3-Methyl-2-nitrobenzoic acid → 2-Methyl-3-nitrobenzoic acid

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Reaction Steps

The disadvantage of this synthesis route is the poor availability of the starting substance 2-methyl-3-nitrobenzoic acid. In Kulic et al., J. Gen. Chem. USSR (Engl.), 60, 2118 (1990), the oxidation of 2,3-dimethylnitrobenzene to 2-methyl-3-nitrobenzoic acid is carried out using aqueous potassium permanganate in the presence of a phase-transfer catalyst at 75° C. In this process, 2-methyl-3-nitrobenzoic acid is not obtained as a pure product, but as a mixture with 3-nitrophthalic acid and smaller amounts of 3-methyl-2-nitrobenzoic acid. A complicated purification is necessary in order to obtain pure 2-methyl-3-nitrobenzoic acid from the crude product. This is at the expense of the yield. A further serious disadvantage is the extremely poor space yield of the oxidation reaction. Per 100 ml of water, only 2.4 g of 2,3-dimethylnitrobenzene are employed (see p. 2121). Moreover, manganese dioxide, which has to be disposed of, is formed during the permanganate oxidation.

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