carboxylic acids and their derivatives - of the simplest carboxylic acids compound systematic name...

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  • Carboxylic Acids and Their Derivatives

  • Families Containing the Carbonyl Group

    O

    CZY

    O

    CCO

    Family Y Z

    aldehyde H or C H

    ketone C C

    carboxylic acid H or C -O-H

    ester H or C -O-C

    acid halide H or C -F,-Cl,-Br,-I

    acid anhydride H or C

    amide H or C -N

  • Carboxylic Acid Functional Group

    Carbonyl + hydroxyl = Carboxyl

    General Formula: R-COOH R C O O H = The carbonyl carbon and oxygen are sp2 hybridized.

    The hydroxyl oxygen is sp3 hybridized.

  • Sources of Carboxylic Acids

    Oxidation of Primary Alcohols and Aldehydes

    R C O HH

    HR C O H

    OR C

    OH

    primary alcohol aldehyde carboxylic acid

    [O][O]

    Substituted Benzenes as a Source of Substituted Benzoic Acids

    CO O

    H

    Benzoic Acid

    MnO4-

    Cr2O72-

  • Nomenclature of Carboxylic Acids

    Names of the Simplest Carboxylic Acids

    Compound Systematic Name Trivial (Common) Name

    HCOOH Methanoic Acid Formic Acid

    CH3COOH Ethanoic Acid Acetic Acid

    CH3CH2COOH Propanoic Acid Propionic Acid

    CH3CH2CH2COOH Butanoic Acid Butyric Acid

    CH3CH2CH2CH2COOH Pentanoic Acid Valeric Acid

    CH3CH2CH2CH2CH2COOH Hexanoic Acid Caproic Acid

    CH3CH2CH2CH2CH2CH2COOH Heptanoic Acid Enanthic Acid

    Systematic Nomeclature

    CH3CH2CH2CHCH2COOH

    CH33-methyl hexanoic acid

    -methyl caproic acid

    CH2CHCOOH

    NH22-amino-3-phenylpropanoic acid

    phenylalanine

  • Physical Properties of Carboxylic Acids

    Boiling Points - Higher than alcohols of similar

    molecular weight

    Carboxylic acids self associate through hydrogen bonds.

    R CO

    O HRC

    O

    OH

    Water Solubility- More water soluble than ethers,

    aldehydes, ketones and alcohols of similar molecular weight

    Carboxylic acids have three opportunities for hydrogen

    bonding.

    R CO

    O H

    HO

    H

  • H3CCH2

    C

    O

    O HO

    H

    H

    H3CCH2

    C

    O

    O

    OH

    HH

    propanoic acidwater

    propanoate ion

    hydronium ion

    Acidity of Carboxylic Acids

  • Acidity of Carboxylic AcidsCarboxylic acids are generally stronger acids than

    phenols but weaker than mineral acids.

  • CH3C

    O

    O H

    CH3C

    O

    O

    OH

    H

    + NaOH

    Na+

    Chemical and Physical Properties of Carboxylic Acids

    Carboxylic acids react with bases.

    acetic acid

    sodium acetate

    Carboxylate salts are ionic and possess much higher boiling and melting points than those of the corresponding carboxylic acids

    (Ionic forces are much stronger than secondary forces).

    Sodium acetate: MP 324C, solid at room temperature Acetic acid: MP 17C, liquid at room temperature

  • Carboxylic acids that have 6 or more carbons are only slightly soluble or insoluble in water. Carboxylate salts are much more soluble than

    their corresponding carboxylic acids because of their ionic nature.

    Chemical and Physical Properties of Carboxylic Acids

    Carboxylic acids have increased solubilities in neutral or basic environments because the acids are converted into

    their carboxylate ions.

    H3CCH2

    CH2CH2

    CH2CH2

    CH2C

    O

    OH

    + NaOH

    H3CCH2

    CH2CH2

    CH2CH2

    CH2C

    O

    O_

    + H2O

    Na+

    H3CCH2

    CH2CH2

    CH2CH2

    CH2C

    O

    OH H3CCH2

    CH2CH2

    CH2CH2

    CH2C

    O

    O_

  • Worksheet

  • CH3CH2 C

    O

    CH CH

    CH3

    CH3

    OHa.

    b.

