CLAISEN REACTION)

Claisen Condensation Reaction using Examples, Intramolecular Claisen Reaction|| HalOForm Reactions (ChlorOForm, BromOForm, IodOForm)||IodOForm Test and Examples|| Alpha-Halogenation (acidic medium) and Examples

Claisen Ester Condensation || Dieckmann's Cyclization || Cannizzaro Reaction

Ester gives nucleophilic addition reaction followed by elimination reaction with carbon nucleopile. When carbon nucleophile is of an ester then the reaction is known as Claisen condensation reaction. This reaction is also carried out between ester and a ketone. A suC Cessful Claisen condensation requires an ester with two alpha- hydrogens and an equivalent amount of base rather than a catalytic amount of base. Consider the given reaction CH_(3)-COOC_(2)H_(5)underset(C_(2)H_(5)OH)overset(C_(2)H_(5)ONa)rarr"enolate ion"underset("Claisen condensation")overset("ether(X)")rarr Product For the above reaction the most reactive ester is :

(a) Give the Claisen ester condensation product of ethyl butanoate. (b) Why does the Claisen ester condensation of ethyl-2-methyl propanoate (I) not take place ? ( c) Why does Claisen condensation of (I) take place by the use of Ph_3 C^(Ө) Na^(oplus) as a base ?

Phenol-Introduction and Methods OF Preparation|| Dow's Process, Sodalime Decarboxylation, Diazotisation, Fenton's Reagent, Fries & Claisen Rearrangement|| Properties OF Phenol, EAS, Reimer Tiemann & Kolbe's Reactions|| Friedel Craft Alkylation and Acylation

Assertion: Esters which contain alpha- hydrogens undergo Claisen condensation. Reason : LiAIH_(4) reduction of esters gives acids