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Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic Chemistry
Volume 39, 2009 - Issue 21
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Original Articles

Improved, Highly Efficient, and Green Synthesis of Bromofluorenones and Nitrofluorenones in Water

, , , &
Pages 3804-3815 | Received 28 Oct 2008, Published online: 07 Oct 2009
 

Abstract

A series of bromo-, nitro-, and bromonitrofluorenones were synthesized chemo- and regioselectively in 90–98% yield via electrophilic aromatic bromination and nitration under mild conditions using water as the sole solvent. These synthetic methods involve simple workup procedures and use only minimal amounts of organic solvents during the purification of products. The newly developed methods have the advantages of being cost-effective and environmentally friendly and could potentially be used for the large-scale synthesis of fluorenone derivatives.

ACKNOWLEDGMENT

This work was supported by the Natural Science Foundation of Shanxi Province (2006011014).

Notes

a Br2 was added in three portions with 4–5 h of interval for each addition. The pH of the reaction was maintained at ∼7 by adding aqueous NaOH to neutralize the HBr released during the reaction.

a HNO3 and H2SO4 were premixed before being added to the reaction media.

b The following concentrations of HNO3 were used: A, 65%; B, 85%; C, 95%.

c Conc. H2SO4 (96%) was used.

d Refers to pure product after recrystallization.

e The acid mixture was added in two portions, with the second batch being added after 1 h.

f The temperature in parentheses refers to that of the heating oil bath.

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