Aldol Condensation Synthesis of Dibenzalacetone using the Claisen-Schmidt Reaction -copy.doc

 Aldol Condensation: Synthesis of Dibenzalacetone using the Claisen-Schmidt Reaction

 Abstract: In this experiment, dibenzalacetone as prepared !ia an aldol condensation reaction beteen acetone and benzaldehyde" Acetone and benzaldehyde ere mixed ith sodium hydroxide and ethanol, and mixed !igorously for #$ minutes" %he crystals ere rinsed ith ith ater then centrifuged" %his as repeated a total of three times" %he dibenzalacetone as then characterized using melting point analysis" %he obser!ed melting point as &#"'(C- )$&" *(C compared to a cited !alue of ))$(C" ))$(C" %he sample as not completely dry and could ha!e contributed to the loer and broader obser!ed melting point" %he percent yield as ))+ ))+ " %his percentage occurred because of the excess moisture in the sample"

ig )" ./uation of Acetone Acetone and 0enzaldehyde to form Dibenzalacetone Dibenzalacetone

Introduction: Dibenzalacetone, or D0A, is often used as an ingredient in sunscreen lotions and sprays because it has spectral properties that ma1e it capable of absorbing 23 light" It is also 1non to possess anti-inflammatory properties and can therefore

be used to treat pain, selling and inflammation" ) Dibenzalacetone can also be used as a ligand in organometallic chemistry, and its deri!ati!es are often utilized as polymer crosslin1ers" * %his experiment demonstrated the Claisen-Schmidt condensation of mixed aldols" .nolate ions ere ere formed hen the molecules ith hydrogens hydrogens alpha to carbonyl groups ere reaction ith a base 45a67"8

Fig. 2 Acetone reaction reaction and Sodium Hydroxide Reaction Reaction

9hen an enolate forms from an aldehyde, it normally reacts ith unreacted aldehydes to form an aldol additioncondensation" ;etones are less reacti!e toard nucleophilic additions and therefore, the enolate formed from a 1etone can be used to react ith an aldehyde" %his is 1non as the Claisen-Schmidt reaction" 9hen the product formed still has a reacti!e alpha hydrogen and and a hydroxide ad@> g %heoretical ield: $")@$+ g =ercent ield: ))>"&& ))>"&&

Finding Limiting Reagent

 Acetone $"$+#m  ) mol A  ) mole prdct prdct  **@g **@g prdct  'E"$ 'E"$E E g  ) mol mol A  F $"*E)' g dibenzalacetone 0enzaldehyde $"**> g 0  ) mol 0  ) mole prdct  **@g prdct  'E"$E g 0  * mol 0  F $"@#'E g dibenzalacetone %he limiting reagent for this reaction is acetone as it yields the least amount of  dibenzalacetone"

Aldol Condensation: Synthesis of Dibenzalacetone Theoretical Yield Yield

 Acetone $"$+#m  ) mol A  ) mole prdct prdct  **@g **@g prdct  'E"$ 'E"$E E g  ) mol mol A  F $"*E)' g dibenzalacetone

Percent Yield Yield

4mass of D0A crystals8 4theoretical yield8

F

$"#*&@ g D0A $"*E)' g D0A

x )$$ F

F ))+"$* yield Discussion and Conclusions: In this experiment, an aldol condensation as carried out under basic conditions" In these types of reactions, carbonyl compounds act as either the enolate ion or the electrophile, or sometimes both" %he carbonyl compound hich becomes the enolate ion must possess at least ) G-carbon" In this experiment, the enolate ion originates from acetone because benzaldehyde lac1s an G-carbon" 0enzaldehyde, therefore, acts as the electrophile in this reaction" %he enolate ion deri!ed from acetone then reacts ith benzaldehyde to form a Hhydroxy1etone" %his H-hydroxy1etone ill then undergo dehydration to form an enome, a con