Question

Suppose you want to determine the inductive effects of a series of functional groups (e.g., \(\mathrm{Cl}, \mathrm{Br}, \mathrm{CN}, \mathrm{COOH}\), and \(\mathrm{C}_{6} \mathrm{H}_{5}\) ). Is it best to use a series of ortho-, meta-, or parasubstituted phenols? Explain.

Short answer

Answer: The best position for studying the inductive effects of the given functional groups in a phenol molecule is the para- substitution position.

Step-by-step solution

Understanding Ortho-, Meta-, and Para- Substitutions

Ortho-, meta-, and para- are the positions of substituents on an aromatic ring (like benzene) relative to some other group already on the ring. Ortho- (1,2-) substitution means the new group is next to the existing group. Meta- (1,3-) substitution means the new group is two positions away from the existing group and para- (1,4-) substitution means the new group is opposite the existing group. Phenols have a hydroxyl group (-OH) attached to the aromatic ring.

Evaluating the Impact of Substituents on Inductive Effects

Inductive effects can be best studied when interactions between functional groups are minimal. Functional groups affect electron distribution in the molecule and their influence decreases as the number of carbon atoms in between increases. Ortho- substituted phenols will have a strong interaction between the functional group and the -OH group due to their close proximity, which makes it difficult to investigate the inductive effects of the functional groups alone. Meta- substituted phenols have the functional groups at a farther distance from the -OH group but may still have some interaction due to the possibility of resonance structures and through-space electron delocalization. Para- substituted phenols have the functional groups and -OH group on opposite sides of the aromatic ring, minimizing their interactions and allowing for a better understanding of the inductive effects of the functional groups.

Conclusion

Based on the above analysis, the best position to study the inductive effects of the given functional groups (Cl, Br, CN, COOH, and C6H5) in a phenol molecule is the para- substitution position. This position allows for the least interaction between the substituted functional group and the phenol -OH group, providing a clearer view of the individual inductive effects.