1880.] 



The A luminium- Iodine Reaction. 



547 



double decomposition, for it does not take place when ready-formed 

 iodide of aluminium is employed. 



The several changes thus described are typical of our "aluminium- 

 iodine reaction." The reaction is quite distinct from that which has 

 lately given beautiful results in the hands of Friedel ; and we have 

 investigated its applicability both for the production of new com- 

 pounds, and for distinguishing between different classes of organic 

 bodies, as well as for throwing light on their comparative constitution. 



Neither zinc nor iron, nor, as far as we know, any other metal can 

 be substituted for aluminium in this reaction ; but the chloride or 

 bromide may be used instead of the iodide, though with less advantage. 



Recent Results. 



For decomposing an alcohol a small quantity of iodine is dissolved 

 in it, the necessary excess of aluminium is added, and the mixture is 

 heated. Evolution of hydrogen gas begins immediately, and proceeds 

 somewhat rapidly until the whole of the metal has passed into com- 

 bination. In this way the aluminium derivatives of the following 

 alcohols have been prepared : — Bthylic, normal propylic, iso-butylic, 

 amylic, benzylic, phenylic, cresylic, and thymolic. The first four of 

 these aluminium derivatives may be distilled in vacuo, and they have 

 thus been separated from the other solid products of the reaction, and 

 obtained in a pure condition. The other aluminic alcohols cannot be 

 distilled, at any rate not without very considerable decomposition. The 

 following alcohols, however, behaved in a different way with the 

 reagent : — 



Methyl alcohol is not decomposed by aluminic iodide and aluminium, 

 but in presence of free iodine it parts slowly with hydrogen, and the 

 same happens when an aluminium-platinum couple is substituted for 

 the metallic aluminium. 



Iso-propyl alcohol. — This is not acted upon in the least by the 

 reagents. 



Getyl alcohol. — On heating this compound with the reagent, hydro- 

 gen is slowly set free, until the temperature reaches about 200° C, 

 when another chemical change is set up, resulting in the formation of 

 cetyl iodide and aluminic hydrate. 



Allylic alcohol. — The first action is identical in character with that 

 which takes place with the alcohols of the C w H 2ra+1 OH series. Instead, 

 however, of the whole of the liberated hydrogen escaping, about 

 30 per cent, of it acts upon the excess of alcohol, splitting it up into 

 propylene and water. 



JEthene alcohol. — The reagent does not liberate hydrogen from this 

 substance, and has but a very slight action upon it. 



Propenyl alcohol. — No hydrogen is evolved, but a double decomposi- 

 tion ensues at about 140° C, yielding allyl iodide, free iodine, and 



VOL. XXX. 2 Q 



