Background: Nitration of aromatic and hetero aromatic compounds has received
enormous attention for the past several decades because many of these nitro products are
used as chemical feed stocks and important intermediates for the synthesis of several lifesaving
drugs, dyes, pharmaceuticals, perfumes, plastics and explosives. The classical nitration
method demands the use of acid mixture (a potent mixture of concentrated nitric and
sulfuric acids), which results in large amounts of inorganic acid waste pumped into the industrial
drains. Such a large acid waste is not only hazardous but also causes environmental
pollution and often leads to over nitration or by-products. Over the years, numerous useful
methods have been developed for environmentally safe nitration. Poly ethylene glycol (PEG) and its derivatives
have been extensively used as phase-transfer catalyst (PTC) in many commercial processes. Inspired by
these procedures we report herein, a clean, economically cheap and, easy to operate, and efficient protocol for
the nitration of aromatic compounds, using laboratory desktop chemicals such as nanocrystalline manganese
(II) carbonate and polyethylene glycols (PEG).
Materials and Methods: Chemicals were purchased from Merck, Sigma-Aldrich. Nitration reactions were
conducted under sonication and microwave irradiation in addition to the conventional method of organic synthesis.
The progress of the reaction was monitored by Thin Layer Chromatography on commercial precoated
TLC plates. Melting points were determined by using open capillary tubes with a Buchi 510 apparatus and
corrected. UV spectra were recorded on a Shimadzu UV-2700 model UV-VIS Spectrophotometer.
Conclusion: In conclusion, a regioselective nitration of a various aromatic compounds using green, available,
inexpensive and easy to handle catalyst PEG/Mn (II) has been reported. The scope and generality of this protocol
was illustrated with several aromatic compounds, short reaction times with good to excellent yields.
Non-conventional methods such as sonochemical and microwave affords the nitration of aromatic compounds
of both ring activated and deactivated compounds.