Question

Rank the following compounds from most reactive to least reactive in an electrophilic aromatic substitution reaction:

Short answer

An electrophilic aromatic substitution reaction constitutes an organic reaction, where the atom connected to an aromatic system is substituted by an electrophile.

Some electrophilic aromatic substitution reactions include aromatic halogenations, the Friedel-Crafts alkylation, and acylation.

Step-by-step solution

Electrophilic aromatic substitution

An electrophilic aromatic substitution reaction constitutes an organic reaction, where the atom connected to an aromatic system is substituted by an electrophile.

Some electrophilic aromatic substitution reactions include aromatic halogenations, the Friedel-Crafts alkylation, and acylation.

Rank the given compounds from the most reactive to the least reactive in an electrophilic aromatic substitution reaction 

The given compounds are ranked as shown below.

Ranking of the compounds based on the reactivity

The N-substituted benzene is more reactive than the O-substituted benzene as the nitrogen is more effective than the oxygen at contributing electrons to the benzene ring, as the nitrogen is less electronegative than the oxygen.

The S-substituted benzene is less reactive because the lone pair electrons of the sulfur are in its 3p orbital and the lone pair electrons of the nitrogen and oxygen are in the 2 p orbital.

The electron delocalization by the overlap of the 3p orbital of the sulfur with the 2p orbital of the carbon is less effective than the electron delocalization by the overlap of the 2p orbital of the nitrogen with the 2p orbital of the carbon.