Download Presentation8_108

Dr. Shatha Alaqeel
ROH
Alcohol
ArOH
Phenol
SP3
SP2
OH
R C O H
Classification and Nomenclature of alcohols
R'
H3C
Carbinol
OH
R
CH2
OH
Primary alcohol
R
CH
R''
OH
Secondary alcohol
R
C
OH
R'
Tertiary alcohol
Nomenclature
 1) Common Nomenclature
Alkyl + alcohol
CH3CH2OH
Ethyl alcohol
CH2=CHOH
Vinyl alcohol
CH2=CHCH2OH
Allyl alcohol
2) IUPAC Nomenclature
 1) Select the longest continuous carbon chain
to which the hydroxyl is directly attached.
 2) Change the name of the alkane corresponding
to this chain by dropping the final -e and
adding the suffix –ol
 3) Number the longest continuous carbon
chain so as to give the carbon atom bearing the
hydroxyl group the lower number.
OH
H3C
Cl
OH
H3C
4-Ethyl-2-hexanol
CH3
H3C
OH
CH3
5-Chloro-3-methyl-1-heptanol
CH3
3-Methyl-1-cyclohexanol
 Primary alcohol

CH3OH
CH3CH2OH
 Common Methyl alcohol
Ethyl alcohol
 IUPAC Methanol
Ethanol
 Secondary and tertiary alcohol
OH
OH
H3C
CH2=CHCH2OH
Allyl alcohol
2-Propen-1-ol
CH3
OH
CH CH3
Isopropyl alcohol Cyclopentyl alcohol
2-Propanol
Cyclopentanol
Methylcyclohexyl alcohol
1-Methyl-1-cyclohexanol
 4) OH group is preferred over the double or triple
bond in numbering.
OH
5-Hepten-2-ol
notice the removal of the (e)
 5) If a compound contains both OH and a double or
triple bond, choose the chain that include them both
CH2CH3
even if this is not the longest chain
CH3CHC=CH2
OH
3-Ethyl-3-buten-2-ol
OH
H2C
OH
HC
CH3
3-buten-2-ol
HO
H3C
OH
4-Pentyn-1-ol
CH3
CH2
5-Ethyl-5-hexen-3-ol
Cl
OH
2-Cyclohexenol
4-Chloro-3-methyl-3-octen-1-ol
8
 Alcohols containing two hydroxyl groups are
commonly called gylcols. In the IUPAC system,
the suffix diol is added to the name of the parent
hydrocarbon when two hydroxyl groups are
present, and the suffix triol is added when there
are three OH groups.
OH
OH
OH
OH
H3C
HO
OH
OH
1,2-Ethanediol
1,2-Propanediol
1,2,3-Propanetriol
Ethylene glycol
Propylene glycol
Glycerol or Glycerin
Nomenclature of Phenols
 2) Compounds that have a hydroxyl group attached
directly to a benzene ring are called phenols
OH
OH
OH
OH
O2N
NO 2
OH
NO 2
Cl
Cl
Cl
Cl
Br
NH2
Phenol
4-Bromo-2-nitrophenol
p-Aminophenol
Cl
NO 2
2,4,6-Trinitrophenol
Pentachlorophenol
OH
OH
OH
CH3
CH3
o-Cresol
m-Cresol
p-Cresol
HO
OH
OH
CH3
OH
OH
OH
OH
Catechol
Resorcinol
OH
HO
Hydroquinone
Pyrogallol
Physical Properties of Alcohols & Phenols
 Solubility of alcohols The first three members are
completely miscible with water. The solubility rapidly
decreases with increase in molecular mass. The higher
members are almost insoluble in water but are soluble in
organic solvents like benzene, ether etc.
 The solubility of lower alcohols is due to the existence of
hydrogen bonds between water and polar -OH group of
alcohol molecules. Phenols too are sparingly soluble in
water. The -OH group in alcohols and phenols contain a
hydrogen bonded to an electronegative oxygen atom.
Thus they form hydrogen bonds with water molecules.
 The solubility increases with branching of chain.
 Phenols are sparingly soluble in water but readily
soluble in organic solvents such as alcohol and ether.
•Boiling points of alcohols Boiling point of alcohols are
much higher than those of alkenes, halo alkenes or ethers
of comparable molecular masses. This is because in
alcohols intermolecular hydrogen bonding exists due to
which a large amount of energy is required to break these
bonds.
•Among isomeric alcohols, the boiling point decreases with
increase in branching in the alkyl group
Boiling points of 1o alcohol < 2o alcohol < 3o alcohol
•As number of hydroxyl groups increase the solubility and
boiling points increase.
Acidity of Alcohols & Phenols
 Alcohols have weak acidic properties.
 Phenol is a strong acid than alcohols because the
negative charge in oxygen is dispersed by
resonance through the benzene ring.
