Carbonyl Compounds Overview
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Questions and Answers

What is the IUPAC name of the compound with the formula $HOC_6H_4C(=O)H$?

  • Salicylaldehyde
  • Benzaldehyde
  • Vanillin (correct)
  • Cinnamaldehyde

    • Which of the following is the correct IUPAC name for 3-methylcyclohexanone?

  • 3-ethylcyclohexanone
  • 2-methylcyclohexanone
  • 3-methylcyclohexanol
  • 5-methylcyclohexanone (correct)

    • Which ketone retains its common name in the IUPAC system?

  • 2-Pentanone
  • Acetone (correct)
  • Butanone
  • Benzophenone

    • What is the general formula representation for acetophenone?

    <p>$C_6H_5C(=O)CH_3$</p> Signup and view all the answers

    What distinguishes ketones in their naming compared to aldehydes?

    <p>They end with -one</p> Signup and view all the answers

    Which reagent is less reactive than LiAlH4 and can be used to reduce esters to aldehydes?

    <p>DIBAL-H</p> Signup and view all the answers

    What product results from the reaction of an acyl chloride with lithium tri-tert-butoxy aluminum hydride at -78°C followed by hydrolysis?

    <p>An aldehyde</p> Signup and view all the answers

    In the synthesis of aldehydes from terminal alkynes, what is the primary role of THF in the reaction mechanism?

    <p>It stabilizes the borane complex</p> Signup and view all the answers

    Which condition is necessary for the reaction involving DIBAL-H to yield aldehydes from esters?

    <p>Low temperature (-78°C)</p> Signup and view all the answers

    What hydride donor is used in the reduction of acyl chlorides to aldehydes in the presence of water?

    <p>Lithium tri-tert-butoxy aluminum hydride</p> Signup and view all the answers

    Which reagent is commonly used to oxidize primary alcohols to aldehydes without over-oxidation?

    <p>Pyridinium dichromate</p> Signup and view all the answers

    What is the product of oxidizing hexanol (C6H13OH) using pyridinium dichromate?

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

    What functional group do aldehydes contain?

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

    Which of the following is formed from the oxidation of a primary alcohol?

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

    Which is an example of a compound that cannot be directly oxidized to an aldehyde?

    <p>Acetic acid</p> Signup and view all the answers

    Which of these reactions represents the oxidation of a primary alcohol to an aldehyde?

    <p>$R-CH_2OH ightarrow^{PDC} R-C(=O)-H$</p> Signup and view all the answers

    What is the oxidation state of aldehydes compared to primary alcohols and carboxylic acids?

    <p>Higher than primary alcohols</p> Signup and view all the answers

    Which aldehyde is derived from hexanoic acid by reduction?

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

    What is a common characteristic of the double bond in aldehydes and ketones?

    <p>It contains both a sigma and a pi bond.</p> Signup and view all the answers

    Which reagent is typically used for the Friedel-Crafts acylation of aromatic compounds?

    <p>Aluminum chloride</p> Signup and view all the answers

    During the hydration of alkynes, what type of compound is formed after Markovnikov addition of water?

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

    What is produced when secondary alcohols undergo oxidation?

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

    What happens to the ozonide intermediate during ozonolysis of alkenes?

    <p>It undergoes hydrolysis to yield aldehydes and ketones.</p> Signup and view all the answers

    What type of reaction mechanism does Friedel-Crafts acylation follow?

    <p>Electrophilic aromatic substitution</p> Signup and view all the answers

    Which of the following oxidizing agents can convert secondary alcohols to ketones?

    <p>Sodium dichromate</p> Signup and view all the answers

    In the hydration of alkynes catalyzed by strong acids, what role does Hg2+ ion play?

    <p>It serves as a catalyst.</p> Signup and view all the answers

    What is the structural formula for an aldehyde?

    <p>$R-C(=O)-H$</p> Signup and view all the answers

    When naming an aldehyde in IUPAC nomenclature, what suffix replaces the final -e?

    <p>-al</p> Signup and view all the answers

    What is the common name often used in place of IUPAC nomenclature for benzenecarbaldehyde?

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

    Which carbon is assigned number 1 when numbering the parent chain of an aldehyde?

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

    Which of the following is an example of a ketone?

    <p>$R-C(=O)-R'$</p> Signup and view all the answers

    What is the structure of formaldehyde?

    <p>$H-C(=O)-H$</p> Signup and view all the answers

    Which of the following aldehydes has a common name that is retained by the IUPAC system?

    <p>$H-C(=O)-CH_3$</p> Signup and view all the answers

    What is the correct IUPAC name for the compound $HOC_6H_4(OCH_3)CH_2-C(=O)-H$?

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

    Study Notes

    Carbonyl Compounds

    • Include aldehydes, ketones, carboxylic acids and carboxylic acid derivatives
    • Studied through nomenclature, classification, synthesis, reactions and physical characteristics

    Aldehydes and Ketones

    • Contain an acyl group
      • Aldehyde: R-C(=O)-H
      • Ketone: R-C(=O)-R
    • Bonded to a H or alkyl groups
      • Formaldehyde: H-C(=O)-H
      • Aldehyde: R-C(=O)-H
      • Ketone: R-C(=O)-R'

    Nomenclature (IUPAC)

