Search results for: ortho-quinone methide.

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ortho-quinone methide.</title> <meta name="description" content="Search results for: ortho-quinone methide."> <meta name="keywords" content="ortho-quinone methide."> <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no"> <meta charset="utf-8"> <link href="https://cdn.waset.org/favicon.ico" type="image/x-icon" rel="shortcut icon"> <link href="https://cdn.waset.org/static/plugins/bootstrap-4.2.1/css/bootstrap.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/plugins/fontawesome/css/all.min.css" rel="stylesheet"> <link href="https://cdn.waset.org/static/css/site.css?v=150220211555" rel="stylesheet"> </head> <body> <header> <div class="container"> <nav class="navbar navbar-expand-lg navbar-light"> <a class="navbar-brand" href="https://waset.org"> <img src="https://cdn.waset.org/static/images/wasetc.png" alt="Open Science Research Excellence" title="Open Science Research Excellence" /> </a> <button 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action="https://publications.waset.org/abstracts/search"> <div id="custom-search-input"> <div class="input-group"> <i class="fas fa-search"></i> <input type="text" class="search-query" name="q" placeholder="Author, Title, Abstract, Keywords" value="ortho-quinone methide."> <input type="submit" class="btn_search" value="Search"> </div> </div> </form> </div> </div> <div class="row mt-3"> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Commenced</strong> in January 2007</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Frequency:</strong> Monthly</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Edition:</strong> International</div> </div> </div> <div class="col-sm-3"> <div class="card"> <div class="card-body"><strong>Paper Count:</strong> 2</div> </div> </div> </div> <h1 class="mt-3 mb-3 text-center" style="font-size:1.6rem;">Search results for: ortho-quinone methide.</h1> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">2</span> In situ Ortho-Quinone Methide Reactions for Construction of Flavonoids with Fused Ring Systems </h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=Vidia%20A.%20Nuraini">Vidia A. Nuraini</a>, <a href="https://publications.waset.org/abstracts/search?q=Eugene%20M.%20H.%20Yee"> Eugene M. H. Yee</a>, <a href="https://publications.waset.org/abstracts/search?q=Mohan%20Bhadbhade"> Mohan Bhadbhade</a>, <a href="https://publications.waset.org/abstracts/search?q=David%20StC.%20Black"> David StC. Black</a>, <a href="https://publications.waset.org/abstracts/search?q=Naresh%20Kumar"> Naresh Kumar</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Flavonoids are naturally occurring compounds that have been shown to exhibit a wide range of biological properties including anticancer and anti-inflammatory activities. However, flavonoids suffer from low bioavailability, which limits their overall utility for therapeutic applications. One of the methods to overcome this limitation is through structural modification of natural flavonoids. In this study, flavanone, isoflavanone, and isoflavene, were structurally modified through the introduction of additional fused-ring systems via ortho-quinone methide intermediates (o-QMs). These intermediates can readily undergo a [4+2] cycloaddition through an inverse-electron-demand Diels鈥揂lder reaction with electron-rich dienophiles. A regioselective Mannich reaction using bis-(N,N-dimethylamino)methane was employed to generate the o-QM precursors of flavanone, isoflavanone, and isoflavene. The o-QM intermediates were subsequently generated in situ through thermal elimination of the dimethylamine functionality and reacted with a variety of dienophiles to produce novel flavonoids with fused-ring systems. A total of 21 novel flavonoid analogs were successfully synthesized. The X-ray crystal structure of cycloaddition adducts, particularly those derived from 3,4-dihydro-2H-pyran and p-methoxystyrene revealed a special case of enantiomeric disorder, where two enantiomers in equal amounts superpose with one another, with the exception for atoms that have opposite configuration. The anticancer properties of fused-ring systems derived from isoflavene were evaluated against the neuroblastoma SKN-BE(2)C, the triple negative breast cancer MDA-MB-231, and the glioblastoma U87 cancer cell lines. One of these cycloaddition adducts had displayed improved anti-proliferative activity against MDA-MB-231 and U87 cancer cell lines as compared to the parent compound. Further anticancer and anti-inflammatory activities of the flavanone and isoflavanone analogs are currently being investigated. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=Diels-Alder%20reaction" title="Diels-Alder reaction">Diels-Alder reaction</a>, <a href="https://publications.waset.org/abstracts/search?q=flavonoids" title=" flavonoids"> flavonoids</a>, <a href="https://publications.waset.org/abstracts/search?q=Mannich%20reaction" title=" Mannich reaction"> Mannich reaction</a>, <a href="https://publications.waset.org/abstracts/search?q=ortho-quinone%20methide." title=" ortho-quinone methide."