a yellow nitrophenolate of mcrcuric nitrate. By the continued action of the acid this is nitrated to the trinitrophenolate and decomposed with the formation of picric acid and the regeneration of mercuric nitrate.
The addition of mercuric nitrate is here written as a 1,4-addition, but 1,2-addition would give the same final product, and there is no evidence in the facts concerning benzene which enables us to choose between the alternative hypotheses. Toluene yields tri-nitro-m-cresol by a similar series of reactions, and it is clear that the nitro group in the addition product of mercuric nitrate and toluene has taken either the 2-, the 4-, or the 6-position, that is, one or the other of the positions activated by the methyl group. In the addition of mercuric nitrate to naphthalene, the nitro group correspondingly may be supposed to go to the active <*-position. If the addition is 1,2-, the product on oxidation will yield a derivative of 0-naphthol. If it is 1,4-, it will yield a derivative of a-naphthol. The two possibilities are indicated below.
H OHgONO, OH OH
Gentle treatment of naphthalene with nitric acid containing mercuric nitrate yields, 2,4-dinitro-a-naphthol in conformity with the belief that the first addition product is 1,4- as represented by the second of the above formulations.
Picric acid was obtained in 1771 by Woulff, who found that
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