The synthesis of some new dimethyltetrahydroquinolines / by Arthur James Ewins and Harold King.

  • Ewins, Arthur James.
Date:
[1912?]
Catalogue details

Licence: Public Domain Mark

Credit: The synthesis of some new dimethyltetrahydroquinolines / by Arthur James Ewins and Harold King. Source: Wellcome Collection.

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    rhombic prisms, melting at 160°. It is sparingly soluble in cold water, but fairly readily so in hot water, alcohol, or acetone: 0*1090 gave 0*2096 C02 and 0*0448 H20. C=52*4; H = 4*6» C11H15N,C6H307N3 requires C = 52*3; 11 = 4*6 per cent. The benzoyl derivative, C18H1QON, prepared by the Schotten- Baumann reaction, crystallises from dilute alcohol in prisms melting at 104—105°. A cetoaceto-m-toluidide, CH3*CO*CH2*CO*NH*C6H4Me. This compound is obtained by a method exactly similar to that employed in the preparation of the ortho-compound. On recrystal¬ lisation from benzene and light petroleum it separated in pearly leaflets melting at 57—58°: 0*1570 gave 0*3972 C02 and 0*0980 H20. C=69*0; H = 6*93. C'11H1302N requires C = 69*l; H = 6*8 per cent. Its general properties are in all respects similar to those of the isomeric ortho-compound. Owing to the low melting point of the solid, however, its separa¬ tion from the crude product was found to be somewhat troublesome. In the preparation of the corresponding 2-hydroxy-4:7-dimethyl- quinoline, therefore, the crude product was directly treated with concentrated sulphuric acid at 100° for fifteen minutes, and the product poured into water. After crystallisation from dilute acetic acid a good yield (41 per cent.) of the hydroxyquinoline melting at 220° was readily obtained. From this the corresponding 4:7-di- methylquinoiine and 4:7- dimethyl-1:2 : 3 :4-tetrahydroquinoline were obtained by zinc dust distillation and reduction by sodium in alcohol respectively. 4 :1 -Dimethylquinoline, CnHnN. 2-Hydroxy-4 :7-dimethylquinoline was distilled with zinc dust as described in the case of the corresponding 2-hydroxy-4 :8-dimethyl- quinoline, and the product worked up as before. In this way from 10 grams of hydroxyquinoline were obtained 3*3 grams of a colour¬ less oil. In order to obtain the pure base it was converted into the picrate, and the base regenerated from the pure salt boiled at 140—141°/15 mm. The picrate was prepared in the manner described for the picrate of 4 :8-dimethylquinoline, and was crystallised from dilute alcohol. It forms broad, rectangular, golden-yellow prisms, melting at 224° : 0*1736 gave 0*3374 C02 and 0*0566 H20. C = 53*0; E]=3*6. CnHnN,C6H307N3 requires C = 52*8; 11 = 3*6 per cent. This salt is very sparingly soluble in cold water, and only moder¬ ately so in hot water or alcohol.