Organic Medicinal Chemicals (Synthetic and Natural)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ... acetic anhydride, and 1 kilo of sulphuric acid (66 Be.) is added gradually, with cooling and stirring. After standing for some hours, until the reaction product dissolves completely in water, an equal volume of water is added and the acetic acid removed by steam distillation. The aqueous solution is then neutralised with barium carbonate and the potassium salt of guaiacol-5-sulphonic acid prepared from the resulting barium salt. The guaiacol-4-sulphonic acid obtained as a by-product in the manufacture of thiocol may be reconverted into guaiacol by heating with phosphoric or sulphuric acids (D. R. P. 250380). Twenty kilos of sodium guaiacol sulphonate are mixed with 100 kilos of 24 % phosphoric acid and the mixture concentrated until the boiling point is over 140. Superheated steam is then blown in, when the guaiacol distils over. In place of phosphoric acid, sulphuric acid of b.p. 135 may be employed. The thiocol obtained by any of the above methods is purified, if coloured, by recrystallisation from water, employing vegetable charcoal as a decolourising agent. Thiocol is a colourless, crystalline powder, neutral, or faintly alkaline to litmus. It is readily soluble in water, slightly so in cold alcohol. It is important that the salt for therapeutic use should be free from the 4-sulphonate. Concentrated nitric acid, added to a 10 % aqueous solution, should afford only a red colour. If the 4-sulphonic acid is present a yellow precipitate of dinitroguaiacol, m.p. 122, is obtained. Ammoniacal calcium or barium chlorides, added to the aqueous solution, should afford no white precipitate. Thiocol is employed for the same purposes as guaiacol. It possesses the advantages of being comparatively tasteless, non-toxic, and of exercising no disturbing action on the d...