C) EPOXIDES : Synthesis of ethylene oxide from ethylene and styrene oxide from styrene. Ring opening reactions of both catalysed by acid and alkali.

1. 1
B.Sc. First year
Students
Semester – II
Unit-IV (C) Epoxides
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. Unit – IV (C)
Epoxides
Epoxides is also called as oxyrane.
LOGO

7. LOGO
Contents
Introduction
1
Preparation of Ethylene oxide
2
Preparation of Styrene oxide
3
Ring opening of styrene oxide by Acid
4
Ring opening of styrene oxide by Alkali
5

8. Introduction:
 Epoxides:
 The cyclic ether in which oxygen becomes one of
the members of ring atoms are called as
epoxides.
Cyclic ether with three membered ring is a epoxide.
 They are also called oxiranes.
Q.1) What are epoxides? Or Define epoxides with suitable examples.
(S-04, W-04, W-05, S-07, W-08, W-09, S-10, W-10, S-11, W-12, S-13, S-16, W-16 & S-19, 1 Mark)
Q.2) Epoxides are cyclic ether. (S-14, ½ Mark)
Q.3) Cyclic ether with three membered ring is a ___________. (W-15 & S-17, ½ Mark)
Q.4) Epoxide is also called as: (S-18, ½ Mark)
(a) Oxirane (b) Phenol (c) Catechol (d) Hydroquinone
Q.5) What is epoxide? (S-18, 1 Mark)
OR
A compound containing the epoxide functional group can be called an epoxy, epoxide, oxirane, and ethoxyline.

9. LOGO
By Dr Pramod R Padole
Epoxides:
 The cyclic ether in which oxygen becomes
one of the members of ring atoms are called epoxides.
OR
A cyclic ether with a three membered ring is an epoxide.
 They are also called oxiranes.

10. Method of Preparation Oxiranes:
Preparation of
Ethylene oxide
or
Epoxide
from
Ethylene:
Preparation of
Styrene oxide
from Styrene
or
Action of
peroxy acid:
Preparation of
Action of
Silver catalyst at 673 K:
Action of
Peroxy acid:

11. LOGO Preparation of Epoxides:
Epoxidation ( Catalytic oxidation):
 Preparation of ethylene oxide From Ethylene:
 or Action of Silver catalyst at 673 K:
When ethylene is treated / heated / subjected with oxygen (catalytic
oxidation) in presence of Silver (Ag) as a catalyst at 673 K (400oC);
to form ethylene oxide or Epoxide.
Q.1) What happens when ethylene is subjected to catalytic oxidation by silver
(Ag) at 673 K? (S-07, 1 Mark)
Q.2) How will you convert: Ethylene to Ethylene oxide? (S-08 & W-11, 1 Mark)
Q.3) What happens when: Ethylene is treated with oxygen in the presence of
Silver ( Ag)? ( W-08, 1 Mark)
Q.4) How will you prepare Ethylene oxide from ethylene?
(S-15, S-16, W-16 & S-18, 2 Mark)
Ethylene oxide was first reported in 1859 by the French chemist Charles-AdolpheWurtz
Ethylene oxide or Epoxide
(Oxirane)
O
H2C CH2
CH2 CH2 + 1
2
O2
Ag, as a catalyst
at 673 K
Ethylene

12. LOGO
By Dr Pramod R Padole
Action of Peroxy acid:
 Synthesis of Ethylene oxide:
When ethylene on oxidation with peroxy acid
(R-COOOH); to form ethylene oxide.
or Preparation of ethylene oxide from Ethylene:
Q.1) How will you obtain / synthesise / prepare: ethylene oxide from ethylene?
(S-06, S-11, S-13, S-14, W-14, S-17 & W-17, 2 Mark)
Q.2) Give one method for the synthesis of ethylene oxide. (W-09, 1 Mark)
Q.3) What happens when ethylene is oxidized by peroxy acid (W-08 & W-11, 1 Mark)
Q.4) Complete the following reaction. (W-14 & W-15, 2 Mark)
Q.5) How will you prepare Ethylene oxide from ethylene? (S-15, S-16, W-16 & S-18, 2 Mark)
Q.6) Complete the following reaction. (S-19, 2 Mark)
H2C CH2 + CH3COOOH ?

