OXONIUM COMPOUNDS McINTOSH 97 



acid, the molecules are probably brought nearer together, and 

 the chemical reaction takes place more rapidly. Acetic acid 

 forms no compound with acetaldehyde and polymerization 

 does not take place. Hydrochloric acid forms a compound, 

 probably quite corriplex, and paraldehyde is rapidly produced, 

 Hydriodic acid forms the complex 



+ 

 CH3 :6:H I 



CH3 



with ether, and alcohol and methyl iodide are produced 

 on standing. Then the alcohol unites with the acid 

 forming 



+ 



CH3 :6:H 1 



H 



and methyl iodide and water are the final product. The 

 importance of these intermediate compounds has been 

 recognized from the time Van't Hoff published his 

 "Ansichten ueber organische Chemie," and has been 

 emphasized by no one more forcefully than by Armstrong in 

 his numerous articles. My interest in these oxonium compounds 

 is largely with two simple classes, one containing the halogen 

 hydrides, and the other the halogens, in combination with 

 organic substances containing oxygen. I shall describe a few 

 of these compounds isolated recently, and shall suggest possible 

 formulae for typical members of both these groups. 



These two classes differ in many respects. The halogen 

 compounds show only a very small heat of formation, while the 

 others evolve from fourteen to twenty thousand calories for 

 each gram molecule. The halogen hydride complexes conduct 

 the electric current in solution and are therefore dissociated; 

 the halogen compounds are not ionized. The molecular con- 

 ductivity increases with concentration'', and this has formed 



2. Walker, Mcintosh and Archibald, Jour. Chem. Soc. 85, 1098 (1904). 



3. Maass and Russel. Trans. Roy. Soc. (Canada) 13,259 (1919). 



