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Questions and Answers
What is the key intermediate in the Chlorination Mechanism?
What is the key intermediate in the Chlorination Mechanism?
Which mechanism involves the formation of a Wheland Intermediate?
Which mechanism involves the formation of a Wheland Intermediate?
What type of intermediate is involved in the Iodination mechanism?
What type of intermediate is involved in the Iodination mechanism?
In which mechanism is a Bromination Intermediate formed?
In which mechanism is a Bromination Intermediate formed?
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Which type of intermediate is crucial in the Nitration mechanism?
Which type of intermediate is crucial in the Nitration mechanism?
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What is the key feature of a Resonance Stabilized Intermediate?
What is the key feature of a Resonance Stabilized Intermediate?
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Which mechanism involves the most stable intermediate out of the options provided?
Which mechanism involves the most stable intermediate out of the options provided?
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What distinguishes a Wheland Intermediate from other intermediates?
What distinguishes a Wheland Intermediate from other intermediates?
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In which mechanism is electron delocalization across the benzene ring most significant?
In which mechanism is electron delocalization across the benzene ring most significant?
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Which type of intermediate requires significant stabilization due to charge separation?
Which type of intermediate requires significant stabilization due to charge separation?
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What is the defining reaction for electrophilic aromatic substitution (EAS)?
What is the defining reaction for electrophilic aromatic substitution (EAS)?
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What is another term used to refer to the species created in electrophilic aromatic substitution (EAS) known as s-complex?
What is another term used to refer to the species created in electrophilic aromatic substitution (EAS) known as s-complex?
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In electrophilic aromatic substitution (EAS), what role does the electrophile play?
In electrophilic aromatic substitution (EAS), what role does the electrophile play?
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What type of intermediate is formed during electrophilic aromatic substitution that is resonance stabilized?
What type of intermediate is formed during electrophilic aromatic substitution that is resonance stabilized?
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What is the common term used for the resonance stabilized intermediate in electrophilic aromatic substitution reactions?
What is the common term used for the resonance stabilized intermediate in electrophilic aromatic substitution reactions?
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Which of the following is NOT a common name for the resonance stabilized intermediate in electrophilic aromatic substitution?
Which of the following is NOT a common name for the resonance stabilized intermediate in electrophilic aromatic substitution?
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What type of bond is formed between benzene and the electrophile in electrophilic aromatic substitution?
What type of bond is formed between benzene and the electrophile in electrophilic aromatic substitution?
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During electrophilic aromatic substitution, what is the role of halogenation?
During electrophilic aromatic substitution, what is the role of halogenation?
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Which of the following reactions involve Friedel-Crafts Alkylation?
Which of the following reactions involve Friedel-Crafts Alkylation?
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What is the general term for adding an acyl group to a benzene ring in electrophilic aromatic substitution?
What is the general term for adding an acyl group to a benzene ring in electrophilic aromatic substitution?
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In the context of aromatic chemistry, what is a Wheland Intermediate?
In the context of aromatic chemistry, what is a Wheland Intermediate?
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What is the primary difference between Bromination and Chlorination mechanisms in aromatic chemistry?
What is the primary difference between Bromination and Chlorination mechanisms in aromatic chemistry?
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Which of the following statements is true regarding the Iodination of aromatic compounds?
Which of the following statements is true regarding the Iodination of aromatic compounds?
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What role does FeBr3 play in the Bromination mechanism in aromatic chemistry?
What role does FeBr3 play in the Bromination mechanism in aromatic chemistry?
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Why is Chlorination considered very similar to Bromination in aromatic chemistry?
Why is Chlorination considered very similar to Bromination in aromatic chemistry?
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What distinguishes Friedel-Crafts Alkylation from Friedel-Crafts Acylation?
What distinguishes Friedel-Crafts Alkylation from Friedel-Crafts Acylation?
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Which statement accurately describes the role of AlCl3 in chlorination reactions?
Which statement accurately describes the role of AlCl3 in chlorination reactions?
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Which characteristic makes Iodination easier compared to Chlorination and Bromination?
Which characteristic makes Iodination easier compared to Chlorination and Bromination?
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'FeBr3' used in Bromination serves mainly as what component?
'FeBr3' used in Bromination serves mainly as what component?
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In Friedel-Crafts Alkylation, what role does 'R-Br' play?
In Friedel-Crafts Alkylation, what role does 'R-Br' play?
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Study Notes
Aromatic Chemistry: Reactions of Benzene
- Electrophilic aromatic substitution (EAS) is a defining reaction of benzene, an electron-rich molecule.
- EAS involves the addition of an electrophile to benzene, creating a resonance-stabilized intermediate, also known as a Wheland intermediate.
Reaction Profile
- A reaction profile shows the energy changes during a reaction, with the reactants on the left and products on the right.
- The reaction profile of EAS shows the formation of a Wheland intermediate, which is a high-energy state.
Wheland Intermediate
- The Wheland intermediate is a resonance-stabilized intermediate formed during EAS.
- Its structure shows the delocalization of electrons, making it a stable species.
Electrophilic Aromatic Substitution (EAS)
- EAS is a general mechanism that involves the addition of an electrophile to benzene.
- The general mechanism involves the formation of a Wheland intermediate, followed by the loss of a proton to form the product.
Examples of EAS
- Bromination: uses FeBr3 and Br2 to form a brominated product.
- Examples of brominated products include Lonafarnib (an anticancer agent) and Bretylium (a treatment for irregular heart rhythms).
- Chlorination: uses AlCl3 and Cl2 to form a chlorinated product.
- Examples of chlorinated products include Indometacin (an NSAID) and Clorgiline (an antidepressant).
- Iodination: uses I2 and HNO3 to form an iodinated product.
- Examples of iodinated products include Calicheamicin (an antitumor agent) and Losartan (an antihypertensive).
Friedel-Crafts Alkylation
- Friedel-Crafts alkylation is a type of EAS that involves the addition of an alkyl group to benzene.
- The reaction uses an alkyl halide and AlCl3 as a catalyst.
- Examples of products include Cumene (a precursor to phenol) and Chlorambucil (a DNA alkylating agent).
Friedel-Crafts Acylation
- Friedel-Crafts acylation is a type of EAS that involves the addition of an acyl group to benzene.
- The reaction uses an acyl halide and AlCl3 as a catalyst.
- Examples of products include Raloxifene (an oestrogen receptor antagonist) and Lucanthone (an anti-parasitic agent).
Sulfonation
- Sulfonation is a type of EAS that involves the addition of a sulfonic acid group to benzene.
- The reaction uses SO3 and H2SO4 to form a sulfonated product.
- Examples of sulfonated products include Sulfanilamide (an antibacterial agent) and Sulfadoxine (an antibacterial agent).
Nitration
- Nitration is a type of EAS that involves the addition of a nitro group to benzene.
- The reaction uses HNO3 and H2SO4 to form a nitrated product.
- Examples of nitrated products include Chloramphenicol (an antibacterial agent) and Flutamide (an antiandrogen).
Summary
- EAS is a general mechanism that involves the addition of an electrophile to benzene.
- Examples of EAS include halogenation, Friedel-Crafts alkylation, Friedel-Crafts acylation, sulfonation, and nitration.
- These reactions form a wide range of products, including pharmaceuticals and agrochemicals.
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Description
Test your knowledge on Aromatic Chemistry with a focus on reaction profiles, Wheland intermediates, and examples of Electrophilic Aromatic Substitution (EAS) reactions. Explore key concepts covered in Slide 5 to Slide 8 of MPharm PHA111 lecture.
