ISOMERIC CHANGE 



227 



In all these cases isomeric change takes place so readily that in 

 spite of repeated and persistent efforts it has often been found 

 possible to isolate only one member of each pair of isomerides, 

 although the existence of the second can be clearly demonstrated 

 by a variety of methods. 



(b) Other Mobile Radicles. — That this readiness to undergo 

 isomeric change is associated with the electrolytic properties 

 of these compounds and does not depend merely on the lightness 

 of the hydrogen atom is shown by the fact that a similar mobility 

 characterises not only the metallic radicle in isodynamic salts 

 such as those of benzamide— 



but also the inert radicles —OH, —CI and — CN when these are 

 present in one of the isomerides in an " electrolytic" or " ionic " 

 form, e.g. in organic bases such as cotarnine — 



C 8 H 6 0/ 



CH 



N(CH,) 



OH 



CH(OH) . NCH, 





C 3 H 6 3 



CH» — C Hi 



Basic form 

 (predominates in aqueous solutions) 



S CH,- 



CH, 



Carbinol form 

 (predominates in ether and chloroform) 



or in salts, such as its chloride (stable in the electrolytic form) — 



CH = NMe 



C 8 H 6 



CI 



CHC1. NCH, 





CsH 6 



S ll 6 , -'3N 



CH,-C,H CH, — CH, 



and its cyanide (stable in the carbinol form) — 



C s H fi O 



'S Xi 6 



CH = NMe 



CH, — CH., 



CN 



< 



C 9 H 6 0,/ 



CHCN. NCH, 



CH, 



CH, 



In all these cases one of the isomerides is an electrolyte, and 

 there can be little doubt that the facility with which the radicle 

 is transferred is closely associated with this fact. 



