1,3-Dialkyl-2-nitrobenzenes (C6H3R2NO 2; R = Me, Et, and Pri) rearrange in trifluoromethanesulphonic acid to the corresponding 4-nitro derivatives; with R = Et, this reaction is accompanied by dehydration to 7-ethyl-3-methylanthranil. The reaction rate increases markedly with the size of the alkyl group; with R = Me, the reaction was studied at 110 °C but, with R = Pri, temperatures of 36-54 °C were used. The studies with R = Me show the reaction to be first-order with the rate coefficients (k1) increasing rapidly with the acidity of the solution [d(log k1)/d(-H 0)] = 1.45, decreasing with acidity to 0.49. Double-labelling experiments with 2H and 15N show the reaction to be intramolecular. 1,2,4-Trimethyl-3-nitrobenzene also rearranges under these conditions to give mainly the 5-nitro isomer. The above results are discussed in terms of a direct 1,3-shift of the nitro group.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of the Chemical Society, Perkin Transactions 2|
|State||Published - 1990|
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