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Organic
Chemistry III
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Professor
Carl C. Wamser
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Chapter
22 Notes
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Phenols
Aryl Halides - Bonding
- resonance electron donation to aromatic ring makes C-X bond stronger
and less polar
- substitution reactions don't occur readily via SN1
or SN2 mechanisms
Phenols - Bonding, Structure, and Properties
- resonance electron donation to aromatic ring makes C-O bond stronger
and less polar
- C-O bond is rarely broken
Acidity of Phenols
- O-H bond is more acidic than alcohols ( pKa ~ 10)
- phenols dissolve in NaOH solution (but not NaHCO3 -
distinguishing them from carboxylic acids)
- electron-withdrawing groups (especially o,p) increase acidity by stabilizing
phenolate anion
Reactions of Phenols
- reactive in electrophilic aromatic substitution (activating, o,p-directing)
- O-acylation (kinetic) vs. C-acylation (thermodynamic)
- Kolbe-Schmitt reaction: formation of salicyclic acid
- Claisen rearrangement: allyl
aryl ether --> o-allylphenol
- aryl alkyl ethers can be cleaved by HI to phenols
- phenolate anion is a good nucleophile for Williamson ether synthesis
- oxidations of phenols generate quinones
