Question

Substituents on an aromatic ring can have several effects on electrophilic aromatic substitution reactions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. From the following lists, select the substituents that have the indicated property. The substituents are written as -XY, where X is the atom directly bound to the aromatic ring.

Answer 1

Activation of the ring towards substitution

-NHCOCH3

-CH3

Withdrawal of electrons through resonance

-NO2

-CN

Ortho/para-directed substitution

-CH3

-OH

Step-by-step explanation:

The substituents present on an aromatic ring strongly influence in its reactivity.

An activating group is one whose presence increases the reactivity of the aromatic ring against the aromatic electrophilic substitution with respect to when that group is absent. The introduction of an activating group in an unsubstituted aromatic compound will frequently lead to a polysubstitution.

This increase in reaction rate is due to the fact that these groups stabilize the cationic intermediate formed during the substitution through the transfer of electronic density on the annular system, either by inductive effect or by resonant effect.

A deactivating group is one whose presence decreases the reactivity, the reaction rate, of the aromatic ring against the aromatic electrophilic substitution with respect to when that group is absent. Therefore, the introduction of a deactivating group in an unsubstituted aromatic compound will make a second substitution more difficult.

In a benzene substituted with an electron donor group, either by inductive or resonant effect, an electrophilic substitution reaction will mainly result in a mixture of ortho and para products, the minority target product being.