Lab Report 7: Aldol Condensation (Acetone and benzaldehyde to dibenzalacetone) PDF

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Summary

Organic chemistry (CHEM2314) lab 7 on aldol condensation. Synthesis of dibenzalacetone from acetone and benzaldehyde. Includes vacuum filtration and melting point temperature range vis Digimelt....

Description

Experiment 7 Aldol Condensation Chloe Lee Teaching Assistant: Atif Shafique Date Performed: November 17, 2021 Date Due: November 24, 2021

Lee 1

Experimental Objective To synthesize dibenzalacetone via aldol condensation using acetone and benzaldehyde.

Reagents Used

Acetone M.W. 58.08 g/mol

Benzaldehyde M.W. 106.12 g/mol

Reaction Scheme

Procedure 3M Sodium hydroxide (2.0 mL) was added into a test tube. Ethanol (1.6 mL), four drops of benzaldehyde (0.212 g), and one drop of acetone (0.05 g) was also added into the test tube and mixed using a glass stirring rod for 15 minutes. The crystal precipitate was separated from the liquid via vacuum filtration using a Hirsch funnel. The crystals were washed twice with water (2 mL) and were left to dry for five minutes. The product crystals were collected and dried again using large filter paper. The mass of the product was determined and its yield was calculated. The melting point was also determined.

Results Product Description The crude products, acetone and benzaldehyde, were clear liquids. The final product was a yellow precipitate with an odor. Experimental Data Mass of final product (g) Melting point temperature range (ºC)

0.058 100-101

Table 1. Mass of final product and melting point range for the product

Lee 2 Yield Calculations Theoretical Yield 0.212 g benzaldehyde •

1 𝑚𝑜𝑙 𝑏𝑒𝑛𝑧𝑎𝑙𝑑𝑒ℎ𝑦𝑑𝑒 106.12 𝑔 𝑏𝑒𝑛𝑧𝑎𝑙𝑑𝑒ℎ𝑦𝑑𝑒

0.05 g acetone • 0.009 mol product •

1 𝑚𝑜𝑙 𝑎𝑐𝑒𝑡𝑜𝑛𝑒 58.08 𝑔 𝑎𝑐𝑒𝑡𝑜𝑛𝑒

= 0. 0020 𝑚𝑜𝑙 benzaldehyde

= 0. 0009 𝑚𝑜𝑙 acetone

234.29 𝑔 𝑑𝑖𝑏𝑒𝑛𝑧𝑎𝑙𝑎𝑐𝑒𝑡𝑜𝑛𝑒 1 𝑚𝑜𝑙 𝑑𝑖𝑏𝑒𝑛𝑧𝑎𝑙𝑎𝑐𝑒𝑡𝑜𝑛𝑒

= 2. 11𝑔 𝑝𝑟𝑜𝑑𝑢𝑐𝑡

Percent Yield 0.058 𝑔 2.11 𝑔

• 100 = 2. 7%

Conclusion The synthesis of dibenzalacetone via aldol condensation of acetone and benzaldehyde was successful. The final product was yellow with a slight odor. The melting point temperature range of the product was 100-101ºC which is about 9 to 10 degrees lower than the expected melting point temperature. This discrepancy may be caused by the presence of water that wasn’t completely eliminated during vacuum filtration and washing with water. The percent yield could have been increased if the reaction was left to cooler and occur for a longer period of time or the product crystals were left to undergo vacuum filtration or to dry for more time....