Alcohols, phenols &ethers
Alcohols, and Phenols
 Alcohols and phenols may be viewed as organic derivatives of water.
and phenols have a common functional group, the hydroxyl
 Alcohols
group, —OH.
 In alcohols the hydroxyl group is attached to an alkyl group, —R.
 In phenols the hydroxyl function is attached to an aromatic ring, Ar.
Classification and Nomenclature of Alcohols
Alcohols are classified into:
IUPAC Name
1. Select the longest continuous carbon chain that contains OH group.
Replace the ending the suffix -ol .
2. If a molecule contains both an -OH group and a C=C or C≡C triple bond.
- The name should include both the hydroxyl and the unsaturated groups.
- The -OH group takes preference before the double or triple bonds in getting the
lower number.
- If a compound contains both OH and a double or triple bond, choose the
chain that include them both even if this is not the longest chain.
CH2CH3
CH2=CH-CHCH3
OH
3-Buten-2-ol
CH3-CH-C=CH2
OH
3-Ethyl-3-buten-2-ol
HC
C-CH2-CH2-OH
3-Butyn1-ol.
-
3. In the IUPAC system.
The suffix diol is added to the name of the parent hydrocarbon when there are two
OH groups. triol is added when there are three OH group
Two OH groups on adjacent carbons are known as 1,2-glycols.
4- Cyclic alcohol, no. starts from C near to OH
OH
OH
C6H5
CH3
3-Methyl cyclohexanol
Br
3-Bromo-2-phenyl cyclopentanol
Common name
listing the alkyl substitutents attached to the hydroxyl group, followed by
the word alcohol.

Primary alcohol
CH3OH

CH3CH2OH
CH2=CHCH2OH

Common
Methyl alcohol
Ethyl alcohol
Allyl alcohol

IUPAC
Methanol
Ethanol
2-Propen-1-ol
 Secondary and tertiary alcohol
OH
OH
H3C
CH CH3
CH3
OH
H2
C
OH
H2C
OH
OH
1
2
3
4
2-phenylethanol
phenol
4-Methyl-2-cyclohexen-1-ol
OH
H2C
OH
OH
ethane-1,2-diol
Ethelene glycol (common name)
1-Phenylmethanol
Benzyl alcohol (common name)
OH
OH
OH
CH3
OH
OH
Trans-1,2-cyclohexanediol
2-Methyl-2-cyclohexenol
1,2-Cyclopentanediol.
Physical Properties of Alcohols
Solubility
As the number of carbons in the alcohol increases, the solubility in
water decreases. when No. of OH  Soluble. in H2Oinc.
Triols Diols and are more soluble in water than monohydroxy alcohols.
OH
OH
OH
OH
OH
OH
Boiling points
The boiling points increase with increase in molecular weights.
OH
OH
OH
The Increase of alcohol BP. is due to the presence of hydrogen bonding
BP. In straight chains is higher than branched
OH
HO
In isomer BP. Dec. with  in alkyl gp.
3 < 2<1
OH
OH
alcohol BP. Higher than it is alkanes ( hydrogen bond)
OH
Alcohols are week acids.
Alcohol weaker acids than phenol and carboxylic acids
OH
Synthesis (Preparation) of Alcohols
1. From alkene .
OH
+ H2O conc.H2SO4
Symmetrical akenes
A
A
A
+
A
H
H2 O
A
A
A
A
H
OH
OH
+
H2 O
H
CH3
H3C
H
Unsymmetrical akenes
H
H
CH3
+
OH
H2O
KMnO4 / OH
CH3
OH
Cis
H2O
OH
2– From alkyl halid
ROH +HX
RX+ HOH
CH2-Cl
CH3
CH3-C-Cl
CH3
H2O
NaOH / H2O
/ OH
CH2-OH
(CH3)3-C-OH + HCl
3] From reduction of aldehyd , ketones & carboxylic acid:
(Reduction of aldehyde and ketone for preparing 1 & 2 alcohol only not 3)
Reducing agent :
- Zn / H+ , Zn / HCl , Na / alcohol ,
-H2 / Pt or Pd or Ni, (all=)
NaBH4 /H2O
( for aldehyd or keton.)
