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Ferricyanide oxidation

The aqueous ferricyanide oxidation of 2-mercaptoethanol to the disulphide is also complex kinetically" . In the pH range used (l.S. l) no complication from ionisation of the thiol is expected. Individual decays of oxidant concentrations are initially second-order but eventually become almost zero-order. For both second-and zero-order paths the rate depends on the first power of the thiol concentration and the former path is retarded by increasing the acidity, an approximately inverse relation existing above pH 3.2. Addition of ferrocyanide transforms the kinetics the rapid, second-order path is inhibited and the zero-order path is accelerated until, at 10 M ferrocyanide, the whole of the disappearance of oxidant is zero-order. Addition of Pb(C104)2, which removes product ferrocyanide, greatly enhances the oxidation rate and the consumption of oxidant becomes rs/-order. Two routes are considered to co-exist (taking due account of the acidity of ferrocyanic acid), viz. [Pg.424]

Rather simple kinetics are shown by the ferricyanide oxidation of //-octyl mercaptan to disulphide in aqueous acetone , viz. [Pg.424]

An interesting catalytic effect upon the alkaline ferricyanide oxidations of ketones is shown by osmium(VIII) tetroxide, the rate expression being... [Pg.426]

The ferricyanide oxidation of formaldehyde is also base-catalysed , the rate law being... [Pg.426]

The ferricyanide oxidation of ascorbic acid at pH 1.1 follows kinetics ... [Pg.433]

The ferricyanide oxidation of various phenols has been examined by Waters et following the pioneering work of Conant et who observed... [Pg.434]

An (emf) study of the ferricyanide oxidation of phloroglucinol revealed kine-... [Pg.434]

By pulse radiolysis of nitrous oxide-saturated aqueous solutions of ferricyanide (2 X 10 " M) and various alcohols (0.1 M), Adams and Willson " were able to obtain absolute rate coefficients for the ferricyanide oxidation of the radicals derived from the alcohols by attack of the solvent irradiation product, OH-. [Pg.492]

Skinner, W. A. Alaupovic, P. Oxidation products of vitamin E and its model, 6-hydroxy-2,2,5,7 8-pentamethyl-chroman. V. Studies of the products of alkaline ferricyanide oxidation. J. Org. Chem. 1963, 28, 2854—2858. [Pg.212]

Schudel, P. Mayer, H. Metzger, J. Riiegg, R. Isler, O. Chemistry of vitaminE n. Structure of potassium ferricyanide oxidation product of tocopherol. Helv. Chim. Acta 1963, 46, 636-649. [Pg.213]

Hexa(hydroxyethyl)pararosaniline nitrile has been used in a chemical radiochromic dosimeter.130 Ferricyanide oxidation of leuco Crystal Violet to Crystal Violet dye finds use in detection of various heavy metals131 at trace quantities. Oxidation of leuco triphenylmethanes by chloramine-T is catalyzed by iodide and therefore is used for detection of iodide.132 On the other hand, the inhibition of the catalytic effect of iodide by some ions can be used for determining traces of Ag(I), Hg(II), Pd(II). In addition, the triphenylmethane leuco dyes, phenolphthalein or phenol red are used extensively as indicators in calorimetric and titrimetric determinations. [Pg.154]

Ferricyanide oxidation of 1,5-disubstituted thiocarbazones (116) give the mesoionic tetrazolium salts (117) under mild conditions (Eq. 21).190 This is in contrast to the strongly alkaline oxidation of carbazides leading to mercapto formazans as shown in Eq. 8 (Section 7.3.1.4). The heterocyclic triazine (118), obtained by the action of a diazonium salt on 2-... [Pg.235]

Abramovitch and Vinutha (71JCS(B)131) reported a semiquantitative study of substituent effects on the rates of ferricyanide oxidation of 3 (R = Me = H, Me, CN, C02Me). On the basis of product ratios 4/5 being the same for the oxidation of the 2- and 6-deuterio isomers of 3 (R = R = Me), they concluded that the formation of a complex 7 is the ratedetermining step compound. 7 then reacts with additional ferricyanide, oxidation taking place within a second complex 8 to give the pyridone (Scheme I). Meanwhile this hypothesis has been confirmed by Russian authors... [Pg.277]

In a study concerning the kinetics and mechanism of osmium tetroxide-catalyzed ferricyanide oxidation of pyridinium and quinolinium salts it was found that the rates of reaction are first order with respect to substrate, alkali, and catalyst, but zero order with respect to ferricyanide concentration (82IJC(A)517). [Pg.279]

Tlie products of alkaline ferricyanide oxidation of pyridinophanium salts 62 (85CB4259) are pyridones 63 in relatively high yields, and traces of 48 (82TH2) (Scheme 13). Similarly, oxidation of 64 yields pyridones 69 almost... [Pg.287]

When 4-alkylated pyridinium salts are exposed to ferricyanide, oxidation at the 4-a-carbon atom competes with pyridone formation and all possible oxidation products 104-109 are produced as complex reaction mixtures. In the case of complete substitution of the 4-a-H atoms (110), pyridones 111 result as unique products in almost quantitative yields. [Pg.292]

The influence of a C-2 substituent upon the reaction course has been investigated. If only a 2-aryl group is present, as in 145 (R = H), then 4-quinolones 146 are formed (85H2375). But ferricyanide oxidation of 2,4-diphenyl derivatives resulted in the release of the 2-phenyl group and formation of the quinolones 147 instead of the exptected indole derivatives (83CCC2965). [Pg.297]

