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ORGANIC CHEMISTRY –II
2
...

They are monoalkyl derivatives of water
...

1) primary alcohols
2) Secondary alcohols of
3) Tertiary alcohols
Primary alcohols:
CH3 – CH2 – OH

CH3 − CH − CH2 − OH
|
CH3

CH3 – CH2 – CH2 – OH
CH3
|
CH3 − C − CH2 − OH
|
CH3

(Ethyl alcohol)

(Propylalcohol)

(Iso butyl alcohol)

Secondary alcohols :
CH3 − CH− CH3
|
OH

(Isopropyl alcohol)

(neo-pentyl alcohol)

Tertiary alcohols :
CH3 − CH2 − CH− CH3
|
OH

CH3
|
CH3 − C − OH
|
CH3

CH3
|
C2H5 − C − OH
|
CH3

(sec butylalcohol) (tertiary butyl alcohol) (tertiary amyl alcohol)

1

Organic Chemistry – II
•

Isomerism in alcohols :
They exhibit chain, position, functional isomerism
...

Organic compound containing one or more asymmetric carbons will exhibit optical isomerism
...

CH3 – OH
CH3 – CH2 – OH
OH
CH3 – CH2 – CH2 –
Doesn’t show optical isomerism
CH3 − CH − OH
|
CH
3

2

Organic Chemistry – II
CH3 − CH− CH2 − CH3
|
OH
CH3 − CH− COOH
|
OH

•
•

Exhibits optical isomerism

Ethyl alcohol :
Grain alcohol or spirit of wines ( C2H5OH)
Preparation :
By the hydrolysis of ethyl halide : (industrial method)
Ethyl halide on hydrolysis with aqueous sodium hydroxide or potassium hydroxide gives ethyl
alcohol
...


•

By the hydrolysis of ester : Hydrolysis of ethyl acetate with aqueous alkali gives ethyl alcohol
...
sulphuric acid
at 75–80°C gives ethylalcohol
...

H2 Ni or
CH 3 − CHO + H 2 ⎯⎯/⎯ ⎯→ CH 3 − CH 2 − OH
LiAlH4

•

From Grignard reagent and formaldehyde: Methyl magnesium halide on reaction with
formaldehyde followed by hydrolysis gives ethyl alcohol
...
In any fermentation process the by product is CO2
...
Molasses still contain about 40% sugar
...
PH is maintained at 4 by adding dilute H2SO4
...
Ammonium Sulphate or Ammonium
phosphate is added to yeast cells which acts as food for yeast
...

zymase

C 6H12 O 6 ⎯⎯ ⎯ ⎯→ 2C 2H5 OH + 2CO 2

•

The alcohol obtained above is 6 – 10% pure which is called as wash or wort
...
6% by fractional distillation
...
6% alcohol is called
rectified spirit
...
6 % alcohol and 4
...

Quicklime (CaO) or magnesium ethoxide [Mg(OC2H5)2] can be used to convert 95
...

Anhydrous CaCl2 is laboratory desiccant but CaCl2 should not used for drying alcohol as if forms
an addition compound with it
...
3C2H5OH
...
The source of starch is crushed and treated with steam
and the product is called Mash
...

Malt contains diastase enzyme
...

In presence of maltase, maltose, converts into glucose which then converts into ethyl alcohol in the
presence of zymase enzyme
...
It is further concentrated to 100% alcohol as listed above
...

2) It has burning taste
3) It forms hydrogen bonds with water and also with it itself therefore it exists as associated
liquid, soluble in water and boiling point is very high (78
...

4) It’s dissolution in H2O is exothermic and there is slight contraction in volume
...

•
•
•

Chemical reactions:
The reactions of alcohols involve either cleavage of O – H bond or C – OH bond
...

2C 2H5 OH + 2Na → 2C 2H5 ONa + H2

based on the above reaction we can say alcohols are slightly acidic
...

H2 O > C 2H5 − OH > CH ≡ CH > CH2 = CH2 > CH3 − CH3

primary alcohol>secondary alcohol>tertiary alcohol
2) with grignard reagent : Ethyl alcohol on reaction with Grignard reagent forms alkane
...

This reaction is catalysed by mineral acid
...

