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Chap 14: ALDEHYDES AND KETONES

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Aldehydes have at least one hydrogen attached to the carbonyl group. ... Starting material for plastics such as Formica and Bakelite. 18 ... – PowerPoint PPT presentation

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Title: Chap 14: ALDEHYDES AND KETONES


1
  • Chap 14 ALDEHYDES AND KETONES
  • The carbonyl group
  • Aldehydes have at least one hydrogen attached to
    the carbonyl group.
  • Ketones have two carbons attached to the carbonyl
    group.

2
  • NAMING ALDEHYDES
  • Find the longest carbon chain that contains the
    aldehyde group.
  • Change ending of the root hydrocarbon name by
    dropping e and adding al.
  • All other branches and groups are named and
    located using standard IUPAC system.
  • Examples

3
  • NAMING KETONES
  • Find the longest chain that contains CO.
  • Using the root alkane name, drop the e ending
    and change to one.
  • Number the longest carbon chain so the CO group
    has the lowest number.
  • Name and number other substituents as before.
  • Examples

4
  • PHYSICAL PROPERTIES
  • The carbonyl group is moderately polar, but it
    doesnt have any hydrogen atoms attached, so it
    cannot hydrogen bond between molecules.

5
  • PHYSICAL PROPERTIES, cont.
  • Because of the polarity of the CO group, these
    groups can interact, but the attraction is not as
    strong as hydrogen bonding.
  • This makes the boiling point of aldehydes and
    ketones higher than alkanes, but lower than
    alcohols.

6
  • PHYSICAL PROPERTIES, cont.
  • The CO group can hydrogen bond with water
    molecules.
  • This makes low molecular weight aldehydes and
    ketones water soluble (they have small
    hydrophobic sections).

H H
O R-C-R
O
7
  • ALDEHYDE AND KETONE REACTIONS
  • Recall the oxidation of alcohols to produce
    aldehydes and ketones

8
  • REACTIONS, cont.
  • The addition of H2 in the presence of catalysts.

9
  • Examples

10
  • REACTIONS, cont.
  • The addition of alcohols to aldehydes produces an
    unstable hemiacetal intermediate.

11
  • REACTIONS, cont.
  • General formulas for
  • Hemiacetals
  • Acetals

12
  • REACTIONS, cont.
  • The addition of alcohol to ketones produces an
    unstable hemiketal intermediate.

13
  • REACTIONS, cont.
  • General formula for
  • Hemiketal
  • Ketal

14
  • REACTIONS, cont.
  • Cyclical hemiacetals and hemiketals are more
    stable than open chains and are important in
    carbohydrate chemistry.

15
  • REACTIONS, cont.
  • Acetals and ketals are stable, but may be
    converted back to aldehydes and ketones through
    acid catalyzed hydrolysis. Hydrolysis is the
    breakage of a bond by reaction with water.
  • Acetal hydrolysis

16
  • REACTIONS, cont.
  • Ketal hydrolysis
  • Specific Example

17
  • IMPORTANT ALDEHYDES AND KETONES
  • Formaldehyde
  • Gas at room temperature
  • Formalin 37 aqueous solution
  • Sterilizer
  • Embalming fluid
  • Starting material for plastics such as Formica
    and Bakelite

18
  • IMPORTANT ALDEHYDES AND KETONES, cont.
  • Acetone
  • (propanone)
  • Important organic solvent
  • Used in such things as nail polish remover
  • Miscible with water

19
  • IMPORTANT ALDEHYDES AND KETONES, cont.
  • Progesterone and testosterone (female and male
    sex hormones) are ketones.
  • Some aldehydes and ketones are very fragrant and
    are used in flavorings.
  • Vanillin (vanilla)
  • Cinnamaldehyde (cinnamon)
  • Citral (citrus flavoring)
  • Camphor (medicinal odor)
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