Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Xanthenol

Oxidation of 9-Fluorenol and 9-Xanthenol in Basic Solution. Fluor-enol and xanthenol react with base and oxygen to give high yields of the ketones, or in the case of fluorenol in DMSO solution, the DMSO-fluore-none adduct. The stoichiometry of the oxidation (Table XI) varies with... [Pg.200]

Carbon-oxygen bond heterolysis is responsible for the observed photolyses of 9-aryl-9-xanthenols ° and llH-benzo[b]fluoren-11-ol. - - Evidence for the formation of the 9-fluorenol radical cation as well as the 9-fluorenyl cation has been obtained from a laser flash photolysis study of 9-fluorenol. 1, l-Di-2-thienylethanol undergoes light-induced dehydration to give i,i-di-2-thienylethylene.Single electron transfer pathways, however, are implicated in the ring cleavage reactions of a,j8-epoxy ketones in the presence of allyltributyltin - or alkylamines. [Pg.387]

From a mechanistic point of view, 9-snbstitnted xanthenols 586 (prepared from the dianion of xanthen-9-one 585 in situ generated by a DTBB-catalyzed lithiation in THF, and different alkyl halides in 31-93% yield) are of interest due to rearrangements, which occurred under acidic conditions . ... [Pg.739]

The oxidations involving lithium ferf-butoxide reach completion (3 minutes for fluorenol, 12 minutes for xanthenol) much sooner than the corresponding reactions utilizing potassium terf-butoxide as base (35 minutes for fluorenol, 27 minutes for xanthenol). This behavior obviously involves Reaction 20 since the initial rates of oxidation were all approximately the same for the lithium- and potassium ferf-butoxide-catalyzed reactions. [Pg.201]

The oxidation of xanthenol and fluorenol showed a number of differences from the oxidation of benzhydrol. No induction period was observed (Figure 5). The rate was enhanced by ferric ion, and the stoichiometry was altered to 0.5 mole of oxygen per mole of fluorenol (Figure 5), apparently because of Reaction 25. [Pg.201]

M xanthenol, 0.22M potassium ferf-butoxide in pyridine (80% )—terf-butyl alcohol (20% ) solution at 27° 3°C. b Moles of oxygen/mole of substrate per minute. [Pg.202]

Oxidation of xanthenol or fluorenol with deficient quantities of oxygen in tert-butyl alcohol produced large quantities of the ketyl, as did reaction of equal molar amounts of the ketone and alcohol in basic solution. In fact, the reaction of the pinacol of fluorenone with excess base in tert-butyl alcohol produced an essentially quantitative yield of the ketyl (19). [Pg.204]

The oxidation of benzhydrol and 9-fluorenol in basic solution again shows a difference in regard to mechanism that can be primarily attributed to a difference in acidity as carbon acids. In tert-butyl alcohol benzhydrol enters into an oxidation scheme as the mono (oxy) anion. The data strongly suggest a free radical chain. Under these conditions the more acidic fluorenol or xanthenol oxidizes via carbanions or dianions. These oxidations can be catalyzed to occur via a free radical chain process by one-electron acceptors, such as nitrobenzene, and a free radical chain process may well be involved in the absence of the catalyst. [Pg.207]

Oxidation of fluorenol and xanthenol alcoholates in f-butanol and mixtures with pyridine and dimethylsulfoxide is accelerated by nitrobenzene [113]. The mechanism suggested is... [Pg.152]

Sahin, Nieger, and Brdse have reported also the oxidative coupling of various hexahydro-xanthenols. The application of an iron complex as oxidant converted the 2-hydroxy-substituted xanthenes 1056 (Scheme 13.26) to the 3,3- t S-coupled biaryl 1057 (565). It appears that these two papers ((564) and (674)) represent the only chemical studies published on the topic of xanthone or xanthene biaiyl-coupUng. [Pg.196]

Sahin H, Nieger M, Erase S (2009) Probing the Oxidation of Functionalized (Hexahydro) xanthenols. Eur J Org Chem 5576... [Pg.261]

Xanthanolides, T24 Xanthenol, T24 Xanthinin, T24 Xanthoaphins, YIO Xanthodactynaphins, YIO Xanthomegnin, Y2 Xanthumin, T24 Xylitol, Cl... [Pg.311]


See other pages where Xanthenol is mentioned: [Pg.333]    [Pg.208]    [Pg.307]    [Pg.307]    [Pg.333]    [Pg.421]    [Pg.472]    [Pg.472]    [Pg.333]    [Pg.200]    [Pg.200]    [Pg.202]    [Pg.202]    [Pg.202]    [Pg.202]    [Pg.202]    [Pg.208]    [Pg.307]    [Pg.307]    [Pg.333]    [Pg.1334]    [Pg.1334]    [Pg.421]    [Pg.429]    [Pg.241]    [Pg.151]    [Pg.18]    [Pg.472]    [Pg.472]    [Pg.962]    [Pg.1062]   
See also in sourсe #XX -- [ Pg.189 ]




SEARCH



Xanthenol, oxidation

© 2024 chempedia.info