Book Cover Organic Chemistry 4e Carey
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Chapter 24: Phenols



Summary | Phenols | Preparation of Phenols | Reactions of Phenols | Reactions of Aryl Ethers | Spectroscopic Analysis | Self Assessment | Quiz |


Reactions of Phenol

Chapter 24: Phenols

Electrophilic Aromatic Substitution

electrophilic aromatic substitution of phenols

Reaction type: Electrophilic Aromatic Substitution

Summary

Reaction
Phenol
Benzene
Nitration dil. HNO3 in H2O or CH3CO2H
HNO3 / H2SO4
Sulfonation
conc. H2SO4
H2SO4 or SO3 / H2SO4
Halogenation
X2
X2 / Fe or FeX3
Alkylation
ROH / H+ or RCl / AlCl3
RCl / AlCl3
Acylation
RCOCl / AlCl3
RCOCl / AlCl3
Nitrosation
aq. NaNO2 / H+
Related reactions

Acylation of Phenols

C vs O acylation of phenols
Reaction type: C-acylation = electrophilic aromatic substitution
O-acylation = nucleophilic acyl substitution
Summary
The Fries rearrangement of aryl esters is promoted by AlCl3

Related reactions

Carboxylation of Phenols (Kolbe-Schmitt reaction)

reaction of a phenolate with CO2
Reaction type: Electrophilic Aromatic Substitution

Summary

hydrogen bonding in salicylate
Check out the CHIME image for the intramolecular hydrogen bond by looking the the position of the shared H atom with respect to the two oxygen atoms

Questions
Aspirin is the acetyl ester of salicylic acid (hence ASA),  how would you make aspirin from salicylic acid ? click for diagram
Can you think of other reactions of nucleophilic species with carbon dioxide ? Grignard reagents, RMgX, react with CO2 to give carboxylic acids, RCO2H (click to review)

Study Tip:
Consider the phenolate to be an enolate, hence reactions at the a-C are typically favored.

 
MECHANISM FOR CARBOXYLATION OF PHENOLS
Step 1:
The nucleophilic phenolate (reacting like an enolate) reacts with the electrophilic carbon of carbon dioxide in the ortho position (compare this with an Aldol reaction)
mechanism of the carboxylation of a phenolate
Step 2:
The non-aromatic cyclohexadienonecarboxylate intermediate tautomerises to the more stable aromatic enol which is further stabilized by an intramolecular hydrogen bond.  An acidic work-up will generate the carboxylic acid.

 

Preparation of Aryl Ethers

 

preparation of aryl ethers

Reaction type : Nucleophilic Substitution

Summary

Question :
Is this method suitable for the preparation of diaryl ethers such as Ph-O-Ph ? No, since aryl halides don't undergo simple nucleophilic substitution reactions

Related Reactions

Oxidation of Phenols

Summary

oxidation of a 1,2-hydroxybenzene      oxidation of a 1,4-dihydroxybenzene
 
Loss of a proton and an electron generates a phenoxy radical
Loss of a second proton and a second electron completes the oxidation.

Can you draw a curly arrow scheme that shows how the quinone may be formed from a diradical  ? click for a diagram

Related Reactions

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