Organic Chemistry: SN2 Reactions and Halides
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What happens when sulphuric acid is used during the reaction of alcohols with KI?

  • It produces iodine. (correct)
  • It produces HI. (correct)
  • It converts KI to KBr.
  • It forms an alkyl halide.

    • Alkyl halides can form hydrogen bonds with water molecules.

    False (B)

    Why are Grignard reagents prepared only under anhydrous conditions?

    They react with any source of proton to give hydrocarbons.

    The main product formed when haloalkanes react with KCN is ______.

    <p>alkyl cyanides</p> Signup and view all the answers

    Match the following halogen compounds with their reactivity in SN2 reactions:

    <p>CH2Cl = Faster SN2 reaction Cyclohexyl chloride = Slower SN2 reaction Iodine compound = Faster SN2 reaction Chlorine compound = Slower SN2 reaction</p> Signup and view all the answers

    Which halide will undergo SN2 reaction faster between CH2Cl and CHCl3?

    <p>CH2Cl (D)</p> Signup and view all the answers

    AgCN primarily forms alkyl cyanides when reacting with haloalkanes.

    <p>False (B)</p> Signup and view all the answers

    What is the reason for the low dipole moment of chlorobenzene compared to cyclohexyl chloride?

    <p>Chlorobenzene has resonance stabilization which reduces its dipole moment.</p> Signup and view all the answers

    Which factor stabilizes the carbocation formed from allylic and benzylic halides?

    <p>Resonance (C)</p> Signup and view all the answers

    P-Chloro benzene has a higher melting point than its ortho and meta isomers due to its symmetry.

    <p>True (A)</p> Signup and view all the answers

    What determines whether alkyl chlorides react to form alcohols or alkenes when treated with KOH?

    <p>The presence of aqueous or alcoholic KOH.</p> Signup and view all the answers

    Allylic and benzylic halides show high reactivity towards the __________ reaction.

    <p>SN1</p> Signup and view all the answers

    Which alkyl chloride is more easily hydrolyzed by aqueous KOH?

    <p>C6H5CHClC6H5 (B)</p> Signup and view all the answers

    The C-Cl bond in chloro benzene has a full double bond character.

    <p>False (B)</p> Signup and view all the answers

    What role do alkoxide ions (RO-) play when alkyl halides are treated with alcoholic KOH?

    <p>They act as strong bases that eliminate HX to form alkenes.</p> Signup and view all the answers

    Match the following reactions/products with their resulting types:

    <p>Aqueous KOH = Alcohol Alcoholic KOH = Alkene SN1 reaction = Carbocation formation Aryl halides = Less reactive towards nucleophilic substitution</p> Signup and view all the answers

    Why are alcohols more soluble in water than hydrocarbons of similar molecular masses?

    <p>Alcohols can form hydrogen bonds with water molecules. (A)</p> Signup and view all the answers

    Phenols are less acidic than alcohols.

    <p>False (B)</p> Signup and view all the answers

    What role does the nitro group play in the acidity of ortho nitro phenol?

    <p>The nitro group increases the polarity of the O-H bond, thereby increasing the acidity.</p> Signup and view all the answers

    In phenol, the acidity is explained by the resonance stabilization of the _________ ion.

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

    Match the following compounds with their respective characteristics:

    <p>Ortho nitro phenol = Steam volatile due to intramolecular hydrogen bonding Para nitro phenol = Less volatile due to intermolecular hydrogen bonding Methoxy phenol = Decreased acidity due to electron-donating group Phenol = More acidic than alcohol due to resonance stabilization</p> Signup and view all the answers

    What happens when phenol reacts with sodium?

    <p>It yields phenoxide and liberates hydrogen. (A)</p> Signup and view all the answers

    The lone pair on the -OH group of phenol deactivates the benzene ring towards electrophilic substitution.

    <p>False (B)</p> Signup and view all the answers

    How does the alkoxide ion differ from the phenoxide ion regarding charge localization?

    <p>The alkoxide ion localizes the negative charge on oxygen, while the phenoxide ion delocalizes the charge.</p> Signup and view all the answers

    What is the reason for the higher boiling point of ethanol compared to methoxymethane?

    <p>Ethanol undergoes intermolecular hydrogen bonding. (B)</p> Signup and view all the answers

    Aryl halides can be used in Williamson synthesis to prepare ethers.

    <p>False (B)</p> Signup and view all the answers

    Explain why aldehydes are generally more reactive than ketones in nucleophilic addition reactions.

