The goal of this lab was to prepare methyl m-nitrobenzoate using electrophilic aromatic substitution using nitration. The reaction used methyl benzoate with the acid catalyst as sulfuric acid. The mechanism for the nitration using methyl benzoate is presented in Figure 1. Figure 1: Benzene can only undergo substitution reactions that are called electrophilic aromatic substitution reactions. Given that benzene rings are used commonly in the production of many organic compounds, the capability to make substitutions to benzene is critical. This can be accomplished by the use of Electrophilic Aromatic Substitution (EAS) as Nucleophilic Aromatic Substitution (NAS) is not possible because of the electron-rich benzene ring, which does not have substituents that withdraw electrons. Since the density in the …show more content…
The resonance of the ring is disrupted temporarily. This resulted in an intermediate arenium ion (also called sigma complex) which is resonance stabilized and electron deficient with a positive charge. The reaction rate is determined by the rate at which the intermediate arenium ion forms. This intermediate arenium ion further undergoes deprotonation by the base yielding Methyl-m-nitrobenzoate. This leads to a restoration of the aromaticity of the ring. The bonding of the carbomethoxy group to benzene is based on the determination of the group as to where the electrophile bonds with the benzene ring. There are two types of groups called electron-donating groups (EDGs) and electron withdrawing groups (EWGs). The EDGs donate electrons, whereas the EWGs withdraw electrons. The bonding of an electrophile will happen at the para or ortho position of EDGs and meta position of an EWG. This is presented in Figure 3. Figure 3: Ortho, Para and Meta