- Li Al H4 /dry ether (all C=O)
O
R-C-H
O
CH3-C-H
O
R-C-R
1) Li Al H4 / dry ether
or NaBH4
1)
2 H3O
OH
R-CH2
1) Li Al H4 / dry ether
2 H3O
or NaBH4
1)
CH3-CH2OH
OH
R-C-R
H
1) Li Al H4 / dry ether
or NaBH4
1)
2 H3O
O
CH3-C-CH3
1) Li Al H4 / dry ether
2 1) H3O
O
R-C-OH 1) NaBH4 Li Al H4
1)
2 H2O
O
1) NaBH4 Li Al H4
CH3-CH2-C-OH
2 H2O
1)
1
OH
R-C-H
H
2
CH3
H
C-OH
CH3
1
CH3CH2CH2OH
4] From Grignard reagent:
for (1 , 2 & 3)
a) with aldehyde :
O
H H + RMgX
1) dry ether
RCH2OH
2) H2O
O
1) dry ether
CH3CH2CH2OH
i- H H+ CH3CH2MgCl
2) H2O
O
ii) CH3-C-H +CH3CH2MgCl
1) dry ether
21) H2O
H
CH3-CH2-C-OH
CH3
b) with ketones:
O
R"-MgX + R-C-R
CH3-MgBr
1)dry ether
2)H2O
O
OH
R-C-R
R"
1)dry ether
2)H2O
OH
CH3
Reactions of Alcohols
-Alcohols doesn't react with strong bases (only with metal )
1- Salt and Ester Formation (Dissociation of O-H Bond) :
2 R-OH +2 Na
2
+Na
CH3-OH
RONa + H2
CH3ONa ( sodium methoxid)
+NaOH
no reac.
+NaHCO3 no reac.
H3C
H2
C
OH
2Na
-H2
H2
C
H3C
O Na
Sodium ethoxide
2-Dehydration (Elimination Reactions) :
conc. H2SO4
OH
+ Minor
maj.
3] Oxidation:
1& 2 only
1 with weaker oxidizing agent------ aldehyde
O
H
Cu / heat
i) R-C-OH
R-C-H (aldehyde)
or CrO3 . pyridine
H
O
Cu / heat
ii) CH3CH2OH
CH3-C-H
weak oxidizing agent)
1 with strong oxidizing agent------ carboxylic acid
CH3
iii) CH-OH
CH3
K2Cr2O7/ acid
or KMnO4, Heat (neutral)
CH3
C
CH3
O
(keton)
O
H
i) R-C-OH
H
H2Cr2O7 / H+ or( K2Cr2O7)
R-C-OH
(carboxylic acid)
or KMnO4, Heat (neutral)
COOH
CH2OH
K2Cr2O7/ acid
iii)
or KMnO4, Heat (neutral)
(benzoic acid)
3 alcohol ------no reaction
4] Reaction with alkyl halides (Substitution Reaction) :
PCl3 or SOCl2 or PBr3
R-OH
CH3CH2OH
CH3
CH3-C-OH
H
PBr3
HCl
CH3CH2Br
CH3
CH3-CH-Cl
CH3
C Cl
CH3
C
CH3
OH
CH3
RX
PCl3
H3C
CH3
Nomenclature and acidity of Phenols
Phenols are generally named as derivatives of the simplest member of the family, phenol.
Phenols is an hydroxyl group attached directly to a benzene ring
OH
OH
OH
NO 2
NH2
4-Ami nophenol
NO 2
O2N
Br
4-Brom o-2-ni trophenol
NO 2
2,4,6-T ri ni trophenol
Picri c acid
OH
OH
OH
CH3
CH3
o-Cresol
2-Methylph.
ee
m-Crysol
3-Methylph.
CH3
p-Cresol
4-Methylph.
OH
OH
CHO
OH
COOH
Cl
2-Hydroxybenzal dehyde 2-Hydroxybenzoi c aci d
-Hydroxybezal dehyde O-Hydroxybezoi c aci d
O
Sal i cyl i c acid
Sal i cyl aldehyde
NH2
ol
3-Ami no-5-Cl orophenol
Acidity of Phenols
Introduction of electron-withdrawing groups, such as NO2 or CN, on
the ring increases the acidity of phenols.
OH
OH
OH
OH
OH



NO2
OCH3
4-Methoxyphenol
p-Cresol (Common)
Phenol
4-Nitrophenol
pH 10
pH = 10
pH = 7
NO2
O2N
O2N

NO2
2,4-Dinitrophenol
pH = 4
NO2
Picric acid
2,4,6-Trinitrophenol
pH = 0.25
(NO2) is e with. (deact.gp) acidity (CH3)is dona.gp. acidity
Introduction of electron-withdrawing groups, such as NO2 or CN, on
the ring increases the acidity of phenols.