13. LOGO
By Dr Pramod R Padole
Action of Peroxy acid:
 Synthesis of Ethylene oxide:
When ethylene on oxidation with peroxy acid (R-COOOH);
to form ethylene oxide.
O
H2C CH2
H2C CH2 + RCOOOH
Ethylene peroxy acid ethylene oxide
(Epoxide)
+ RCOOH
Using peracids:
O
H2C CH2
H2C CH2 + CH3COOOH
Ethylene peracetic acid ethylene oxide
(Epoxide)
+ CH3COOH
1)
Acetic acid
O
H2C CH2
H2C CH2 + C6H5COOOH
Ethylene perbenzoic acid ethylene oxide
(Epoxide)
+ C6H5COOH
2)
Benzoic acid

14. LOGO
[ Styrene oxide]
From Styrene:

15. Preparation of Styrene oxide:
or Action of peroxy acid:
Synthesis of Styrene oxide:
When styrene on oxidation with peroxy acid
(R-COOOH); to form styrene oxide.
Q.1) How will you obtain / synthesise / prepare: styrene oxide from styrene?
(S-06, S-11, S-13, S-14, W-14 & S-17, 2 Mark)
Q.2) Give method for the synthesis of styrene oxide. (W-09 & S-18, 2-3 Mark)
Q.3) What happens when styrene is oxidized by peroxy acid? (W-08 & W-11, 1 Mark)
Q.4) Styrene oxide is prepared by oxidation of styrene with peroxy acid. (W-12, ½ Mark)
Q.5) How will you prepare styrene oxide from styrene? (S-15, S-16, W-16, S-19 & W-19, 2 Mark)
Q.6) What happens when styrene is reacted with peroxy acid? (W-15, 2 Mark)

20. pramodpadole@gmail.com By: Dr Pramod R Padole
Chemical Reactions of
Styrene oxide:
Ring opening
of
styrene oxide
catalysed by
Acid
(HCl):
Styrene oxide
Chemical Reactions
Ring opening
of
styrene oxide
catalysed by
Alkali
(NaOH):

21. LOGO
By Dr Pramod R Padole
Ring opening of Styrene oxide
catalysed by Acid (HCl):
in presence of CHCl3

22. By Dr Pramod R. Padole
Ring opening of styrene oxide catalysed by Acid (HCl):
Q.1) How does styrene oxide reacts with HCl? (W-06, 1 Mark)
Q.2) Explain:- Ring opening reaction of styrene oxide catalysed by Acid ( HCl).
(W-07, S-16, W-16 & W-19, 2-4 Mark)
Q.3) Write the reaction involved in the Ring opening of styrene oxide catalysed by Acid (HCl).
(W-09, 1 Mark)
Q.4) Explain the mechanism of acid catalysed Ring opening of styrene oxide. (W-10, 2 Mark)
Q.5) How will you convert: Styrene oxide to 2-chloro-2-phenyl ethanol? (W-11, 1 Mark)
Q.6) Complete the following reaction. (S-14, 2 Mark)
Q.7) Discuss the ring opening reaction in styrene oxide – catalysed by acid. (W-14, 2 Mark)
Q.8) Explain the Ring opening reaction of epoxides catalysed by Acid ( HCl). (W-17, 4 Mark)
Q.9) Explain the Ring opening reaction catalysed by acid ( HCl). (S-19, 4 Mark)
O
HC CH2
+ HCl
CHCl3 ?

