Which of the following is a correct statement regarding electrophilic aromatic substitution? A. Many suitable electrophiles are unreactive and can be stored for long periods of time prior to use. B. The carbocation intermediate will lose a proton to regain aromaticity, usually from a position other than the site of the electrophilic attack. C. Formation of the carbocation intermediate has a high activation barrier due to loss of aromaticity. D. Reformation of the aromatic ring has a low activation barrier and therefore occurs slowly. E. The carbocation intermediate has several resonance structures and is negatively charged.

Which of the following is a correct statement regarding electrophilic aromatic substitution? A. Many suitable electrophiles are unreactive and can be stored for long periods of time prior to use. B. The carbocation intermediate will lose a proton to regain aromaticity, usually from a position other than the site of the electrophilic attack. C. Formation of the carbocation intermediate has a high activation barrier due to loss of aromaticity. D. Reformation of the aromatic ring has a low activation barrier and therefore occurs slowly. E. The carbocation intermediate has several resonance structures and is negatively charged.

Organic Chemistry: A Guided Inquiry

2nd Edition

ISBN:9780618974122

Author:Andrei Straumanis

Publisher:Andrei Straumanis

Chapter13: Substitution

Section: Chapter Questions

Problem 26E

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For each horizontal row of substituted benzenes, indicate a. the one that is the most reactive in an electrophilic aromatic substitution reaction. b. the one that is the least reactive in an electrophilic aromatic substitution reaction. c. the one that yields the highest percentage of meta product in an electrophilic aromatic substitution reaction.
For each horizontal row of substituted benzenes, indicatea. the one that is the most reactive in an electrophilic aromatic substitution reaction.b. the one that is the least reactive in an electrophilic aromatic substitution reaction.c. the one that yields the highest percentage of meta product in an electrophilic aromatic substitution reaction.
What is the importance of proton transfer in the formation of ester? A.The carbonyl carbon is easily attacked by the nucleophile. B. The oxygen that has been attached to the two alkyl groups will become stable. C. The removal of a bulky substituent attached to the reactive site stabilizes the compound. D. none of the above
What is the first step in the general mechanism for electrophilic aromatic substitution? a. aromatic ring protonation b.loss of the electrophilic aromatic ring c. deprotonation of the aromatic ring d.addition of the electrophilic to the aromatic ring.
Which is/are NOT TRUE about bimolecular nucleophilic substitution reactions? Select one or more: 1. A carbocation intermediate is formed. 2. A strong nucleophile displaces a halogen atom in a concerted mechanism. 3. Presence of polar aprotic solvents promotes this reaction. 4. Methyl halides react faster than secondary alkyl halides.
Why do we need to use lewis acids before electrophilic aromatic substitution reaction proceeds? to produce a better nucleophile to make the reaction proceed faster to make the starting material more activated to produce a better electrophile
Electrophilic aromatic substitutions proceed in two stages. 1. Attack of the aromatic ring on the electrophile. 2. Regeneration of the stable aromatic system by loss of a positively charged unit, usually a proton. Br Br₂/FeBr3 Draw one resonance structure for the intermediate formed when the electrophile is attacked by benzene in the reaction above. • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • Do not include lone pairs in your answer. They will not be considered in the grading.
What is the rate-determining step in an electrophilic substitution of benzene? Select one: O A. Loss of an H* ion from the arenium carbocation to reform the aromatic ring. O B. Attachment of the electrophile to the benzene ring. O C. O D. The step that generates the electrophile. regeneration of the reaction catalyst.
Specify the reaction conditions to favour the indicated elimination mechanism. a. Strong base, such as hydroxide, an alkoxide, or equivalent b. Water or alcohol or equivalent weak base with heat c. Weak acid, such as formic acid, or equivalent d. Strong base, such as hydroxide, an alkoxide, or equivalent
5. Which of the following is a true statement? A. Electrophile must be electron deficient. B. Steric effect contributes to the SN1 reactivity of tertiary alkyl halides. C. Retention products could be observed in SN2 reaction. D. The nucleophilicity of a species is equal to its basicity. E. Non-polar solvent is suitable for nucleophilic substitution.
Good nucleophiles that are weak bases favor substitution overelimination. Explain this ?
What is the rate-determining step in the mechanism of an electrophilic substitution reaction of benzene? Select one: OA. Attachment of the electrophile to benzene ring. OB. Bonding of catalyst to electrophile precursor. O C. Reformation of acid catalyst. OD. Formation of the electrophile. OE. Loss of H+ ion form arenium ion intermediate to reform aromatic ring.