Aldol Condensation

Objective

The objectives of this experiment are to perform and learn aldol condensation mixture of benzaldehyde (3-nitrobenzaldehyde) and ketones, to form an α,β – unsaturated ketone.

Introduction

In the presence of a strong base, two molecules of aldehyde or ketone may combine to form a β-hydroxaldehyde or a β-hydroxyketone. The aldol reaction requires an aldehyde or ketone that contains at least one α-hydrogen in order to form enolate ion. As in this experiment, we used a base-catalysed condition which means the acid α-hydrogen will be protonated to form the enolate. The enolate ion (carbanion) will act as the actual nucleophilic reagent. The aldol addition shows that carbonyl compounds can react as both an electrophile and a nucleophile. The addition of enolate anions to aldehydes/ketones will form a product. The product form is an organic compound that contains both functional group of aldehyde and alcohol. Thus, the reaction is call as aldol condensation.

Apparatus

Erlenmeyer flask

Glass rod

Spatula

Buchner funnel

Vacuum

Beaker

Ice bath

Filter paper

Graduated cylinder

Reagents

3-nitrobenzaldehyde

Acetophenone

95% ethanol

NaOH

Methanol

Ice water

Procedure

0.75 g of 3-nitrobenzaldehyde was added into a 50 ml Erlenmeyer flask. 0.60 ml of acetophenone was added and followed by 4.0 ml of 95% ethanol to the flask containing aldehyde. The flask was swirled in water bath in order to mix the reagents and dissolved them. After that the solution was left to cool to room temperature. 5.00 ml of NaOH was added and was stirred until the entire solidified or become cloudy. 10 ml of ice water was added to the flask. Cooling and stretching was done to initiate crystallization. Mixture then transferred into a beaker with 15 ml of ice water. The solid formed was collected by using Buchner funnel. The crude was washed with cold water and left to air dry for 30 minutes. The solid was weighed and per cent...