A) PHENOLS: Methods of formations a) from aniline & b) from cumene. Acidic character, Reaction of Phenols- a) Carboxylation (Kolbe’s reaction), b) Fries Rearrangement, c) Claisen Rearrengement and d) Reimer – Tiemann reaction.

1. 1
B.Sc. First year
Students
Semester – II
Unit-IV A) Phenols
by
Dr Pramod R Padole

2. 2

4. pramodpadole@gmail.com
By Dr Pramod R. Padole
Unit-IV
B) Ethers C) Epoxides
A) Phenol

5. Unit IV
Phenols: Methods of formations
a) from aniline & b) from cumene.
Acidic character of Phenol,
Reaction of Phenols-
a) Carboxylation (Kolb’s reaction),
b) Fries Rearrangement, c) Claisen Rearrengement and
d) Reimer – Tiemann reaction.
A
Ethers: Diethyl ether: Preparation by Williamson’s
synthesis and continuous etherification process,
Chemical Reactions with cold and hot HI
B
Epoxides: Synthesis of ethylene oxide from ethylene
and styrene oxide from styrene.
Ring opening reactions of both catalysed by acid and alkali
C

6. LOGO
Unit-III
A) Phenols:

7. A) Phenols or Carbolic Acid
Introduction:
(1) Phenols are aromatic hydroxy compounds in which
hydroxyl group (-OH) is directly attached (linked) to the aromatic ring.
Or (2) Phenols are the organic compounds containing benzene
ring bonded to a hydroxyl group.
They are also known as carbolic acids.
 Phenols are acidic whereas alcohols are neutral.
Q.1) What are phenols? (W-11, W-13, S-17 & S-19, 1 Mark)
Q.2) Aromatic hydroxyl compounds in which hydroxyl group is directly linked to the aromatic
ring are called_____. (S-14, ½ Mark)
Q.3) The molecular formula of Phenol is C6H6O (C6H5-OH) (S-14, ½ Mark)
Q.4) Which of the following compound is called as carbolic acid. (S-15 & W-17, ½ Mark)
(a) Phenol (b) Ethanol (c) Glycerol (d) Ether
Q.5) What are dihydric and trihydric phenol? Give all the isomers dihydric and trihydric and
trihydric phenol. (W-19, 4 Mark)

8. Classification of Phenol:
Trihydric phenol
Monohydric phenol
Dihydric phenol
Depending on the number of hydroxyl groups attached attach to the aromatic
(benzene) ring, phenols can be classified into three types.
contain one -OH group
contain two -OH groups.
contain three -OH groups

9. LOGO Classification of Phenol:
Monohydric phenols
A compound having only one hydroxy group attached to an
aromatic (benzenoid) ring are known as monohydric phenols.
Molecular formula of Phenol is C6H6O (C6H5-OH)

10. Q.2) WHAT ARE CRESOLS? (S-12, 1 MARK)
ANS: METHYL SUBSTITUTED PHENOLS
ARE CALLED
CRESOLS.

11. Classification of Phenol:
Dihydric phenols
contain two -OH groups.
They may be ortho-, meta- or para- derivative.
Dihydric phenols:
A compound having two hydroxy groups
attached to an aromatic (benzenoid) ring are
known as dihydric phenols.

12. Classification of Phenol:
Trihydric phenol
contain three -OH groups
Trihydric phenols:
A compound having three hydroxy groups attached
to an aromatic (benzenoid) ring are known
as trihydric phenols.

13. Unit-IV (A) Phenols:
From
Aniline
Phenols
Preparation or Synthesis
From
Benzene
or
Cumene
or
(iso-propylbenzene):

14. 1) Preparation of Phenol from Aniline:
Q.1) How will you obtain / synthesise / prepare: Phenol from Aniline?
(W-14, S-15, S-17 & W-17, 2 Mark)
Q.2) How will you convert: Aniline to Phenol? (W-16, 2 Mark)
Q.3) What happen when, Aniline on diazotization with NaNO2 + HCl?
Q.4) Complete the following reaction: (S-18, 2 Mark)
Ans: From Aniline:
When aniline (Aromatic primary amines) is
reacted with nitrous acid (NaNO2 + HCl) in cold
condition; to form Benzenediazonium salt,
which is further hydrolyzed with acid (dil. H2SO4);
to form phenol as a final product.
This process is called as diazotization.
NH2
+ NaNO2 + HCl
273-278 K Dil. H2SO4
H2O
? ?

