NOVEMUKR o. 1909] 



SCIENCE 



621 



The weakly acid tautomeric amides, 

 acetoaeetie ester, etc., react, as a rule, only 

 very slowly with alkyl halides, acid chlo- 

 rides, etc., at ordinary temperatures, be- 

 cause these weak acids fui'nish few anions 

 of the tautomeric forms to react with the 

 alkyl halides. The addition of bases such 

 as pyridine, alkalies or other metallic 

 hydroxides, or sodium ethylate, causes 

 an increase in the reaction velocity, or a 

 catalysis, because the base forms, to a 

 greater or lesser extent depending upon 

 the strength of the acid or base, tautomeric 

 salts of the amide, acetoaeetie ester, etc. 

 These salts, because they are more highly 

 ionized than the acid, furnish the solution 

 with a greater concentration of the anions 

 of the two or more tautomeric forms, and 

 hence the reaction velocity is increased. 

 This acceleration is exactly analogous to 

 the catalysis of amides, oximes, esters and 

 cane sugar by acids in water, in which, 

 according to the theory developed by 

 Kastle, Bredig, Lapworth, Acree, Gold- 

 sehmidt, Stieglitz and Euler, the cations 

 of these substances are hydrolyzed. The 

 free bases (amides, oximes, etc.) are so 

 weak that the.y furnish only a few cations 

 (CH3CONH3+6H, etc.). But when acids 

 are added these weak bases unite with them 

 and form salts to a greater or less extent. 

 These salts are highly ionized and hence 

 furnish the solution with a much greater 

 concentration of cations, and the reaction 

 is accelerated merely on account of this 

 greater concentration of cations. 



0:(^ CO 

 NCH, 



aH.N— N 



0:6- C:0 + N; 



This theory has enabled us to predict 

 mathematically and prove experimentally 

 the following propositions : 



1. The old equations used by Ostwald 

 and modified by Hantzsch and Stieglitz, 

 to express the dissociation constants of such 

 tautomeric acids and salts, especially in the 

 phenolphthalein series, were wrong because 

 these workers embodied in them only the 

 ionization of one of the tautomeric forms; 

 our point of view led us to equations for 

 these dissociation constants which are ac- 

 knowledged by the other workers to be cor- 

 rect and which have been tested experi- 

 mentally by our own work and that of 

 Wegscheider. 



2. Our point of view on tautomeric com- 

 pounds led us to a correct interpretation of 

 the phenomena of abnormal hydrolysis 

 which we have tested experimentally by 

 reaction velocity methods. 



3. The alkyl halide reacts with the anions 

 and not appreciably with the molecular 

 form of the salt. 



4. The equilibrium is between the molec- 

 ular forms of the salts and not between 

 the anions as assumed by Knorr, Lapworth, 

 Nef, Wislicenus and others. In this ease, 

 then, we have a reaction of molecules, and 

 not of anions. 



5. Our theory enabled us to predict and 

 verify quantitatively, experimentally, the 

 following important facts in the formation 

 of isomeric esters from various salts of ura- 

 zoles and different alkyl halides: 



(a) Different salts and the same alkyl 



CsHsN-NC.Hs 



K, 



NCH, 



a + CjHjI 



to 



K,r. 



0:r^ 



I LI 



CeHsljr- 



ONa 



0:C CO -1- Na 



K, 



NCIT. 



C,HJ 



0:(^ C:0 + Na -f I 



0:0 COaiL + Na + I 

 NCH, 



