Alcohols, Ethers, and Thiols

1
Alcohols, Ethers, and Thiols

• Structure
• Nomenclature
• Properties
• Reactions of Alcohols

2
Compounds

• Alcohols -OH hydroxyl CH3-OH
• CH3CH2-OH
• Ethers -O- CH3-O-CH3
• Thiols -SH sulfhydryl CH3-SH
• CH3CH2-SH

3
Learning Check Al1

• Classify each as an alcohol, ether, or a thiol
  
• _____ CH3CH2-O-CH3
• B. _____ CH3CH2OH
• C. _____ CH3CH2CH2SH

4
Solution Al 1

• Classify each as an alcohol, ether or thiol
• __ether__ CH3CH2-O-CH3
• __alcohol__ CH3CH2OH
• __thiol CH3CH2CH2SH

5
Alcohols

• In an alcohol, a hydroxyl group (OH) is attached
  to a carbon chain.
• In a phenol, a hydroxyl group (OH) is attached
  to a benzene ring.

6
Classification of Alcohols

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

7
Learning Check

• Classify each alcohol as
• 1) primary, 2) secondary, or 3) tertiary.
• OH
• A. ___CH3CHCH2CH3
• B. ___ CH3CH2CH2OH
• C. ____HOCH2CH2CH2CH2CH3

8
Solution

• Classify each alcohol as
• 1) primary, 2) secondary, or 3) tertiary.
• OH
• A. 2 CH3CHCH2CH3
• B. 1 CH3CH2CH2OH
• C. 1 HOCH2CH2CH2CH2CH3

9
Alcohols

• Alcohol OH group is covalently held by a
  saturated carbon bond
• Found in major kinds of organic substances such
  as carbohydrates, proteins, nucleic acids

10
Classification of Alcohols

• Simple alcohols
• monohydric alcohols have one OH
• dihydric alcohols have 2 OH groups
• trihydric alcohols have 3 OH groups
• CH3CH2CH2OH CH2CH CHOH
• Monohydric
  
• OH OH
• Dihydric Trihydric

OH
OH
11
Classification of Alcohols

• Primary (1º) Secondary (2º ) Tertiary (3º)
• H CH3 CH3
• CH3-C-OH CH3-C-OH CH3-C-OH
• H H
  CH3
• 1 CH3 2 CH3 3 CH3
• attached attached attached
• to C-OH to C-OH to C-OH

12
Learning Check Ox-Red 1

• Classify the following monohydric alcohols as 1º,
  2º, or 3º
• OH
• A. CH3CH2CH2OH B. CH3-CH-CH2CH3
• C. D. OH
• CH3-C-CH2CH3
• CH3

13
Solution Ox-Red 1

• Classify the following monohydric alcohols as 1º,
  2º, or 3º
• OH
• A. CH3CH2CH2OH 1º B. CH3-CH-CH2CH3 2º
  
• C. 2º D. OH
  3º
• CH3-C-CH2CH3
• CH3

14
Naming Alcohols

• A carbon compound that contain -OH (hydroxyl)
  group
• In IUPAC name, the -e in alkane name is replaced
  with -ol.
• CH4 methane
• CH3OH methanol (methyl alcohol)
• CH3CH3 ethane
• CH3CH2OH ethanol (ethyl alcohol)

15
Naming Alcohols

• IUPAC- rules similar to those for naming alkanes
• Determine the parent alcohol chain by selecting
  the longest parent chain of C that includes the C
  to which the OH is attached
• Number the parent chain from whichever end gives
  the lower to the C that holds the OH
• OH takes precedence over alkyl groups or
  halogen atoms
• CH3
  CH3
• CH3CHCH2CH2OH CH3CCH2CH2CHCH2CH3
• 
  CH3 OH

16
Naming Alcohols

• Write the that locates the OH group in front of
  the name of the parent chain and separate this
  from the name of the parent by a hyphen
• When 2 or more OH groups are present, use name
  endings such as diol (for 2-OH groups) triol
  (for 3-OH groups)
• HO-CH2-CH2-OH
• 1,2-ethanediol

17
Naming Alcohols

• Compounds containing -OH and CC are referred to
  as unsaturated alcohols. In numbering the parent
  chain, the location of the -OH takes precedence
  over the CC.
• HOCH2CH2 CH2CH3
• C C
  
• H H
• cis-3-hexen-1-ol

18
More Names of Alcohols

• IUPAC names for longer chains number the chain
  from the end nearest the -OH group.
• CH3CH2CH2OH 1-propanol
• OH
• CH3CHCH3 2-propanol
• CH3 OH
• CH3CHCH2CH2CHCH3 5-methyl-2-hexanol

19
Learning Check Al 2

• Name the following alcohols
• A. OH
• CH3CHCHCH2CH3
• CH3
• OH
• B.

