Predominant ortho-selective mononitration of low-melting and liquid phenols and hydroxycoumarins in moderate to high yields has been accomplished upon grinding with solid cerium (IV) ammonium nitrate (CAN). Microwave-assisted expeditious CAN-mediated nitration of relatively high melting phenols and hydroxycoumarins with high efficiency and selectively under solvent-free conditions has been also developed to address the problems of sluggishness and low yield for these reluctant substrates.
Nitration was incomplete for substrates (entries 7-9 and 12) to the extents of 10-30% under simple aggregation (condition a); the yields in all the above cases were based on unrecovered starting material.
22.
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(a) BuckinghamJ., (Ed.), Dictionary of Organic Compounds, 5th edn, Vol. IV, Chapman and Hall, New York, 1982.
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