A manual of elementary chemistry : theoretical and practical / by George Fownes.

  • Fownes, George, 1815-1849.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: A manual of elementary chemistry : theoretical and practical / by George Fownes. Source: Wellcome Collection.

    976/1062 (page 948)
    filtered. The impure isatin which separates on cooling is washed with water containing a little ammonia, and recrystallised. Both these processes require careful management, or the oxidising action proceeds too far, and the product is destroyed. Isatin forms deep yellowish-red prismatic crystals of great beauty and lustre: it is sparingly soluble in cold water, freely in boiling water, and also in alcohol. The solution colour's the skin yellow, and causes it to emit a very disagreeable odour-. Isatin cannot be sublimed. A solution of potash dissolves isatin with purple colour: from this solution acids precipitate the isatin unchanged. On boiling, however, the colour is destroyed, and the liquid yields on evapora- tion crystals of the potassium-salt of isatic acid, C1BH14N2O0. In the free state this acid is a white and imperfectly crystalline powder, soluble in water, and easily decomposed into isatin and water. By chlorine isatin is converted into chlorisatin, C1BH8C12N204, a body closely resembling isatin itself in properties. If an alcoholic solution and excess of chlorine be employed, other products make their appearance, as perchloroquinone or chloranil, C6C1402, tri- chloroplienol, C6H3C130, and a resinous substance. The former of these substances, the position of which in the quinone series has been already noticed (p. 802), yields further products with potash and ammonia. Bromisatin is easily formed. The change which isatin and its chlorinated and brominated congeners undergo when submitted to the action of melting potassium hydrate has been already considered in the section on the Organic Bases (p. 883). Exposed to the action of hydrogen and ammonium sulphide, isatin yields several new compounds, as isathyde, sulphisathydc, &c A hot solution of isatin, treated with ammonium sulphide, deposits sulphur, and yields isathyde, C16H12N204, a white crystal- lised substance which bears to isatin the same relation as white to blue indigo. If the ammonium sulphide be replaced by hydro- gen sulphide, bisulphisathyde, C16H12N202S2, is produced, which is derived from the former by substitution of two atoms of sulphur for oxygen. An alcoholic solution of potash converts this last compound into sulphisathydc, C1GH12N203S. Under the influence of cold aqueous solution of potash, bisulphisathyde yields indin, C1(iH12NQ02, which is isomeric with white indigo. When treated with boiling potash, indin fixes the elements of two molecules of water, and becomes indinic acid, C16H16N204, the potassium-salt of which forms fine black needles.* * Respecting the constitution of isatin and its derivatives, see Baeyer, Ann. Ch. Pharm. cxl. 295, Supplement-baud vii. 56; Baeyer and Em- merling, Zeitschrift fur Chemie [2], vi. 213; Kekule, ibid. vi. 254; also Watts's Dictionary of Chemistry, Supplement, p. 734: further, Emmerling and Engler, Bevichte d. deutschen chemischen Gesellschaft, iii. 885; Ann. Chim. Pkys. [4], xxv. 132.