1. Chemeketa Community College
Alcohols, Ethers,
Phenols, and Thiols
Chapter 22
Larry Emme
Chemeketa Community College

2. Functional Groups

3. The various classes of compounds are identified by the presence of certain characteristic groups called functional groups.
Through the chemical reactions of functional groups, it is possible to create or synthesize new substances.

5. Classification of Alcohols

6. Alcohols are classified by the number of R groups (i. e
Alcohols are classified by the number of R groups (i.e. carbon atoms) attached to the hydroxyl carbon as shown here. 6 6

7. Tests for Alcohols

8. Lucas Test
Addition of ZnCl2 in concentrated HCl forms a “turbid” solution. Order of reactivity is 3o > 2o >> 1o.

9. 9 9

10. Polyhydroxy alcohols and polyols are general terms for alcohols that have more than one –OH group per molecule.
Polyhydroxy compounds are very important molecules in living cells, as they include the carbohydrate class of biochemicals.

11. Structural Representations of Alcohols
An alcohol such as 2-butanol can be written in a single-line formula by enclosing the –OH group in parentheses and placing it after the carbon to which it is bonded. =

12. Application to Biochemistry
Blood sugar (glucose) contains five alcohol groups. Using the structure of glucose shown here, label each group as 1°, 2°, or 3°.
O=CHCH(OH)CH(OH)CH(OH)CH(OH)CH2OH

13. Application to Biochemistry

14. Naming Alcohols

15. IUPAC Rules for Naming Alcohols
Select the longest continuous chain of carbon atoms containing the –OH group.
Number the carbon atoms in this chain so that the one bearing the -OH group has the lowest possible number.

16. IUPAC Rules for Naming Alcohols
3. Form the parent alcohol name by replacing the final –e of the corresponding alkane by
–ol. When isomers are possible, locate the position of the –OH group by placing the number (hyphenated) of the carbon atom to which the –OH is bonded immediately before the parent alcohol name.
4. Name each alkyl side chain (or other group), and designate its position by number.

17. Name CH3CH2CH2CH2OH
1-butanol

18. Nomenclature of Alcohols

19. Physical Properties of Alcohols

20. Physical Properties of Alcohols
The physical properties of alcohols are related to those of both water and alkane hydrocarbons.
An alcohol molecule is made up of a waterlike hydroxyl group joined to a hydrocarbonlike alkyl group.

21. Boiling Points of Alcohols
Alcohols have relatively high boiling points.
The boiling points of the normal alcohols increase in a regular fashion with increasing number of carbon atoms.
Branched-chain alcohols have lower boiling points than corresponding straight-chain alcohols.

23. Alcohols containing up to three carbon atoms are infinitely soluble in water.
The –OH group on the alcohol molecule is responsible for both the water solubility and relatively high boiling points of the low-molar-mass alcohols.

24. Hydrogen Bonding in Alcohols

27. Glucose is one of the most important carbohydrates in biochemistry
Glucose is one of the most important carbohydrates in biochemistry. It has six carbons and five alcohol groups (molar mass = g). How would you predict the water solubility of glucose to differ from that of 1-hexanol?

28. Effect of Hydroxyl Groups on Solubility
Note the difference in solubility of hexanol (only one –OH
group) and glucose ( five –OH groups).
CH3CH2CH2CH2CH2CH2OH
1-hexanol
(solubility = 0.6g/100g H2O)
D-glucose
(solubility = 95g/100g H2O) 28 28

29. Effect of Branching on Boiling Point
A branched-chain alcohol will have a lower boiling point
than the corresponding straight-chain alcohol.
For example 2-butanol is branched and has a b.p. of
91.5 C versus 118 C for 1-butanol.
CH3CH2CH2CH2OH
1-butanol 29 29

30. Chemical Properties of Alcohols

31. Chemical Properties of Alcohols
Acidic and Basic Properties
Oxidation
Dehydration
Esterification (Chapter 24)

32. Basic Properties
If an alcohol is mixed with a strong acid, it will accept a proton (act as a Brønsted-Lowry base) to form a protonated alcohol or oxonium ion.

33. Acidic Properties Alcohols can also act as Brønsted-Lowry acids.
The resulting anion in the alcohol reaction is known as an alkoxide ion (RO-).

