Ch. 18 - Reactions of Aromatics: EAS and BeyondSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Nucleophilic Aromatic Substitution

See all sections
Sections
Electrophilic Aromatic Substitution
Benzene Reactions
EAS: Halogenation Mechanism
EAS: Nitration Mechanism
EAS: Friedel-Crafts Alkylation Mechanism
EAS: Friedel-Crafts Acylation Mechanism
EAS: Any Carbocation Mechanism
Electron Withdrawing Groups
EAS: Ortho vs. Para Positions
Acylation of Aniline
Limitations of Friedel-Crafts Alkyation
Advantages of Friedel-Crafts Acylation
Blocking Groups - Sulfonic Acid
EAS: Synergistic and Competitive Groups
Side-Chain Halogenation
Side-Chain Oxidation
Birch Reduction
EAS: Sequence Groups
EAS: Retrosynthesis
Diazo Replacement Reactions
Diazo Sequence Groups
Diazo Retrosynthesis
Nucleophilic Aromatic Substitution
Benzyne
Additional Practice
EAS: Sulfonation Mechanism
EAS: Gatterman–Koch Reaction
EAS: Total Benzene Isomers
EAS: Polycyclic Aromatic Hydrocarbons
EAS: Directing Effects
Resonance Theory of EAS Directing Effects
Activated Benzene and Polysubstitutions
Clemmensen Reduction
EAS: Dueling Benzenes
Hydrogenation of Benzene
EAS: Missing Reagent
EAS: Synthesis
Diazonization of Aniline
Diazo Coupling Reactions
SNAr vs. Benzyne
Aromatic Missing Reagent
Aromatic Synthesis
Aromatic Retrosynthesis
EAS on 5-membered Heterocycles

In the presence of strong nucleophiles, benzene can do a Nucleophilic Aromatic Substitution, also called SNAR. Unlike EAS, where addition is initiated by the presence of a strong electrophile, addition-elimination can also be initiated by a strong nucleophile in the presence of a good aryl leaving group.

Concept #1: General Mechanism

The Dow Process (mentioned above), a typical SNAr reaction, requires tons of heat and pressure to proceed forward. This is due to the instability of the anionic sigma-complex. However, Withdrawing groups or Heteroatoms in the Ortho or Para positions (WHOP) will stabilize the intermediate.

 

Concept #2: The Meisenheimer Complex

Example #1: Which ipso-substitution is more favored

Example #2: NAS in the addition-elimination pathway

Practice: Provide the structure of the product formed from the reaction of 1-bromo-2,4,6- trinitrobenzene with one equivalent of sodium methoxide. 

Sorry for any confusion, guys. Even though Jules uses the abbrevation "NAS", just know that SNAR will be the correct, more direct term to use moving forward :).

Practice: Provide the major organic product for the following reaction.

Practice: Provide the major organic product for the following reaction. 

Practice: Which of the following compounds is most likely to undergo nucleophilic aromatic substitution via the addition-elimination pathway? 

Practice: Which of the following compounds is most likely to undergo nucleophilic aromatic substitution via the addition-elimination pathway? 

Additional Problems
Predict the major product for the following reaction paying attention to the regio- and stereochemistry.  
Predict the major product for the following reaction paying attention to the regio- and stereochemistry.
Which of the following is not true about Meissenheimer complexes? a. They are resonance-stabilized anions b. They are formed upon addition of a nucleophile to aryl halides c. They are aromatic d. They are intermediates in nucleophilic aromatic substitution reaction which take place by an addition-elimination mechanism  e. All of them are true
Place the following molecules in order of their reactivity with CH3S– Na+ via an SnAr mechanism. Label the most reactive as #1 and the least reactive as #4. Work carefully. There will be no partial credit or regrades on this problem.
Predict the principal organic product of the following reaction.
Predict the major product for each of the following reactions paying attention to the regio- and stereochemistry. If there is no reaction, write just “No Reaction.”    
Draw the structural formula of the major organic product in the box below.  
Draw a reasonable mechanism for the reaction below. 
Draw the organic product(s) for the following reaction. Indicate stereochemistry where appropriate. Assume an aqueous workup, when necessary. A reasonable answer may be “ No Reaction.”
Rank the following compounds in descending order of reactivity toward hydroxide ion with the most reactive first and the least reactive last.
Which description is most applicable to the mechanism of this reaction?
Which aryl chloride reacts the fastest with NaOH?
What is the expected product of this reaction?
Which of the following would most readily undergo a nucleophilic aromatic substitution (via the addition-elimination pathway)?
Draw the anionic intermediate in of a nucleophilic aromatic substitution (addition-elimination) involving the following reaction.Chlorobenzene and KOH
Draw the anionic intermediate in of a nucleophilic aromatic substitution (addition-elimination) involving the following reaction.4-chloropyridine and sodium methoxide
What is the product when compound T reacts with sodium methoxide in methanol at high temperatures?  
 Predict the product(s) for the following reaction. When appropriate, Iabel major and minor.
Predict the principal organic product of the following reaction.
Which of the following compounds is least reactive in the nucleophilic aromatic substitution reaction with NaOH? a. 2,4-dinitrochlorobenzene b. p-nitrochlorobenzene c. m-nitrochlorobenzene d. 3,5-dinitrochlorobenzene e. o-nitrochlorobenzene
Provide a detailed, stepwise mechanism for the following reaction.
Which one of the following would most readily undergo nucleophilic aromatic substitution via the addition-elimination pathway?
Which one of the following would most readily undergo nucleophilic aromatic substitution with sodium methoxide?
Provide the mechanism that occurs when a nucleophile Nu- reacts with 2-chloropyridine in an addition-elimination pathway
Show the anionic intermediate in a nucleophilic aromatic substitution reaction involving the following pyrimidine derivative and sodium methoxide.
Draw an example of a Meisenheimer Complex that is capable of forming at room temperature
Which one of the following compounds would most readily undergo nucleophilic aromatic substitution with Na+ -OCH3 via the addition-elimination pathway?
Two major organic products are formed in the reaction of p-chlorotoluene with sodium amide. Draw the structure of both products.
Draw the major organic product formed with para-bromonitrobenzene reacts with sodium ethoxide under heated conditions. 
Draw the structure of the organic product formed from the reaction of sodium methoxide with 1-chloro-4-nitrobenzene. Be sure to show formal charges.