Announcements

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Announcements Agenda (03/12/07)

• Pick Up Quizzes
• Exam THIS Wednesday!
• Covers Ch 7, 8, 10-12 (not 12.6, on Exam 3)
• Practice Exam Key Posted!
• Review TONIGHT _at_ 630p (Room 1019)
• Today
• Ethers Thiols
• Aldehydes Ketones (12.4-12.5)
• Note Benedicts Test, Tollens Test, Iodoform
  Test will not be on Wednesdays Exam!

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Last Time Alcohol Classification

• determined by the number of alkyl groups directly
  attached to the carbon bonded to the hydroxyl.
• primary (1), secondary (2), or tertiary(3).
• Primary (1º) Secondary (2º)
  Tertiary (3º)1 group 2 groups 3 groups
  H CH3 CH3
  
• CH3COH CH3COH CH3COH
  H
  H
  CH3

3
Last Time Dehydration of Alcohols

• Alcohols dehydrate when heated with an acid
  catalyst
• Lose H and OH from adjacent carbon atoms
• H OH
• HCCH H, heat HCCH H2O
• H H H H
• alcohol alkene

4
Last Time Oxidation of 1? Alcohols

• When a primary alcohol is oxidized, O,
• one H is removed from the OH.
• another H is removed from the C bonded to -OH.
• an aldehyde is produced.
• O
• Primary alcohol Aldehyde
• OH O
• O
• CH3CH CH3CH H2O
• H
• Ethanol Ethanal
• (ethyl alcohol) (acetaldehyde)

NOTE If enough oxidant around, will go on to
form carboxylic acid!
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Oxidation of Secondary (2?) Alcohols

• When a secondary alcohol is oxidized, O,
• one H is removed from the OH.
• another H is removed from the C bonded to -OH.
• a ketone is produced.
• O
• secondary alcohol ketone
• OH O
• O
• CH3-C-CH3 CH3-C-CH3 H2O
• H
• 2-propanol (isopropyl alcohol)
  2-propanol (dimethyl ketone)
• 
  

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Oxidation of Tertiary ( 3)?Alcohols

• Tertiary 3? alcohols do not readily oxidize.
  O
• Tertiary alcohol no reaction
• OH
• O
• CH3-C-CH3 no product
• CH3 no H on the C-OH to
  oxidize
• 2-methyl-2-propanol

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Oxidation of Ethanol in the Body

• In the body,
• enzymes in the liver oxidize ethanol.
• aldehyde product impairs coordination.
• blood alcohol over 0.4 can be fatal.
  O O
• 
  
• CH3CH2OH CH3CH CH3COH 2CO2
  H2O
• ethanol acetaldehyde
• acetic acid

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Ethanol CH3CH2OH

• acts as a depressant.
• kills or disables more people than any other
  drug.
• is metabolized at a rate of 12-15 mg/dL per hour
  by a social drinker.
• is metabolized at a rate of 30 mg/dL per hour by
  an alcoholic.

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Effect of Alcohol on the Body

10
Alcohol Contents in Common Products

• Ethanol Product
• 50 Whiskey, rum, brandy
• 40 Flavoring extracts
• 15-25 Listerine, Nyquil, Scope
• 12 Wine, Dristan, Cepacol
• 3-9 Beer, Lavoris

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Ethers

• contains an -O- between two carbon groups
  (R-O-R).
• has a common name that gives the alkyl names of
  the attached groups followed by ether.
• CH3-O-CH3 CH3-CH2-O-CH3
• dimethyl ether ethyl
  methyl ether

12
Boiling Points of Ethers

• Ethers
• are only modestly polar.
• have an O atom, but there is no H attached.
• cannot form hydrogen bonds between ether
  molecules.

13
Solubility of Alcohols Ethers in Water

• Alcohols and ethers
• are more soluble in water than alkanes because
  the oxygen atom can hydrogen bond with water.
• with 1-4 C atoms are soluble, but not with 5 or
  more C atoms.

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Comparing Solubility Boiling Points

• Molar Boiling
  Soluble
• Compound Mass Point (C)
  in Water?
• Alkane CH3-CH2-CH3 44 -42 No
• Ether CH3-O-CH3 46 -23 Yes
• Alcohol CH3-CH2-OH 46 78 Yes

15
Ethers as Anesthetics

• Anesthetics
• inhibit pain signals to the brain.
• like diethyl ether CH3-CH2-O-CH2-CH3 were used
  for over a century, but caused nausea and were
  flammable.
• developed by the 1960s were nonflammable.
• Cl F F
  Cl F H
• 
  
• H-C-C-O-C-H H-C-C-O-C-H
• 
  
• F F F
  H F H
• Ethane(enflurane) Penthrane

16
MTBE

• Methyl tert-butyl ether
• CH3
• CH3-O-C-CH3
• CH3
• is second in production of organic chemicals.
• is an additive used to improve gasoline
  performance.
• use is questioned since the discovery that MTBE
  has contaminated water supplies.

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Thiols

• are carbon compounds that contain a SH group.
• are named in the IUPAC system by adding thiol to
  the alkane name of the longest carbon chain.
• the -SH group may also be called a mercapto
  group

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Thiols

• Thiols
• often have strong odors.
• are used to detect gas leaks.
• are found in onions, oysters, and garlic.

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Oxidation of Thiols

• When thiols undergo oxidation,
• an H atom is lost from each of two SH groups.
• the product is a disulfide.
• O
• CH3-SH HS-CH3 CH3-S-S-CH3 H2O

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Aldehydes and Ketones

• An aldehyde contains a carbonyl group (CO),
  which is a carbon atom with a double bond to an
  oxygen atom.
• In a ketone, the carbon of the carbonyl group is
  attached to two other carbon atoms.

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Naming Aldehydes

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Aldehydes in Flavorings

• Several naturally occurring aldehydes are used as
  flavorings for foods and fragrances.

Benzaldehyde (almonds)
Cinnamaldehyde (cinnamon)
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Naming Ketones

• as IUPAC, the -e in the alkane name is replaced
  with one.
• With a common name, the alkyl groups attached to
  the carbonyl group are named alphabetically
  followed
• by ketone.
• O O
  
• CH3 -C-CH3 CH3-C-CH2-CH3 propanone
  2-butanone
• (dimethyl ketone) (ethyl
  methyl ketone)

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Ketones in Common Use

Nail polish remover, solvent Propanone,
Dimethylketone, Acetone
Butter flavoring
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Properties of Aldehydes Ketones

• The polar carbonyl group provides dipole-dipole
  interactions.
• ? ?- ? ?-
• CO CO
• Without an H on the oxygen, aldehydes and ketones
  cannot form hydrogen bonds to each other.

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Boiling Points

• Aldehydes and ketones have
• polar carbonyl groups (CO).
• ? ?-
• CO
• attractions between polar groups.
• ? ?- ? ?-
• CO CO
• higher bps than alkanes and ethers of similar
  mass.
• lower bps than alcohols of similar mass.

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Comparison of Boiling Points

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Solubility in Water

• The electronegative O atom of the carbonyl group
  of aldehydes and ketones forms hydrogen bonds
  with water.

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Tollens Test

• Tollens reagent,
• which contains Ag, oxidizes aldehydes, but not
  ketones.
• Ag is reduced to metallic Ag, which appears as
  a mirror in the test tube.

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Benedicts Test

• Benedicts reagent, which contains Cu2, reacts
  with aldehydes that have an adjacent OH group.
• An aldehyde is oxidized to a carboxylic acid,
  while Cu2 is reduced to give red Cu2O(s).