> ortho-quinone methide.</a> </p> <a href="https://publications.waset.org/abstracts/74903/in-situ-ortho-quinone-methide-reactions-for-construction-of-flavonoids-with-fused-ring-systems" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/74903.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">251</span> </span> </div> </div> <div class="card paper-listing mb-3 mt-3"> <h5 class="card-header" style="font-size:.9rem"><span class="badge badge-info">1</span> Corrosion of Steel in Relation with Hydrogen Activity of Concentrated HClO4 Media: Realisation Sensor and Reference Electrode</h5> <div class="card-body"> <p class="card-text"><strong>Authors:</strong> <a href="https://publications.waset.org/abstracts/search?q=B.%20Hammouti">B. Hammouti</a>, <a href="https://publications.waset.org/abstracts/search?q=H.%20Oudda"> H. Oudda</a>, <a href="https://publications.waset.org/abstracts/search?q=A.%20Benabdellah"> A. Benabdellah</a>, <a href="https://publications.waset.org/abstracts/search?q=A.%20Benayada"> A. Benayada</a>, <a href="https://publications.waset.org/abstracts/search?q=A.%20Aouniti"> A. Aouniti</a> </p> <p class="card-text"><strong>Abstract:</strong></p> Corrosion behaviour of carbon steel was studied in various concentrated HClO4 solutions. To explain the acid attack in relation of H+ activity, new sensor was realised: two carbon paste electrodes (CPE) were constructed by incorporating ferrocene (Fc) and orthoquinone into the carbon paste matrix and crossed by weak current to stabilize potential difference. The potentiometric method at imposed weak current between these two electrodes permits the in situ determination of both concentration and acidity level of various concentrated HClO4 solutions. The different factors affecting the potential at imposed current as current intensity, temperature and H+ ion concentration are studied. The potentials measured between ferrocene and chloranil electrodes are directly linked to the acid concentration. The acidity Ri(H) function defined represents the determination of the H+ activity and constitutes the extend of pH is concentrated acid solutions. Ri(H) has been determined and compared to Strehlow Ro(H), Janata HGF and Hammett Ho functions. The collected data permit to give a scale of strength of mineral concentrated acids at a given concentration. Ri(H) is numerically equal to the thermodynamic Ro(H), but deviated from Hammett functions based on indicator determination. The CPE electrode with inserted ferrocene in presence of ferricinium (Fc+) ion in concentrated HClO4 at various concentrations is realized without junction potential and may plays the role of a practical reference electrode (FRE) in concentrated acids. Fc+ was easily prepared in biphasic medium HClO4-acid by the quantitative oxidation of ferrocene by the ortho-chloranil (oQ). Potential of FRE is stable with time. The variation of equilibrium potential of the interface Fc/ Fc+ at various concentrations of Fc+ (10-4 - 2 10-2 M) obeyed to the Nernst equation with a slope 0.059 Volt per decade. Corrosion rates obtained by weight loss and electrochemical techniques were then easily linked to acidity level. <p class="card-text"><strong>Keywords:</strong> <a href="https://publications.waset.org/abstracts/search?q=ferrocene" title="ferrocene">ferrocene</a>, <a href="https://publications.waset.org/abstracts/search?q=strehlow" title=" strehlow"> strehlow</a>, <a href="https://publications.waset.org/abstracts/search?q=concentrated%20acid" title=" concentrated acid"> concentrated acid</a>, <a href="https://publications.waset.org/abstracts/search?q=corrosion" title=" corrosion"> corrosion</a>, <a href="https://publications.waset.org/abstracts/search?q=Generalised%20pH" title=" Generalised pH"> Generalised pH</a>, <a href="https://publications.waset.org/abstracts/search?q=sensor%20carbon%20paste%20electrode" title=" sensor carbon paste electrode"> sensor carbon paste electrode</a> </p> <a href="https://publications.waset.org/abstracts/17546/corrosion-of-steel-in-relation-with-hydrogen-activity-of-concentrated-hclo4-media-realisation-sensor-and-reference-electrode" class="btn btn-primary btn-sm">Procedia</a> <a href="https://publications.waset.org/abstracts/17546.pdf" target="_blank" class="btn btn-primary btn-sm">PDF</a> <span class="bg-info text-light px-1 py-1 float-right rounded"> Downloads <span class="badge badge-light">355</span> </span> </div> </div> </div> </main> <footer> <div id="infolinks" class="pt-3 pb-2"> <div class="container"> <div style="background-color:#f5f5f5;" class="p-3"> <div class="row"> <div class="col-md-2"> <ul class="list-unstyled"> About <li><a href="https://waset.org/page/support">About Us</a></li> <li><a href="https://waset.org/page/support#legal-information">Legal</a></li> <li><a target="_blank" rel="nofollow" href="https://publications.waset.org/static/files/WASET-16th-foundational-anniversary.pdf">WASET celebrates its 16th foundational 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Search results for: ortho-quinone methide.