    <p>Aldehydes are more reactive than ketones due to steric and electronic reasons.</p> Signup and view all the answers

    Benzaldehyde is __________ reactive than propanal in nucleophilic addition reactions.

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

    Match the following compounds to their corresponding properties:

    <p>Ethanol = Undergoes hydrogen bonding Methoxymethane = Does not undergo hydrogen bonding Benzaldehyde = Less reactive in nucleophilic addition Propanal = More reactive in nucleophilic addition</p> Signup and view all the answers

    What hinders the nucleophilic attack of CN- on 2,2,6-Trimethylcyclohexanone?

    <p>Steric hindrance from three methyl groups. (D)</p> Signup and view all the answers

    Phenoxide ion is stabilized by two equivalent resonating structures.

    <p>False (B)</p> Signup and view all the answers

    Why is carboxylic acid a stronger acid than phenol?

    <p>Carboxylic acid is stronger because the carboxylate ion is more stabilized due to the negative charge being on the electronegative oxygen atom.</p> Signup and view all the answers

    What is the main reason aniline is less basic than ammonia?

    <p>Aniline is involved in resonance (B)</p> Signup and view all the answers

    Cyanohydrin can be formed easily in cyclohexanone due to steric hindrance.

    <p>False (B)</p> Signup and view all the answers

    What is the disadvantage of the ammonolysis process?

    <p>It yields a mixture of primary, secondary, tertiary amines, and quaternary ammonium salts.</p> Signup and view all the answers

    Alkyl amines are _____ than ammonia.

    <p>stronger bases</p> Signup and view all the answers

    What should be removed to shift the equilibrium in ester formation in the presence of an acid catalyst?

    <p>Both water and ester (B)</p> Signup and view all the answers

    Match the following processes with their outcomes:

    <p>Cyanohydrin formation = Good yield in cyclohexanone Aniline preparation = Not suitable via Gabriel phthalimide synthesis Ammonolysis = Mixture of amines Esterification = Reversible reaction</p> Signup and view all the answers

    The lone pair of electrons on one –NH2 group in semicarbazide participates in resonance.

    <p>True (A)</p> Signup and view all the answers

    Why do aryl halides not react with potassium phthalimide in Gabriel phthalimide synthesis?

    <p>Aryl halides do not undergo nucleophilic substitution reactions under ordinary conditions.</p> Signup and view all the answers

    What is the order of basicity of amines in gas phase?

    <p>3o &gt; 2o &gt; 1o (B)</p> Signup and view all the answers

    Aniline can undergo Friedel-Crafts reaction.

    <p>False (B)</p> Signup and view all the answers

    Why is aniline more stable than anilinium ion?

    <p>Aniline can be stabilized by more resonating structures compared to anilinium ion.</p> Signup and view all the answers

    The basic strength of amines is determined by the overall effect of +I effect, hydration effect, and ______ effect.

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

    Which statement is true about the stabilization of aniline?

    <p>It has more resonating structures than anilinium ion. (D)</p> Signup and view all the answers

    Match the amines with their order of basic strength in different cases:

    <p>(CH3)2NH = 2o &gt; 1o &gt; 3o CH3NH2 = 2o &gt; 3o &gt; 1o (CH3)3N = 3o &gt; 1o &gt; 2o (C2H5)2NH = 2o &gt; 3o &gt; 1o</p> Signup and view all the answers

    Tertiary amines are less basic than secondary amines in gas phase.

    <p>True (A)</p> Signup and view all the answers

    What role do diazonium salts play in organic synthesis?

    <p>They help prepare substituted aromatic compounds that cannot be made by direct substitution.</p> Signup and view all the answers

    Study Notes

    Organic Chemistry - Reasoning Questions

    • Sulfuric Acid and KI Reaction with Alcohols: Sulfuric acid converts KI to HI and then to iodine. This prevents its use in alcohol reactions with KI.

    • Alkyl Halides and Water Miscibility: Alkyl halides are not miscible with water because they cannot form hydrogen bonds with water molecules. Energy is needed to overcome the existing hydrogen bonds in water to dissolve them, and less energy is released when the alkyl halide and water interact.

    • KCN and AgCN Reaction with Haloalkanes: KCN produces alkyl cyanides primarily because the carbon-carbon bond is more stable. AgCN forms isocyanides mainly due to the greater readiness of nitrogen to donate an electron pair.

    • SN2 Reaction Rate Comparison: Primary halides undergo SN2 reactions faster than secondary or tertiary halides. Primary halides have less steric hindrance. Iodine is a better leaving group in SN2 reactions than chlorine, so iodides react faster.

