Phenols are aromatic organic compounds where a hydroxyl group (-OH) is directly bonded to a benzene ring. This direct attachment significantly influences their properties and reactivity compared to aliphatic alcohols. Phenols are more acidic than alcohols due to the stabilization of the phenoxide ion (the conjugate base) through resonance within the benzene ring. This resonance also affects their reactivity in electrophilic aromatic substitution reactions. Understanding phenols is key to understanding many reactions and applications in organic chemistry.
Match the following terms with their definitions:
| Term | Definition |
|---|---|
| 1. Phenol | a. A reaction where an electrophile replaces a hydrogen atom on an aromatic ring. |
| 2. Aromatic | b. A salt or ester of phenol. |
| 3. Electrophilic Aromatic Substitution | c. An organic compound containing a hydroxyl group directly bonded to a benzene ring. |
| 4. Phenoxide Ion | d. Exhibiting enhanced stability due to cyclic delocalization of electrons. |
| 5. Phenyl Ether | e. The conjugate base formed when a phenol loses a proton. |
(Answers: 1-c, 2-d, 3-a, 4-e, 5-b)
Phenols are (1) __________ acidic than alcohols because the (2) __________ ion is stabilized by (3) __________ within the benzene ring. This increased acidity allows phenols to react with (4) __________ to form phenoxide salts. The presence of electron-donating groups on the benzene ring (5) __________ the acidity of the phenol.
(Answers: 1. more, 2. phenoxide, 3. resonance, 4. bases, 5. decreases)
Explain how the structure of a phenol affects its acidity compared to an aliphatic alcohol. Be sure to include resonance structures in your answer.
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