34. Reactivity of Alcohols with Na or K
The order of reactivity of alcohols with sodium or potassium is:
primary > secondary > tertiary.
Reactivity decreases with increasing molar mass, since the –OH group becomes a relatively smaller, less significant part of the molecule.

35. Oxidation
Oxidation is the loss of hydrogen or the gain of bonds to oxygen by the organic reactant.
Carbon atoms exist in progressively higher stages of oxidation in different functional groups.

37. The –OH group gives an organic compound the capability of forming an aldehyde, ketone, or carboxylic acid.

38. Common Oxidizing Agents
KMnO4
K2Cr2O7 O2

39. Dehydration
Alcohols can be dehydrated with sulfuric acid to form alkenes.

40. Dehydration
For many alcohols, there is more than one way to remove water. Therefore the double bond can be located in different positions.
The major product in such cases is the alkene in which the C=C bond has the greatest number of alkyl substituents on it (or the least number of hydrogens).

41. Saytzeff’s Rule
During intramolecular dehydration, if there is a choice of positions for the carbon-carbon double bond, the preferred location is the one that generally gives the more highly substituted alkene – that is, the alkene with the most alkyl groups attached to the double-bond carbons.

42. Esterification (Conversion of Alcohols to Ethers)
An alcohol can react with a carboxylic acid to form an ester and water.

43. Utility of the Hydroxyl Functional Group

44. Common Alcohols

45. Three General Methods for Making Alcohols
Hydrolysis of an ester.
Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).
Catalytic reduction of aldehydes and ketones.

46. Hydrolysis of an Ester
Hydrolysis is a reaction of water with another species in which the water molecule is split.

47. Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).
CH3CH2Cl + NaOH(aq)  CH2CH3OH + NaCl

48. Catalytic Reduction of Aldehydes and Ketones
Produces primary and secondary alcohols.
Chapter 23

49. Preparation of Methanol
Methanol is a common industrial solvent prepared
by the high-pressure catalytic hydrogenation of carbon monoxide.
The most economical nonpetroleum source of carbon monoxide for making methanol is coal. 49 49

50. Uses of Methanol
Conversion to formaldehyde (use in manufacture of polymers).
Manufacture of other chemicals, especially various kinds of esters
Denaturing ethyl alcohol
Industrial solvent

51. Ethanol Large quantities of ethanol are prepared by fermentation.
The conversion of simple sugars to ethanol is accomplished by yeast.
Industrially, ethanol is made by acid-catalyzed addition of water to ethylene.

52. Uses of Ethanol
An intermediate in the manufacture of other chemicals such as acetaldehyde, acetic acid, ethyl acetate, and diethyl ether.
A solvent for many organic substances.
A compounding ingredient for pharmaceuticals, perfumes, flavorings, etc.
An essential ingredient in alcoholic beverages.

53. 2-Propanol (Isopropyl Alcohol)
2-Propanol is made from propene.

54. Uses of 2-Propanol (Isopropyl Alcohol)
To manufacture other chemicals (especially acetone).
As an industrial solvent.
As the principal ingredient in rubbing alcohol formulations.

55. Ethylene Glycol (1,2-Ethanediol)
Industrial synthesis

56. Uses of Ethylene Glycol (1,2-Ethanediol)
In the preparation of the synthetic polyester fiber Dacron and film Mylar
As a major ingredient in “permanent-type” antifreeze cooling systems
As a solvent in the paint and plastic industries
In the formulations of printing ink and ink for ballpoint pens.

57. Glycerol (1,2,3-Propanetriol)
Glycerol (also known as glycerine) is an important trihydroxyalcohol.
It is obtained as a by-product of the processing of animal and vegetable fats to make soap and other products.
It is synthesized commercially from propene.

58. Each directly related to the three –OH groups.
Uses of Glycerol
Each directly related to the three –OH groups.
As a raw material in the manufacture of polymers and explosives (nitroglycerin).
As an emollient in cosmetics.
As a humectant in tobacco products.
As a sweetener.

59. Phenols

60. Phenols
The term phenol is used for the class of compounds that have a hydroxy group attached to an aromatic ring.
The parent compound is also called phenol, C6H5OH.