C 2H5 OH + CH3 COCl → CH3 COOC 2H5 + HCl

C 2H5 OH + (CH 3 CO )2 O → CH 3 COOH + CH 3 COOC 2H5

5) With hydrogen halides : Ethyl alcohol on reaction with hydrogen halides in the presence of
anhydrous ZnCl2 gives ethyl halide
...

3 C 2H5 OH + PCl3 → 3C 2H5 Cl + H3PO 3
3 C 2H 5 OH + PBr3 ⎯
⎯→ 3C 2H 5 Br + H 3 PO 3
3 C 2 H 5 OH + PI 3 ⎯
⎯→ 3C 2H 5I + H 3 PO 3
C2H5 − OH + PCl5 → C2H5Cl + POCl3 + HCl

8) With SOCl2 : Thionyl chloride reacts with ethyl alcohol to give ethyl chloride
...

con
...
H 2 SO 4

2C 2H5 OH ⎯⎯⎯⎯⎯⎯ → C 2H5 − O − C 2H5 + H2O
⎯
0
140 C

(diethyl ether)
conc
...

Instead of conc
...

conc
...
Al 2 O 3

C 2H5 OH ⎯⎯⎯⎯⎯⎯→ C 2H 4 + H2O
350 0 C

10) Reduction : Ethyl alcohl is reduced to ethane by HI / red P
...

0

Cu 300 C
CH3 − CH2 − OH ⎯⎯,⎯ ⎯ → CH3 − CHO + H2
⎯

(acetaldehyde)

5

Organic Chemistry – II
b) On oxidation with acidified potassium permanganate (KMnO4) or potassium dichromate
(K2Cr2O7)
ethyl alcohol forms acetic acid
...


12) with Chlorine : Chlorine oxidises ethyl alcohol to chloral
...

C 2H5 OH + CaOCl2 + H2O → CHCl3 + (HCOO)2 Ca + HCl

14) Iodoform reaction : Yellows crystals of CHI3 will be formed when ethylalcohol is treated
with I2 solution and potassium hydroxide
...

ETHERS : [R – O – R1 →alkoxy alkanes]
•

ether is the dialkyl derivative of water

•

⎡H − O − H ⎤
⎢
⎥
⎣R − O − R⎦

ether is the anhydride of alcohol
...

1) Symmetrical ethers (or) simple ethers are
R = R′ R – O – R
CH3 – O – CH3
C2H5 – O – C2H5
2) unsymmetrical ethers (or) mixed ethers :
R ≠ R′
R – O – R′
CH3– O – C2H5
C2H5 – O – CH2 – CH2 – CH3
Isomerism shown by ethers:
Ethers will exhibit metamerism, functional isomerism and chain isomerism
...
H2SO4 at 1400C
...
H2SO4
2C 2H5 OH ⎯⎯⎯⎯⎯→ C 2H5 − O − C 2H5 + H2 O
⎯
0
140 C

b) By the dehydration of ethyl alcohol in presence of anhydrous alumina at 2500C
...

2C 2H5 Cl + Ag 2 O → C 2H5 − O − C 2H5 + 2AgCl

3) Williamson’s synthesis : Alkyl halides react with sodium alkoxides to produce ethers
...

C 2H5 Cl + NaOC 2H5 → C 2H5 − O − C 2H5 + NaCl

•

Physical properties :
1) It is a colourless liquid with pleasant smell
...
Therefore it is highly
volatile, low boiling point 307
...

3) It is inflammable
...

5) It forms explosive mixture with air [ether +O2 → etherperoxide]
O
110
C2H 0
C2H

•
•
•
•

In ether ‘O’ is sp3 hybridised, shape is angular
...

It is slightly polar and its μ ≠ 0
...

Therefore ethers are not easily oxidisable and they will not decolourise permanganate or
dichromate
...

α

dark

α1

CH3 − CH 2 − O − CH 2 − CH 3 + 2Cl 2 ⎯⎯ ⎯→ CH3 − CH− O − C H− CH3 + 2HCl (α, α1 −dichloro diethyl ether)
|

7

|

Cl

Cl

Organic Chemistry – II
Cl
Cl
|
|
CH3 − CH2 − O − CH2 − CH3 + 2Cl 2 ⎯⎯ ⎯⎯→ CH3 − C − O − C − CH3 (αα, α1 α1 −tetrachloro diethyl ether)
|
|
Cl
Cl
sunlight

In dark the two α - hydrogens are substituted by two chlorines on reaction with chlorine
...

