Oxidation with bromite

Chlorite ion is oxidized rapidly to chlorine dioxide by ozone at pH 4, yielding one mol CIO2 per mol O3 when chlorite is in excess (k > lO" (39). The oxidation of bromite to bromate by ozone is too rapid to measure. Chlorine dioxide is oxidized rapidly to chlorate. Chlorate, bromate, and iodate ions do not react with ozone. 

In opocinchenine the hydroxyl group must, therefore, be in the ortho-position relative to the point of attachment of the benzene ring to the quinoline nucleus. The relative positions of the two ethyl groups are determined by the fact that apocincheninic acid ethyl ether on oxidation with lead peroxide and sulphuric acid gives the lactone of hydroxyopo-cincheninic acid ethyl ether (I), which, on oxidation by sodium hypo-bromite, yields quinolylphenetoledicarboxylic acid (II). 

Since aldehydes are notoriously polymerizable and difficult to manipulate, the products of periodate oxidation are oftentimes further oxidized, with hypohalite, to carboxylic acids, or are reduced to the corresponding alcohols. Oxidation has been more usually employed than reduction, since acids frequently form crystalline salts and other conveniently prepared derivatives. A process of oxidation of these aldehydic products by hypo-bromite, in the presence of barium carbonate or strontium carbonate, was developed and used extensively by Hudson and his coworkers.107 110 194-199,90s Their method can best be illustrated by an example the further oxidation of the dialdehyde, VI, shown previously (see p. 16) to be obtained by the oxidation of the methyl a-D-aldohexopyranosides. The isolation of... 

The traditional method of oxidizing hydrazine derivatives makes use of halogens or hypohalites as oxidizing agents. The techniques range from the preparation of l,l -azobis(l-cyclohexanenitrile) by the addition of bromine to an alcoholic hydrochloric acid solution of the corresponding hydrazine [89], through the use of bromine water [90, 91] to oxidations with sodium hypo-bromite [64] or sodium hypochlorite [92]. 

Hydrastine has been prepared by the hydrogenolysis of the 1-phenyl-l/f-5-tetrazolyl ether of (—)-a-narcotoline,154 and in the racemic form by the reductive cyclization of the quaternary salt of the keto-acid (53) that is obtained from oxidoberberine (51) as described above.133 The lactone (80), prepared by the dye-sensitized photo-oxidation of oxidonorcoralyne followed by reduction with sodium borohydride and from 6 -acetylpapaveraldine by oxidation with hypo-bromite followed by reduction, has been TV-methylated and reduced with sodium borohydride to an isomer of cordrastine.133 Cordrastine itself has been synthesized by the electrolytic reduction of a mixture of the iminium salt (81) and bromomeconine (82), a process that has been shown to be of general applicability to the synthesis of alkaloids of this group.155... 

Most of mixtures of oxidizer and red phosphorus possess very high sensitivity. The results of drop hammer tests for this kind of mixture is shown in Sec.3.3. In the range of experiments, the mixtures of red phosphorus with bromite, chlorite and sodium peroxide possess very high sensitivity. 

Bromine-Silver oxide. The reaction of bromine in the presence of a silver salt, usually the oxide, with a tertiary alcohol gives in good yield a product of the insertion of oxygen. Thus 1,3,3-trimethylcyclohexanol (1) is transformed into the bicyclic ether (4) in 75% irield. It is suggested that the reaction proceeds through the hypo-bromite (2), the decomposition of which is catalyzed by silver ions. 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or aHyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propanetricarboxylic acid by oxidation of /S-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of a-methyl-a -oxalosucdnic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-sucdnaldehyde dioxime from the ammonium salt of a-methyl-butyric add by oxidation with. hydrogen peroxide from P-methyllevulinic add by oxidation with dilute nitric acid or h3 bromite from 8-methyladipic acid and from the decomposition products of glyceric add and pyruvic add. The method described above is a modification of that of Higginbotham and Lapworth. ... 

The most widely used, and often most convenient reagents for such one-pot reactions are sodium hypochlorite (45) or hypobromite (16). These reactions are performed in the presence of an organic base (generally triethylamine) that normally enhances the yield of cycloaddition products (45). This method was employed for many intermolecular reactions (71) and also seems especially suited for intramolecular ones (72-77) as well as for the solid-phase synthesis (78) of 2-isoxazolines. Hypohalite can also be replaced by sodium bromite in combination with a catalytic amount of tri-n-butyltin chloride (79). In a related method, O-tributylstannyl oximes were treated with fert-butyl hypochlorite to produce nitrile oxides that were trapped with alkenes or alkynes to afford the corresponding isoxazolines or isoxazoles in moderate to good yield (80). 

Other oxidizing agents such as bichromate, iodate, bromate, chlorite, bromite, chloramine T, and peroxosulfate are not equally suitable for all dyes and are seldom used, for price reasons or because of contamination of the wastewater with heavy metals. Sodium hypochlorite requires careful metering and can be used only with sulfur dyes that are relatively fast to chlorine. 

Ammonium cerium(IV) nitrate or cerium(IV) sulfate will catalyze the selective oxidation of secondaiy alcohols with sodium bromate as cooxidant, in this case remote C—C double bonds interfere, but 1,2-diols are not cleaved. It has been found that sodium bromite in aqueous acetic acid will act as a selective oxidant for secondary mary diols without the need for other catalysts (Scheme 21). ... 

Sodium bromite oxidizes secondary alcohols in preference to primary alcohols. Menthol treated with sodium bromite in aqueous acetic acid at room temperature affords an 86% yield of menthone after 5.5 h [739]. 

TEMPO is a commercially available nitroxyl radical-containing reagent that catalyzes the oxidation of primary and secondary alcohols in conjunction with co-oxidants (oxygen, hypochlorite, bromite, hypervalent iodine, or peroxy acids).The catalyst is particularly useful for the oxidation of optically active a-alkoxy- or a-amino alcohols to the corresponding aldehydes without loss of enantiomeric purity. ... 

There are a variety of stoichiometric oxidants that can be used in conjunction with 2,2,6,6-tetramethylpiperdine 1-oxyl (TEMPO), including TCCA, iodobenzene diacetate, meto-chloroperbenzoic acid (wi-CPBA), sodium bromite, sodium hypochlorite, and /V-chloi osuccinirnide. TEMPO can be used to oxidize primary alcohols to aldehydes or carboxylic acids, based on reaction conditions. A particularly attractive feature is that the product is usually isolated quite pure after concentration of the organic layer. 

When solutions of lead or bismuth salts are treated with alkali hypo-bromite, lead peroxide and higher oxides of bismuth are formed. These products react with benzidine acetate to give benzidine blue (seepage 282). However, if bismuth salts are heated alone with alkali hydroxides, a yellow precipitate forms, [probably BiO(OH)] and, when once formed, is not converted into higher bismuth oxides on treatment with h3q)obromite. This resistance is applied in the detection of lead in bismuth salts. The following procedure is recommended in the examination of pharmaceutical bismuth preparations (e.g., bismuth sub-gallate, -tannate, -salicylate). 

Small amounts of oxygen gas may be made from small amounts of Oi -enriched water (25 to 200 mg.) by the procedure described by Anbar (1958) for the isotopic analysis of oxygen in water. Sodium hypo-bromite is formed in situ from aqueous sodium hydroxide and bromine in a sealed tube, and, in the presence of a trace of cobaltic oxide, the hypo-bromite decomposes with the evolution of oxygen. The sealed tube is then broken open on a vacuum line. The oxygen is drawn off and the water recovered by distillation. 

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