Methyl Benzoate Lab Report

Michael Bent
Mohamed Mire
CHEM 220-12
4/13/2016
Methyl Benzoate Labs
The first part of the lab regarded an esterification leading to the formation of Methyl Benzoate (C8H8O2). The purpose of this lab was to convert benzoic acid to methyl benzoate by means of utilizing a reflux acid catalyzed reaction with methanol; purity of the final product was assessed by means of both proton and carbon NMR. The extent to which a reaction’s products are reverted back into the original reactants is denoted by the equilibrium constant. The esterification reaction that's taking place in this lab has a low equilibrium constant (about 2.3) which means that a very low yield of the methyl benzoate product would be generated. There are a couple of mechanisms that

The reflux process lasted an hour after which the generated mixture was separated by a separatory funnel. The sulfuric acid functioned as the acid catalyst and worked to protonate the carbonyl carbon of the benzoic acid compound leading to a more reactive nucleophile. Protonation of the carbonyl carbon allows for the generation of a tetrahedral intermediate structure composed of both the benzoic acid and the methanol. The removal of water from the tetrahedral intermediate leads to tautomerized structure that becomes methyl benzoate when a loss of hydrogen is registered in the tautomerized oxygen.After the hour of refluxing was done, the resultant mixture was separated into an organic layer and an aqueous layer by means of a separatory funnel. The separation process was aided by a diethyl ether solvent the usage of which saw the aqueous layer to be the bottom layer of the refluxed

A third peak with an integration of 3 was upfield of the benzene proton peaks. This peak corresponds to the protons of the methyl component of the ether substituent. Normally methyl protons would show up further upfield but the presence of the highly electronegative oxygen atom lead to increased deshielding of the protons. Carbon NMR showed six peaks the most deshielded carbon falling at a PPM of about 162. The most upfield of the carbons was at a PPM of 48 and belonged to the methyl carbon at the end of the ether substituent. A range of four carbon peaks falling between PPMs of 120-130 represented the benzyl compound of the methyl benzoate product.
In part two of the lab methyl benzoate was subjected to a nitration resulting in the formation of methyl-3-nitrobenzoate. The purpose of part two was to add a nitrogen group to methyl benzoate by means of an electrophilic aromatic substitution (EAS) reaction. An EAS reaction pertains to the substitution of an aromatic hydrogen for an electrophile by means of an electrophilic attack on the aromatic ring which in this case is benzene. The product of the reaction was purified by recrystallization and characterized by both NMR spectra and melting point