Alcohols and phenols have weak acidic properties.
Phenols are much stronger acids than alcohols.
Preparation of phenols
1-From Diazonium salts:
N2Cl
OH
H2SO4 (heat)
H3O or H2O
N2
2-From alkali fusion of sodium benzene-sulfonates:
SO3H
H2SO4
SO3 ,heat
2 NaOH
350 o
SO3H
CH3
NaOH (70%) or KOH(30%)
o
2
350-350
C
O : Na+
OH
H3 O
or H+
O : Na +
CH3
H3 O
or H+
OH
CH3
Reactions of Phenols
EWilliamson ether synthesis
OH
OC2H5
ONa
NaOH
-H2O
C2H5Br
Ethyl phenyl ether
( Ethoxy benzene )
EEster formation
O
O
H3C
O
OH
O
CH3
H3C
COOH
COOH
O
Or
O
H3C
Cl
Asprine
Acetyl salicylic acid
2-Reaction of aromatic nucleus of phenol (Electrophilic Substitution)
OH
OH
NO2
(dil) HNO3
o
250 C
NO2
OH
OH
OH
o
CCl24 4, 5 C
+ Br2 / CCl
SC
Br
EHalogenation
Br
OH
+3Br2 / H2O, 250o Br
Br
3 HBr
Br
o
conc. H2SO4 / 25 C
OH
SO3H
E Salt formation via strong base or active metal
E Williamson ether synthesis
E Ester formation
E Friedel-Crafts acylation: Fries rearrangement
E Halogenation
E Coupling with diazonium salts
E Kolbe-Schmitt Carboxylation
E Reimer-Tiemann reaction
OR
EWilliamson
ether
synthesis
ESalt formation
via strong base
or active metal
-
O Na
EEster
formation
1. NaOH
+
O
2. RX (primary)
NaOH
CO2
4-7 atm
heat
OH
or
(RCO) 2 O
Na
AlCl 3
OH
-
C O Na
+
O
EKolbeSchmitt
Carboxylation
ArN
CHCl 3
OH
+
2
R
NaOH
OH
O- Na +
C
O
H
N
EReimerTiemann
reaction
N
Ar
C
O
RCOCl
or
R
C
O
ECoupling with
diazonium salts
EFriedel-Crafts
acylation: Fries
rearrangement
Reimer-Tiemann Reaction Mechanism
O
C
CHCl 3
Overall:
OH
NaOH/H
heat
salicylaldehyde
2O
OH
CHCl 3 + OH CC l3
H
CC l3 -
-
+
H 2O
CC l2 + Cl
a carbene
O
OH
O
+ OH -
H
O
O
O
CC l2
H
+
CHCl 2
H
CC l2
O-
OH
CHCl 2
-
H 2O
heat
O
C
H
+
2 HC l
ETHER
Structure and nomenclature of ethers
Ethers are compounds of formula R -0-R', where R and R' may be alkyl groups or
aryl (benzene ring) groups.
H
O
water
H
R
O
alcohol
H
R
O
R
ether
Common names (Alkyl Alkyl Ether Names)
Common names of ethers are formed by naming the two alkyl groups on oxygen
and adding the word ether. Under the current system, the alkyl groups should be
named in alphabetical order.
Common : Methyl Phenyl ether (anisole)
IUPAC : Methoxy benzene
Common: Diphenyl ether
IUPAC : Phenoxy benzene
H3C
O
CH3
H3C
3-Methoxyhexane
CH3
O
CH3
H3C
5-Ethoxy-2-heptene
CH3
O
1-Phenoxy-1-propene
Physical Properties of Ether
Boiling Points
The boiling points of ethers are lower than those of alcohols having the same molecular weights
compound
Formula
MW
Bp (°C)
ethanol
CH3-CH2-OH
46
78
Dimethyl ether
CH3-O-CH3
46
-25
propane
CH3-CH2-CH3
44
-42
Solubility in water
Ethers are much less soluble in water than alcohols.
More water-soluble than hydrocarbons of similar molecular
weight.
