Synthesis of Benzilic Acid
Synthesis of benzilic acid from benzoin utilizing a multi-step reaction.
Names: Arian Karim
TA Name: Sayantan Das
Lab Day & Time: Thursday 7:30-11:40
Lab Section #:
Abstract
The main purpose of this experiment was to synthesize benzilic acid from benzoin. This requires a multistep synthesis with benzyl as an intermediate product. The first step required HNO3 as an oxidizing agent and the second step required KOH and HCl. The percentage yields of benzil and benzilic acid were 59.5% and 21.9% respectively. The calculated melting point of benzil was 90.1-91.6 which suggested some impurities, but the MP of benzilic acid was 149.3-151.5 which suggested a pure yield. The IR further confirmed the identity of benzylic acid with two OH peaks and the carbonyl peak.
Introduction
The purpose of this experiment was to synthesize benzilic acid from benzoin. Part A was omitted from the experiment and benzoin became the starting reagent. For this experiment a multistep synthesis was required. In the first part (Part B) benzoin was oxidized using nitric acid to make benzyl as a product. This reaction is characterized by the orange gas of nitrogen oxide that is liberated as a byproduct of the reaction. In Part C the benzyl was combined first with potassium hydroxide to make the carboxylate salt intermediate and second with hydrochloric acid to from the benzylic acid.
For both reactions the organic compound was the limiting reagent, so one mole of product is expected for each mole of organic reagent. Crystallization was performed in both parts in order to eliminate any impurities in the product. The identities of the products were tested using IR and melting points methods. At the end a percentage yield calculation of benzilic acid was done.
Figure 1. Benzylic acid synthesis reaction
The mechanism for benzylic acid from benzyl is showed in Figure 2. First the negatively charged hydroxide group from the potassium hydroxide attacks one of the partially
Names: Arian Karim
TA Name: Sayantan Das
Lab Day & Time: Thursday 7:30-11:40
Lab Section #:
Abstract
The main purpose of this experiment was to synthesize benzilic acid from benzoin. This requires a multistep synthesis with benzyl as an intermediate product. The first step required HNO3 as an oxidizing agent and the second step required KOH and HCl. The percentage yields of benzil and benzilic acid were 59.5% and 21.9% respectively. The calculated melting point of benzil was 90.1-91.6 which suggested some impurities, but the MP of benzilic acid was 149.3-151.5 which suggested a pure yield. The IR further confirmed the identity of benzylic acid with two OH peaks and the carbonyl peak.
Introduction
The purpose of this experiment was to synthesize benzilic acid from benzoin. Part A was omitted from the experiment and benzoin became the starting reagent. For this experiment a multistep synthesis was required. In the first part (Part B) benzoin was oxidized using nitric acid to make benzyl as a product. This reaction is characterized by the orange gas of nitrogen oxide that is liberated as a byproduct of the reaction. In Part C the benzyl was combined first with potassium hydroxide to make the carboxylate salt intermediate and second with hydrochloric acid to from the benzylic acid.
For both reactions the organic compound was the limiting reagent, so one mole of product is expected for each mole of organic reagent. Crystallization was performed in both parts in order to eliminate any impurities in the product. The identities of the products were tested using IR and melting points methods. At the end a percentage yield calculation of benzilic acid was done.
Figure 1. Benzylic acid synthesis reaction
The mechanism for benzylic acid from benzyl is showed in Figure 2. First the negatively charged hydroxide group from the potassium hydroxide attacks one of the partially