Nitration of Methyl Benzoate to form Methyl-m-nitrobenzoate via Aromatic Substitution Linh Ngoc Thuy Nguyen Seattle Central Community College Professor: Dr. Esmaeel Naeemi Date: February 21st, 2012 Abstract In this experiment, methyl-m-nitrobenzoate, followed the electrophilic addition of aromatic ring, would be formed from the starting material methyl benzoate and nitric acid, under the catalysis of concentrated sulfuric acid. The reaction between nitric acid and sulfuric acid resulted in the formation of nitronium ion NO2+. It then acted as strong electrophile that nitrated the benzene ring.
After that, vacuum filtration and recrystallization were methods used to obtain the final product with minimal impurities. The mass of product collected was 3. 835g, making a percent yield of 94. 5%. The product was successfully made since nitro group can be observed at peak 1531.
3 in the IR spectrum, doublet peak at 4. 0 ppm in the proton NMR, and peak at 60 ppm in the C13 NMR. The purification of 95. 2% can also be observed in the GCMS. Introduction Nitration is an electrophilic aromatic substitution reaction, where a nitro group is being added into the benzene ring, in return to the losing of a hydrogen.First, nitronium ion is made by the reaction between nitric acid and sulfuric acid, with sulfuric acid acting as a protonated reagent.
The nitronium ion is a strong electrophile that can react with benzene ring to form the arenium ion intermediate, despite the fact that it can temporarily lose its stability provided by the resonances. After that, it regains its stability by deprotonating the intermediate and yields the final product, in this case is methyl-m-nitrobenzoate. This experiment will be carried out under controlled temperature of 15oC or lower, since higher temperature will result in the second nitro group addition.ediates, with the positive charge at either the ortho, para, or meta position. The major product is the meta product due to the carboxyl and nitro groups both being powerful electron withdrawing groups. The meta attack on the methyl benzoate is the only attack that doesn’t yield have a resonance structure that isn’t highly unstable, so the meta attack is the most resonance stabilized (compared to the attack at either the ortho or para positions).
While the percent yield was a little low for the experiment, the melting point data and the IR spectra both support the notion that the nitro group was successfully added to the methyl benzoate. Additional reading on the subject allowed for the defense of the meta attack as opposed to the ortho or para attack of the nitro group, which was a successful learning opportunity to see “nature’s laziness”, or the desire to form the structure with the most stability and lowest energy of activation