Preparation of ethers
1]Dehydration of alcohols
The dehydration of alcohols takes place in the presence of acid catalysts (H2SO4,
H3PO4) under controlled temperature. The general reaction for ether formation is:
R O H
+
H
H O R
+
heat
Examples
2
HO CH3
H2SO4, 140 C
H3C O CH3
+ H2O
methyl ether
methyl alcohol
(100%)
2
HO CH2CH3
ethyl alcohol
H2SO4, 140 C
H3CH2C O CH2CH3
ethyl ether
(88%)
+ H2O
R O R
+
H2O
2]The Williamson synthesis of ethers
R-OH + Na (metal)--------- R-O-Na ( sod. Alkoxid)+ H2
Sod. alkoxides + organic halides (1&2) )--- ether (sy. &unsy.)
R
O- Na+
+
R
X
+
R
O R
+ NaX
ether
alkyl halide
sodium alkoxide
O- Na+
R
R
X
O R
+ NaX
ether
alkyl halide
sodium phenoxide
t-Butyl methyl ether
OCH3
O-Na
CH3Cl
NaCl
Methyl Phenyl ether
(anisole)
OC2H5
O-Na
C2H5Br
NaBr
Ethyl phenyl ether
Alkoxide from alcohol
The alkoxide is commonly made by adding Na or K to the alcohol
Examples
+
O Na
OH
Na
OCH2CH3
CH3CH2
Br
+
cyclohexanol
sodium
NaBr
ethoxycyclohexane
cyclohexyloxide
OCH3
OH
1) Na
2) CH3-I
3,3-dimethyl-2-pentanol
3,3-dimethyl-2-pentanol
2-ethoxy-3,3-dimethypentane
2-ethoxy-3,3-dimethypentane
Reaction of Ether
1) Cleavage of ethers by hot concentrated acids
When ethers are heated in concentrated acid solutions, the ether linkage is broken..
General equation:
R O R
heat
+
H
X
R OH
+
R
X
(concentrated)
CH3CH2 O CH2CH3
+
heat
H
I
CH3CH2OH
+ CH3CH2I
(concentrated)
OCH3
H2O
HI heat
OH
CH3I
If an excess of acid is present, the alcohol initially produced is converted into an
alkyl halide by the reaction.
Cyclic Ethers (Epoxide)
Epoxides are cyclic ethers in which the ether oxygen is part of a
three-membered ring.
C
C
O
an epoxide
The simplest and most important epoxide is ethylene oxide.
O
ethylene oxide
Synthesis of Cyclic ether
Peroxy acid Epoxidation:
Peroxy acids (sometimes called per acids) are used to convert alkenes to epoxides. If the
reaction takes place in aqueous acid, the epoxide opens to a glycol. Because of its desirable
solubility properties, meta-chloroperoxybenzoic acid (MCPBA) is often used for these
epoxidations.
Example:
MCPBA
O
CH2Cl2
cyclohexene
Cl
MCPBA :
epoxycyclohexane
O
C-O-O-H
O
+
O
R-C-O-O-H
i] CH2=CH2
O
+
RCO3H
R-C-O-H
O
Reaction of Epoxides
Their reactivity is due to the strain in the three-membered ring, which is relieved
when the epoxide ring is opened after a reaction has taken place.
Examples of ring-opening reactions of ethylene oxide that form commercially
important products are:
1- Epoxides open in acidic solutions to form glycols.
O
R
CH
H3O
CH
OH
+
R
R
CH
CH
R
OH
2- Epoxides open in acidic alcohol solutions to form 2-alkoxy alcohols.
..
H3C
OH
O
+
R
CH
CH
R
+
H3O
OCH3
R
CH
OH
CH
R
3- When an epoxide reacts with a hydrohalic acid ( HCl,HBr, or HI), a halide
ion attacks the protonated epoxide.
X
O
H
X
+
R
CH
CH
R
R
CH
CH
R
OH
4- Reactions of Epoxides with Grignard and Organolithium Reagents
OH
O
R'
MgX
+
R
CH
1) ether
CH
R
R
CH
2) H3O+
or R'
Li
R'
CH
R
H2O/ H+
OHCH2-CH2OH
CH3OH/ H+
OH OCH3
CH2CH2
HX / H+
O
1)CH3MgX/ether
2)H2O
1)Li Al H4
2) H3O
NH3
Phenol
X OH
CH2-CH2
CH3CH2CH2OH
CH3CH2OH
OH NH2
CH2-CH2
CH2CH2
Ph OH
O