Direct Iodination of Certain Nitroaromatic Compounds
Abstract Generated abstract
This paper examines the extension of a one-stage direct iodination method to selected nitroaromatic substrates, addressing the limited availability of iodine-containing aromatic intermediates. Using iodine in the presence of a sulfuric and nitric acid mixture, with acetic acid and carbon tetrachloride as reaction media components, the authors iodinated o-nitrotoluene, 4-nitrodiphenyl, and alpha-nitronaphthalene. The reactions gave 4-iodo-o-nitrotoluene, 4,4′-iodonitrodiphenyl, and 1-nitro-5-iodonaphthalene in reported yields of 55 percent, 50 percent, and 30 percent, respectively. The work presents these syntheses as shorter alternatives to previously reported multistep routes and notes the potential use of the products as intermediates for dyes and biologically active compounds.
Full Text
DIRECT IODINATION OF SOME NITROAROMATIC COMPOUNDS
A. M. SEDOV, N. T. KOZHAKINA, A. N. NOVIKOV
(Presented by the scientific-methodological seminar of the Chemical-Technological Faculty)
The lack of effective methods for the synthesis of many representatives of the aromatic series containing iodine in the ring is the reason why many of them are difficult to obtain and why the range of iodine-containing intermediates, products, and chemical reagents is small. B. V. Tronov and A. N. Novikov proposed a simple, one-stage method for obtaining iodine-containing aromatic compounds, the essence of which consists in the direct replacement of aromatically bound hydrogen by iodine in the presence of a sulfuric-nitric acid mixture [1].
However, this method has been applied to a small number of substrates. In the present work the task was set of extending the method of direct iodination in the presence of a sulfuric-nitric acid mixture to a broader range of aromatic compounds. As objects of investigation we selected nitroaromatic compounds: o-nitrotoluene, 4-nitrodiphenyl, and α-nitronaphthalene, from which, by direct iodination, we synthesized 4-iodo-o-nitrotoluene, 4,4′-iodonitrodiphenyl, and 1-nitro-5-iodonaphthalene. According to the literature, these same compounds had previously been obtained in 4 stages through nitro-, amino-, and diazonium compounds [2, 3, 4].
The iodinated nitroaromatic compounds obtained may serve as intermediates for the synthesis of dyes and biologically active substances.
Experimental Part
To a mixture of the starting nitro compound, iodine, glacial acetic acid, and carbon tetrachloride (3–5 ml), there was added dropwise, [[unclear: continuation cut off on page]]
Table 1
| Starting substance: name | Starting substance: amount, g-mol | Iodine, g-atom | Acids, ml: acetic | Acids, ml: nitric | Acids, ml: sulfuric | Temperature, °C | Time, h | Reaction products: name | Yield, % | M.p., °C |
|---|---|---|---|---|---|---|---|---|---|---|
| o-Nitrotoluene | 0.05 | 0.05 | 15 | 3.4 | 11 | 100 | 0.8 | 4-Iodo-o-nitrotoluene | 55 | 60–61 (from alcohol) |
| 4-Nitrodiphenyl | 0.1 | 0.1 | 100 | 9.0 | 10 | 90–95 | 1.5 | 4,4′-Iodonitrodiphenyl | 50 | 211–212 (from toluene) |
| α-Nitronaphthalene | 0.025 | 0.025 | 30 | 8.0 | 8 | 100–110 | 3 | 1-Nitro-5-iodonaphthalene | 30 | 163–164 (from alcohol) |
gradually, with vigorous stirring, a mixture of nitric acid of density 1.4 and sulfuric acid of density 1.83–1.84. After completion of the synthesis, the mass was diluted with water; the precipitate was filtered off, washed with water, and recrystallized from the appropriate solvent. The reaction conditions, products, their yields, and melting points are given in Table 1.
Conclusions
- By direct iodination in the presence of a sulfuric–nitric acid mixture, the following were obtained from o-nitrotoluene, 4-nitrodiphenyl, and $\alpha$-nitronaphthalene: 4-iodo-o-nitrotoluene, 4,4′-iodonitrodiphenyl, and 1-nitro-5-iodonaphthalene.
References
- A. N. Novikov, ZhOKh, 24, 655 (1954); ZhOKh, 29, 58 (1959).
- A. Reverdin, G. Kacer, Ber., 30, 3001 (1897).
- L. Sholl, Monatsh., 42, 404 (1921).
- R. Belcher, J. Ch. Soc., 1334 (1953).