Synthesis of Dibenzalacetone by Aldol Condensation of Benzaldehyde and Lab Report

Synthesis of Dibenzalacetone by Aldol Condensation of Benzaldehyde and Acetone - lab Report ExampleUnder basic conditions, the carbonyl group of acetone having an alpha hydrogen mite is converted to an enolate ion (Mc Murry, 1999, pp. 939). The enolate ion thus produced is a strong nucleophile and attacks the carbonyl group of the accepting partner, which in this sheath is benzaldehyde (Mc Murry, 1999, pp. 939). An alkoxide is invented as a result of this nucleophilic attack. The alkoxide then undergoes protonation by H2O, forming a neutral condensation mathematical intersection, hydroxyketone. This undergoes dehydration in presence of NaOH, forming an enolate ion, hydroxyenolate, which then forms Benzalacetone by loss of a hydroxyl group. Benzalacetone also has alpha hydrogen, which again forms enolate ion under basic conditions, similar to the first step. This enolate nucleophilically attacks another Benzylaldehyde molecule. Subsequent reactions are similar to those already di scussed, leading to the formation of dibenzalacetone, the final product. Thus, two molecules of benzaldehyde and one molecule of acetone are required to form one molecule of dibenzalacetone. O O O CH3 C CH2 H CH3 C CH2 H C OH- Acetone Enolate ion- nucleophilic attack on benzaldehyde O OH O O- CH3 C CH2 CH CH3 C CH2 CH OH- ?-Hydroxyketone Alkoxide O OH O CH3 C CH- CH CH3 C CH = CH Hydroxyenolate Benzalacetone O CH = CH C CH = CH Dibenzalacetone (iii) Experimental Benzaldehyde (80 l), acetone (29 l), and ethanolic NaOH (1.0 ml) were used in this experiment. The reaction was carried out in a conical vial containing a magnetic spinvane, according to the procedure specified in the SC214 applicative manual, page 41. Filtration of the product was done using a Hirsch funnel, and the Craig tube method was used for purification and recrystallization of the product as per the SC214 practical manual, page 42. Melting point and IR spectrum were also obtained for the ch aracterization of the product. (iv) Results The weight and coming back of the product (dibenzalacetone) are calculated as follows (1) Calculation of mass of the product Weight of glass= 37.458 g Weight of glass along with Dibenzalacetone crystals= 37.502g Therefore, mass of Dibenzalacetone crystals= 37.502 37.458 = 0.044g (2) Calculation of proceeds of the product % Yield of Dibenzalacetone = Benzaldehyde is the limiting reactant in this experiment No. of moles of Dibenzalacetone= = = 0.001877 = 1.87 ? 10-4 moles No. of moles of Benzaldehyde= = = 0.000784 =7.84 ? 10-4 moles Since 2 benzaldehyde molecules are involved in each reaction, =7.84 ? 10-4/2 = 3.92 moles % yield of Dibenzalacetone= = = 0.477?100 = 47.7% Therefore, % yield of Dibenz