Question
Draw the different geometric isomers for dibenzalacetone (there are 3 of them). Why is the trans isomer formed in this experiment?

The purpose of this experiment is to svnthesize dibenzalacetone (trans, trans-1. 5-diphenvl-1.4 pentadien-3-one) through the Aldol condensation of acetone with benzaldehyde. The synthesis begins bv using a strong base to generate the acetone enolate ion. Water (not shown) is formed as a byproduct. The equilibrium position of this reaction strongly favors the starting acetone, and the amount of acetone enolate formed is quite small:; however, the enolate is extremely nucleophilic. 0 CH H3C H2 Being a very strong nucleophile, this enolate attacks the carbonyl of benzaldehyde and forms a β-carbonyl alkoxide ion. This alkoxide ion abstracts a proton from water to form a B-hvdroxy ketone. Sodium hydroxide abstracts another acidic alpha H to form a stabilized carbanion. The electron pair on carbon is used to eliminate the hydroxide ion, forming an alpha-beta unsaturated ketone in an irreversible step. This is an example of an Elcs mechanism. Note that in this reaction, the intermediate alcohol is dehvdrated under basic conditions, unlike most alcoholl dehydrations, which are generally El mechanisms under acid conditions. The Elca mechanism is made possible by the presence of the carbon vl, which stabilizes the intermediate carbanion
Draw the different geometric isomers for dibenzala
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