ALCOHOLS AND ETHERS
Introduction to Alcohols
• Compounds in which the hydroxyl group is bonded to an alkyl
group are called alcohols. They are known as alkyl derivative of water.
• R–H
H – OH
R – OH
alkane
water
alcohol
Example 1
Which of the following is an alcohol?
Example 2
Which of the following is not an alcohol?
1. Classification of Alcohols
A. According to The number of –OH Groups
1. Monohydric Alcohols
CH3OH
methyl alcohol
CH3CH2OH
ethyl alcohol
CH3CH2CH2OH
propyl alcohol
Example 3
Which of the following is a monohydric alcohol?
2. Polyhydric Alcohols
B. According to The Carbon Atom Having The –OH Group
o
1. Primary (1 )Alcohols
Example 4
Which of the following is a polyhydric alcohol?
o
2. Secondary (2 )Alcohols
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3. Tertiary (3 )Alcohols
Example 5
Which of the followings are tertiary alcohols?
2. Nomenclature of Alcohols
• Common names are used for simpler alcohols. Common names are
derived by naming the alkyl group attached to the –OH group and
then the word “alcohol” is added.
H3C OH
Methyl Alcohol
According to IUPAC system;
• Change last letter “–e” with “–ol” in the alkane name of longest
carbon atom chain in which hydroxyl group is bonded.
• Number the carbon atoms in the chain starting from nearer to the
hydroxyl group. Indicate the position of the hydroxyl group by using
number.
• If there are more than one –OH group, use “di, tri, tetra…” before
–ol .
4-methyl 2-pentanol
4-bromo-3-methyl 2-butanol
3-cyclopentyl 1-propanol
2, 4-dimethyl 1, 4-pentanediol
Example 8
What is the correct name for the following structure?
A. 1-bromo-2-methyl 3-cyclopentanol
B. 1-bromo-2-methyl 3-pentanol
C. 2-methyl-3-bromo 1-cyclopentanol
D. 3-bromo-2-methyl 1-cyclopentanol
Example 9
Which of the following is 2, 3, 4-trimethyl 1-hexanol?
Example 10
Which of the following is the isomer of 2, 3-dimethyl 2-butanol?
3-amino 2-butanol
5-chloro-2-methyl 1,3,4-hexanetriol
Example 6
Name the following structures according to IUPAC system.
Example 7
Which of the following structures is named wrongly?
3. Physical Properties of Alcohols
• Alcohols have both polar and non polar parts in their structures.
• C1 to C11 are colorless and have characteristic smell.
• Water soluble, solubility decreases with increasing chain length.
But increases with branching.
• Boiling points of alcohols increase with increasing molecular
weight and the number of hydroxyl group in the molecule.
4. Chemical Properties of Alcohols
• In the first group of reactions alcohols may serve as acids (proton
donors) and they dissociate in manner similar to water.
Salt formation: Alcohols form salts with active metals such as Na, K,..
etc.
Ester formation: In the presence of an acid catalyst, alcohols react
with acids to form esters.
Example 14
How many liters of hydrogen gas is produced at STP, when
2.3 g of sodium is put into excess ethanol?
A. 1.12 B. 2.24 C. 4.48 D. 8.96
• Inorganic acids also form esters with alcohols. Such as the
esterification of glycerol with HNO3 forms glyceryl trinitrate, is an
explosive ingredient in dynamite.
Example 15
Predict the result of following reactions.
• In the second group of reactions hydroxyl group is replaced. First
type is conversion of alcohols to alkyl halides.
Example 16
What are the result of following oxidation reactions.
•
Second type is dehydration.
• Third type is oxidation of alcohols. KMnO4 and K2Cr2O7 oxidize 1
o
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and 2 alcohols, 3 alcohols cannot be oxidized.
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Example 17
Write the equations for each of the following.
A. n-propyl alcohol to propene
B. n-butyl alcohol to butanoic acid
C. 2-pentanol to diethyl ketone
D. t-butyl alcohol to t-butyl bromide
E. Isobutyl alcohol to methyl ethyl ketone
Example 11
Arrange the following compounds in order of increasing
solubilities.
