Potassium lead ferricyanide

Lead ferricyanide, Pb3[Fe(CN)6]2.16H20, is obtained by double decomposition of lead nitrate with potassium ferricyanide. It yields dark reddish brown crystals. 

Lead ferricyanide nitrate, Pb3[Fe(CN)6]2.Pb(N03)2.12H20, and Lead potassium ferricyanide, PbK[Fe(CN)6].3H20, have been described.3... 

Molecular imprinted polymer recognition and on line electrogenerated chemiluminescence detection. Most CL results from a direct oxidation reaction or an oxidation reaction with energy transfer. Commonly used oxidants include hydroperoxide, oxygen, potassium permanganate, ferricyanide, tetravalent cerium ion, lead dioxide and oxygen free radical such as superoxide anion ( 02 ), hydroxy radical ( OH) and nitric oxide (NO). 

Methylpyridinium quaternary salts, such as (12), undergo oxidation in alkaline solution in the presence of potassium ferricyanide to give 2-pyridones, eg, A/-methyl-2-pyridone [694-85-9] (16). Frequendy nucleophilic attack at position 2 by excess hydroxide leads to ring opening this and synthetically useful recycli2ations have been reviewed (17). 

The most suitable oxidizing agent is potassium ferricyanide, but ferric chloride, hydrogen peroxide ia the presence of ferrous salts, ammonium persulfate, lead dioxide, lead tetraacetate or chromate, or silver and cupric salts may be useful. Water mixed, eg, with methanol, dimethylformamide, or glycol ethers, is employed as reaction medium. 

A weighed amount of sample is dissolved in a mixture of propanone and ethanoic acid and titrated potentiometrically with standard lead nitrate solution, using glass and platinum electrodes in combination with a ferro-ferricyanide redox indicator system consisting of 1 mg lead ferrocyanide and 0.5 ml 10% potassium ferricyanide solution. The endpoint of the titration is located by graphical extrapolation of two branches of the titration plot. A standard solution of sodium sulfate is titrated in the same way and the sodium sulfate content is calculated from the amounts of titrant used for sample and standard. (d) Water. Two methods are currently available for the determination of water. 

The dehydrogenation of dioximes symmetrically substituted (17, R=Ri, Scheme 6.4) with a variety of oxidants, including potassium ferricyanide, halogens, hypohalides, nitric acid, nitrogen dioxides, and lead tetracetate, is a common route to symmetrically substituted furoxans. 

Marchand and co-workers reported a synthetic route to TNAZ (18) involving a novel electrophilic addition of NO+ NO2 across the highly strained C(3)-N bond of 3-(bromomethyl)-l-azabicyclo[1.1.0]butane (21), the latter prepared as a nonisolatable intermediate from the reaction of the bromide salt of tris(bromomethyl)methylamine (20) with aqueous sodium hydroxide under reduced pressure. The product of this reaction, A-nitroso-3-bromomethyl-3-nitroazetidine (22), is formed in 10% yield but is also accompanied by A-nitroso-3-bromomethyl-3-hydroxyazetidine as a by-product. Isolation of (22) from this mixture, followed by treatment with a solution of nitric acid in trifluoroacetic anhydride, leads to nitrolysis of the ferf-butyl group and yields (23). Treatment of (23) with sodium bicarbonate and sodium iodide in DMSO leads to hydrolysis of the bromomethyl group and the formation of (24). The synthesis of TNAZ (18) is completed by deformylation of (24), followed by oxidative nitration, both processes achieved in one pot with an alkaline solution of sodium nitrite, potassium ferricyanide and sodium persulfate. This route to TNAZ gives a low overall yield and is not suitable for large scale manufacture. 

In another example of oxidation without fission, the major product obtained from the reaction of methyl 2-pyridylacetate with ethyl a-bromopropionate was not the expected indolizine (63) but its oxidation product (64). This was shown by a repetition of the reaction under nitrogen leading to (63), which subsequently could be oxidized to (64) by potassium ferricyanide (70JCS(C)1434). An oxidative dimerization at the 3-position of 1,2-dimethylin-dolizine was achieved with potassium ferricyanide (71TL1273) or palladium on charcoal in boiling xylene (81BCJ2833). 

