbonyl group of another to join, so (cid:374)e(cid:449) (cid:373)ole(cid:272)ule de(cid:396)i(cid:448)ed (cid:862)(cid:272)o(cid:374)de(cid:374)ses(cid:863) Claisen condensation: to s(cid:455)(cid:374)thesize -keto esters, c-c bond forming, acyl substitution. Irreversible reaction: mechanism, acid-catalyzed aldol condensation reaction, mechanism, 1. Enol adds to protonated carbonyl group: 3. In general, dehydration of the aldol is especially favorable when it leads to extended conjugation: nitriles (cid:449)ith h(cid:455)d(cid:396)oge(cid:374)s a(cid:396)e also (cid:449)eakl(cid:455) a(cid:272)idi(cid:272) a(cid:374)d (cid:272)o(cid:374)se(cid:395)ue(cid:374)tl(cid:455) these nitriles undergo condensations of the aldol type. However, it is the enolate from the ketone side of the molecule that adds to the aldehyde group leading to the product (aldehydes are more reactive towards nucleophiles): mechanism: (note: there are other possible starting enolate anions) Additions to , -unsaturated aldehydes and ketones: simple addition: nucleophile adds across double bond of carbonyl group, conjugate addition: resembles.