C 2H 5 − O − C 2H 5 +

1
O 2 → C 2H 5 − O − O − C 2H 5
(explosive )
2

(or)

C 2 H 5 − O− C 2 H 5

↓
O

It is

freed from peroxide by treating with ferrous sulphate
...
H2SO4 : Diethyl ether is hydrolysed to ethyl alcohol in presence of sulphuric acid
dil
...
mineral acids
...
mineral acids like HCl, H2SO4, HNO3 etc
...
Formation of these oxonium salts with the mineral acids is the indication of its basic
nature
...
C 2H5 − O − C 2H5 + HI → C 2H5 − OH + C2H5 − I
•

With hot and excess of HI , both C – O bonds are cleaved and two moles of C2H5 – I are formed
C 2H5 − O − C 2H5 + 2HI → 2C 2H5 − I + H2O

•
•
•

In case of mixed ethers I– of HI is added to smaller alkyl group
...

The reaction of ether with HI forms the basis for Ziesel’s method
...

an
C2H5 − O − C2H5 ⎯⎯
...
NH3
...
⎯ 3 → C 2H6 + C 2H5 OH
⎯

8

Organic Chemistry – II
ELECTROPHILIC SUBSTITUTION
...

a solvent for oils, fats, waxes, plastics etc
...

the extraction of organic compounds from aqueous solutions
...

an inert medium for various reactions (ex
...

an anaesthesia in surgery without causing any damage to heart or lungs
...
) (IUPAC name : 2-Bromo-2- chloro-1,1,1-trifluroethane)
5
...

Refrigerant along with dry ice (solid CO2 ) which produces a temperature around -110°C
i)
Enthrane (CHFCl − CF2 − O − CHF2 ) and isoflurane ( CF3CHCl − O − CHF2 ) are used as
anesthetics in place of diethyl ether as the later one has slow effect
...

ii)
Eg :

1
...


2
...


3
...
THYMOL
is present in thyme and mint are used as flavourings and in perfumes
...


( NaNO2 + H 2 SO4 )

red colouration
3) Catalytic

Aldehyde, H2 is

dehydrogenation

↓ alkali
blue colouration

produced

with copper at

3000 c

RCH 2OH
↓

Ketone, H2 is produced

R2COH →

Dehydration takes place

giving alkene and H2O

R2CO + H 2

(CH 3 )3 COH

→

CH 3 − C = CH 2 + H 2O
1

RCHO + H 2

CH 3

4) Oxidation

(O )
RCH 2OH ⎯⎯→

(O )
R2CHOH ⎯⎯→

with acidified

RCHO

R2CO

Ketone + acid ⎯⎯→

↓ (O)
RCOOH

↓ (O)

Mixture of acids

KMnO4

same number
of carbon atoms
in alcohol,
aldehyde and acid

Mixture of
alcohol and
ketone contain
same no
...
of
carbons

11

R3 C − OH

(O)
⎯⎯→
(O )

ketone contains lesser
no
...

alcohol
...
of carbons than
that of ketone
...


CH 3 − CH 2 − + O − H + OSO3 H
|
H
ii) Formation of carbonation
...


...


CH 3 − CH 2 − + O − H ⇔ CH 3 − C H 2 + H 2 O :
|
H
iii) Elimination of proton to get alkene

Since the rate determining step is the formation of carbocation, the rate of dehydration is directly
proportional to the formation of carbocation
...

2

•

•

4

The dehydration of 1o alcohol goes by E2 mech nism, but that of 2o and 3o alcohols go by E1
mechanism
...
It states
that hydrogen is removed from β − carbon that is bonded to the least number of hydrogen atoms
...
Dehydration of 2-butanol predominantly gives 2-butene
...
3CaCl2 , C2 H 5OH
...
3CuSO4

USES OF SOME IMPROTANT COMPOUNDS
(Methanol and ethanol)
METHANOL
1
...
pt 670 C
...
,
2
...

3
...
6% ethyl alcohol +
4
...

4
...


b) Surgical spirit = 95% rectified spirit + 5% MeOH
In denaturation of ethyl alcohol copper sulphate is added to give colour and pyridine is added to
make it a foul smelling liquid
...


USES OF ETHYL ALCOHOL
1
...
,
2
...

3
...

A source for the preparation of acetaldehyde, chloral, chloroform, iodoform, acetic acid ether etc
...

