ELECTROLYTIC SYNTHESIS OE DIBASIC ACIDS. 219 



For pure adipic acid Ostwald found the constant to be -00371.* The two substances are 

 thus identical. 



Synthesis of Suberic Acid. 



An alkaline solution of caustic potash acts on glutaric ether very slowly in the cold. 

 The mixture of the substances in calculated quantities must be boiled for some hours in 

 order that the semi-saponification may take place. The solution of ethyl potassium 

 glutarate is prepared for electrolysis precisely as in the preceding case. 



When the electrolysis is completed, a colourless oil is seen to float to the surface, 



and this contains, besides the synthetic ether and ethyl alcohol, small quantities of other 



ethereal electrolytic products. The alcohol is driven off on the water-bath, and the other 



impurities are removed by freezing and separating the suberic ether. An analysis of the 



substance thus purified yielded the following numbers : — 



•1137 gr. substance gave -2602 gr. C0 2 and -0959 gr. H 2 



Found. Calculated for C 12 H 22 4 . 



C 62 - 41 per cent. 6261 per cent. 



H . 937 „ 956 



The ether distilled between 265° and 275°. On saponifying it we got the potassium salt 



crystallisable from alcohol, and this we ignited to obtain the percentage of potassium. 



•2484 gr. substance gave 1388 gr. K 2 C0 3 . 



Found. Calculated forK 2 C 8 H 12 4 . 



K . . . 31 "6 per cent. 31 "2 per cent. 



The acid prepared from the potassium salt had the melting-point 138°, that of suberic 

 acid being 140°. From hot water it separated in hard feathery crystals. As we found 

 from parallel experiments, its salts exhibited the same solubility as those of the suberic 

 acid derived from castor-oil. An affinity determination gave the following results : — 



Synthetic Suberic Acid, COOH(CH 2 ) 6 -COOH. 

 Moo =351. 



V 



128 



2100 



worn 



5-98 



K 



•00298 



256 



29-05 



8-27 



•00292 



512 



40-49 



11-54 



•00294 



1024 



5616 



1600 



•00298 



2048 



76-94 



21-92 



•00300 





K = 



•00296 





Ostwald for the ordinary acid found K= -00258, t while Bethmann, with a " perfectly 

 pure" preparation obtained the value '003114 In consequence of this discrepancy we 

 have determined the constant for the purified acid from castor-oil anew. The results we 

 obtained are shown in the following table : — 



* Ostwald, loc. cit., 283. t Ostwald, loc. cit., 283. 



J Bethmann, Zeitsch. fur physikal. Chera., v. 401, 1890. 

 VOL. XXXVI. PART I. (NO. 7). 2 K 



