3-Nitrochalcone Synthesis

The objective of this experiment was to synthesize 3-nitrochalcone from 3- nitrobenzaldehyde. This was accomplished with a Diels-Alder reaction that utilized 3-nitrobenzaldehyde and acetophenone. After the reaction was completed, purification of the product was conducted using semi-microscale recrystallization. The melting point of the product was 136-141 oC, which is in the close vicinity of the literature melting point of 146 oC. The theoretical yield of 3-nitrochalcone was 0.253g and the yield after filtration was 0.22g (percent yield of 86.9%). The percent yield after recrystallization, was 80.9%.

INTRODUCTION
The goal of this experiment was the synthesis of 3-nitrochalcone from 3-nitrobenzaldehyde and acetophenone as shown in Figure 1:

Figure 1: Synthesis of 3-Nitrochalcone from 3-Nitrobenzaldehyde and Acetophenone Source: cnx.org
The mechanism for the synthesis of 3-nitrochalcone is presented in Figure 2. The alpha carbon on the acetophenone is deprotonated, followed by the attack of the alpha carbon anion on the carbonyl carbon on the 3-nitrobenzaldehyde. Next, is the protonation of the oxygen from the 3-nitrobenzaldehyde, which is then followed by an elimination reaction where this acts as a leaving group. The product is the trans-alkene present in the product.

Figure 2: Mechanism
For the theoretical mass calculation, a mole of 3-nitrochalcone is used. The purity of the product is confirmed based on the experimental melting point of 142°C which is in close vicinity of the literature melting point of 146°C. Potential source of errors could be in the filtration process which could decrease the actual yield. In addition, there could be moisture present in the solid leading to errors in the weight. Based on the NMR spectral data, the frequency of the signals was 15.6Hz, which is very close to the theoretical frequency of 12-18Hz. This confirms that the compound is