1. MICROWAVE ASSISTED SYNTHESIS…

2. Objectives : Range of Microwave Microwave Evolution Instrumentation
Introduction
Range of Microwave
Microwave Evolution
Instrumentation
Interaction of MW with Molecules
Choice of Solvent
Kinetics of Reaction (about Product)
Applications
Hoffman Elimination
Hydrolysis
Oxidation of Toluene

3. What is Microwave ?
Microwave radiation is a form of energy, relatively low in the electromagnetic spectrum.
As like other waves it consist of its own characteristic property.

4. Electromagnetic spectrum
Light comparison
Name
Wavelength
Frequency(HZ)
Photon Energy (eV)
Gamma ray
less than 0.02 nm
more than 15 EHz
more than 62.1 keV
X-Ray
0.01 nm – 10 nm
30 EHz – 30 PHz
124 keV – 124 eV
Ultraviolet
10 nm – 400 nm
30 PHz – 750 THz
124 eV – 3 eV
Visible
390 nm – 750 nm
770 THz – 400 THz
3.2 eV – 1.7 eV
Infrared
750 nm – 1 mm
400 THz – 300 GHz
1.7 eV – 1.24 meV
Microwave
1 mm – 1 meter
300 GHz – 300 MHz
1.24 meV – 1.24 µeV
Radio
1 mm – 100,000 km
300 GHz – 3 Hz
1.24 meV – 12.4 feV

5. Microwave Representation…

6. Microwave Evolution…
In 1986, Gedye and Giguere/Majetich found the application of Microwave irradiation to their reactions, as opposed to “conventional” heating techniques, such as heating a reaction on a hotplate, enabled more rapid product formation.

7. Instrumentation…

8. Interaction of MW with Sample…
Microwave irradiation falls below x-rays, UV, visible, and infrared in the energy spectrum, with a frequency of 300 to 300,000 megahertz (MHz). Because microwave irradiation is at such a low frequency, below that of x-rays, UV, and even infrared, it will only cause bonds to rotate, not break.

9. Diagrammatic Representation…

10. Choice of Solvent…
Every solvent and reagent will absorb microwave energy differently.
They each have a different degree of polarity within the molecule.
A solvent have a stronger dipole to cause more rotational movement in an effort to
align with the changing field.
Most organic solvents can be broken into three different categories ,

11. Solvent Chart…

12. Kinetics of Reaction…

13. Applications… General applications of Microwave Chemistry are,
Microwave Assisted synthesis using Water.
Microwave Assisted synthesis using Organic Solvents.
Solvent free Reactions.

14. Microwave Assisted synthesis using Water…
Hoffman Elimination :
Quaternary Ammonium salts are heated at high temperature and the
Yield is low. Use of Microwave irradiation has led to high yield.

16. Hydrolysis… Hydrolysis of Benzyl Chloride :
Hydrolysis of Benzyl Chloride with water in Microwave oven gives 97% yield
of Benzyl alcohol in 3 min. Whereas conventional method takes about 35 min.

18. Oxidation of toluene :
Oxidation of toluene by conventional method takes 10 – 12 hr. but
by Microwave irradiation the reaction completed in 7 min. with 40%
yield.

20. THANK YOU