15. 1) Preparation of Phenol from Aniline:
Ans:
From Aniline:
NaNO2 HCl
N H2
HNO2
HNO2
NaCl
+
+
0 - 5 0
C
+
NaNO2/HCl
O=N-OH + H Cl
(- 2 H2O)
Sodium nitrite Nitrous acid
in Ice cold
condition
Nitrous acid
Aniline
(Aromatic 1o
amine)
or 0 - 5 0
C
in Ice cold
condition
Benzene diazonium chloride
(B.D.C.)
or Diazonium salt
Acid hydrolysed by
dil. H2SO4
OH
N2 Cl
+ H2O + N2 + HCl
Phenol
+ H---OH

16. 2) From Benzene or Cumene or (iso-propylbenzene):
Q.1) How will you obtained / prepare Phenol from cumene?
(W-05, S-06, S-11, W-11, S-15, S-17, W-17 & W-18, 2 Mark)
Q.2) Give the synthesis / prepare phenol from cumene? (W-09, 2 Mark)
Q.3) Complete the following reaction. (S-16, 2 Mark)
Q.4) Cumene is isopropyl benzene. (W-14, ½ Mark)
Q.5) How Phenol is prepared from cumene? (S-19 & W-19, 2 Mark)
Q.6) Cumene is isopropyl benzene. (W-19, ½ Mark)

17. 2) From Benzene or Cumene or (iso-propylbenzene):
Ans: From Cumene (iso-propylbenzene):
Cumene is isopropyl benzene.
It is prepared from the reaction of benzene with propylene.
Cumene on oxidation by Cobolt naphthanate (as catalyst) in presence of dil.
Na2CO3 solution (alkaline medium) at 403 K; to form cumene hydroperoxide,
which on further treated with dil. H2SO4 at 333 K, undergoes rearrangement;
to form phenol (main product) and acetone (by-product).
C H
CH3
CH3-CO-CH3
OH
+ O2
air
Co - Naphthalate
Cumene
(isopropyl benzene) Cumene hydroperoxide
dil. H2SO4,
Heat at 333 K
H
+ CH3 CH CH2
Benzene
Propylene
CH3
dil. Na2CO3
COOH
CH3
CH3
403 K
+
Phenol Acetone

18. Acidic Character
or Acidic Nature of Phenol:
:
Q.1) Explain: Acidic nature / character of phenol.
(S-04, W-04, S-05, S-06, W-08, S-09, W-09, S-10, W-10, W-11, W-12, S-13, W-13, S-14, …
S-15, W-15, S-16, W-16, S-18 & W-18, 4 Mark)
Q.2) Explain why: Alcohols are neutral while Phenols are acidic? (S-07, 2 Mark)
Q.3) Nature of phenol is acidic. (W-12 & W-13, 1/2, Mark)
Q.4) Acidity of phenol is due to the resonance stabilization of phenoxide ion (phenolate anion).
(W-14, ½ Mark)

19. Acidic character / nature of Phenol:
 The acidic character of phenol can be
explained on the basis of resonance theory.
1) According to resonance theory, phenol is the resonance
hybrid of the following resonating structures.
The lone pair of electron on oxygen atom is in conjugation
with the double bonds of the benzene ring.
Therefore, it can take part in delocalization such that the
lone pair is donated to benzene ring.
OH
I II III
Phenol
Resonance structures of Phenol has both + & - ve charge
Three R.S. place a -ve charge on C-atoms in the ring



:
:
OH
:
OH
:
OH
:
OH
:

