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
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. In this experiment, student will observe the mechanism of electrophilic aromatic substitution reaction through the nitration of methyl...
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