2,4-Toluenedisulfonic acid

Benzaldehyde-2,4-disulfonic acid from toluenedisulfonic acid (Mn02 ) 303... 

Methyl groups attached to an aromatic ring can be converted into aldehyde groups by a mixture of manganese dioxide and moderately concentrated sulfuric acid.363 The process is recommended particularly for oxidation of compounds that dissolve in 90-95% sulfuric acid. However, provided that sulfonation does not intervene, oleum or a mixture of sulfuric and acetic acid may be used. Almost all toluene derivatives can thus be converted into aldehydes e.g., 0-toluenesulfonic acid and 2,4-toluenedisulfonic acid give 80% yields of the corresponding aldehydes by this method.364... 

Only one of the six possible toluenedisulfonic acids is prepared by the sulfonation reaction, toluene-2,4-disulfonic acid. This acid is the predominant product of the sulfonation of toluene, o- and p-toluenesulfonic acid, and o- and p-toluenesulfonyl chloride. Toluene-2,4,6-trisulfonic acid is obtained from the reaction of potasaum toluene-2,4-disulfonate (1 mole) with chlorosulfonic acid (3 moles) at 240 . ... 

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