Sabrina(Jingyao) Liao
Purpose
This experiment illustrates an electrophilic aromatic substitution reaction of a benzene derivative, methyl benzoate (an ester).
Reaction

Mechanism

Table of reactants and reagents
Reactant/reagent | Amount (g/ml) | Moles (mol) | Molar mass (g/mol) | Density (g/ml) | mp (C) | comments |
Sulfuric acid | 6 ml | 0.113 mol | 98.079 g/mol | 1.840 g/ml | 10.31 celsius | reacgent |
Nitric acid | 3 ml | 0.069 mol | 63 g/mol | 1.42 g/ml | -42 celsius | reacgent |
Methanol | 20 ml | 0.495 mol | 32 g/mol | 0.792 g/ml | -93.3 celsius | washing |
Methyl benzoate | 2.491 g | 0.0183 mol | 136.15 g/mol | 1.094 g/ml | -15 celsius | washing |
Calculations

Methyl benzoate: 2.491 g / 136.15 g/mol = 0.0183 mol
Procedure
A 25 ml round bottom flask was set up and being hold by a ring stand with a small clamp. The flask was cooled in an ice-water bath. Then, 3 ml of concentrated sulfuric acid was obtained inside the flask using 10 ml graduated cylinder. After being cooled, the clamp was removed from the ring stand and the flask was whirled gently. Then 3ml of concentrated nitric acid was added into the flask using the same graduated cylinder as before while the flask was being swirled. The mixture was cooled down within the ice water bath after the clamp was placed back on the ring stand. Then, two 125 Erlenmyers flasks were acquired. One was labeled “H2O” while the other one was labelled “MeOH/H2O”. A new ice-water bath was set up and 20 ml of distilled water and 20 ml of 80:20 methanol, water were obtained inside the prelabelled flasks which were placed in the new ice-water bath. After that, a 50 ml round bottom flask was placed in another ring syand with a clamp. Then 2.491 g of methyl benzoate was obtained inside the round bottom flask, followed by the product being cooled by being placed inside the ice bath for five mins. After that, 3ml of sulfuric acid was added inside the mixture while being swirled. The mixture was then placed inside the icebath again. After it was being cooled down, 6ml of nitric acid/ sufuric acid mixture was added inside the mixture dropwise while the 50ml flask was being swirled in the ice water bath. After that, the flask was removed from the icebath and the mixture was left under the room temperature for 13 mins. Then, the product was added into a 100 ml beaker that contains 25.016 g of crushed ice. After waiting for the ice to melt, the crystals were extracted from vacuum filtration. Through the process of vacuum filtration, the beaker was washed using 20 ml of ice-cold water, 10 ml of the cold 80:20 methanol/water mixture. Then the crystals were purified further through recrystallization.
Firstly, the crystals were placed in a 50ml beaker. 6ml of methanol was added inside the beaker which was then placed on a hot plate. The mixture was mildly boiled until the crystals were fully dissolved. The hot plate was then removed and the solution was cooled down to room temperature until the crystals started to form. The solution was then furthered cooled down by being placed on ice followed by being purified by suction filtration. Cold methanol/water mixture was used to rinse crystals remaining on the wall of the beaker. The product was then dried by vacuum and the final product was transferred ino a preweighed vial. The final mass of the product was measured and it was 2.064 grams. The melting point was measured as 78.6 celsius.
Table of products
product | Yield (g) | yield(mol) | Theoretical yield(g) | Percent yield | Molar mass | Actual mp (C) | literature mp (C) |
Methyl 3-nitrobenzoate | 2 .064 grams | 0.011 mol | 3.32 g | 62.2% | 181.15 g/mol | 78.6 C | 77-80 celcius |
Calculation

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