Nitration of Methyl Benzoate
Johnson, Chad Philip; T/Th Lab, 8:00am
Submitted February 23
rd
, 2012
Introduction
Benzene containing compounds are known to have special properties that cause them to react
differently than other molecules. The conjugated system of dienes in aromatic rings provide extra
stability, making traditional addition reactions across available pi double bonds very difficult (McMurry
520). However, substitution reactions occur and are relatively simple to carry out in the laboratory.
Many considerations must be made before performing substitution reactions on benzene rings.
The order in which reactions are performed plays an important role in the changing reactive properties of
the molecule: substituting a particular functional group onto benzene will not only change the molecular
structure, but it also affects the reactivity of the ring and potentially removes the possibility of certain
reactions. Some functional groups—such as –CH
3
, –OH, and –NH
2
—are electron donating, “activating” a
ring for further substitutions, and direct subsequent reactions to the ortho- and para- positions. Other
functional groups—such as –COOH, –NO
2
, and –SO
3
H—are electron withdrawing, “deactivating” the ring,
and instead direct toward the meta positions (McMurry 561).
In this experiment I reacted methyl benzoate with nitric acid in order to observe the position of the
substituted nitro group as it appeared in the product. The benzene of the reactant methyl benzoate is
deactivated by an ester in the –COOCH
3
substituent, suggesting that the nitro group adds only to a meta
position within the ring and forms methyl m-nitrobenzoate (see Figure 1). I performed this reaction by
using concentrated sulfuric acid (H
2
SO
4
) to protonate nitric acid (HNO
3
) which forms an electrophilic
Figure 1. Reaction of methyl benzoate with nitric acid to form methyl m-nitrobenzoate (Pavia 353).