    • Grignard Reagent Preparation: Grignard reagents require anhydrous conditions because they react with protons in the presence of water to form hydrocarbons, making the synthesis useless.

    • Dipole Moment of Chlorobenzene and Cyclohexyl Chloride: Chlorobenzene has a lower dipole moment than cyclohexyl chloride due to increased electron density on the chlorine atom and conjugation with pi electrons of the ring.

    • Hydrolysis of Haloarenes: C6H5CH2Cl is more readily hydrolyzed by KOH than C6H5CHClC6H5 because the positive charge on the carbocation intermediate is more stabilized by the two phenyl groups in the second compound.

    • Melting Points of chloro-benzene Isomers: p-chlorobenzene has a higher melting point than the ortho and meta isomers. This occurs because of better crystal lattice fitting from the symmetry in p-chlorobenzene.

    • Alcohols vs. Phenols Acidity: Phenols are more acidic than alcohols due to resonance stabilization of the phenoxide ion, where the negative charge is delocalized, whereas in the alkoxide ion the negative charge is localized.

    • Acidity of Ortho Nitro and Methoxy Phenols: Ortho nitrophenol is more acidic than ortho methoxyphenol because the nitro group is electron withdrawing and increases the polarity of the O-H bond.

    • Ortho vs. Para Nitrophenol Volatility: Ortho nitrophenol is steam volatile due to intramolecular hydrogen bonding, while para nitrophenol is less volatile due to intermolecular hydrogen bonding, increasing association in the substance.

    • Reactions Showing Phenol Acidity: Phenols react with active metals like sodium and potassium to form phenoxides and release hydrogen, and they react with aqueous sodium hydroxide to form sodium phenoxide and water.

    • Electrophilic Substitution Activation in Phenols: The -OH group activates benzene rings toward electrophilic substitution due to resonance (+R effect), increasing electron density at ortho and para positions.

    • Boiling Points of Ethanol and Methoxymethane: Ethanol has a higher boiling point than methoxymethane because ethanol can form hydrogen bonds, whereas methoxymethane cannot.

    • Alcohol vs. Hydrocarbon Solubility in Water: Alcohols are more soluble in water than comparable hydrocarbons due to ability to form hydrogen bonds with water molecules.

    • Ammonolysis Disadvantages: Ammonolysis often yields a mixture of primary, secondary, tertiary amines and quaternary ammonium salts.

    Additional Topics

    • Steric Hinderance and Nucleophilic Attack in Cyanohydrin Formation: Steric hindrance in 2,2,6-trimethylcyclohexanone prevents nucleophilic attack, hindering cyanohydrin formation.

    • Semicarbazide's Reactivity: Only one amine group in semicarbazide participates in resonance, reducing its nucleophilicity.

    • Aminolysis Disadvantages: Ammonolysis often yields several amine types.

    • Comparison of Amines' Basicities: Tertiary amines are more basic in the gas phase than primary or secondary amines due to steric effects, facilitating protonation.

    • Anilinium Ion Stabilization: Anilinium ions are stabilized by resonance, lowering their basicity compared to ammonia.

    • Aniline Basicity vs. Ammonia: Aniline's basicity is reduced by resonance of its nitrogen lone pair with the aromatic ring.

    • Friedel-Crafts Reactions and Aniline: Aniline cannot undergo Friedel-Crafts reactions because the nitrogen in aniline acts as a strong deactivating group.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Grade XII Organic Reasoning Questions with Solutions PDF

    Description

    This quiz covers key concepts in organic chemistry related to the reactivity of alkyl halides, SN2 reactions, and the role of different reagents. Test your understanding of how various factors affect the reaction mechanisms, the stability of carbocations, and the behavior of haloalkanes in different chemical environments.

    More Like This

    Mastering SN1 and SN2 Reactions
    5 questions

    Mastering SN1 and SN2 Reactions

    WondrousZeal avatar
    WondrousZeal
    SN2 and SN1 Reactions Overview
    26 questions

    SN2 and SN1 Reactions Overview

    BeneficiaryPalladium5817 avatar
    BeneficiaryPalladium5817
    Organic Chemistry: SN1 and SN2 Reactions
    8 questions

    Organic Chemistry: SN1 and SN2 Reactions

    PositiveDiction4315 avatar
    PositiveDiction4315
    Organic Chemistry Reactions Quiz
    55 questions

    Organic Chemistry Reactions Quiz

    ReceptiveOceanWave3196 avatar
    ReceptiveOceanWave3196
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser