Electrophilic Aromatic Substitution Quiz
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Questions and Answers

What is the primary effect of activating groups on substituted benzene during electrophilic attack?

  • They decrease the overall reactivity compared to benzene.
  • They influence both the rate of the reaction and the site of attack. (correct)
  • They solely determine the rate of the reaction.
  • They only affect the reactivity of the ring.

    • Which position do activating groups primarily direct substitution in during electrophilic aromatic substitution?

  • Meta position only.
  • Ortho and para positions. (correct)
  • Equally among all positions.
  • None of the above.

    • When toluene is nitrated, what percentage of the product is expected to be meta-nitrotoluene?

  • 37%
  • 96%
  • 4% (correct)
  • 59%

    • What is considered an example of an activating group in electrophilic substitution?

    <p>Methyl group.</p> Signup and view all the answers

    In the nitration of toluene, what is the ratio of ortho- to para-nitrotoluene products obtained?

    <p>59:37</p> Signup and view all the answers

    Which statement is true about the reactivity of toluene compared to benzene?

    <p>Toluene is more reactive than benzene.</p> Signup and view all the answers

    What type of directors are groups that lead to a higher reactivity in electrophilic substitution?

    <p>Ortho-para directors.</p> Signup and view all the answers

    What will happen to the reactivity of a substituted benzene ring if a deactivating group is present?

    <p>It becomes less reactive than benzene.</p> Signup and view all the answers

    Which of the following compounds is also known as p-chlorophenol?

    <p>4-chlorophenol</p> Signup and view all the answers

    What is the generic name for compounds like o-cresol, m-cresol, and p-cresol?

    <p>Methyl phenols</p> Signup and view all the answers

    Which of the following is a type of benzenediol?

    <p>Resorcinol</p> Signup and view all the answers

    What functional group characterizes phenols?

    <p>Hydroxyl group</p> Signup and view all the answers

    Why do phenols have relatively high boiling points compared to alcohols with similar molecular weights?

    <p>Intermolecular hydrogen bonding</p> Signup and view all the answers

    Which naturally occurring phenol is found in oil of cloves?

    <p>Eugenol</p> Signup and view all the answers

    What is the boiling point of phenol?

    <p>182°C</p> Signup and view all the answers

    Compared to alcohols, how are phenols classified in terms of acidity?

    <p>Stronger acids</p> Signup and view all the answers

    What are the starting organic compounds in the Cumen hydro peroxide process?

    <p>Benzene and propene</p> Signup and view all the answers

    At what temperature range does the second reaction of the Cumen hydro peroxide process occur?

    <p>95-135°C</p> Signup and view all the answers

    What type of reactions do phenols readily undergo?

    <p>Aromatic electrophilic substitution reactions</p> Signup and view all the answers

    Which aspect of the hydroxyl group in phenols influences its chemical reactivity?

    <p>It is ring-activating and ortho - para directing</p> Signup and view all the answers

    What is a consequence of phenols being used as antioxidants?

    <p>They can trap peroxy radicals</p> Signup and view all the answers

    How do phenols compare to alcohols in terms of acidity?

    <p>Phenols are stronger acids than alcohols</p> Signup and view all the answers

    What is formed alongside phenol in the final step of the Cumen hydro peroxide process?

    <p>Acetone</p> Signup and view all the answers

    What type of compound undergoes oxidation to form benzo-1,4-quinone?

    <p>Phenols</p> Signup and view all the answers

    What property makes phenols acidic?

    <p>The benzene ring withdraws electrons, making the oxygen atom positive.</p> Signup and view all the answers

    How do phenols react with carboxylic acid anhydrides?

    <p>They form esters through substitution reactions.</p> Signup and view all the answers

    Which statement is true regarding the solubility of phenols and carboxylic acids in aqueous NaHCO3?

    <p>Carboxylic acids are soluble, while phenols are not.</p> Signup and view all the answers

    What is the characteristic reaction pattern of benzene compared to the Kekule structure?

    <p>Benzene preferentially undergoes substitution reactions.</p> Signup and view all the answers

    What does a heat of hydrogenation of Δ° = -120 kJ/mol indicate about cyclohexane?

    <p>Cyclohexane is thermodynamically stable.</p> Signup and view all the answers

    What is the main difference in stability between conjugated and isolated double bonds?

