Pharmacy Student
Alcohols, Ethers and Epoxides
Introduction—Structure and Bonding
• Alcohols contain a hydroxy group (OH) bonded to an sp3 hybridized carbon.
2
Physical Properties of Alcohols
Alcohols have considerably higher boiling points.
Molecules of alcohols hydrogen bond to each other.
•Alcohols can hydrogen bond to water and have solubility
in water
The alcohol groups form hydrogen
bonding which makes the short
chain molecules soluble in water.
The solubility in water decreases as
the chain length increases.
Reactions of Alcohols
1- Reaction with alkali metal (Na- K)
R OH + Na
R ONa + ½ H2
CH3CH2OH + Na
CH3CH2ONa + ½ H2
Reactions of Alcohols
• 2- Action Of Hydrogen Halideds (HX):
• Alcohol unlike alkyl halides in which the halogen atom serves
as a good leaving group, the OH group in alcohols is a very
poor leaving group.
• For an alcohol to undergo nucleophilic substitution, OH
must be converted into a better leaving group. By using
acid, ¯OH can be converted into H2O, a good leaving
group.
2- Action Of Hydrogen Halideds (HX):
ROH + HX
CH3CHCH3 + HBr
OH
R-X + H2O
CH3CHCH3+ H2O
Br
3- Formation of Haloalkane
Ethanol and PCl5
C2H5OH(l) + PCl5(s)  C2H5Cl(g) + POCl3(l) + HCl(g)
Ethanol and SOCl2
C2H5OH(l) + SOCl2(l)  C2H5Cl(g) + SO2(g) + HCl(g)
4-Dehydration by the action of heated alumina (Al2O3) or
conc H2SO4 give Olefins:
Primary alcohols can dehydrate to ethers
This reaction occurs at lower temperature than the
competing dehydration to an alkene.
Step 1
CH3CH2-OH
H+
CH3CH2-OH2
-H2O
CH3CH2
Step2
CH3CH2 + HO-CH2CH3
Step 3
CH3CH2-O-CH2CH3
H
CH3CH2-O-CH2CH3
H
- H+
CH3CH2-O-CH2CH3
HSO4
-
diethyl ether
Williamson continuous etherification

CH3-C (CH3)2-CH2OH

CH3-C (CH3)2CH2



- H+
H+
CH3-C
rearrangement
-H O
(CH3)2CH2OH2 2
CH3-C-CH2 CH3
CH3
CH3-C = CH CH3 2- methyl -2- butene
CH3
R
C
Cl
R'OH
R
OR' + HCl Acid chloride
C
O
O
Alkyl acetate
Acid Anhydride
R
C
O
O
C
R'OH
R
R
O
C
OR' + R
C
O
Ester
O
Carboxylic acid
R
C
O
OH
R'OH
H
+
R
C
O
OR' + H 2 O
Ester
OH
Acid








R-CO OH + H OR’ H2SO4 RCOOR’ + H2O
OH
OH
..
H+
R-C-OH
R-C-OH R’ O..H R-C-OH
O
O ‘R
OH
O H
H
+
-H2O R-C
R-C-OH2
-H
OR’
OR’
R-C-OR’
O ESTER







