398 Hale —Initiative Action of Iodine and other 



oxidized to gluconic acid or dextronacid, CH 2 (OH)*(CH.OH) 4 * 

 C0 2 H, e. g., chlorine or bromine will cause the reaction thus :* 



C 6 H 12 6 + Br 2 +H 2 = CH 9 (OH);(CHOH) 4 -COOH + 2HBr. 



dextrose gluconic acid 



Habermaimf oxidized dextrin by the same reaction to dex- 

 tronacid, as he named it, but HerzfeldJ proved conclusively 

 that chlorine or bromine oxidizes dextrose, maltose, and dex- 

 trin to the same acid, gluconic acid, i. e., that gluconic acid, 

 maltonacid, and dextronacid are identical; and that the dis- 

 cordant results of other experimenters are due to the constant 

 production, by bromine at least, of saccharic acid, as a by- 

 product. It is possible that one or both of these acids may be 

 produced by the action of iodine. JSTow the action of the 

 weak oxidizer iodine appears to be strengthened by a catalytic 

 action of the arsenite. That the arsenite is not essential to 

 the action, however, is shown by the fact that iodine in pres- 

 ence of acid potassium carbonate will induce the slow forma- 

 tion of erythrodextrin from amidulin in the absence of 

 arsenite. In a corked flask, 20 cm3 of amidulin, 10 cm3 of acid 

 potassium carbonate, 5 cm3 of iodine solution, and 5 cm3 of water 

 were set away. After standing some time the blue color 

 changed to purple. The red increased and finally, after six 

 months time, the free iodine disappeared entirely and the solu- 

 tion became colorless. A few drops of iodine added to a few 

 cubic centimeters of the solution turned it a deep red. A 

 thorough shaking with chloroform removed the iodine from 

 the erythrodextrin red and left a mere trace of blue, showing 

 that a bare trace of amidulin was still left. The action was 

 not due to germ growth ; first, because the amidulin and the 

 erythrodextrin formed from the amidulin would have been 

 destroyed in a much shorter time ; secondly, because the 

 potassium iodide present prevents germ growth ; and lastly, 

 because there was no visible evidence of germ growth. 



Schonbein§ has suggested an oxidizing action of iodine upon 

 starch in the following experiment. He heated in a closed 

 vessel for an hour at 100° C. a mixture of a solution of iodine 

 in water and of dilute starch paste. On cooling, the solution 

 did not become blue, but reacted feebly acid, and on introduc- 

 ing dilute sulphuric acid and several drops of potassium nitrite 

 became blue at once. Mercuric nitrate formed a recognizable 

 amount of mercuric iodide. 



It seems probable that iodine may further the hydrolysis of 

 amidulin by oxidizing a sugar nucleus to an organic acid, and 



*Habermann, Ann. Chem. (Liebig), civ, 121; Kiliani, ditto, ccv, 182. 



f Ann. Chem. (Liebig), cixii, 297. 



i Ibid., ccxx, 335 ff. 



§Schonbein, Journ. prakt. Chem., lxxxiv, 402. 