    Aldehydes

    • Replace the final -e from the alkane with -al
      • Pentanal: CH3CH2CH2CH2C(=O)H
      • Butanal: CH3CH2CH2C(=O)H
      • Hexanal: CH3(CH2)4C(=O)H
    • Aldehydic carbon is assigned No. 1, despite the presence of alkyl substituents, π-bonds, or hydroxyl groups
    • When attached to a ring system, add the suffix Carbaldehyde
      • Benzenecarbaldehyde: C6H5C(=O)H
      • Cyclohexanecarbaldehyde: C6H11C(=O)H
      • 2-Naphthalenecarbaldehyde: C10H7C(=O)H
    • Benzaldehyde is more frequently used than benzene carbaldehyde
    • Examples of aldehydes:
      • Propanal: CH3CH2C(=O)H
      • 5-Chloropentanal: ClCH2CH2CH2CH2C(=O)H
      • Cyclohexanecarbaldehyde: C6H11C(=O)H
      • Benzenecarbaldehyde, Benzaldehyde: C6H5C(=O)H
      • Cyclopentanecarbaldehyde: C5H9C(=O)H
    • Common names retained in the IUPAC system:
      • Formaldehyde: H-C(=O)-H
      • Acetaldehyde: CH3-C(=O)-H
      • Methanal: H-C(=O)-H
      • Ethanal: CH3-C(=O)-H
    • Some aromatic aldehydes obtained from natural sources have pleasant fragrances:
      • Benzaldehyde: C6H5C(=O)H (from bitter almonds)
      • Vanillin: HOC6H4(OCH3)C(=O)H (from vanilla beans)
      • Salicylaldehyde: HOC6H4C(=O)H (from meadowsweet)
      • Cinnamaldehyde: C6H5CH=CHC(=O)H (from cinnamon)
      • Piperonal: C8H6O3 (made from safrole; odor of heliotrope)

    Ketones

    • Use the same procedure as for aldehydes
    • Replace the -e in the corresponding alkane with -one, assigning the lowest number to the C=O
      • Butane: CH3CH2CH2CH3
      • Butanone: CH3CH2C(=O)CH3
    • Examples of ketones:
      • Acetone: CH3C(=O)CH3 (propanone or dimethyl ketone)
      • Acetopheneone: C6H5C(=O)CH3 (1-phenylethanone or methypheyl ketone)
      • Benzophenone: C6H5C(=O)C6H5 (diphenylmethanone or diphenyl ketone)
      • 2-Butanone: CH3CH2C(=O)CH3 (ethyl methyl ketone)
      • 2-Pentanone: CH3C(=O)CH2CH2CH3 (metyl propyl ketone)
    • IUPAC rules allow naming ketones as alkyl alkyl ketones
      • Ethyl propyl ketone
    • Ketonic group (C=O) can be named as prefix (oxo)
      • 4-Oxopentanoic acid: CH3CH2CH(C=O)CH2COOH (levulinic acid)

    Nomenclature of Aldehyde and Ketones (IUPAC)

    • R-C(=O)- named as substituents called alkanoyl or acyl groups
      • Methanoyl or formyl: H-C(=O)-
      • Ethanoyl or acetyl: CH3-C(=O)-
      • 2-Methanoylbenzoic acid (o-formylbenzoic acid): HOC6H4(C=O)H
      • 4-Ethanoylbenzenesulfonic acid (p-acetylbenzenesulfonic acid): CH3C(=O)C6H4SO3H
      • 1,3-diphenyl-2-propanone: C6H5CH2C(=O)CH2C6H5
      • 3-Hexanone: CH3CH2CH2C(=O)CH2CH3 (not 4-hexanone)
      • 4-Methyl-2-pentanone: CH3CH(CH3)CH2C(=O)CH3 (not 2-methyl-4-pentanone)
      • 4-Methylcyclohexanone: CH3C6H9C(=O)
      • 4,4'-Dimethylpentanal: (CH3)2CHCH2CH(CH3)C(=O)H
      • 5-Hexenal: CH2=CHCH2CH2CH2C(=O)H
      • 2-Phenylpropanedial: C6H5CH2CH(C=O)C(=O)H
      • Cyclopentanecarbaldehyde: C5H9C(=O)H
      • 1-Naphthalenecarbaldehyde: C10H7C(=O)H

    Synthesis of Aldehydes and Ketones

    A) Synthesis of Aldehydes

    • From oxidation of 1° alcohols using pyridinium dichromate (PDC) or pyridinium chloro chromate (PCC) in anhydrous media
      • R-CH2OH -> R-C(=O)-H
    • From reduction of acyl chlorides, esters, and nitriles using aluminum hydride derivatives
    • From terminal alkynes using borane (BH3)
      • CH3C≡CH -> CH3CH2CH(OH)2 -> CH3CH2CH(OH)-OH -> CH3CH2C(=O)H
    • Borane is added anti-Markownikove's, THF aids in the process

    B) Synthesis of Ketones

    • From oxidation of 2° alcohols using Cr(VI)
      • R-C(=O)-R' -> R-C(=O)-R'
    • From ozonolysis of alkenes
      • R-C(=O)-C(=O)-R' -> R-C(=O)-R + R'-C(=O)-H
    • From hydration of alkynes using strong acids and Hg2+ ion
      • RC≡CR' + H2O -> RCCH2R’
    • From Friedel-Crafts acylation of aromatic compounds using acyl chlorides and carboxylic acid anhydrides in the presence of aluminum chloride
      • ArH + RC(=O)-Cl -> Ar-C(=O)-R + HCl
      • ArH + (RC(=O))_2O -> Ar-C(=O)-R + R-C(=O)-OH

    Physical Properties of Aldehydes and Ketones

    A) Structure and Bonding

    • Polar compounds with a dipole moment along the carbon-oxygen double bond
    • High electronegativity of oxygen displaces electron density toward oxygen in both σ and π components of C=O bond.

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