The document presents a seminar on microwave-assisted synthesis as a green chemistry approach, outlining the technique's principles, merits, and applications. It highlights faster reaction times, energy savings, and higher yields while acknowledging potential hazards and costs. The conclusion emphasizes the technique's efficiency and adaptability in various fields, including medicinal chemistry and material sciences.

1. MICROWAVE ASSISTED
SYNTHESIS
A Green Chemistry Approach
Seminar Presentation
Presented by –
Garima Singh
Enroll no. –
CSJMA24000003450
Masters Of Pharmacy
(First Year)
Presented to –
School of Pharmaceutical sciences
(pharmaceutical chemistry)
Session – 2024-25

3. CONTENTS
 Introduction
 Merits and Demerits
 Microwave assisted Organic Reactions
 Applications
 Conclusion
 Refrence

4. INTRODUCTION

Microwave – It is a form of electromagnetic energy that falls at the lower
frequency of the electromagnetic spectrum in the range of 300 to 300,000
MHz .
 A frequency of 2.45 GHz is preferred because it has the right penetration
depth for laboratory reaction conditions.
 Microwave Assisted Reactions – Microwave irradiation has become
more popular as a potent technique for rapid and efficient synthesis of a
variety of compounds .
 Microwave heating produces heat in the entire material in the same rate
and at the same time at a high speed and at high rate of reaction .
 The microwave chemistry is also called Green Chemistry because it does
not produce any hazardous material like gas, fumes , heating etc.

5. MERITS DEMERITS
 Faster Reaction
 Energy saving
 Green synthesis
 Possibility of stirring
 Uniform and selective heating
 Better yield and high purity
 Continuous power output
 Sudden increase in temperature
may lead to distortion of
molecules
 Very vigorous and that can be
hazardous
 Microwave reactors are expensive
and delectated
 Heat force control is difficult
 Closed container is dangerous
because it could be burst

6. MICROWAVE ASSISTED ORGANIC
REACTIONS
 Microwave assisted reactions using solvents
1. Hydrolysis
Hydrolysis of benzyl chloride with water in microwave oven gives 97 % yield of
benzyl alcohol in 3 min .
The usual hydrolysis in normal way takes about 35 min .
Cl
benzyl chloride
+ H
O
H
water
MW , 3 min
OH
benzyl alcohol 97 %

7. 2. Esterification
A mixture of benzoic acid and n – propanol on heating in a microwave oven
for 6 minutes in conc. Sulfuric acids gives propylbenzoate .
3. Decarboxylation
Coventional decarboxylation of carboxylic acids involve refluxing in
quinoline in presence of copper chromate and the yields are low . However ,
in the presence of microwaves decarboxylation takes place in much shorter
time .
O
OH
benzoic acid
+ HO
n propanol
Conc. H2SO4
MW 6 min
O
O-
propylbenzoate
H
N
COOH
6 methoxy indole 2 carboxylic acid
H3CO
MW 12 min
quinoline
N
H
H3CO
6 methoxyindole 99%

8.  Microwave assisted reactions under solvent
free conditions
1. Aromatic Nucleophilic Substitutions
Formation of substituted Triazines are carried out using sodium phenoxide
and 1,3,5-trichlorotriazine under microwave irradiation (6min) . The
products , 1,3,5 –triaryloxytriazines are obtained in 85-90 % yields .
2. Deacetylation
Conventional process takes long time and the yields are low . Use of
microwave irradiation reduces the time of deacetylation and the yields are
good .
Na+
O-
sodium phenoxide
+
1,3,5 trichlorotriazine
MWI , 6 min
85 to 90 %
N
N
N
OAr
ArO OAr
N
N
N
Cl Cl
Cl
1,3,5 triaryloxytriazines
CH(OAC)2
benzaldehyde diacetate
Neutral alumina
MW 40 seconds
benzaldehyde
CHO

9.  Microwave assisted reactions using solid liquid
phase
1. O-Alkylation
Preparations of ethers were carried out from β-napthol using benzyl bromide and
1-butyl-3-methyl-imidazolium tetrafluoroborate under micrpwave irradiation
(6-12 min) the products were isolated in 75-90 % yields .
2. Oxidation
Oxidation of secondary alcohols to acetone derivatives was carried out using
tetrabutylammonium bromide and dichloromethane under microwave irradiation
(6-8 min) , products were isolated in 70-99 5 yields .
R1
OH
R2
PCC, TBAB , MWI
DCM , 6-8 min , 70-99 %
R1
O
R2
OH
BzBr , [BMm] BF
6-12 min , 75-90 %
O

10. APPLICATIONS OF MICROWAVE
ASSISTED REACTIONS
o Heck reaction
It is most important C-C bond forming reaction .
o Suzuki reactions
It is defined as palladium catalysed cross coupling of aryl halide with
boronic acids .
HC Br
x
+ COOH
Pd (OAC)2 , Pd-catalyst
Et2 N , Me CN
MW . 15 min
COOH
HC
X
R
X
+
R'
(OH)2B
Pd (OAc)2 , TBAB , Na2CO3
H2O
MW , 5 min
R R'

11. o Negishi and Kumada reaction
It is the coupling of Grignand reagents with alkyl , vinyl , or aryl halides
under Ni/Pd catalysis .
o Ullman condensation reaction
Cl
+
OMe
BrMg
PdCl2 (PPb2)
MW , 10 min
OMe
I
Iodobenzene
Hydrogen Catalyst
Conventional
OR
Microwave heating Biphenyl
+ 2 + 2I2
Benzene

12. CONCLUSION
 Microwave assisted synthesis is a convenient way toward the goal of green
chemistry . Microwaves irradiation can be used to in chemical synthesis as
a heat source ; it is very efficient and can be used to significantly reduce
reaction times of numerous synthetically useful chemical
transformations .
 Microwave-assisted synthesis has advantages over conventional
technology : it is more energy efficient and it can lead to improved isolated
yields of products with green synthesis .
 The advantages of this enabling technology have more recently , been
exploited in the context of multistep total synthesis and medicinal
chemistry / drug discovery , and have additionally penetrated related
fields such as polymer synthesis , material sciences , nanotechnology and
biochemical procsses .

13. REFRENCES
 Surati , M.A. Jauhari , S. & Desai , K.R. 2012 , A brief review :
Microwave assisted organic reation , Scholars Research Library ,
vol 4, no. 1, pp. 645-661
 Ahluwalia , V.K. & Kidwai , M. 2004 , New trends in Green
chemistry : Microwave Induced Green Synthesis , Anamaya
Publishers , New Delhi , 263 pp.
 Shrldon RA, Arends I, Hanefeld U. Green Chemistry and
Catalysis , Wiley , Wienheim, 2007 ; 1-2

14. THANK YOU !
FOR LISTENING………….