Nitration of Methyl Benzoate
Autor: Sunny Sloth • November 30, 2015 • Lab Report • 899 Words (4 Pages) • 921 Views
[pic 1]
Overall Reaction:
[pic 2]
Theory:
The -COOCH3 group (called an ester group) is a deactivating group for electrophilic aromatic substitution. It is also a meta-directing group. Nitration will therefore proceed slower for methyl benzoate than it would for benzene, but the reaction still proceeds fast enough to be profitable. A dinitro side-product is not a concern because the first nitro group to attach is also ring- deactivating. Nitric acid alone does not provide high enough concentration of nitronium ion, NO2+, (the actual attacking electrophilic species.) Therefore, sulfuric acid is added to the nitric acid and the following reaction occurs:
[pic 3]
The nitronium ion then attacks the ring meta to the ester group. Hydrogen is subsequently lost to restore the aromatic ring.
PRE-LAB/POST Lab or DURING THE LAB:
- Draw the mechanism for the formation of methyl 3-nitrobenzoate.
- Explain why methyl ester group is a meta director?
- Show the resonance structures to illustrate the stabilization of the intermediate in the formation of methyl 3-nitrobenzoate
Procedure:
In a 5-mLconical vial(from your blue micro kit), cool 0.6 mL of conc. sulfuric acid to 0-2oC and then add 0.3 g of methyl benzoate. Again, cool the mixture to between 0-10oC.
Now add a few drops at a time, using a Pasteur pipette, a cooled mixture of 0.4 ml of sulfuric acid and nitric acid(already prepared for you). During the addition of the acids, swirl the mixture frequently (or use magnetic stirring) and maintain the temperature of the reaction mixture in the range of 5-15oC. This will be a slow process.
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