Potassium permanganate alkanes with

The alkenes are distinguished from the alkanes by their solubility in concentrated sulphuric acid and their characteristic reactions with dilute potassium permanganate solution and with bromine. Characterisation may be based upon the determination of their physical and/or spectral properties. Characterisation by way of solid adducts with nitrosyl chloride has been quite widely used in the terpene field the preparation of adducts with 2,4-dinitrobenzenesulphenyl chloride is described below (see also Section 8.1.1, p. 1128). 

Reaction with potassium permanganate. Dilute or alkaline solutions of KMn04 oxidize unsaturated compounds. Alkanes and aromatic compounds are generally unreactive. Evidence that a reaction has occurred is observed by the loss of the purple color of KMn04 and the formation of the brown precipitate manganese dioxide, Mn02. 

A10% solution of potassium permanganate is bright purple. When this reagent reacts with an olefin, the purple color disappears and a fine brown suspension of manganese dioxide may be seen. While we will use permanganate simply to distinguish between alkenes and alkanes, it is also an important preparative reagent ... 

Solution It is known that alkanes and benzene are quite inert to oxidation with potassium permanganate in aqueous alkali. However, alkyl and aryl groups attached to benzene rings can be oxidized to carboxyl (-COOH) groups with hot, alkaline permanganate. For example. 

Alkanes are not particularly reactive they do not readily react with dilute acids, cdkaUs, or oxidizing agents such as potassium permanganate and sodium dichromate. They do, however, burn in a plentiful supply of oxygen to form carbon dioxide and water ... 

As the reaction occurs, the purple color of the permanganate ion is replaced by the brown precipitate of manganese dioxide. Because of this color change, the reaction can be used as a chemical test to distinguish alkenes from alkanes, which normally do not react with potassium permanganate. 

Combining the known fluoride-catalysed 1,4-addition of primary nitro-alkanes to aP-unsaturated ketones with the use of potassium permanganate on silica gel as an effective reagent for the Nef reaction provides an attractive route to 1,4-diketones (Scheme 46). The strategy offers great potential, but the... 

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