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Reactivity of sulphur-centered radicals with indolinonic and quinolinic aminoxyls.
No full textIndolinonic, phenylimino-indolinonic and quinolinic aromatic aminoxyls readily react with sulfur-centered radicals, generated upon reaction with p- methylthiophenol at room temperature The main product is the deoxygenated derivative i.e the corresponding amine. The other compounds, obtained in low yields, are N-substituted amines and amines substituted in a conjugated position with respect to the amino group by arylthiyl, arylsulphinyl, arylsulphonyl and arylsulphonyloxy radicals. The formation of the products are explained by the initial attack of the thiophenol radical onto the NO· function to give an unstable adduct which decomposes to aminyl and arylsulphinyl radicals. From here the reaction can take two different routes to give the products obtained
Competition between nucleophilic addition and electron-transfer process in the reaction of 9-diazo-10-antrone with Grignard reagents
No full text9-diazo-10-anthrone reacts with RMgX (R = Me, Et, Bu n, 5-hexenyl, Pr/, benzyl, Bu t) essentially
yielding 9-alkylazo-10-hydroxy derivatives, which are isolated in their tautomeric quinoid structure as
alkylhydrazones of 9,10-anthraquinone. The yields of these compounds decrease as the oxidation potentials (Eox)
of the Grignards decrease: at the same time additional compounds, formed through a radical mechanism, are
obtained in higher yields. The reaction has been interpreted as a competition between single electron transfer
(SET) and nucleophilic attack, which occur with ratios varying with the oxidation potentials of the Grignard
reagents. Evidences for the SET pathway have been found performing an experiment in the presence of 2,2.6,6-
tetramethylpiperidine-l-oxyl (TEMPO) as a scavenger of C-centered radicals
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Complexes of substituted aromatic hydrocarbons with tetracyanoethylene: a reinvestigation
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