Dimethylcarbodihydrazide (280) reacts with aldehydes to afford 1,5-dimethyltetrahydro-l,2,4,5-tetrazin-6-ones (281), which can be oxidized by silver oxide, potassium ferricyanide or lead dioxide to yield radicals (282) related to the verdazyls these can be transformed into tetrahydro-l,2,4,5-tetrazines (283) by hydrogenation over palladium (80AG766). 

Iron(III) acetylacetonate, 211 Iron carbonyl, 152 Potassium ferricyanide, 255 Tri-jji-carbonylhexacarbonyldiiron, 320 Lead Compounds Iodine-Lead tetraacetate, 243 Lead tetraacetate, 62, 95, 155, 295 Lead tetraacetate-Diphenyl disulfide, 156... 

Substrates 1-3 are readily prepared with a few steps as illustrated in Scheme 4. After methylation of pyridine with dimethyl sulfate, oxidation with potassium ferricyanide in the presence of sodium hydroxide leads... 

The Diels-Alder adduct of fulvene and di(2,2,2-trichloroethyl)azodiearboxylate after selective monohydrogenation of the endocyclic pi bond can lead to the bicyclic biscarbamate 107. The electrochemical removal of the TV-protecting carbamoyl groups in a DMF—LiC104—(Hg) system is followed by the oxidation with potassium ferricyanide to give the azo compound 108 which on thermal decomposition forms the linearly fused tricydopentanoid 109 in over 50 % yield (from 107, Scheme 3-41)88a). 

With certain compounds, such as pyrazoline carboxylic acids and esters, potassium ferricyanide or silver nitrate has been used,509 and for those compounds unsubstituted on nitrogen, mercuric oxide or acetate.76 Lead dioxide has been successful for the oxidation of 1-alkyl-and 1-arylpyrazolines,9i 76,83 and in certain instances even chromic acid, but not hydrogen peroxide or silver oxide.76 See also L. Smith521 and Birkinshaw et al.b22... 

The usual method of synthesis of this system is by condensation of a diketone with 3,4-diamino-oxadiazoles (151). The alternative use of butyllithium followed by a bis-chlorooxime leads to the formation of the derivative (152) <91JHC1677> which can be cyclized to a bis(oxadiazolo)pyrazine (Equation (20)). Tetrahydro derivatives are formed from the bis-oximes (153) which give either the furoxan derivatives (155) (70-98%) by oxidation with potassium ferricyanide or the oxadiazoles (154) (55-70%) on heating (Scheme 14) <85JOC5l23>. 

The availability of a-dioximes, which makes them the most common source of furazans also accounts for their widespread use in furoxan preparations. Divers oxidizing agents have been employed, including alkaline hypohalites, potassium ferricyanide, lead tetraacetate, oxides of nitrogen, cerium(IV) ion, AModosuccinimide (80H(14)1279), and phenyl-iodine(III) bistrifluoroacetate. Electrochemical oxidation has also been reported. 

The oxidation of pyridinium salts with alkaline potassium ferricyanide provides a facile route to A -subslituted pyridones (Scheme 4.29a), although the sensitivity of pyridinium salts to nucleophilic attack may lead to ring fission reactions (Scheme 4.29b). 

More intensive dehydrogenation of primary amines having two hydrogen atoms on the adjacent carbons leads to nitriles. Such dehydrogenations are accomplished by argentic oxide cobalt peroxide [1136], nickel peroxide [936], lead tetraacetate [443, 444], sodium hypochlorite [692], potassium ferricyanide [924], and potassium ruthenate [196] (equation 513). 

Benzoyl disulfide has been obtained by the reaction of benzoyl chloride with hydrogen sulfide, hydrogen disulfide, hydrogen trisulfide, potassium sulfide, sodium disulfide, lead sulfide, sodium hydrosulfite, sodium thiosulfate, sulfhydrylmagnesium bromide, and thiobenzamide. It is also formed by reaction of benzoic anhydride with hydrogen sulfide. The better preparative methods involve the oxidation of thiobenzoic add by means of air,hydrogen peroxide or sulfur monochloride, or of the sodium or potassium salt by means of air, - chlorine, iodine, copper sulfate, - potassium ferricyanide, - or ferric chloride. - ... 

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