20
Solution Al 2

• Name the following alcohols
• A. OH 3-methyl-2-pentanol
• CH3CHCHCH2CH3
• CH3
• OH
• B. cyclobutanol

21
Naming Alcohols

• The IUPAC system replaces the -e in the name of
  the alkane main chain with ol.
• Common names for simple alcohols use the alkyl
  name followed by alcohol.
• CH4 methane CH3OH methanol
  (methyl alcohol)
• CH3CH3ethane CH3CH2OH ethanol
  (ethyl alcohol)

22
Naming Alcohols

• In the IUPAC names for longer chains, the chain
  is numbered from the end nearest the -OH
  group.CH3CH2CH2OH 1-propanol
  OH CH3CHCH2CH3 2-butanol
  CH3 OH
  CH3CHCH2CHCH3
  4-methyl-2-pentanol

23
Some Typical Alcohols

• OH
• rubbing alcohol CH3CHCH3
• 2-propanol (isopropyl alcohol)
• antifreeze HOCH2CH2OH
• 1,2-ethanediol (ethylene glycol)
• 
  OH
• glycerol HOCH2CHCH2OH
• 1,2,3-propanetriol

24
Learning Check

• Name the following
• A. CH3CH2CH2CH2OH
• OH CH3
• B. CH3CHCHCH2CH3
• C.

25
Solution

• A. CH3CH2CH2CH2OH
• 1-butanol
• OH CH3
• B. CH3CHCHCH2CH3
• 3-methyl-2-pentanol
• C. cyclopentanol

26
Learning Check

• Write the structure of each of the following
• A. 3-pentanol
• B. ethyl alcohol
• C. 3-methylcyclohexanol

27
Solution

• Write the structure of the following
• A. 3-pentanol OH
• CH3CH2CHCH2CH3
• B. ethyl alcohol CH3CH2OH
• C. 3-methylcyclohexanol

28
Naming Phenols

• A phenol is a benzene ring with a hydroxyl group.
  
• For two substituents, assign C-1 to the carbon
  attached to the OH.
• Number the ring to give the lowest numbers.
• The prefixes o, m, and p are used for common
  names.

29
Examples of Phenols
30
Phenols in Medicine

• Many phenols are used as antiseptics and
  disinfectants.

31
Derivatives of Phenol

• Compounds of phenol are the active ingredients in
  the essential oils of cloves, vanilla, nutmeg,
  and mint.

32
Thiols

• Thiols are carbon compounds that contain the SH
  group.
• In the IUPAC name, thiol is added to the alkane
  name of the longest carbon chain.

33
Naming Thiols

• In thiols with long carbon chains, the chain is
  number to locate the -SH group.CH3CH2CH2SH
  1-propanethiol SH
  CH3CHCH3
  2-propanethiol

34
Thiols in Nature

• Thiols
• Often have strong or disagreeable odors.
• Are used to detect gas leaks.
• Are found in onions, oysters, and garlic.

35
Ethers

• Ethers contain an -O- between two carbon groups.
• Simple ethers are named by listing the alkyl
  names in alphabetical order followed by
  ether.CH3OCH3 dimethyl
  etherCH3OCH2CH3 ethyl methyl
  etherCH3CH2OCH2CH3 diethyl ether

36
Naming Ethers

• Contain an -O- between two carbon groups
• The common names of ethers made by naming the
  attached alkyl groups alphabetically and adding
  ether.
• IUPAC names are seldom used for simple ethers
• CH3-O-CH3 dimethyl ether
• CH3-O-CH2CH3 ethyl methyl ether

37
IUPAC Names for Ethers

• In the IUPAC system, the shorter alkyl group and
  the oxygen are named as an alkoxy group attached
  to the longer alkane.
• methoxy propane
• CH3OCH2CH2CH3
• Numbering the longer alkane gives
• 1-methoxypropane.

