Esmeralda Curiel
Organic Chemistry
October 7, 2014

Experiment 42- Nitration of Methyl Benzoate

INTRODUCTION

The study of nitration of Methyl benzoate is important because it is an example of an electrophilic aromatic substitiution reaction, in which a proton of the aromatic ring is replaced by a nitro group. The purpose of this experiment is to nitrate methyl benzoate and produce Methyl m-nitrobenzoate. The raw product will be washed with methanol and purified by crystallization. The purified product will be chracterized by percent yield and melting point.

As detailed in Pavia's Organic Laboratory techniques the reaction is expected to proceed via the following mechanism

PROCEDURE
The experiment was conducted using the procedures detailed in pages 347-352 of
Pavia D., Lampman G. M., Kriz G. S., and Engel R. G. A Small Scale Approach to Organic Laboratory Techniques, Third Edition). There were no exemptions to the procedure and this experiment was performed in collaboration with Paula Mendoza.

RESULTS Key quantities and properties for this experiment are summarized in Tables 1-3. Relevant chemical quantities and properties are presented in Table 1, table 2 contains the calculations for determining the limiting reactant. Table 3 contains the summary of the characterization results.Relevant experimental observations performed during the experiment are described in Table 4.

Table 1: Relevant chemical quantities and properties
Compound
Quantities
Properties
Methyl benzoate
3.05g
Clear liquid
Sulfuric acid
2.0 mL
Clear liquid
Nitric Acid
2.0 mL
Clear liquid
Water
24 mL
Clear liquid
Methanol
10 mL
Clear liquid

Table 2: Calculations for Theoretical
Methyl benzoate

Nitric Acid

Table 3: Summary of Characterization Results
Melting Point Range
68-74 °C
Percent Yield
61.4%
Calculations:

The reactant limiting product yield in this experiment was identified to be Methyl benzoate from data Table 2 and as calculated and shown in Table 2. The limiting reactant methyl benzoate should give 4.06g as compared to 5.75g from Nitric acod, therefore the maximum amount expected would be 4.06g from the 3.05g of methyl benzoate and 2.0mL nitric acid we used.

The theoretical yield again would be 4.06g of Methyl m-nitrobenzoate. Our yield came out to be 2.4934g thus giving us a percent yield of 61.4% as shown in Table 3.

ANALYSIS

In theory, the subject reaction should proceed through electrophilic aromatic substitution. The carbomethoxy group on the benzene ring directs meta, as a result, methyl m-nitrobenzoate is the principal product formed. One would expect to be more than one substitiution but the carbomethoxy and nitro group deactivate the ring against further substitution. Methyl m-nitrobenzoate has a melting point of 78°C with a theoretical yield of 4.06g. Our experiment yielded 2.50g giving us a 61.4% yield with a melting point range of 68-74°C. According to last year's results the mean percent yield was 66% and melting point was 65°C. Our results