2- Acid chloride:
RCOCl +R’OH
CH3COCl + C2H5OH
Acetyl chloride
3- Acid Anhydride:
(R CO)2O + R’OH
(CH3CO)2O +C2H5OH
CH3COOH acetic acid
R-C-OOR’ + HCl
CH3COOC2H5 + HCl
ethyl acetate
RCOOR’ + RCOOH
CH3COOC2H5+
ethyl acetate
Reactions of Alcohols: Dehydration
• Dehydration, like dehydrohalogenation, is a  elimination reaction in
which the elements of OH and H are removed from the  and 
carbon atoms respectively.
• Dehydration is typically carried out using H2SO4 and other
strong acids, or phosphorus oxychloride (POCl3) in the
presence of an amine base.
20
• Typical acids used for alcohol dehydration are H2SO4 or ptoluenesulfonic acid (TsOH).
• More substituted alcohols dehydrate more easily, giving rise to the
following order of reactivity.
21
• When an alcohol has two or three  carbons, dehydration is
regioselective and follows the Zaitsev rule.
• The more substituted alkene is the major product when a mixture of
constitutional isomers is possible.
22
A- 10 Alcohol gives aldehydes:
Cu/ 350 oC
CH3CH2OH
CH3CHO + H2
B- Secondary Alcohol gives Ketones:
OH
O
Cu/350oC
CH3CHCH3
CH3CCH3 + H2
C- Tertiary alcohol gives Olefins:
OH
Cu/350oC
CH3C- CH3
CH3-C=CH2
CH3
CH3
8-Oxidation of Alcohols
The reactions of alcohols have a central role in organic chemistry
because alcohols can be converted to many of the other
functional groups.
Oxidation is
• a loss of electrons
• a more positive oxidation
number
• a loss of hydrogen atoms
• the addition of oxygen atoms.
• more bonds to oxygen
1 Bond to O
Alkane
Alcohol (1°)
CH3
2 Bonds to O
Aldehyde
[O]
[O]
CH3
Reduction is
• a gain of electrons
• a less positive oxidation
number
• a gain of hydrogen atoms
• the loss of oxygen atoms
• the loss of bonds to oxygen.
OH
CH3
CH2
C
Carboxylic acid
[O]
O
CH3
3 Bonds to O
H
[O]
O
CH3
C
OH
CO2 + H2O
Primary alcohols
Secondary alcohol
aldehydes
Ketones
Don’t oxidise
tertiary alcohol
Carboxylic acid


Subtraction: Remove -H from alcohol group
Remove -H from alcohol carbon
H
H3C
H2
C
C
H2
OH
H2 H
O
C
H3C
C
O
H
(O)
+
H
H
H3C
H2
C
O
C
H


Subtraction: Remove -H from alcohol group
Remove -H from alcohol carbon
H
H 3C
H
H
OH
CH
O
O
CH3
H 3C
C
H
+ (O)
CH3
O
H 3C
C
CH3



CH3CH2OH

NaOH
I
2
oxid
CH3CHO
CHI3 + HCOONa
3I
Cl3CHO iodal
2
substitution

Victor Meyer Test: It is carried in four steps:



Step 1. Add concentrated HI to the alcohol. The alcohol is converted
to the alkyl halide.
R-OH + HI
RI + H2O



Step 2. Add silver nitrite(AgNO2) solution. The alkyl halide is
converted to nitroalkane.
R-I + AgNO2
R-NO2 + AgI

Step 3. Add nitrous acid, HONO (NaNO2 + H2SO4)
 Step 4. Add KOH solution.
blood color represents a 1o alcohol blue color indicates a 2o alcohol

no color indicates a 3o alcohol



Dihydric alcohols Glycols
They are saturated hydrocarbons in which 2
hydrogen atoms are replaced by 2(OH) groups.
They are classified into α, β, γ according to the
relative position of the OH groups in the
molecule.

1- Hydrolysis of Vic-dihalides:
Cl
Cl
OH OH

CH2-CH2 + NaOH

2- Mild oxidation:
CH2 =CH2 KMnO4/ (O)



CH2-CH2
CH2-CH2
OH OH
Chemical reactions:


Chemical reactions:
3- Oxidation:
CHO
glyoxal
CHO
( O)










Preparation:
1- Hydrolysis of fats and oils under pressure at 220oC:
CH2
OCOR
CH
OCOR + NaOH
CH2
OCOR
Triglyceride
CH2
OH
CH
OH + 3 RCOONa
CH2
OH
Glycerol
Soap
Cl2/40oC ClCH2-CH=CH2 HOCL

CH3-CH=CH2


CH2-CH-CH2 soda lime CH2-CH-CH2
Cl Cl Cl
-HCl
Cl
O

Hydrolysis


CH2
CH
CH2
OH
OH
OH




1- Action of H2SO4:
CH2
OH
H2SO4
CH
OH
conc
CH2
OH
CH2
CH
CH2
OH
OH




CHO
- H2O
CH2
H2SO4
CH2OH
CHO
CH Acrolein
CH2
:
Oxidation of Alcohols
oxidation [O]
OH
O
H
reduction [H]
H OH
C
R1
R2
[O]
R1
2° alcohols
H H
C
R1
OH
1° alcohols
O
C
R2
ketone
[O]
R1
O
C
aldehyde
[O]
H
R1
O
C
OH
carboxylic acids
KMnO4 and chromic acid (Na2Cr2O7, H3O+) oxidize secondary alcohols to ketones,
and primary alcohols to carboxylic acids.