Bunting and Kauffman (84CJC729) studied both the kinetics and mechanism of disproportionation and ferricyanide oxidation of 154 in aqueous base. Ferricyanide ion oxidation is kinetically first-order in each of ferricyanide ion... [Pg.298]

H-NMR spectral studies. Moreover, the mechanism of ferricyanide oxidation of 166 has been established (78JOC1132). The rate-determining abstraction of hydride ion by ferricyanide leads to isoquinolone 169 and a species [HFe(CN)6] that rapidly reacts with a second ferricyanide ion to give two ferrocyanide ions. This mechanism is contrary to the results in the pyridine series (cf Section 1I,A,2 and II,A,3). [Pg.301]

The Moura group propose the formation of a stable cyano-bridged diiron derivative following ferricyanide oxidation of the superoxide reductases (SORs) from Treponema pallidum and from Desulfovibrio vulgaris.10 Spectroscopic evidence for a ferrocyanide adduct with the bridge (SOR)Fe-NsC-Fen(CN)5 came from mass and IR measurements, where the Fe co-ordination is made up of four equatorial histidine N atoms and an axial cysteinyl S atom, and it is proposed... [Pg.388]

The ferricyanide oxidation of 4//-thiopyrans 206b to corresponding dioxocyclohexylidene derivatives 423 proceeds in the same manner as in the pyran series.250 Simple 4-thiopyrone (325) and mesoxalic acid were isolated after oxidation of 4-hydroxy-4//-thiopyran (2) with potassium permanganate.4... [Pg.239]

The use of zinc sulfate to catalyze the potassium ferricyanide oxidation procedure251 is worthy of comment. It is possible that other metals would also catalyze this oxidation, but their presence in the system would have a deleterious effect on thfe fluorescence of the final product, while Zn++ ions have relatively little effect. For instance, Cu++ ions would be expected to catalyze the oxidation stage, but they would also have a strong quenching effect on the fluorescence of the final products.144 Some of the Zn++ ions will also presumably be removed from the solution as insoluble zinc ferro-cyanide. Anton and Sayre have recently questioned the value of zinc sulfate as a catalyst at low pH.252... [Pg.280]

Unsubstituted 3-hydroxythiophene is less stable than 2-hydroxythiophene (63AHC(l)l). This instability may be due to oxidative coupling. In order to confirm this, 2,5-dimethyl-3-hydroxythiophene was subjected to ferricyanide oxidation (72ACS31). Racemic and meso forms of 2,2, 5,5 -tetramethyl-bi-4-thiolen-3-one (445) were isolated. When the a-substituent was r-butyl instead of methyl, exposure to air gave 2-(2,5-di-r-butyl-4-thiolen-3-one) 3-(2,5-di-r-butylthienyl) ether (446), formed by carbon-oxygen coupling. [Pg.821]

Only para coupling was observed during the alkaline ferricyanide oxidation of 4-hydroxy-3-(3-hydroxybenzoyl)benzoic acid. 7-Hydroxy-9-oxoxanthene-2-carboxylic acid (515) was obtained in 21% overall yield from methyl 4-hydroxybenzoate (78JCS(P1)876). The synthesis utilizes a photochemical Fries rearrangement of methyl 4-(3-methoxybenzoyloxy)benzoate to prepare the benzophenone (514 Scheme 189). A similar route was used to prepare 2-hydroxy-2 -methoxybenzophenones, which undergo intramolecular cyclization with loss of methanol on treatment with base. [Pg.837]

Methylation of 2,4-dimethoxy-l,8-naphthyridine was shown to take place at N-8 [to give (140)], by potassium ferricyanide oxidation to the appropriate iV-methyl naphthyridinone.152 Similarly, treatment of the monomethiodide of 1,8-naphthyridine gave the expected naphthyridin-2-one (141).56... [Pg.167]

A better synthesis of a-(l,2-dithiol-3-ylidene)ketones from thio-pyran-4-thiones consists in the reaction with sodium hydroxide in dimethylformamide (DMF), followed by ferricyanide oxidation (Eq. 3).11... [Pg.167]

Pyridone Formation by Alkaline Ferricyanide Oxidation or 3-Substituted Pyridinium Salts... [Pg.306]

Chemical difference spectra (ascorbate-reduced minus ferricyanide-oxidized) showed the presence of P700 in these particles. The non-detergent-treated particles were unable to penetrate into 6% polyaciylamide gels, and all the chlorophyllous material was retained at the top of the gel after electrophoresis, indicating the absence of free Chl-proteins in these particles. [Pg.172]


See other pages where Ferricyanide oxidation is mentioned: [Pg.400]    [Pg.127]    [Pg.91]    [Pg.259]    [Pg.231]    [Pg.8]    [Pg.214]    [Pg.48]    [Pg.27]    [Pg.258]    [Pg.346]    [Pg.283]    [Pg.301]    [Pg.306]    [Pg.608]    [Pg.43]    [Pg.91]    [Pg.60]    [Pg.97]    [Pg.312]    [Pg.187]   
See also in sourсe #XX -- [ Pg.504 ]

See also in sourсe #XX -- [ Pg.504 ]




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Ferricyanide

Ferricyanide as oxidant

Ferricyanide oxidations, alkaline

Oxidants ferricyanide

Oxidants ferricyanide

Oxidation by ferricyanide

Oxidation potassium ferricyanide

Oxidation with ferricyanide

Oxidation with potassium ferricyanide

Oxidation—continued with potassium ferricyanide

Oxidative coupling Potassium ferricyanide

Oxidative cyclization, ferricyanide coupling

Oxidative decarboxylation, potassium ferricyanide

Potassium ferricyanide in oxidative decarboxylation

Potassium ferricyanide oxidant

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