Potassium permanganate aromatics with

Aromatic nitro compounds that contain a side chain (e.g. nitro derivatives of alkylbenzenes) may be oxidised to the corresponding acids either by alkaline potassium permanganate (Aromatic hydrocarbons, Section 9.6.3, p. 1238) or, preferably, with a sodium dichromate-sulphuric acid mixture in which medium the nitro compound is more soluble. 

A primary or secondary alkyl side chain on an aromatic ring is converted to a carboxyl group by reaction with a strong oxidizing agent such as potassium permanganate or chromic acid. 

In an attempt to protect thiophenols during electrophilic substitution reactions on the aromatic ring, the three substituted thioethers were prepared. After acetylation of the aromatic ring (with moderate yields), the protective group was converted to the disulfide in moderate yields, 50-60%, by oxidation with hydrogen peroxide/boiling mineral acid, nitric acid, or acidic potassium permanganate. ... 

Anilines are converted into nitrosoarenes ArNO by the action of hydrogen peroxide in the presence of [Mo(0)(02)2(H20) (HMPA)]224, whereas catalysis of the reaction by titanium silicate and zeolites results in the formation of azoxybenzenes ArN (0)=NAr225. Azo compounds ArN=NAr are formed in 42-99% yields by the phase-transfer assisted potassium permanganate oxidation of primary aromatic amines in aqueous benzene containing a little tetrabutylammonium bromide226. The reaction of arylamines with chromyl chloride gives solid adducts which, on hydrolysis, yield mixtures of azo compounds, p-benzoquinone and p-benzoquinone anils 234227. 

The nitrosodisulfonate salts, particularly the dipotassium salt called Fremy s salt, are useful reagents for the selective oxidation of phenols and aromatic amines to quinones (the Teuber reaction). - Dipotassium nitrosodisulfonate has been prepared by the oxidation of a hydroxylaminedisulfonate salt with potassium permanganate, " with lead dioxide, or by electrolysis. This salt is also available commercially. The present procedure illustrates the electrolytic oxidation to form an alkaline aqueous solution of the relatively soluble disodium nitrosodisulfonate. This procedure avoids a preliminary filtration which is required to remove manganese dioxide formed when potassium permanganate is used as the oxidant. " ... 

Reaction C. Oxidation of the Side Chain in Aromatic Compounds. (A., 122,184 133, 41 137, 308 141,144 147, 292 B., 7,1057 19, 705 Z. Ch., 4, 119) (Fittig).—When aromatic compounds containing aliphatic side chains attached to the nucleus are treated with certain oxidising agents (potassium permanganate, dilute nitric acid, and chromic acid), the side chain is oxidised until only a carboxylic group attached to the nucleus remains the end methyl group, if there are several carbon atoms... 

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. 

To prepare 2-aminopyridine by treatment of pyridine with potassium amide in liquid ammonia at —33 °C and using permanganate as oxidant was not successful. No reaction takes place under these conditions. The aromaticity of the pyridine ring is too high to allow nucleophilic amide addition. It was surprisingly observed that treatment of a solution of 3-nitropyridine in liquid ammonia (thus without the presence of potassium amide) with potassium permanganate, gave after work-up a mixture of... 

There have been few studies of the reactions of these ring systems. For example only one case of oxidation of a partially reduced ring system to form an aromatic ring is reported. The N-methylpyrrolo[2,3-aromatic compound (7) on treatment with potassium permanganate (Equation (1)) <87JHC545>. 

Some aromatic carboxylic acids are also commercially important. Benzoic acid is used as an ingredient in medications, a preservative in foods, and a starting material for synthesis. Benzoic acid can be produced by the oxidation of toluene with potassium permanganate, nitric acid, or other strong oxidants. 

---