ISOMERIC CHANGE 247 



deliberate addition of alkali, and a considerable proportion of 

 the enolic form appears to persist when equilibrium has been 

 attained. 



C 8 H N < 



/H /CO.NH, 



C CO.NH, ^C.CO.NH, 



CsHi 4 



CsHi/ 1 

 CO 'C.OH CO 



a-Amide Enolic amide a'-Araide 



The isomeric change which takes place in a freshly prepared 

 solution of the amide or piperidide is readily followed by 

 observing its rotatory power from time to time ; but when the 

 results are plotted out in the form of curves these are found 

 not to obey the unimolecular law, but to be inflected in character. 

 This exceptional behaviour is almost certainly due to the con- 

 version of the a-amide or piperidide into an enolic form of 

 similar rotatory power, followed by a further change into an 

 a'-compound of widely different rotatory power; in the first 

 stage the rotation would alter but little, and towards the end 

 of the action the rate of change must again be very slow, so 

 that under these conditions an inflected curve must inevitably 

 result. 



