Affinities of Poly basic Acids. 



27 



Monobasic Acids. 1 



Dibasic Acids. 2 



Formic Acid 



... "0214 



Oxalic Acid ... ic 



■ 



Acetic „ 



... -0018 



Malonic „ 



•171 s 



Propionic „ 



... -00134 



Succinic „ 



•00665 



Butyric „ 



... "00149 



Glutaric ,, 



•00475 



Valeric „ 



... -00161 



Adipic „ 



•00371 



Hexylic ,, 



... -00145 



Pimelic „ 



•00357 



It is seen at once that while in both series the affinities 

 of the acids decrease as the homologous series are ascended, 

 in every case the affinity of a monobasic acid is more than 

 doubled by the introduction of a second carboxyl group, 

 indicating that the two carboxyl groups have a mutual 

 strengthening influence upon one another. It appears also 

 that this influence decreases in extent as the distance 

 between the two groups is increased. 



The influence which other groups than the carboxyl 

 group may effect upon the affinity of an acid can be illus- 

 trated among the dibasic acids of the oxalic acid series. 

 The following tables of affinity-constants have been 

 compiled from papers by Bethmann 4 , Walden 5 , and 

 Walker 6 : — 



Malonic Acid 0-171. 



Methyl-malonic . . . 



•086 



Dimethylmalonic . . . 



•076 



Ethyl- 



•127 



Diethyl- 



74 



Propyl- 



-II 3 



Dipropyl- 





Benzyl- 



•I5 1 



Dibenzyl- 



4*i 



1 Ostwald : Zeit.fur phys. Ch. ; 3.174 (1889). 





2 Ostwald: ibid 3.271 (1889). 





3 Bethmann : ibid 5.402 (1890). 





4 Zeit. f. phys. Ch. 5. 403 (1890). 





5 Ibid, 8, 433 (1892). 





8 /. C. S. 61, 69 



6(1892). 







