1.3 LIMITATIONS
The limitations of microwave chemistry are mainly, its scalability, limited applications
and health hazards, which can be solved in years to come.
1.3.1 LACK OF SCALABILITY
The yield obtained by using commercial microwave apparatus is limited to a few
grams. Although there have been developments in the recent past relating to the
scalability of microwave equipment but still there is a gap that needs to be filled by
making this technology scalable. This is particularly true for reactions at the industrial
production level and for solid-state reactions.
1.3.2 LIMITED APPLICABILITY
The use of microwaves as a source of heating has limited applicability for materials
as only polar molecules absorb them. Microwaves cannot heat materials such as sulfur
(nonpolar), which are transparent to these radiations. Although microwave heating
increases the rate of reaction and yield in certain reactions, but it also results in
reduction in yield as compared to conventional heating methods in some reactions.
1.3.3 SAFETY HAZARDS
Although manufacturers of microwave heating apparatus have made microwaves a
safe source of heating, even then some times, uncontrolled reaction conditions may
result in undesirable results, for example, chemical reactions involving volatile reactants
under superheated conditions may result in explosive conditions. Moreover,
improper use of microwave heating for rate enhancement of chemical reactions involving
radioisotopes may also result in uncontrolled radioactive decay.
1.3.4 HEALTH HAZARDS
Health hazards related to microwaves may be caused by the penetration of microwaves.
While microwaves operating at a low frequency range are only able to penetrate
the human skin, higher frequency range microwaves can reach other organs
of the body also. Research has proved that prolonged exposure to microwaves may
result in the complete degeneration of body tissues and cells. It has also been established
that constant exposure of DNA to high frequency microwaves during a
biochemical reaction may result in complete degeneration of the DNA strand.