A preservative for biological specimens, an antifreeze for automobile radiotors, a fuel in spirit
lamps, stoves, a petrol substitute known as power alcohol
...

Sugar increases in ripe grapes and yeast grows on the outer skin
...
If air is present it
oxidises alcohol to acids

PHENOL
NAMING OF PHENOLS
Molecule

Common name

IUPAC name

Phenol

Phenol

O-cresol

m-cresol

p-cresol

Catechol

2-methyl phenol

3-methyl phenol

4-methyl phenol

Benzene-1,2-diol
13

Organic Chemistry – II

Resorcinol

Benzene-1,3-diol

Hydroquinone (or)quinol Benzene-1,4-diol

2,6-dimethyl phenol
METHODS OF PREPARATION OF PHENOL :
1) Phenol was first isolated from coaltar
...
H 2 SO4 , SO3
⎯⎯⎯⎯⎯→
⎯

5)

H 2O , warm
⎯⎯⎯⎯
→

molten NaOH
⎯⎯⎯⎯⎯
→

HCl
⎯⎯→
⎯

From cumene : Phenol is manufactured from cumene (isopropyl benzene)

+

O2 ( oxidation with air )
⎯⎯⎯⎯⎯⎯⎯
→
+CH 3COCH 3 cumene hydroperoxide

H / H 2O
⎯⎯⎯⎯
→

14

+ N 2 + HCl

+ NaCl

Organic Chemistry – II
ACIDITY OF PHENOLS : The reactions of phenol with metals as well as NaOH indicate it is
relatively more acidic than alcohols and also water
...
The hydroxyl group in phenol is directly attached to sp 2 carbon of benzene ring
...
Because of this oxygen develops still more electron seeking character and
releases proton by taking the shared pair of electrons with it
...
On the basis of resonance stabilization of phonoxide ion
...

Electron releasing group of phenol decrease the acidity of phenols
...

The order of the strength of phenols is as follows

>

>

>

>

>

>

>

=

PHYSICAL AND CHEMICAL PROPERTIES OF PHENOLS
PHYSICAL : 1) Phenol has higher boiling point than the arenes or haloarenes or ethers of same
molecular weight
...

2) Phenols are relatively more soluble in water due to their ability to form hydrogen bonding with
water
...

CHEMICAL PROPERTIES :
1) Acidic nature of phenol :
Alcohols and phenols react with active metals like Na, K, Al etc to liberate hydrogen gas
...

C6 H 5OH + NaOH → C6 H 5ONa + H 2O
The acidic nature of alcohols is due to the polar nature of O-H group
...
This
decreases the acidic strength
...

ESTERIFICATION OF PHENOL :
Phenols react with carboxylic acids and their derivatives like acid chlorides and anhydrides to
form esters
...

C6 H 5OH + RCOOH → C6 H 5 − O − CO − R + H 2O
pyridine
C6 H 5OH + RCOCl ⎯⎯⎯→ C6 H 5 − O − CO − R + HCl
Salicylic acid on acetylation gives acetyl salicylic acid known as Aspirin
...
H 2 SO4
⎯
+ (CH 3CO) 2 O ⎯⎯⎯⎯→

Electrophilic aromatic substitution reactions of phenol
In phenol, -OH group is ring activating and ortho and para directing as these positions get more
electron density through resonance structures
...
HNO3
⎯⎯⎯⎯
→
+
O-nitrophenol is steam volatile due to intramolecular hydrogen bond
...

Phenol when treated with conc
...
HNO3
⎯⎯⎯⎯
→
Now a days picric acid is prepared by treating phenol with conc
...
HNO3
...
H 2 SO4
⎯⎯⎯⎯→

conc
...

Phenol reacts with bromine water and gives 2,4,6-tribromo phenol (white precipitate)

H 2O
+3Br2 ⎯⎯⎯
→
0 − 50 C

c) REIMER-TIEMANN REACTION :
Phenol when treated with chloroform in the presence of NaOH give salicylaldehyde
...

f) OXIDATION : Phenol oxidation with chromic acid ( Na2Cr2O7 + H 2 SO4 ) produces benzoquinone,
which is a conjugate diketone
...

2) It is strong antiseptic
...

3) It is used as a preservative for ink
...

5) It is used for causterising wounds caused by the bite of mad dogs
...

ii) Aqueous phenol gives white precipitate with bromine water
...


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