38
Learning Check

• Name each of the following compounds
• A. CH3CH2 OCH2CH3
• CH3
• B. CH3CH2CHCH2CH2OH
• C. CH3CH2CH2SH

39
Solution

• Name each of the following compounds
• A. CH3CH2 OCH2CH3
• Diethyl ether or ethoxyethane (IUPAC)
• CH3
• B. CH3CH2CHCH2CH2OH
• 3-Methyl-1-pentanol
• C. CH3CH2CH2SH
• 1-Propanethiol

40
Learning Check

• Draw the structure of each compound.
• A. 2-Butanethiol
• B. Ethyl methyl ether
• C. 2-Methyl-1-butanol

41
Solution

• Draw the structure of each compound.
• A. 2-Butanethiol
• SH
• CH3CHCH2CH3
• B. Ethyl methyl ether CH3CH2OCH3
• C. 2-Methyl-1-butanol
• CH3
• HOCH2CHCH2CH3

42
Learning Check

• CH3CHOCH3
• CH3

B.
O
C. CH3CH2CH2OCH3
43
Solution

• CH3CHOCH3
• CH3

isopropyl methyl ether dicyclohexyl
ether methyl propyl ether
B.
O
C. CH3CH2CH2OCH3
44
MTBE

• Methyl tert-butyl ether
• CH3
• CH3-O-C-CH3
• CH3
• Second in production or organic chemicals
• Additive to improve gasoline performance
• Use in question with discovery of contaminated
  water supplies

45
Ethers as Anesthetics

• Anesthetics inhibit pain signals to the brain
• CH3CH2-O-CH2CH3 used for over a century (Morton,
  1846)
• Causes nausea and is highly flammable
• 1960s developed nonflammable anesthetics
• Cl F F
  Cl F H
• H-C-C-O-C-H H-C-C-O-C-H
• F F F
  H F H
• Ethrane
  Penthrane

46
Thiols

• Contain the functional group -SH
• Named by adding thiol to the name of the longest
  carbon chain that contains the SH
• Retain the final e.
• Number the -SH group in longer chains
• CH3-SH methanethiol
• CH3-CH2SH ethanethiol
• SH
• CH3-CH-CH3 2-propanethiol

47
Thiols

• Many thiols have disagreeable odors
• Used to detect gas leak
• Found in onions, oysters, and garlic
• Onions CH3CH2CH2-SH
• Garlic CH2 CHCH2-SH
• Skunk spray
• CH3 H
  C C
• H CH2SH
• trans-2-butene-1-thiol

48
Learning Check Ox-Red 4

• Write the structure of the following
• A. 3-pentanol
• B. Dimethyl ether
• C. 3-methylcyclobutanol

49
Solution Ox-Red 4

• Write the structure of the following
• OH
• A. 3-pentanol CH3CH2CHCH2CH3
• B. Dimethyl ether CH3-O-CH3
• C. 3-methylcyclobutanol

50
Boiling Points of Alcohols

• Alcohols contain a strongly electronegative O in
  the OH groups.
• Thus, hydrogen bonds form between alcohol
  molecules.
• Hydrogen bonds contribute to higher boiling
  points for alcohols compared to alkanes and
  ethers of similar mass.

51
Physical Properties of Alcohols

• Hydrogen bonding dominates the physical
  properties
• OH is quite polar it can donate or accept
  hydrogen
• bonds
• Much higher boiling points greater solubility in
  water than hydrocarbons of the same mass
• Special enzymes in the liver attach OH groups to
• molecules of toxic substances to make them
  more soluble

52
Physical Properties of Alcohols
53
Physical Properties of Alcohols

• C and H have nearly identical electronegativities
  
• Large difference in electronegativity between C-O
  and O- H
• Polar compounds
• Molecule is attracted to 2 neighboring molecules
  by 2 H bonds
• Water is attracted to 3 neighboring molecules by
  3 H bonds

H
O
H
O
H
H
O
H
O
CH3
H
H
54
Physical Properties of Alcohols

• As the size of the R group (R-OH) in a monohydric
  alcohol molecules increases, the alcohol molecule
  became more and more alkane-like.
• H20 has no attraction for the long hydrocarbon
  chains
• Alcohols w/ 5 or more C are insoluble in water
  however, they do dissolve in nonpolar solvents

55
Boiling Points of Ethers

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

56
Physical Properties of Ethers

• Almost as chemically unreactive as alkanes.
• Cannot donate H bonds
• The O of the ether can accept H bonds therefore
  ethers are more soluble in water than alkanes
• Both 1-butanol its isomer diethyl ether
  dissolves in water to a greater extent than
  pentane

