280 ORGANIC CHEMISTRY 



to the formation of a different, less stable, or more reactive molecule. 

 Now if this is the correct explanation of the catalytic action of acids, 

 it is clear that by this same salt or ion forming power, they should 

 in certain cases retard action instead of accelerating it, provided the 

 ion or salt is more stable than the free base. That must be an inevit- 

 able consequence of this theory, and we have brought its complete 

 experimental confirmation in work recently published on the molecu- 

 lar rearrangement of certain organic bases according to 



NH 2 NHCO 2 C 2 H 5 



OC0 2 C 2 H 5 OH 



by a shifting of a carbethoxy group. The bases are exceedingly weak 

 ones, and their salts, again, are hydrolyzed according to 



NH 3 C1 NH 3 OH 



X + H 2 0<=>X +HC1 



OC0 2 C 2 H 5 OC0 2 C 2 H 5 



Hydrochloric acid retards but does not prevent the rearrangement, 

 and it was proved that it retards it quantitatively by salt formation 

 and that the velocity of the rearrangement remains rigorously pro- 

 portionate to the concentration of the free base present at any 

 moment. For instance the velocity constant was found to be & base = 

 .0566 at the beginning of the reaction, and .0567 at its end ten hours 

 later. 



Now these great changes in speed of reaction are the main charac- 

 teristics of catalytic action; and we have in these cases a very simple 

 explanation of it. It remained, however, to ascertain whether the 

 two other important characteristics for many catalytic reactions are 

 also in agreement with our conception of salt formation when rig- 

 orously applied first, as explained for the catalysis of methyl 

 acetate, the fact that the catalyzing acid need not appear to combine 

 with any of the reacting substances, and second the fact that in a 

 reversible reaction it need not measurably change the final condition 

 of equilibrium. These points were tested by the application of our 

 fundamental conception to the catalysis of methyl acetate. The 

 intimate connection with the work on the imido-ethers is recognized 

 as follows: we found above the velocity of saponification of imido- 

 esters to be 



doc 



= kX(Salt) 



ctt 



But according to Walker and Arrhenius 

 (Salt) =KX (Base) X (H) 