23. By Dr Pramod R. Padole
Ring opening of styrene oxide catalysed by Acid (HCl):
Ring opening of styrene oxide catalysed
by acid(HCl):
When styrene oxide is treated / reacted with HCl (acid)
in presence of CHCl3, undergoes ring opening; to form
2-chloro-2-phenyl-ethanol.
O
HC CH2
Stryene oxide
+ HCl CHCl3
CH CH2 OH
Cl
1
2
2-chloro-2-phenyl-ethanol

24. Mechanism of Ring opening of styrene
oxide catalysed by Acid (HCl):
Step – 1) Attack of proton (H+)
During ring opening of styrene oxide in presence of acid (HCl);
first protonation takes place; to form Oxonium compound
Step – 2) Attack of nucleophile (Cl-)
Followed by attack of nucleophile; to form
2-chloro-2phenyl-ethanol.

25. pramodpadole@gmail.com By Dr Pramod R. Padole
Mechanism catalysed by Acid:
Mechanism:
During ring opening of styrene oxide in presence of acid
(HCl); first protonation (H+) takes place which is followed by attack of
nucleophile; to form 2-chloro-2phenyl-ethanol.
O
HC CH2
Stryene oxide
HCl H Cl
+
CH CH2 OH
Cl
1
2
2-chloro-2-phenyl-ethanol
Step-1) Attack of proton, H
:
:
H
+
protonation
O
HC CH2
Oxonium compound
: H
Step-2) Attack of nucleophile, Cl
O
HC CH2
Oxonium compound
: H
+ Cl
Attack of
nucleophile

26. LOGO
Ring opening of styrene oxide
catalysed by Alkali (NaOH):
1-phenyl,1,2-ethane-diol.

27. Ring opening of styrene oxide catalysed by
Alkali (NaOH):
Q.1) How does styrene oxide reacts with NaOH? (W-06, 1 Mark)
Q.2) Write the reaction involved in the Ring opening of styrene oxide catalysed by
alkali ( NaOH).
Q.3) Explain the mechanism of alkali catalysed Ring opening of styrene oxide.
Q.4) Discuss the ring opening reaction in styrene oxide – catalysed by alkali.
(W-14, 2 Mark)
Q.5) Explain: Ring opening reaction catalysed by Alkali ( NaOH). (S-15, 4 Mark)
Q.6) Explain the Ring opening reaction of epoxide catalysed by Alkali (NaOH) or
base. (W-15, S-18 & W-18, 4 Mark)
Q.7) Explain the Ring opening reaction of styrene oxide catalysed by alkali
(NaOH). (S-17, 4 Mark)

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LOGO
By Dr Pramod R Padole
Ring opening of styrene oxide
catalysed by alkali (NaOH):
 When styrene oxide is treated / reacted with
dil. NaOH(alkali), undergoes SN2 reaction; to form
1-phenyl,1,2-ethane-diol.
O
HC CH2
Stryene oxide
+ H2O
NaOH CH CH2 OH
OH
2
1
1-phenyl-1,2-ethane-diol
dil.

29. pramodpadole@gmail.com By Dr Pramod R. Padole
Mechanism of Ring opening of styrene oxide
catalysed by alkali (NaOH):
Step-1) Formation of alkoxide ion:
 When styrene oxide attacks with OH- ion,
as a nucleophile, as SN2 reaction; to form
alkoxide ion.
NaOH Na OH
+
O
HC CH2
Stryene oxide
OH
:
:
+
Attack of
nucleophile
NaOH
dil.
CH CH2 O
OH
2
1
Alkoxide ion
SN2 reaction

30. Mechanism of Ring opening of styrene oxide
catalysed by alkali (NaOH):
 Step – 2) Formation of product:
 When alkoxide ion which rapidly abstracts a proton
from the solvent; to form 1-phenyl,1,2-ethane-diol,
as a final product
(- NaOH)
Na
+
CH CH2 OH
OH
2
1
1-phenyl-1,2-ethane-diol
CH CH2 O
OH
2
1
Alkoxide ion
+
H
OH
Abstracts a proton
from solvent
water
+ OH

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

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Sem-II (Unit-IV) by Dr Pramod R. Padole
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