Properties of Alcohols
Isomers of Butanol and Properties of n-alcohols
Classification of Alcohols
Primary (1º)
H
Secondary (2º )
CH3
CH 3-C-OH
CH 3-C-OH
H
H
1C
attached
to C-OH
2C
attached
to C-OH
Tertiary (3º)
CH 3
CH 3-C-OH
CH 3
3C
attached
to C-OH
Oxidation
vIs a gain of oxygen (O)
or
vA loss of hydrogen (H)
Alcohols
1Ealcohols are oxidized to
aldehydes and 2E alcohols
are oxidized to ketones
Alcohols
1E
2E
aldehydes ketones
Oxidation of Alcohols
[O]
Primary alcohol
aldehyde
OH
O
[O]
CH 3-C-H
;
CH3-C-H
H
Ethanol
(ethyl alcohol)
Ethanal
(acetaldehyde)
Oxidation of Alcohols
[O]
Secondary alcohol
OH
ketone
O
[O]
CH3-C-CH 3
2-Propanol
(isopropyl alcohol)
;
CH 3-C-CH 3
2-propanone
(dimethyl ketone,
“acetone”)
Oxidation of Alcohols
[O]
Tertiary alcohols
OH
CH3-C-CH 3
CH3
no reaction
[O]
no product
no H on the C-OH to oxidize
2-Methyl-2-propanol (tert-butyl alcohol)
Oxidation of Ethanol in the
Body
l Enzymes in the liver oxidize ethanol
l Aldehyde product impairs coordination
l Blood alcohol over 0.4% can be fatal.
O
O
;
CH3CH2OH
ethyl alcohol
;
CH3CH
CH3COH
2CO2 + H2O
acetaldhyde acetic acid
Synthesis of Alkyl Halides from Alcohols.
R-OH
+
HX
à
R-X
+
i) HX = HCl, HBr, HI
ii) may be acid catalyzed (H+)
iii) ROH: 3o > 2o > CH3 > 1o
iv) rearrangements are possible except with most 1 o
ROH
H2O
CH3
CH3CCH3
OH
+
tert-butyl alcohol
2-methyl-2-propanol
HCl
à
CH3
CH3CCH3 + H2O
Cl
tert-butyl chloride
2-chloro-2-methylpropane
3o alcohol can form H-bonds from hydroxyl
Alkyl halide is less polar,can’t form H bonds and
is not soluble in water produced (cloudy)
CH3
CH3CCH3
OH
+
tert-butyl alcohol
2-methyl-2-propanol
HCl
à
CH3
CH3CCH3 + H2O
Cl
tert-butyl chloride
2-chloro-2-methylpropane
Hydroxyl Hydrogen is the most polar
in a 3o alcohol
Halogenation is fastest in tertiary
alcohols
CH3-OH
+
methyl alcohol
methanol
HCl
à CH -Cl3 + H2O
methyl chloride
Chloromethane
Hydroxyl Hydrogen is the least polar in
a 1o alcohol
Halogenation is slowest in primary
alcohols
butan-1-ol
2-methylpropan-2-ol
butan-2-ol
2-methylpropan-1-ol
SOLVENT PROPERTIES OF ALCOHOLS
Solubility
Low molecular mass (short chain) alcohols are miscible
with water due to hydrogen bonding between the two
molecules
Longer chain alcohols are less miscible
since the carbon chain is nonpolar and is
unable to H-bond with water