    <p>Conjugated double bonds are usually more stable than isolated double bonds.</p> Signup and view all the answers

    Why is the stability of benzene greater than that predicted by the Kekule structure?

    <p>It can resonate between multiple forms.</p> Signup and view all the answers

    Which heat of hydrogenation result is consistent with the stability of 1,3-cyclohexadiene?

    <p>Δ° = -240 kJ/mol.</p> Signup and view all the answers

    What is the initial step in side-chain oxidation of alkylbenzenes?

    <p>Oxidizing the benzylic hydrogen</p> Signup and view all the answers

    What is produced as a final product when alkenylbenzenes with longer alkyl groups undergo oxidation?

    <p>Benzoic acids</p> Signup and view all the answers

    When using KMnO4 and H3O+ in side-chain oxidation, which part of the molecule is predominantly oxidized?

    <p>The benzylic carbon</p> Signup and view all the answers

    Which groups can undergo side-chain oxidation with hot alkaline potassium permanganate?

    <p>Alkenyl, alkynyl, and acyl groups</p> Signup and view all the answers

    Which additional reagent is needed after KMnO4 for converting the benzene ring to a carboxyl group?

    <p>H2O2</p> Signup and view all the answers

    What happens to the carbon atoms in the side chain during the oxidation process?

    <p>They are cleaved off and lost</p> Signup and view all the answers

    In the steps of oxidation described, what form does the central carbon atom take before it is oxidized to a carboxyl group?

    <p>A benzylic carbon</p> Signup and view all the answers

    What is a notable feature of side-chain oxidations compared to benzylic halogenations?

    <p>Both involve the abstraction of benzylic hydrogen</p> Signup and view all the answers

    Study Notes

    Electrophilic Aromatic Substitution

    • Activating groups: increase the rate of electrophilic aromatic substitution
    • Ortho-para directors: groups that direct the electrophilic attack to the ortho and para positions
    • Methyl group (CH3) is an activating group and an ortho-para director: toluene, a compound with a methyl group on a benzene ring, reacts faster than benzene in electrophilic substitution

    Specific Examples of Aromatic Compounds

    • Phenol is the base name for many compounds with a hydroxyl group (OH) and a benzene ring
    • Cresols are methyl phenols, with a methyl group and a hydroxyl group on a benzene ring.
    • Benzenediols are compounds with two hydroxyl groups on a benzene ring.
    • Examples of naturally occurring phenols: tyrosine (amino acid), methyl salicylate (oil of wintergreen), eugenol (oil of cloves), thymol (thyme)

    Properties of Phenols

    • Higher boiling points compared to similar molecular weight compounds due to intermolecular hydrogen bonding
    • Stronger acids than alcohols due to resonance and charge delocalization in phenoxide ions

    Reactions of Phenols

    • Undergo aromatic electrophilic substitution reactions; hydroxyl group is ring-activating and ortho-para directing
    • Phenols with large groups ortho to the hydroxyl group are useful as antioxidants
    • Phenols can be oxidized
    • Phenols are acidic, with pKa values smaller than 11
    • Phenols react with carboxylic acid anhydrides and acid chlorides to form esters

    Distinguishing and Separation of Phenols from Other Compounds

    • Phenols dissolve in NaOH, but most alcohols do not.
    • Most phenols are insoluble in aqueous $NaHCO_3$, but carboxylic acids are soluble.

    Stability of Benzene

    • Benzene is more stable than suggested by its Kekule structure due to thermochemical results.
    • Hydrogenation of cycloalkanes and cycloalkenes provides evidence for the stability of benzene.

    Oxidation Reactions of Benzene

    • Potassium permanganate (KMnO4) in base can oxidize the side chains of alkylbenzenes, ultimately producing benzoic acid.
    • Alkenyl, alkynyl, and acyl groups can also be oxidized by hot alkaline potassium permanganate.
    • Ozonolysis, followed by hydrogen peroxide treatment, can convert the benzene ring of an alkylbenzene to a carboxyl group.

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    Description

    Test your knowledge on electrophilic aromatic substitution! This quiz covers key concepts such as activating groups, ortho-para directors, and specific examples of aromatic compounds like phenols and cresols. Dive into the fascinating world of organic chemistry and enhance your understanding of aromatic reactions.

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