Resonance hybrid
+ R-effect

20. Acidic character / nature of Phenol:
2) Due to resonance, the oxygen atom of the –OH group develops
a positive charge and try to attract the shared electron pair
between O-H bond.
This makes the O-H bond weak and, there, phenol can easily
donate (released) proton as shown below:-
Phenol is weakly acidic and at high pH gives the phenolate
anion, C6H5O−
It is also called phenoxide ion
PhOH ⇌ PhO− + H+ (K = 10−10)
O H
Phenol
:
:
O
:
:
:
Phenoxide ion
+ H
proton

21. pramodpadole@gmail.com By Dr. Pramod R. Padole
Acidic Character or Acidic Nature of Phenol:
3) The phenoxide ion is obtained by the loss of proton from
phenol is found to be more stable by resonance than phenol.
4) In short, phenol is acidic, because of following two
reasons:-
i) O–H bond becomes weak due to resonance.
ii) Phenoxide ion obtained by loss of proton (H+) gets
stabilized by resonance more than phenol.
5) Such type of resonance is not possible in alcohols
(aliphatic or aromatic) and therefore, they are neutral.
I II III
Resonance structures of Phenoxide ion
having only one -ve charge on C-atoms in the ring
O
:
+ R-effect
O H
Phenol
:
:
O
:
:
:
Phenoxide ion
- H
O
:
:
O
:
:
:

22. www.themegallery.com

23. pramodpadole@gmail.com By Dr. Pramod R. Padole
What is phenol used for medically?
Phenol is used
to relieve pain and irritation caused by sore
throat, sore mouth, or canker sores.
This medicine is available without a
prescription; however, your doctor may have
special instructions on the proper use and dose
for your medical problem.
Phenol-based compounds have been found to
have some cancer prevention properties.
Phenol may have its share of uses and health benefits,
but it can also be toxic or cause long-term health effects
if you’re exposed to it in high amounts.

24. LOGO
Named Reactions of Phenol:
Pure phenol is used in certain
medical procedures and as an
ingredient in numerous
treatments and laboratory
applications.
Phenol is used as a preservative.

25. Named Reactions of Phenol:
A
Kolbe’s Reaction
(Carboxylation)
B
Fries Rearrangement
C
Claisen Rearrangement
D
Reimer-Tiemann Reaction
Named
Reactions of
Phenol

26. LOGO
Kolbe’s Reaction:
Preparation of Salicyclic Acid:
Named Reactions of Phenol
Carboxylation

27. pramodpadole@gmail.com By Dr. Pramod R. Padole
Kolbe’s Reaction:
or Preparation of Salicylic Acid or Carboxylation:
Q.1) Explain: Kolbe’s Reaction with respect to phenol.
(S-05, S-06, W-07, W-11, S-12, S-13, W-13, S-14, W-14, S-15, W-15, W-16 & W-18, 2 Mark)
Q.2) Explain: Kolbe’s Carboxylation / Kolbe’s Reaction. (S-18 & W-19, 2 Mark)
Q.3) Give the Kolbe’s Reaction of Phenol. (S-19, 2 Mark)
Kolbe's reaction: It is three step reaction.
When phenol is heated with aq. NaOH; to form sodium phenoxide,
which is further heated with CO2 (carbon dioxide) at 398K & under
pressure; to form sodium salicylate, which on acidification by dil. HCl;
to form salicylic acid.
This reaction is popularly known as Kolbe's reaction.
OH ONa
CO2
398K
OH
COO Na
OH
COOH
Phenol
Sodium Phenoxide
aq. NaOH
Sodium salicylate
Salicylic Acid
under pressure
H
+ NaCl
on acidification by
dil. HCl
H--Cl
(- H2O)
Na--OH
Step-1
Step-2
Step-3

28. LOGO
Fries Rearrangement
or Preparation of
o- & p- hydroxyl acetophenone:
Q.1) Explain Fries Rearrangement.
(W-04, S-05, W-06, S-11, S-12, S-13, W-15, W-16, S-17, W-17 & W-19, 2-4 Mark)
Q.2) What happens when Phenol is reacted with acetic anhydride? (W-15, 2 Mark)
Q.3) How will you obtain: Mixture of ortho and para hydroxyl acetophenone from
Phenol? (W-18, 2 Mark)
Q.4) Give the Fries Rearrangement of Phenol. (S-19, 2 Mark)