    CO

    O H

    Cl

    H3C

    H3C

    1. Give an appropriate name for each compound.

  • 2. Give structure(s) and name(s) for the major organic product(s) of the following reactions

    a. _____________________________________ b. _____________________________________

    CH3CH2 C

    O

    CH CH

    CH3

    CH3

    OH NaOH, H2O

    CO

    O H

    Cl

    H3C

    H3C KOH, H2O

  • Carboxylic Acid Esters

    R C

    O

    OH RHO R C

    O

    RO+ + H2OH+

    Synthesized from a carboxylic acid and an alcohol:

    carboxylic acid alcohol or

    phenol

    ester

    Nomenclature base on parent alcohol and carboxylic acid:

    CH3 C

    O

    OH CH3HO CH3 C

    O

    CH3OCH2CH2 + + H2O

    methanolpropanoic acid methyl propanoate

    hydrolysis

    condensation

  • Worksheet

  • Carboxylic Acid EstersAdditional Nomenclature examples:

    CH3 C

    O CH3

    CH2O

    CH3

    CH

    C

    O

    CH3CH2OCH3CH2CHCH2CH3

    C

    OCH3

    CH O CH3CH2CH2CH3

    isobutyl acetate

    ethyl 3-methyl pentanoate

    isopropyl butanoate

  • 4. Give an appropriate name for each compound. a.

    b.

    c.

    CO

    O CH2F

    F

    CH3

    COCH2 CH

    CH3

    CH3

    O

    OC

    O

    CH2 CHCH3

    CH3

    `ethyl 2,4-difluoro benzoate

  • Physical Properties of Esters

    Ester molecules cannot hydrogen bond to each other.

    Therefore, esters have much lower boiling and melting points than those of carboxylic acids.

    Propanoic acid, bp 141C Methyl acetate , bp 57C

    Esters are less soluble in water than are carboxylic acids because esters cannot form as many hydrogen bonds to

    water molecules as can carboxylic acids.

    CH3 C

    O

    OHCH2 CH3 C

    O

    CH3O

  • Physical Properties of Esters

    The secondary forces in esters are weaker than those in aldehydes and ketones, and thus esters have lower melting

    and boiling points.

    Methyl acetate, bp 57C Butanal, bp 76C

    Esters have about the same water solubilities as aldehydes and ketones because all three hydrogen bond to water equally well.

    CH3 C

    O

    CH3O C

    O

    CH3CH2CH2 H

  • Esters Have Characteristic Odors

    C

    O

    O C

    O

    OCH3C

    O

    OCH2CH3

    Pear ApplePineapple

    C

    O

    OHC

    O

    O

    Raspberry Rum

    C

    O

    O

    Banana

    C

    O

    O

    C

    O

    OOrangePeach

  • Amides - Structure and Classification

    Subclassification

    C

    O

    NH

    H

    R1C

    O

    N

    H

    R1R2 C

    O

    NR1R2

    R3

    1 2 3

    Can amides engage in hydrogen bonding??

  • Amides - Structure and Classification

    The amide is better represented as a dipolar ion:

    C

    O

    N C

    O

    N

    Because the bond between the carbonyl carbon atom and the nitrogen atom has a partial double bond character, the bond angles about the carbonyl carbon atom and nitrogen atom are both close to 120 (sp2 hybridization).

    The dipolar ion nature of the amide bond is very important in determining the structure and function of protein molecules.

  • Amides - Synthesis

    At low temperatures a carboxylic acid and an amine will take part in a simple acid-base reaction to form an ammonium salt.

    R1 C

    O

    OH R2H N R1 C

    O

    O+R3

    R2H N

    R3

    H

    20-50o C

    carboxylic amine ammonium acid carboxylate

  • Amides - Synthesis

    At a higher temperature, a condensation reaction takes place between the carboxylic acid and the amine.

    carboxylic ammonia primary acid amide

    carboxylic 1 amine secondary acid amide

    R1 C OH HH N+H

    R1 C

    O

    H N

    H>100o C+ H2O

    O

    R1 C

    O

    OH R2H N+H

    R1 C

    O

    R2 N

    H>100o C+ H2O

    carboxylic 2 amine tertiary acid amide

    R1 C

    O

    OH R2H N+R3

    R1 C

    O

    R2 N

    R3>100o C+ H2O

  • Amides - Nomenclature

    CH3C C

    O

    H N

    HCH3

    CH3

    2,2-dimethyl propanamide

    HN CH2CH2CH3C

    O

    N-propyl benzamide

  • Amides - Synthesis and Nomenclature

    CH3 C

    O

    OH CH3H N+H

    CH3 C

    O

    CH3 N

    H>100o C+ H2O

    acetic acid methylamine N-methylacetamide

    NH2

    C

    O

    OCH3C

    O

    CH3+

    HN CH3C

    O

    + CH3COOH

    aniline acetic N-phenyl acetic anhydride acetamide acid

  • H CH2CH3CO

    NCH2CH2CH3

    NO2

    CH2CH3CO

    NH

    HC

    O

    OHformic acid

    CO

    OH

    benzoic acid

  • Amides - Physical Properties

    Amides have the strongest secondary attractive forces and the highest melting and boiling points of any covalent organic compounds.

    Potential Hydrogen Bonds:

    R CO

    N H

    H

    RCO

    NH

    H

  • Amides - Physical Prop

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