Alkaline permanganate

C (decomp.) It is made by the oxidation of toluene-o-sulphonamide with alkaline permanganate. Saccharin has about 550 times the sweetening power of sucrose, and is used extensively as a sweetening agent, usually in the form of the sodium salt. The use of saccharin is restricted in the U.S. 

Since, however, some compounds, such as aniline (p. 164), react very rapidly with bromine by substitution, the bromine test should whenever possible be confirmed by the alkaline permanganate test. 

Oxidation, (a) Unsaturation test. Dissolve about o-i g. of cinnamic acid or of a soluble cinnamate in about 5 ml. of 10% NajCOg solution. To the cold solution add 1% aqueous KMn04 drop by drop. Immediate decolorisation denotes unsaturation. (Note. Many easily oxidisable substances, e.g.y formic acid, acetaldehyde, etc.y also rapidly decolorise alkaline permanganate. Cinnamates, however, do not reduce Fehling s solution.)... 

Alkaline permanganate. Heat under reflux i g. of i,2 naph thoquinone, 50 ml. of saturated aqueous KMn04 solution and 2 g. of anhydrous NajCO for 30 minutes. Then proceed as for oxidation of benzyl chloride (p. 393). 1,2-Naphthoquinone gives phthalic acid, m.p. 195°. Phenanthraquinone gives diphenic acid, HOOC CeH CeH COOH, m.p. 229°. 

Oxidation of a side chain by alkaline permanganate. Aromatic hydrocarbons containing side chains may be oxidised to the corresponding acids the results are generally satisfactory for compounds with one side chain e.g., toluene or ethylbenzene -> benzoic acid nitrotoluene -> nitrobenzoic acid) or with two side chains e.g., o-xylene -> phthalic acid). 

Oxidation of side chains. The oxidation of halogenated toluenes and similar compounds and of compounds with side chains of the type —CHjCl and —CH OH proceeds comparatively smoothly with alkaline permanganate solution (for experimental details, see under AromcUic Hydrocarbons, Section IV.9,6 or under Aromatic Ethers, Section IV,106). The resulting acid may be identified by a m.p. determination and by other teats (see Section IV,175). 

Aromatic aldehydes react with the dimedone reagent (Section 111,70,2). All aromatic aldehydes (i) reduce ammoniacal silver nitrate solution and (ii) restore the colour of SchifiF s reagent many react with sodium bisulphite solution. They do not, in general, reduce Fehling s solution or Benedict s solution. Unlike aliphatic aldehydes, they usually undergo the Cannizzaro reaction (see Section IV,123) under the influence of sodium hydroxide solution. For full experimental details of the above tests, see under Ali-phalic Aldehydes, Section 111,70. They are easily oxidised by dilute alkaline permanganate solution at the ordinary temperature after removal of the manganese dioxide by sulphur dioxide or by sodium bisulphite, the acid can be obtained by acidification of the solution. 

Printed circuit boards manufacture is aided by the use of KMnO. Alkaline permanganate solution is used to remove resin smeared on the interior hole wall of multilayered printed circuit boards. Additionally the hole wall is etched, resulting in a surface with excellent adhesion characteristics, for electrodeless copper (250). The alkaline permanganate etchback system containing >60 g/L KMnO and 40-80 g/L NaOH at 70—80°C, is effective for difunctional, tetrafiinctional, and polyimide resin substrates, where the level of etchback is direcdy proportional to the immersion time (10—20 min) (251). 

Alkaline permanganate pretreatment of steel for the removal of heat scale and smut prior to acid pickling results in faster descaling and reduced metal attack (see Metal surface treatments Metal treatments). Stainless steel alloys can also be cleaned by alkaline permanganate followed by pickling in nonoxidi2ing acids (260). 

The oxidation of quinazoline with alkaline permanganate is still the preferred route to pyrimidine-4,5-dicarboxylic acid (04CB3643). 

The degradation of more complex substances can be regarded as another route to pteridine derivatives. Already in 1895 tolualloxazine was oxidized by alkaline permanganate to lumazine-6,7-dicarboxylic acid, and further heating led in a stepwise decarboxylation to lumazine (3) (1895CB1970). 

The intermediate products (I) and (II) lose water, forming hydrohydrastinine and oxyhydrastinine respectively. Alkaline permanganate converts oxyhydrastinine into hydrastinic acid (III), C HgOgN, needles, m.p. 164° this in turn is oxidised by dilute nitric acid to hydrastic acid methylimide (IV), CJ0H7O4N, m.p. 227-8°, which, when warmed with potassium hydroxide solution, furnishes methylamine and hydrastic acid (V). 

Bicucine, C20H19O7N, H2O. This alkaloid has m.. 222° (dec.) and — 115 4° (N/10, KHO) but in N/HCl it shows mutarotation — 145° to — 100°,due to the formation of an equilibrium mixture of bicucine and bicuculline. Alkaline permanganate oxidises it to 3 4-methylene-dioxyphthalic acid, isolated as the ethylimide. In view of its formation from bicuculline by the action of alkali, Manske has suggested for its formula (II) or (III), the former representing it as the nomarceine (p. 208) analogue of bicuculline, whilst (III) makes it the hydroxy-acid corresponding to the lactone, bicuculline and is preferred. 

Heating isoxazole derivatives with aqueous-alkaline permanganate leads to a complete degradation of the heterocycle. With arylisoxa-zoles this results in readily identifiable aromatic acids, from which can be deduced the orientation of electrophilic substitution reac-tions. ° Also, the stability of various heterocycles can be compared. Thus, under these reaction conditions, the pyrazole ring is more stable than that of isoxazole (cf. 197198). ... 

Recently, the successful oxidation with alkaline permanganate of 3-chloro-5-hydroxymethylisoxazole (199) and 3-chloro-5-acetylisoxa-... 

Weed, R. D., Dendritic Pitting of Stellite by Alkaline Permanganate Solutions , J. Electrochem. Soc., 110, 178c (1963)... 

For alkaline permanganate, the following mechanism has been proposed ... 

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