Electrophilic Aromatic Substitution

Objective

The objective of this exercise is to explain the observed effects of ortho-para and meta directing substituents of electrophilic aromatic substitution in terms of the partial charge on each aromatic carbon atom.

Procedure

Use PM3 to calculate the partial charge on each unique aromatic carbon in nitrobenzene:

Use the calculated data to fill in the table below.

Position Partial Charge
Ortho  
Meta  
Para  

Use these results to state whether -NO2 is an ortho-para directing substituent or a meta-directing substituent for electrophilic aromatic substitution. Explain whether or not this result agrees with what you learned in organic chemistry. Use any piece of structure drawing software to draw appropriate resonance structures.

Similarly, determine whether -CH3 is ortho-para directing or meta-directing substituent for electrophilic aromatic substitution. Explain whether or not this result agrees with what you learned in organic chemistry.

Position Partial Charge
Ortho  
Meta  
Para  

Key Return to index