5,7-Dinitroquinazoline-4-ones undergo nucleophilic displacement of a nitro group with N-, S-, and O-nucleophiles. In contrast to previously studied dinitro-substituted benzoannulated five- and seven-membered heterocycles (where a high degree of selectivity was observed), these quinazolines mostly yield mixtures of regioisomeric substitution products. At the same time, primary and secondary amines react selectively to afford 5-aminoquinazolones (peri-substitution). A similar effect is observed for some other polynitroaromatic compounds with adjacent nitro and carbonyl groups. This phenomenon is attributed to a stabilization of the intermediate peri-sigma-complex by intramolecular hydrogen bond N(+)-H...O double bond C.
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http://dx.doi.org/10.1021/jo702532x | DOI Listing |
Acta Crystallogr F Struct Biol Commun
August 2024
Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA 98109, USA.
J Hazard Mater
January 2019
Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France.
Sulfate radical (SO)-based oxidation of nitrophenols (NPs) have been widely studied; however, formation of potentially more toxic polynitroaromatic intermediates has been overlooked. In this contribution, we systematically investigated the degradation of four NPs by a SO-based oxidation process. Degradation efficiency of NPs followed the order: 2-nitrophenol (2-NP) > 4-nitrophenol (4-NP) > 2,4-dinitrophenol (2,4-DNP) > 2,6-dinitrophenol (2,6-DNP).
View Article and Find Full Text PDFFluorescence chemo-sensors for species of environmental and biological significance have emerged as a major research area in recent years. In this account, we describe fluorescence quenching as well as enhancement-based chemo-sensors obtained by employing -symmetric 1,3,5-triphenylbenzene (1,3,5-TPB) as the fluorescence signalling unit. 1,3,5-TPB is a thermally and photochemically stable fluorescent platform with π-electron-rich characteristics.
View Article and Find Full Text PDFACS Omega
July 2017
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India.
An azo-linked covalent organic polymer, Py-azo-COP, was synthesized by employing a highly blue-fluorescent pyrene derivative that is multiply substituted with bulky isopropyl groups. Py-azo-COP was investigated for its sensing and gas adsorption properties. Py-azo-COP shows selective sensing toward the electron-deficient polynitroaromatic compound picric acid among the many other competing analogs that were investigated.
View Article and Find Full Text PDFPhys Chem Chem Phys
June 2014
Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India-400 076.
A supramolecular fluorophore, 1,3,5-tris(4'-aminophenyl)benzene (TAPB), selectively senses polynitroaromatic compounds (PNAC), viz. 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), picric acid (PA), m-dinitrobenzene (m-DNB) and p-dinitrobenzene (p-DNB) through donor-acceptor complexation. Steady-state and time resolved fluorescence measurements indicate predominantly static quenching of the TAPB fluorophore with TNT, DNT, m-DNB and p-DNB.
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