Example 18
How many liters of ethylene at STP can be prepared from
40 g of 92% ethyl alcohol by 70% yield?
5. Preparation of Alcohols
A. Hydration of Alkenes
Example 12
Which of the following has the highest boiling point?
B. Hydrolysis of Alkyl Halides
Example 13
Which of the following alcohol has the highest melting point?
Example 19
Perform the following transformations.
A. ………  1-propanol
B. ………  isobutanol
C. ………  ter-butanol
Example 20
What is the result of following reaction?
Chloro cyclobutane + NaOH  ……………
Example 21
Which alcohol and how many grams are produced by the
hydration of 9.6 g of 2-butene?
6. Some Important Alcohols
1. Methyl Alcohol
It is colorless, flammable, and has characteristic odor.
It is highly toxic, can cause blindness, large quantities
cause death. To prevent poisoning pyridine is added.
It can be used as antifreeze in radiators.
It is soluble in water and organic solvents, and can also
dissolve fats and resins.
It is the most acidic member of monohydric alcohols.
It can easily burn with a bluish flame.
It can be easily oxidized to formaldehyde and CO2.
It is also called wood alcohol. Because it is first obtained from the
distillation of wood.
In industry it is produced from water gas (CO + H2) under high pressure
and temperature in the presence of catalyst.
About 40% of methanol production is converted to formaldehyde, and
from there into products as diverse as plastics, plywood, paints,
explosives, and permanent press textiles.
2. Ethyl Alcohol
It is colorless, soluble in water and has a characteristic smell, affecting
the central nervous system.
95% of its solution is called ethyl alcohol, used in laboratories.
100% pure ethyl alcohol is named as absolute alcohol.
It is a important organic solvent, used in the preparation of
tincture of iodine, paints, essence, perfumes and cosmetics.
In medicine it is used as disinfectant.
It is commonly prepared from grape juice by fermentation.
Preparation of Ethyl Alcohol
It is produced from fats and oils in basic medium.
7. Introduction to Ethers
Ethers are alcohol derivatives resulting from the condensation of
alcohols.
General formula is CnH2n+2O
8. Nomenclature of Ethers
First name the groups attached to oxygen atom in alphabetical order,
and then read the word “ether”.
If the groups are symmetric, use –di before the name of the group.
Example 22
9. Physical Properties of Ethers
Bond angle is not equal to 180o in R-O-R, they have a limited polarity.
They are more volatile than their corresponding alcohols.
Boiling point increases by the increasing molecular weight. Branching
lowers the boiling point.
Since ethers are polar they are soluble in many polar and non polar
substances very well.
10. Physical Properties of Ethers
Chemically ethers resemble alkanes rather than alcohols or water.
When ethers are heated with concentrated strong acid halides they
undergo decomposition reactions.
R-O-R + H-X → R-O-H + R-X
Example 22
C2H5-O-C2H5 + H-Cl → C2H5-OH + C2H5-Cl
3. Glycol
Alcohols containing two –OH groups are called gylcols. The most
common glycol is ethylene glycol, C2H4(OH)2.
It is colorless, odorless, syrupy liquid, completely miscible in water.
Since it has low melting point it is used as antifreeze in radiators.
It is also used in hydraulic brake fluid in cars, as a liquid, oil, ink and
resin solvent.
4. Glycerin or Glycerol
The simplest trihydric alcohol, C3H5(OH)3.
It is colorless, odorless, syrupy liquid, soluble in water, methanol and
ethanol. It absorbs moisture well.
It is used in the production of dynamite, invented by Alfred Nobel, a
Swedish scientist.
It is also used in tobacco, shaving and toilet soaps, cosmetics, lotions,
ointments, antifreeze, cellophane, printing-press ink.
11. Preparation of Ethers
1. Dehydration of Alcohols
2. The Williamson Synthesis of Ethers
Example 23
2C2H5-OH → C2H5 -O- C2H5 + H2O
C2H5-Cl + C2H5-ONa → C2H5 -O- C2H5 + NaCl
12. Diethyl Ethers
The most commonly known ether. Colorless, volatile, flammable liquid
with characteristic odor.
Causes fainting when inhaled, used in medicine as an anesthetic.
Good solvent for organic substances.