Nitration Of Methyl Benzoate Lab Report

Introduction:

From the lab book (1), Experiment 12.2A discusses the nitration of methyl benzoate to give an example of an electrophilic aromatic substitution reaction. This is seen in this experiment as a hydrogen on methyl benzoate is replaced with a nitronium ion. To achieve this an acid-base reaction, sulfuric acid and nitric acid react to produce a nitronium ion, a hydronium ion, and 2 bisulfate ions as seen in Structure 1. The nitronium ion reacts with an aromatic ring forming a sigma complex, Structure 2; which further stabilizes generating an aromatic ring due to conjugation, Structure 3. The formation of an intermediate is not mandatory, however it appears to be an easier resonance stabilizing mechanism (2). The final products of this nitration of Methyl benzoate for this experiment can be seen in Structure 4. Structure 1: The Formation of a Nitronium Ion

Structure 2: Reaction of the Nitronium Ion with the Aromatic Ring Structure 3: Sp3 – Hybridized Carbon Intermediate Further Stabilizing to form an Aromatic Ring Structure 4: Expected Final Products, Meta, Ortho, and Para conformations

Results and Discussion:

This experiment needed to be performed slowly so as to not produce a powerful explosive known as 2,4,6-trinitrotoluene also known as TNT. This meant that a cooled sulfuric and nitric acid solution was added dropwise (~0.05 ml,) every two and half minutes. Crystals recovered from suction filtration using a Hirsch funnel were rinsed with cold water and methanol to remove

1H-NMR was conducted and did not show a strong singlet around 2.4, which would rule out Methyl 2-nitrobenzoate. The formation at 8.8 is seen in Methyl 3-nitrobenzoate, but not seen in Methyl 4-nitrobenzoate. Our 1H-NMR contained peaks from 7.2 to 8.8 and thus would suggest the major presence of Methyl 3-nitrobenzoate. The color and appearance of the resulting product was a beige crystalline