Chapter 13, Problem 37P

Interpretation Introduction

Interpretation:

The principal organic product for each reaction is to be identified.

Concept introduction:

All activating substituents in the ring are ortho and para directing.

Halogen substituents are ortho and para-directing but slightly deactivating.

Meta directing substituents are strongly deactivating.

When a benzene ring contains two or more substituents, the cumulative effects of its substituent predict its reactivity and the site of further substitution.

The regioselectivity of electrophilic aromatic substitution is controlled by the more activating substituent.

The substitution usually occurs at the less hindered site, when two positions are comparably activated.

Often the directing effects of substituents strengthen each other.

Electrophilic aromatic substation can take place at both the ortho and para positions, if an activating and o-p directing substituent is attached to a benzene ring.

If a deactivating and meta directing substituent is attached to a benzene ring, electrophilic aromatic substitution can take place at both meta positions.

Electrophilic aromatic substation can take place at both meta positions, if a deactivating and meta directing substituent is attached to a benzene ring.

For a biphenyl compound, two benzene rings are connected by a single bond. In substituted biphenyls, each ring is numbered separately using primed and nonprimed numbers. The numbering begins at the carbon containing single bond. If only one substituent is present in the biphenyl ring, then its position is designated as being ortho, meta, or para to the other ring.