57
Physical Properties of Ethers
The boiling points of simple ethers are like
those of the alkanes of comparable formula mass
much less than alcohols
58
Solubility of Alcohols and Ethers in Water

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

59
Physical Properties of Thiols

• Small difference in electronegativity between
• S-H therefore nonpolar covalent bond
• Lack of polarity
• Little association by H bonding
• Less soluble in H2O than other polar solvents
  alcohols

60
Physical Properties of Thiols
61
Reactions of Alcohols

• Alcohols undergo combustion with O2 to produce
  CO2 and H2O.
• 2CH3OH 3O2 2CO2 4H2O Heat
• Dehydration removes H- and -OH from adjacent
  carbon atoms by heating with an acid catalyst.
• H OH
• H, heat
• HCCH HCCH H2O
• H H H H
• alcohol alkene

62
Reactions of Alcohols
Zaitsevs rule dehydration of alcohol normally
forms the alkene with the more highly substituted
(or more highly branched) double bond. B/c of
stability EASE OF
DEHYDRATION 1o alcohols 2o alcohols
3o alcohols
H CH3
CH3 CH3-C-OH CH3-C-OH CH3-C-OH H
H
CH3
63
Formation of Ethers

• Ethers form when dehydration takes place at low
  temperature.
• H
• CH3OH HOCH3 CH3OCH3 H2O
• Two Methanol Dimethyl ether

64
Oxidation

• Is a gain of oxygen (O)
• or
• A loss of hydrogen (H)

65
Oxidation of Alcohols

• 1alcohols are oxidized to aldehydes and 2
  alcohols are oxidized to ketones
• Alcohols
• 1 2
• aldehydes ketones

66
Oxidation and Reduction

• In organic chemistry, oxidation is a loss of
  hydrogen atoms or a gain of oxygen.
• In an oxidation, there is an increase in the
  number of C-O bonds.
• Reduction is a gain of hydrogen or a loss of
  oxygen. The number of C-O bonds decreases.

67
Oxidation of Primary Alcohols

• In the oxidation O of a primary alcohol, one H
  is lost from the OH and another H from the
  carbon bonded to the OH.
• O
• Primary alcohol Aldehyde
• OH O
• O
• CH3CH CH3CH H2O
• H
• Ethanol Ethanal
• (ethyl alcohol) (acetaldehyde)

68
Oxidation of Secondary Alcohols

• The oxidation of a secondary alcohol removes one
  H from OH and another H from the carbon bonded
  to the OH.
• O
• Secondary alcohol Ketone
• OH O
• O
• CH3CCH3 CH3CCH3 H2O
• H
• 2-Propanol Propanone
• (Isopropyl alcohol) (Dimethylketone
  Acetone)

69
Oxidation of Tertiary Alcohols

• Tertiary alcohols are resistant to
  oxidation. O
• Tertiary alcohols no reaction
• OH
• O
• CH3CCH3 no product
• CH3 no H on the C-OH to
  oxidize
• 2-Methyl-2-propanol

70
Learning Check

• Select the product for CH3CH2CH2OH.
• 1) CH3CHCH2 2) CO2 H2O
  O
• 3) CH3CH2CH
• A. H, heat B. O
• C. O2

71
Solution

• A. H, heat 1) CH3CHCH2
• O
• B. O 3) CH3CH2CH
• C. O2 2) CO2 H2O

72
Ethanol CH3CH2OH

• Ethanol
• 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.

73
Oxidation of Alcohol in the Body

• Enzymes in the liver oxidize ethanol.
• The aldehyde produced impairs coordination.
• A blood alcohol level over 0.4 can be fatal.
  O
  
  CH3CH2OH CH3CH 2CO2
  H2OEthyl alcohol acetaldehyde

74
Effect of Alcohol on the Body

75
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

76
Reaction of Ethers

• Resemble hydrocarbons
• Resistant to chemical reactions
• At room temperature ethers do not react w/ strong
  acids, bases, or with strong oxidizing or
  reducing agents
• Good solvent properties

77
Reaction of Thiols
Thiols are oxidized to disulfides

O CH3CH2SH HSCH2CH3 ethanethiol
CH3CH2S-SCH2CH3

diethyldisulfi
de
78
Reduction

• Is a loss of oxygen (O)
• or
• gain of hydrogen (H)