Potassium nitrosodisulfonate, oxidation

Various 2,6-di8ubstituted p-benzoquinones have been prepared by oxidation of the corresponding 2,6-disubstituted phenols with potassium nitrosodisulfonate or lead dioxide in formic acid. Oxidative coupling of 2,6-disubstituted phenols to poly-2,6-disubstituted phenylene ethers followed by treatment of the polymers in acetic acid with lead dioxide is reported to give low yields of the corresponding 2,6-disubstituted p-benzoquinones. 

In addition to the aforementioned syntheses of various carbazole-l,4-quinone alkaloids, many formal syntheses for this class of carbazole alkaloids were also reported. These syntheses involve the oxidation of the appropriate 1- or 4-oxygenated-3-methylcarbazoles using Fremy s salt (potassium nitrosodisulfonate), or PCC (pyridinium chlorochromate), or Phl(OCCXI F3)2 [bis(trifluoroacetoxy)iodo]-benzene. Our iron-mediated formal synthesis of murrayaquinone A (107) was achieved starting from murrayafoline A (7) (see Scheme 5.34). Cleavage of the methyl ether in murrayafoline A (7) and subsequent oxidation of the resulting intermediate hydroxycarbazole with Fremy s salt provided murrayaquinone A (107) (574,632) (Scheme 5.113). 

Hydroxycarbazole gave the p-quinone (22) and 2-hydroxycarbazole the o-quinone (23) on oxidation with potassium nitrosodisulfonate. ... 

Potassium nitrosodisulfonate, 258 other methods Bis(tributyltin) oxide, 41 /-Butyl hydroperoxide-Dichlorotris-(triphenylphosphine)rutheni-um(II), 54 Dibutyltin oxide, 95 Hydrogen hexachloroplatinate(IV)-Copper(II) chloride, 145 4-Methoxy-2,2,6,6-tetramethy 1-1 -oxopiperidinium chloride, 183 of alcohols to carboxylic acids Cetyltrimethylammonium permanganate, 69... 

Potassium nitrosodisulfonate, 258 Trimethylsilyl chlorochromate, 327 By hydrolysis of acetals or thioacetals Amberlyst ion-exchange resin, 152 Methylthiomethyl p-tolyl sulfone, 192 By isomerization of allylic alcohols N-Lithioethylenediamine, 157 By oxidation of aromatic side chains Trimethylsilyl chlorochromate, 327 From oxidative cleavage of alkenes [Bis(salicylidene-7-iminopropyl)-methylamine]cobalt(II)... 

Reduction of ketone (81) with zinc and acetic acid produced the 4-hydroxypyrazoles (87), whereas reaction with dithionite gave the corresponding 1,4-dihydroxypyrazoles (88). These compounds could be oxidized with Fremy s salt (potassium nitrosodisulfonate) to the 3,4-diazacyclopentadienone 3-oxides. 

Peroxidic reagents may dehydrogenate C-8-Na. The example of this involves the conversion of isostrychnic acid (XXXIII) by hydrogen peroxide in formic or acetic acids in the presence of catalytic quantity of cobalt salt or by potassium nitrosodisulfonate, into the lactone bases CLXXIV (R = H and OH) (144, 145). In both cases, the initially formed simple 3-H indole is oxidized further, probably by way of the tautomeric enamine, to the 13-oxy derivative, which then lactonizes. 

Uncondensed phenolic units in lignin have been estimated by a color reaction based on oxidation with potassium nitrosodisulfonate (Fremy s salt) (Adler and Lundquist 1961) as illustrated below ... 

Quinones can he prepared hy the oxidation of phenols, dihydroxy-henzenes, dimethoxyhenzenes and anilines. For example, 1,4-dihydroxy-henzene (hydroquinone) can he oxidized in good yield using sodium chlorate in dilute sulfuric acid in the presence of vanadium pentoxide and also hy manganese dioxide and sulfuric acid and hy chromic acid. Other reagents which convert hydroquinones to quinones include Fremy s salt [potassium nitrosodisulfonate, (KS03)2N0] and cerium(IV) ammonium nitrate [CAN, Ce(NH4)2(N03)J. 

Oxidations with potassium nitrosodisulfonate have been reviewed in detail. ... 

The presence of an amino group on an aromatic ring often results in oxidation of the ring to a quinone. The classical and industrial method is the treatment of anilines with potassium dichromate and sulfuric acid. Thus, aniline at room temperature is converted into p-benzoquinone in 86% yield [647], and 2,5-dimethylaniline at 80 °C gives a 55% yield of p-xyloquinone [648. A specific reagent for such oxidations is the Fremy salt, potassium nitrosodisulfonate (equation 528) [490. The oxidation of the amino group takes place even if it is acylated (equation 529) [1190. ... 

OXIDATION WITH POTASSIUM NITROSODISULFONATE (FREMY SALT)... 

Potassium permanganate. Dimethyl sulfide-Chlorine. Dimethyl sulfoxide. Dimethyl sulfoxide-Chlorine. Dimethylsulf-oxide Sulfur trioxide. Dipyridine chro-mium(VI) oxide. Iodine. Iodine-Potassium iodide. Iodine tris(trifluoroacetate). Iodosobenzene diacetate. Isoamyl nitrite. Lead tetraacetate. Manganese dioxide. Mercuric acetate. Mercuric oxide. Osmium tetroxide—Potassium chlorate. Ozone. Periodic acid. Pertrifluoroacetic acid. Potassium ferrate. Potassium ferricyanide. Potassium nitrosodisulfonate. Ruthenium tetroxide. Selenium dioxide. Silver carbonate. Silver carbonate-Celite. Silver nitrate. Silver oxide. Silver(II) oxide. Sodium hypochlorite. Sulfur trioxide. Thalli-um(III) nitrate. Thallium sulfate. Thalli-um(III) trifluoroacetate. Triphenyl phosphite ozonide. Triphenylphosphine dibromide. Trityl fluoroborate. 

Teuber oxidized equilenin with potassium nitrosodisulfonate in aqueous acetone and isolated the bright red o-quinone in high yield. 

Oxidation of phenols to quinones. Forrester and Thompson2 noted that potassium nitrosodisulfonate, an inorganic radical useful for the oxidation of phenols, amines,... 

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