Nitration of Methyl Benzoate
Abstract: This procedure demonstrates the nitration of methyl benzoate to prepare methyl m-nitrobenzoate. Methyl benzoate was treated with concentrated Nitric and Sulfuric acid to yield methyl m-nitrobenzoate. The product was then isolated and recrystallized using methanol. This reaction is an example of an electrophilic aromatic substitution reaction, in which the nitro group replaces a proton of the aromatic ring. Following recrystallization, melting point and infrared were used to identify and characterize the product of the reaction.
Purpose: The purpose of this experiment is to synthesize methyl nitrobenzoate from methyl benzoate, concentrated nitric acid, and concentrated sulfuric acid via an …show more content…
The amount of dinitration increases at high temperature because of the activation energy that is required to substitute the nitro functional group onto the aromatic ring. When adding two NO2 groups to the aromatic ring, the first NO2 group will require less activation energy than the second NO2 group. Increased heat provides more energy (in the form of heat) to add the second NO2 group. When the temperature is high, the activation energy is decreased. Therefore, when the temperature of the reaction is low, chances of yielding a dinitro compound are much lower than at high temperatures. 3. Why is it important to add the nitric acid/sulfuric acid mixture slowly during a 15-minute period?
If the nitric acid/sulfuric acid mixture is added too quickly, the temperature of the reaction would rapidly increase and exceed 15 °C, therefore increasing the formation of ortho and para isomers of methyl m-nitrobenzoate. Thus, the yield of the desired product is reduced. By slowly adding the acid mixture, the formation of the side products is greatly reduced. 4. Interpret the infrared spectrum of methyl m-benzoate.
C-H stretch of the aromatic at 3100 cm-1, strong peak near 1750 cm-1 representing the carbonyl ester stretch, two NO2 stretches at 1520 cm-1 and 1300 cm-1, and an aromatic stretch near 1600 cm-1. 5. Indicate the product formed on nitration of each of the following compounds: a. Benzene: Nitrobenzene b. Toluene: