Question

Explain the following

observation: the
nitration of the
phenylacetonitrile
compound produces
the other, meta, and
para isomers with
percent yields of 24,
20, and 56.
respectively, even
though it has an
electron-attracting
group in its structure.

Answer 1

The nitration of phenyl acetonitrile produces the meta and para isomers with higher percent yield due to the electronic effects of the nitro group.

Step-by-step explanation:

The observation that the nitration of phenyl acetonitrile produces the meta and para isomers with higher percent yield, even though it has an electron-attracting group in its structure, can be explained based on the electronic effects of the nitro group. The nitro group is an electron-withdrawing group, which deactivates the ring towards electrophilic substitution reactions such as nitration. This means that the reaction is less favorable at the ortho position, leading to a lower yield of the ortho isomer. On the other hand, the meta and para positions are more accessible for nitration, resulting in higher yields for these isomers.

Answer 2

The directing effects of substituents on the benzene ring during electrophilic aromatic substitution reactions is what causes the yields.

The nitrile group (-CN) of phenylacetonitrile is an electron-withdrawing group. In electrophilic aromatic substitution reactions, electron-withdrawing groups are typically regarded as meta-directing. The nitrile group isn't joined to the benzene ring directly in this instance, though. Being a substituent, the phenyl ring itself has the ability to donate and withdraw electrons.

The combined electron-withdrawing and electron-donating actions of the phenyl ring and the nitrile group in the nitration of phenylacetonitrile affect the overall directing effect. A moderate ortho-para directing influence is the end result. This results in the formation of para, ortho, and meta isomers; however, the para isomer is preferred, which explains why the para product has a higher percent yield (56%) than the other two.