61. Naming Phenols
Many phenols are named as derivatives of the parent compound, via the general methods for naming aromatic compounds.

62. Derivatives of Phenol
Compounds of phenol are the active ingredients in the essential oils of nutmeg, thyme, cloves, and vanilla. 62

63. Common Phenols

64. Common Phenols/Alcohols

65. Common Phenols/Alcohols

66. Common Phenols

67. Herbicides produced by Phenols

68. Properties of Phenols

69. Properties of Phenols Colorless, crystalline solid, mp = 41 °C
Highly poisonous
More acidic than alcohols and water

70. Production of Phenol

71. Production of Phenol Phenol is obtained from coal tar.
Several commercial methods are used to produce phenol synthetically.

72. Ethers

73. Ethers
Ethers have the general formula below where both R groups can be the same or different.
ROR′

76. Naming Simple Ethers
Name each alkyl group in alphabetical order followed
by the word ether as shown here.
Use a prefix if both alkyl groups are the same. 76 76

77. Naming Ethers Using IUPAC Rules
Name the longest continuous carbon chain corresponding to the parent alkane.
2. Change the –yl ending of the other hydrocarbon group to –oxy to obtain the alkoxy group name.
3. Combine the two names from Steps 1 and 2, giving the alkoxy name and its position on the longest carbon chain first, to form the ether name.
For example…
…would be named methoxyethane 77 77

78. Examples of Naming Alkoxy Groups78 78

79. Examples of Naming Ethers79 79

80. Structures and Properties of Ethers

81. Properties of Ethers
Ethers are somewhat more polar than alkanes, but are much less polar than alcohols.
Ethers – especially diethyl ether – are exceptionally good solvents for organic compounds.

83. Formation of Peroxides from Ethers
Oxygen of the air slowly reacts with ethers to form unstable peroxides that are subject to explosive decomposition.

84. Preparation of Ethers

85. Preparation of Ethers by Intramolecular Dehydration
Ethers can be prepared by splitting out water from two
molecules of an primary alcohol. This type of reaction is
known as a condensation reaction. 85 85

86. Williamson Synthesis of Ethers
The alkyl halide, RX, may be a methyl or primary group, but not a secondary or tertiary alkyl group or an aryl group.
The alkoxide, R’ONa, may be methyl, primary, secondary, tertiary, or an aryl group.
RX + R’ONa  ROR’ + NaX
Alkyl halide
alkoxide
ether

87. Thiols

88. are similar to alcohols contain a thiol (-SH) group
Thiols or mercaptans
contain sulfur
are similar to alcohols
contain a thiol (-SH) group
often have strong odors
found in cheese, onions, garlic, and oysters
are used to detect gas leaks 88

89. Thiols
are named in the IUPAC system by adding thiol to the alkane name of the longest carbon chain.
(Methyl Mercaptan) 89

90. Properties of Thiols Foul odors. 2. Oxidation to disulfides:
2 RSH  R-S-S-R
[O]
thiol
disulfide

92. Striped Skunk (Mephitis mephitis) Thiols
E-2-buten-1-thiol %
3-methyl-1-butanethiol %
2-quinolinemethanethiol %

93. For pets that have been sprayed, bathe the animal in a mixture of 1 quart of 3% hydrogen peroxide (from drug store), 1/4 cup of baking soda (sodium bicarbonate) and a teaspoon of liquid detergent. After 5 minutes rinse the animal with water. Repeat if necessary. The mixture must be used after mixing and will not work if it is stored for any length of time. DO NOT STORE IN A CLOSED CONTAINER - it releases oxygen gas so it could break the container. This mixture may bleach the pet's hair.

94. Why tomato juice is believed to eliminate skunk odor
Why tomato juice is believed to eliminate skunk odor. Bathing an animal in tomato juice seems to work because at high doses of skunk spray the human nose quits smelling the odor (olfactory fatigue). When this happens, the odor of tomato juice can easily be detected. A person suffering olfactory fatigue to skunk spray will swear that the skunk odor is gone and was neutralized by the tomato juice. Another person coming on the scene at this point will readily confirm that the skunk spray has not been neutralized by the tomato juice.

95. The End