One can view the initial steps of the claisen condensation as analogous to ketone chemistry. Enolates of esters are less acidic than enolates of ketones or aldehydes and can therefore undergo chemistry with less reactive compounds. The archetypal example in this condensation involves the reaction of two molecules of ethyl acetate induced by ethoxide ion. The mechanism of the reaction is shown below. : the conden nsation belo ow gives a - acetoacet tate and henc ce the self-co ondensation of esters is sometimes k known as the e acetoaceta ate ester con densation. Under the reaction conditions, the material rests as the deprotonated form until acted upon by the addition of acid which returns the hydrogen. The claisen reaction mixture must be quenched with acid before isolation of the product. Acetic acid or aq. ammonium chloride are often employed. Note that anions derived from the -ketoester have two carbonyl groups available for conjugation.