Alcohols react with Na (or K) like water to give the
alkoxide
 Introduction of electron-withdrawing groups, such as
NO2 or CN, on the ring increases the acidity of phenol,
introducing EDG decrease the acidity of phenols
OH
O 2N
NO 2
OH
HO
NO 2
>
>
NO 2
OH
OH
NO 2
>
NO 2
>
H3C
Preparation
of
alcohols
1- From alkenes
H
+
H2SO 4
H2O
OH
CH3
CH3
KMnO 4 / OH
-
OH
OH
OH
1) RCO 3H
2) H 3O
+
OH
2- From alkyl halide
CH3
Br
OH
dil KOH
Cl
CH3
H2O
HO
CH3
CH3
CH3
CH3
3- From aldehyde, ketone and carboxylic acid
O
R
1) LiAlH 4 0r NaBH 4
C
H
2) H 3O
+
R
R'
O
R
C
CH2 OH
1) LiAlH 4 0r NaBH 4
R'
2) H 3O
+
R
CH
OH
O
R
1) LiAlH 4
C
OH
2) H 3O
+
R
CH2 OH
4- From Grignard reagent
R'
O
R
+
C
R'MgX
H
1) Dry ether
R
OH
2) H 2O
HO
O
H3C
CH
+
C
C2H5MgX
H
1) Dry ether
2) H 2O
H3C
CH
C2H5
R'
O
R
C
+
R'
R''MgX
1) Dry ether
R
2) H 2O
+
R''
CH 3MgX
1) Dry ether
OH
2) H 2O
R''
O
+
C
2 R''MgX
1) Dry ether
R
2) H 2O
OR'
C
+
OC 2H5
2 CH 3MgX
1) Dry ether
2) H 2O
C
OH
R''
CH3
O
H3C
OH
CH3
O
R
C
H3C
C
H3C
OH
Preparation of Phenols
1- Hydrolysis of Diazonium salts
+
N2 Cl
OH
-
H2SO4 / H2O
+
N2
Heat
2- Fusion of sodium with benzene-sulfonates:
-
O Na
SO 3H
OH
+
H3O
NaOH / 350
+
3- From alkyl halide:
-
O Na
Cl
NaOH / 350
300 atm
OH
+
H3O
+
Reaction of Alcohols and Phenols
1- Salt Formation
+
OH
2 R
2 Na
OH
+
+
Sodium alkoxide
Alcohol as acid
H3C
-
O Na
2R
+
Na
-
O Na
H3C
+
Sodium Methoxide
Methanol
-
OH
O Na
+
+
Na
Sodium Phenoxide
H2
2- Dehydration
H2C
-
H3C
+
CH3
H2O
1 Butene minor
CH3
HO
H3C
+
CH3
H2O
-
2 Butene major
3- Ester formation
O
R
O
+
+
C
H
R'OH
R
+
C
OH
H2O
OR'
O
COOH
C
+
+
CH 3OH
OCH 3
H
+
4- Reaction with alkyl halide
R
OH
+
HX or SOX 2 , PX3, PX5
Heat
ZnCl 2
R
X
H2O
5)
Oxidation Of Alcohols
Alcohols can be oxidised depending on their class
 For oxidation to take place easily you must have two hydrogen atoms on adjacent C
and O atoms.
1°
R
H
H
C
O
+
[O]
R
H
2°
R
C
O
+
H 2O
O
+
H 2O
H
H
H
C
O
+
[O]
R
R
C
R
This is possible in 1° and 2° alcohols but not in 3° alcohols.
3°
R
R
H
C
O
R
+
[O]
21
R
CH2 OH
O
Cu or CrO 3 / pyridine
heat
H
adehyde
Primary alcohol
H3C
CH2 OH
weak oxidizing reagent
R
O
Cu or CrO 3 / pyridine
H3C
heat
H
+
H2Cr 2O7 or K 2Cr 2O7/ H
R
CH2 OH
Primary alcohol
O
R
or KMnO 4 / heat
OH
carboxylic acid
R'
R
CH
OH
K2Cr 2O 7 or KMnO 4
O
R
heat
R'
ketone
Secondary alcohol
OH
+
O
K2Cr 2O 7 / H
R'
R
+
C
OH
H2CrO 7 / H
No reaction
heat
R''
Tertiary alcohol
OH
O
+
HO
KMnO 4 / heat
H2CrO 7 or Na 2CrO 7 / H
or KMnO 4 / heat
Phenol
O
p-Benzoquinone
HO
Hydroquinone
6- Reaction of aromatic ring of phenols
OH
Br
Br
Br2 / H2O
HO
HO
Br
HO
Br2 / CCl 4
Br
+
Br
HO
HO
NO 2
dil HNO 3
+
OH
conc HNO 3
O 2N
O 2N
HO
conc H2SO 4
NO 2
NO 2
OH
SO 3H
+
SO 3H