Alcohols, Phenols, and Ethers

1
Alcohols, Phenols, and Ethers

• Structure
• Nomenclature
• Properties
• Reactions

1
2
Alcohols

• Alcohol OH group is covalently held by a
  saturated carbon bond
• General formula R-OH
• The OH is called a hydroxyl group
• Found in major kinds of organic substances such
  as carbohydrates, proteins, nucleic acids

2
3
Examples of Alcohols
CH3CH2CH2OH CH3CH-CHOH

OH OH
OH
OH
3
4
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

4
5
Naming Alcohols

• Determine the parent chain by ensuring that it
  includes the C to which the OH is attached
• The parent name is the alkane name with the final
  
• e replaced with -ol
• 3. Number the parent chain at the end nearest to
  the C that holds the OH
• --OH takes precedence over alkyl groups,
  halogens, and multiple bonds
• 4. Number and name all other substituents
  followed by the location of the OH in front of
  the name of the parent chain

5
6
Examples of Alcohols
CH3CH2CH2OH CH3CH-CHCH3

Br OH
CH3 CH3CHCH2CH2OH

CH3 CH3CCH2CH2CHCH2CH3

CH3 OH
6
7
Naming Alcohols

• When 2 or more OH groups are present, use the
  alkane name followed by diol (for 2-OH groups)
  triol (for 3-OH groups), etc.
• -to help with pronunciation, retain the final e
  of the alkane name followed by diol or triol
• If the OH group is on a ring, the OH group is
  assumed to be on C 1
• HO-CH2-CH2-OH

OH
OH
7
8
Naming Alcohols

• 6. 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.
• HO-CH2CH2 CH2CH3
• C C
  
• H H
• cis-3-hexen-1-ol

8
9
Common Names of Alcohols

• For alcohols with 4 carbons or less, common names
  exist
• Named by using the alkyl group name followed by
  the word alcohol
• CH3OH methyl alcohol
  CH3
• 
  
  CH3-C-OH
• t-butyl
  alcohol CH3

9
10
Ethanol CH3CH2OH

• Also called Ethyl Alcohol
• Acts as a depressant
• Kills or disables more people than any other drug
• 12-15 mg/dL ethanol metabolized by a social
  drinkers in one hour
• 30 mg/dL ethanol metabolized by an alcoholic in
  one hour.

10
11
Alcohol in Some Products

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

11
12
Some Typical Alcohols
Anti-freeze

• OH
• rubbing alcohol CH3CHCH3
• 2-propanol (isopropyl
  alcohol)
• antifreeze HO-CH2-CH2-OH
• 1,2-ethanediol (ethylene
  glycol)
• 
  OH
• glycerol HO-CH2-CH-CH2OH
• 
  1,2,3-propanetriol

12
13
Physical Properties of Alcohols

• Alkyl group is nonpolar and OH is polar so the
  physical properties depend on which portion is
  dominant
• Hydrogen bonding dominates the physical
  properties
• Much higher boiling points and greater solubility
  in water than hydrocarbons of the same mass
• Multiple -OHs increase the solubility
• Special enzymes in the liver attach -OH groups to
  
• molecules of toxic substances to make them
  more soluble

13
14
Physical Properties of Alcohols
Table 14.3, p373
14
15
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
15
16
Learning Check 1

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

16
17
Solution 1

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

17
18
Learning Check 2

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

18
19
Solution 2

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

19
20
Alcohol Synthesis
Hydration
Reduction
21
Reactions of Alcohols

• Combustion
• Dehydration
• -Intramolecular
• -Intermolecular
• Oxidation

22
Reactions of Alcohols

• Intramolecular Dehydration the loss of H and OH
  from a single molecule
• An elimination rxn
• H OH
• H-C-C-H H-CC-H H2O
• H H H H
• alcohol alkene

H2SO4 180oC
22
23
Reactions of Alcohols

• Zaitsevs rule major product of intramolecular
  dehydration is the alkene that has the greatest
  of alkyl groups attached to the Cs of the double
  bond
• Dehydration is the reverse rxn of hydration
• Le Chateliers principle used to predict the
  favored direction of a reversible rxn

23
24
Reactions of Alcohols

• Intermolecular Dehydration the loss of H and OH
  from 2 molecules to yield a larger molecule and a
  small one, usually water
• A condensation rxn only works with 1o alcohols
• CH3CH2OH
• 
  CH3CH2-O-CH2CH3 H2O
• CH3CH2OH
• 2 alcohols ether

H2SO4 140oC
24
25
Oxidation

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

25
26
Oxidation of Alcohols

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

26
27
Oxidation of Primary Alcohols

• O more O
• Primary alcohol aldehyde
  carboxylic acid
• OH O
  O
• O moreO
  
• CH3-C-H CH3-C-H
  CH3COH
• H
• Ethanol Ethanal
  Ethanoic acid
• (ethyl alcohol) (acetaldehyde)
• Oxidizing agents- O - KMnO4, K2Cr2O7, H2CrO4

27
28
Oxidation of Secondary Alcohols

• O
• Secondary alcohol ketone
• OH O
• O
• CH3-C-CH3 CH3-C-CH3
• H
• 2-Propanol 2-propanone

28
29
Oxidation of Tertiary Alcohols

• O
• Tertiary alcohols no reaction
• OH
• O
• CH3-C-CH3 no product
• CH3 no H on the C-OH to oxidize
• 2-Methyl-2-propanol