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Fries Rearrangement or
Preparation of o- & p- hydroxyl acetophenone:
Fries Rearrangement:
When phenol is first reacted with acetic anhydride in
presence of aqueous NaOH; to form phenyl acetate, which is
further heated with aluminium chloride (AlCl3 as a catalyst),
then it undergoes intramolecular rearrangement; to form
mixture of ortho-hydroxy acetophenone and para-hydroxy
acetophenone.
 This reaction is known as Fries rearrangement.
OH
CH3CO
O-COCH3
Heated with AlCl3
OH
COCH3
OH
COCH3
Phenol
phenyl acetate o-hydroxy
acetophenone
aq. NaOH
+
p-hydroxy
acetophenone
CH3CO
O
Acetic anhydride
(- CH3COOH)
H
H
1
2
3
4
1
2
1
2
3
4

30. LOGO
“ Add your company slogan ”
Reimer-Tiemann
Reaction
or Preparation of
Salicylaldehyde:

31. Reimer-Tiemann Reaction:
or Preparation of Salicylaldehyde:
 Reimer Tiemann reaction:
When phenol is reacted / treated with chloroform(CHCl3) in presence
of aqueous sodium hydroxide (aq. NaOH); to form intermediate product,
which on acidification by dil. HCl; to form salicylaldehyde.
In this reaction an aldehyde group (-CHO) introduced in phenolic ring at ortho position.
Q.1) Explain or Write the reaction involved in:- Reimer-Tiemann Reaction with respect to phenol.
(W-04, S-06, W-06, S-08, W-09, S-10, W-11, S-12, S-13 & S-14, 2 Mark)
Q.2) How will you obtain / synthesise / prepare: salicylaldehyde from phenol? (W-05 & W-17, 2 Mark)
Q.3) What happens when Phenol is treated with CHCl3 in alkaline medium? (W-08, 1 Mark)
Q.4) Explain Reimer-Tiemann Reaction. (S-15, S-17, S-18, W-18 & W-19, 2 Mark)
+ NaCl
H--Cl
OH
CHCl3
O Na
CHO
dil.HCl
Heat
OH
CHO
Phenol
sodium salicylaldehyde
(Intermediate product)
aq. NaOH
Salicylaldehyde
(o-hydroxy-benzaldehyde)
Chloroform
acidification by
H

32. LOGO
Claisen- Rearrangement
or
Preparation of
o-allyl phenol:

33. LOGO
Claisen- Rearrangement
or
Preparation of o-allyl phenol:
Q.1) Explain or Write the reaction involved in:- Claisen- Rearrangement with respect to phenol.
(W-05, S-06, W-08, S-10, W-10, S-13, W-13 & W-14, 2 Mark)
Q.2) How will you obtain / synthesise / prepare: o-allyl phenol from allyl phenyl ether? (W-12, 2 Mark)
Q.3) What happens when allyl phenyl ether is heated with 473 K?
Q.4) Complete the following reaction. (S-14 & S-16, 2 Mark)
Q.5) Explain: Claisen Rearrangement. (W-15, W-17 & W-19, 2 Mark)
Q.6) Complete the following reaction: (S-18, 2 Mark)
Q.7) Complete the following reaction: (W-18, 2 Mark)
OH
? ?
473 K
Br-CH2-CH=CH2
-H-Br
OH
? ?
473 K
Br-CH2-CH=CH2
acetone
+
K2CO3

34. LOGO Claisen- Rearrangement
or
Preparation of o-allyl phenol:
Claisen Rearrangement:
When allyl phenyl ether on heated alone at 473 K;
to form o-allyl phenol.
This reaction is called a Claisen rearrangement.

35. Dr. Pramod R. Padole
Professor
Department of Chemistry
Shri Shivaji Science College, Amravati
Mobile: 9422158188
Email: pramodpadole@gmail.com

36. LOGO

37. LOGO
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Sem-II (Unit-IV : Phenols) by Dr Pramod R. Padole
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