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Properties of substance:

7-methyl-8-nitroquinoline



skc-file

Group of substances:

organic

Physical appearance:

crystals

Empirical formula (Hill's system for organic substances):

C10H8N2O2

Melting point (°C):

186-187

Synthesis 1:

Reference: Tomisek, A., Graham, B., Griffith, A., Pease, C. S., & Christensen, B. E. Syntheses of Certain 8-Nitroquinolines / Journal of the American Chemical Society. - 1946. - Vol. 68, No. 8 pp. 1588 [doi: 10.1021/ja01212a063]



Forty grams of 7-methylquinoline was added gradually with cooling to 100 cc. of cooled concentrated sulfuric acid. After the mixture had cooled to room temperature, 16 cc. of fuming nitric acid (d. 1.5) was added in one portion. After standing for three hours, the mixture was poured into 1.2 liters of water. The amorphous product was filtered and washed with water. The product was dissolved in hot alcohol, treated with charcoal, and then recrystallized. A yield of 31.7 g. (61%) of short white rods, m. p. 183°, was obtained. Mixed m. p. tests indicated an identical product with that obtained from the Skraup reaction.

Anal. Calcd. for C10H8N2O2: C, 63.82; H, 4.29: N, 14.89. Found: C, 63.87; H, 4.51; N, 14.72.

Synthesis 2:

Reference: Tomisek, A., Graham, B., Griffith, A., Pease, C. S., & Christensen, B. E. Syntheses of Certain 8-Nitroquinolines / Journal of the American Chemical Society. - 1946. - Vol. 68, No. 8 pp. 1588 [doi: 10.1021/ja01212a063]

The 2-nitro-3-toluic acid was converted to its amide and this in turn subjected to the Hoffman degradation. The prepared toluidine was subjected to the Skraup synthesis using molar quantities and conditions as given by Richter and Smith.

[Sixteen and two-tenths grams of the orange-colored 2-nitro-3-toluidine, 39.2 g of glycerol (dried by passing dry air through the liquid for three hours at 170—180°) and 18.4 g of arsenic pentoxide were weighed into a three-necked flask. This was then equipped with a glycerol-sealed stirrer, thermometer dipping into the liquid and a Pyrex water-cooled condenser with a calcium chloride tube for eliminating atmospheric moisture.

Twenty one and six-tenths grams of sulfuric acid (sp. gr. 1.84) was added through the condenser with vigorous stirring, and at such a rate as to maintain the temperature below 130°. The temperature was then held at 130—135° for one hour and finally the mixture was kept in active reflux for six additional hours.]

The reaction mixture was then diluted with 100 cc. of water, cooled to about 0° and filtered. The solid material was extracted with boiling dilute hydrochloric acid. The acid solution was neutralized with ammonia and the crude 7-methyl-8-nitroquinoline was removed by filtration and washed with water and dried. The yield was 8.7 g. (43%) of black needles.

The original mother liquors were treated with excess ammonia and the solid was removed by filtration. The precipitate was dissolved in hydrochloric acid, and this solution was diazotized over a period of three hours by the addition of a large excess of sodium nitrite. The mixture was heated to 80°, cooled to 0° and filtered. The filtrate was made strongly basic with sodium hydroxide, and the resulting precipitate was washed with water. The product, after treatment with charcoal and recrystallization from alcohol, gave 2.5 g. (12%) additional material. These crude products were fractionally recrystallized from alcohol. The second crop of crystals gave a relatively pure yellow product, m. p. 181—183°.

References:

  1. Свойства органических соединений: Справочник. - Под ред. Потехина А.А. - Л.: Химия, 1984. - pp. 400-401 [Russian]

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