ELECTROLYTIC SYNTHESIS OF DIBASIC ACIDS. 221 



This number differs considerably from the value -00234 observed by Ostwald * for the 

 acid obtained from castor-oil. We therefore purified a preparation of the ordinary acid 

 by repeated recrystallisation from water, and subjected it to an investigation of its con- 

 ductivity. 



Sebacic Acid from Castor-Oil. 



Moo =350 



V 



M 



100m 



K 



256 



28-08 



8-02 



•00273 



512 



39-01 



11-14 



•00273 



1024 



5335 



15-24 



•00268 



k = -00271 



This agrees perfectly with the number found for the synthetic acid. 

 The yield on electrolysis amounts to somewhat more than 20 per cent, of the 

 theoretical. 



Synthesis of n-Dicarbododecanic Acid, COOH(CH 2 )i 2 COOH. 



The starting-point for this synthesis was suberic acid prepared from castor-oil. This 

 was first converted into the diethyl ether, which was then transformed into the ethyl- 

 potassium salt according to the directions given on p. 217, and electrolysed. 



The product of electrolysis is again a clear colourless oil, which is heated on the 

 water-bath to drive off any alcohol, and then allowed to cool. After a short interval the 

 oil solidifies to a white fatty-looking substance. When this is dried on porous tile there 

 remains a mass of lustrous white crystals, which melt and solidify again at 27°. Analysis 

 yielded the formula C 18 H 34 4 . 



•1249 gr. substance gave -3146 gr. C0 2 and -1235 gr. H 2 0. 



Found. Calculated for C 18 H 34 4 . 



C 6869 per cent. 68-79 per cent. 



H . 1098 „ 1083 



The substance has thus the composition of the diethyl ether of an acid C 12 H 24 (COOH) 2 

 as was to be expected. The ether is insoluble in water, moderately soluble in ether and 

 cold alcohol, much more so in hot alcohol. It cannot be distilled undecomposed. 

 Alcoholic potash attacks it very slowly in the cold ; on boiling, a considerable quantity of 

 ethyl-potassium salt separates, even when there is a large excess of potash, and this resists 

 further saponification although the treatment may be continued for hours. The complete 

 saponification is best effected by pouring the melted ether slowly into a strong boiling 

 solution of alcoholic potash ; the potassium salt then separates in white granular masses. 

 The acid precipitated from the potassium salt is very sparingly soluble in water (1 part 

 in 4000 parts of boiling, and in 20,000 parts of cold water), tolerably soluble in cold alcohol 

 and in ether, easily soluble in boiling alcohol. It crystallises from water and alcohol in 



* Ostwald, loc. cit., 284. 