29
30
Halogenation

• A halogen substitutes for the hydroxyl group
  yielding an alkyl halide
• No mixture of products (a single product)
• 3 R-OH PX3 3 R-X H3PO3

Heat
30
31
Learning Check 3

• Select the product for the reaction of
  CH3CH2CH2OH in the following conditions
• 
  
• 1) CH3CHCH2 2) CO2 H2O 3) CH3CH2CH
• A. H, heat _________
• B. O __________

31
32
Solution 3

• Select the product for the reaction of
  CH3CH2CH2OH in the following conditions
• A. H, heat 1) CH3CHCH2
• O
• B. O 3) CH3CH2CH

32
33
Phenols

• Phenol compound that has an OH attached to a
  carbon that is a part of an aromatic ring
• General formula Ar-OH
• Aryl (Ar) aromatic carbon system that has one H
  removed

34
Phenol Nomenclature

• IUPAC naming uses rules used to name derivatives
  of benzene
• Phenol is parent name
• Start numbering the ring with the carbon that
  contains the hydroxyl group it is assumed to be
  1 and is not in the name
• Number in the direction that gives the lowest
  numbers to the substituents

35
Properties of Phenols

• Only slightly soluble in water
• Flammable
• Have antiseptic and disinfectant properties
• Cannot be dehydrated
• Can be halogenated

36
Phenol Acidity
37
Ethers

• Contain an -O- between two carbon groups
• General formula R-O-R
• The R groups do not have to be identical
• CH3-O-CH3 CH3-O-CH2CH3

37
38
Naming Ethers-Common Names

• The common names of ethers are made by naming the
  attached alkyl groups alphabetically and adding
  ether
• if both groups are identical, use the prefix di-
• CH3-O-CH3 dimethyl ether
• CH3-O-CH2CH3 ethyl methyl ether

38
39
Naming Ethers-IUPAC Names

• Named as substituted hydrocarbons
• The smaller hydrocarbon and the O atom is an
  alkoxy group and is a substituent on the larger
  hydrocarbon group (the parent)
• Alkoxy group an OR group

39
40
Naming Ethers-IUPAC Names

• Find the longest carbon chain that does not
  include the OR group and use the alkane name as
  the parent
• Change the yl ending of the other alkyl group
  and replace it with oxy to get the alkoxy name
• Use the alkoxy name, with a locator , followed
  by the parent

41
Learning Check 4
What is the name of the following ethers.

• CH3CHOCH3
• CH3

B.
O
C. CH3CH2CH2OCH3
41
42
Solution 4
What is the name of the following ethers.

• CH3CHOCH3
• CH3

isopropyl methyl ether dicyclohexyl
ether methyl propyl ether
B.
O
C. CH3CH2CH2OCH3
43
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

43
44
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
  F H F
• H-C-C-O-C-H F-C-C-O-C-H
• F F F
  F Cl F
• Enflurane
  Isoflurane

44
45
Cyclic Ethers

• Cyclic ethers the O of the ether is a part of a
  ring
• Heterocyclic cyclic compound where a C is
  replaced with a heteroatom (O, N, etc)

45
46
Physical Properties of Ethers

• BP similar to alkanes and much lower than
  alcohols of similar mass
• More soluble in water than alkanes and similar to
  that of alcohols of similar mass
• Are flammable and form unstable peroxides
• Almost as chemically unreactive as alkanes.

46
47
Physical Properties of Ethers
The boiling points of simple ethers are like
those of the alkanes of comparable formula mass
much less than alcohols
47
48
Reaction of Ethers

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

48
49
Thiols

• Thiol compound where an SH group is bonded to
  a saturated C atom
• Called mercaptans in the past
• Are sulfur analogs of alcohols
• Contain the functional group SH, called a
  sulfhydral group
• CH3-SH CH3-CH2SH
• SH
• CH3-CH-CH3

49
50
Thiol Nomenclature

• Named just like alcohols except the ol ending is
  replaced with ethiol (with the e retained from
  the alkane name)
• CH3-SH methanethiol
• CH3-CH2SH ethanethiol
• SH
• CH3-CH-CH3 2-propanethiol

50
51
Properties of Thiols

• Many thiols have disagreeable odors and low
  boiling points
• More reactive than corresponding alcohols
• Used to detect gas leak
• Found in onions, oysters, and garlic
• Onions CH3CH2CH2-SH
• Garlic CH2 CHCH2-SH

51
52
Physical Properties of Thiols
52
53
Reaction of Thiols
Thiols are oxidized to disulfides

O CH3CH2SH HSCH2CH3 ethanethiol
CH3CH2S-SCH2CH3 2H


diethyldisulfide
53
54
Thioethers

• Thioether compound where sulfur (S) is bonded
  to 2 Cs using single bonds
• Also called sulfides
• Are sulfur analogs of ethers
• General formula R-S-R
• More reactive that corresponding ether
• Named like ethers except you replace ether with
  sulfide and alkoxy with alkylthio in IUPAC
  naming

54
55
Learning Check 5

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

55
56
Solution 5

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

56
57
Compounds

• Alcohols -OH hydroxyl CH3-OH
• Ethers -O- CH3-O-CH3
• Thiols -SH sulfhydryl
  CH3-SH
• Thioether -S-
  CH3-S-CH3

57
58
Learning Check 6

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

58
59
Solution 6

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

59