ELECTROLYTIC SYNTHESIS OF DIBASIC ACIDS. 363 



The dissociation constant was determined with the following result: — 

 Anti-s-dimethylsuccinic acid prepared by electrolytic synthesis. 

 COOHCH(CH 3 )-CH(CH 3 )COOH. 

 ^oo =354". 



V 



M 





100m 



K 



56-55 



3002 





8-47 



00139 



1131 



41-66 





11-74 



00138 



226-2 



57-18 





1615 



00138 



452-4 



77-69 





21-95 



00137 



904-8 



1044 

 K 



= 00138. 



29'49 



00137 



The number found by Bischoff and Walden # was K = 0-0122. A control deter- 

 mination gave the value K = 0"0133. 



We determined the basicity of the two acids by titration with baryta water, using 

 phenolphthalein as indicator, with the following results : — 



I. 0-1020 gramme of the anfci-acid required, for neutralisation, 13 - 12 cc. l/9'45 normal baryta 

 water. 



II. 0'0793 gramme of the para-acid required, for neutralisation, 10 - 20 cc. l/9 - 45 normal baryta 



water. 



Calculated for C 4 H 8 (COOH) 2 . Pound. 



I. II. 



Carboxyl-hydrogen . . 1-370 1-361 1-361 



Synthesis of the Symmetrical Diethylsuccinic Acids. 



The ethyl-potassium ethylmalonate was subjected to electrolysis in exactly the same 

 way as has just been described in the case of the methylmalonate. From 150 grammes 

 of the salt prepared by the general method already described, we obtained, after electro- 

 lysis, 63 grammes of an ethereal product, which on fractionation gave 40 grammes of an 

 oil boiling above 200°. This was saponified by boiling with 30 grammes of caustic 

 potash dissolved in alcohol. The mixed acids, obtained in the usual way from the 

 potassium salts, contained a considerable quantity of a tarry substance, which could, 

 however, be to a great extent removed by dissolving the acids in water, and shaking the 

 solution with a little ether in which the impurity is comparatively easily soluble. The 

 aqueous solution was then completely extracted with ether. The oily acids left on 

 evaporating the ether solidified in the course of a few hours. A small quantity of a 

 syrupy substance was removed by spreading the mixture on a porous earthenware plate, 

 and the acids were separated, as in the previous case, by fractional crystallisation from 

 aqueous solution. We also found benzene a useful solvent for effecting complete 

 separation of the two isomeric acids. 



* Berichte der deutschen chemischen Gesellschaft 22, 1821. 



