P-Toluic acid

The toluic acids (or methylbenzoic acids ) form in chemistry a group of substances derived from both the benzoic acid as well as from toluene. The structure consists of a benzene ring with an added carboxy (-COOH) and methyl group (- CH3) as a substituent. Due to their different arrangement of three structural isomers (ortho, meta or para) result with the molecular formula C8H8O2. Primarily, they are to be regarded as methyl-substituted benzoic acids.

Properties

The toluic acids are white to yellowish solids. The melting points differ significantly. 4- toluic acid, which has the highest symmetry, has the highest melting point. The electron- impact- induced mass spectrum of 2 -toluic acid on the one hand differs significantly from those of the other two positional isomers, as over the ortho effect the elimination of water from the molecular ion is favored.

Representation

From the xylenes, the toluic obtained by oxygen (e.g., in the presence of cobalt stearate as catalyst); there is only one methyl group is selectively oxidized. Is used, however, stronger oxidants such as potassium permanganate or chromic acid, both methyl groups, are oxidized and thus transformed to o-xylene, phthalic acid, isophthalic acid and m-xylene to p-xylene to terephthalic acid.

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