Methyl Benzoate Lab Report

The purpose of this laboratory experiment was to react methyl benzoate with nitric acid and identify the position of the substituted nitro group in the final product molecule. Methyl benzoate was added to cool concentrated sulfuric acid in order to amplify the directing effect of the nitro group addition, such that without the sulfuric acid the protonation would have happened at the carbon oxygen double bond. The mixing of concentrated nitric acid with concentrated sulfuric acid was to achieve Reaction 1 from Table 1, formation of the nitronium ion. Both of these reactions were kept at temperatures around 0°C, since they are exothermic reaction and presence of heat could lead to production of unnecessary dinitro by-products.

The nitronium ion mixture was slowly added to the concentrated sulfuric acid methyl benzoate mixture to prevent vigorous reaction that if present could lead to unwanted dinitro by-products. The mixture after settling and heating to room temperature was poured over ice in order to rapidly cool the sample inducing formation of the crystals. The water was allowed to melt before it was vacuum filtered to neutralize the acid that might be remaining

So, the first reaction Table 1.1 was the formation of the electrophile. The mixture of concentrated sulfuric acid and methyl benzoate served in order to create a resonance stabilized arenium ion intermediate. In this reaction the benzine ring is deactivated by the ester in the -COOCH3 meaning that the electrophile nitronium ion was added to the meta position to form methyl m-nitrobenzoate (Table 1.2). This is the major product due to the carboxyl and nitro group being very powerful electron withdrawing groups. This was confirmed by the melting point which ranged from 73-75°C while the literature meting point has a range of