ELECTROLYTIC SYNTHESIS OF DIBASIC ACIDS. 375 



quite normally, in accordance with the equations I. and II. given in our former paper. 

 "We are not as yet able to give an altogether satisfactory explanation of the formation of 

 the sebacic ether. It is almost certain that the ether occurs ready formed in the crude 

 product of the electrolysis, for no appearance of decomposition was observed during the 

 distillation, and the thermometer rose regularly to the boiling-point of the ether. It 

 might be supposed that a substance CaHsOOC^CHaVCOO^CH^g'COOC^ was formed, 

 in accordance with equation II. , and was converted by the action of alcohol into sebacic 

 ether and the ether of a hydroxy-acid. It is not, however, easy to see how such an 

 action should take place. The possibility of a direct decomposition of the ethyl-potassium 

 sebate into sebacic ether and potassium sebate seems to be excluded, for although this 

 decomposition does take place slowly at 100° in the presence of water, the very char- 

 acteristic smell of sebacic ether was scarcely perceptible in an aqueous solution of ethyl- 

 potassium sebate, after standing for hours at 40°. 



Similar products were observed in some other cases. They do not occur in any 

 notable quantity in the case of the alkylmalonic acids, where we find another secondary 

 product, the ether of the saturated monobasic acid differing from the alkylmalonic acid 

 by C0 2 . Thus we obtained from ethylmalonic acid what seems to be a mixture of 

 crotonic acid and normal butyric acid, perhaps in accordance with the equation — 

 2CH 3 -CH 2 CHCOOC 2 H 5 = CH 3 CH : CH-COOC 2 H 5 + CH 3 CH 2 -CH 2 -COOC 2 H 5 + 2C0 2 



COO- 



Limits of Applicability of the Method. 



We have made a number of experiments in order to determine to what classes of 

 acids, besides the acids of the malonic acid series, the electrolytic method of synthesis is 

 applicable. 



The first series to which we directed our attention was that of the unsaturated 

 dibasic acids. At our request, Dr John Shields prepared ethyl-hydrogen fumarate and 

 ethyl-hydrogen maleate, and examined their properties. His results have been published 

 in the Journal of the Chemical Society 59, 737. 



When a colourless, concentrated solution of ethyl-potassium fumarate was electro- 

 lysed it gradually became yellow, but even after an hour no ethereal layer formed. The 

 electrolysed solution was extracted with ether and the ether evaporated, when there 

 remained a small quantity of a viscid liquid which united slowly with bromine. The 

 bromine compound gave off hydrobromic acid at ordinary temperatures. Ethyl- 

 potassium maleate behaved in exactly the same way. When the anode and the 

 cathode were separated from each other by a small porous cell placed in the crucible, the 

 liquid remained colourless, but no ethereal layer was produced, An approximate 

 analysis of the escaping gas showed that it consisted essentially of hydrogen (52 per 

 cent.), carbonic acid (40 per cent.), and oxygen (4 per cent.), and unsaturated hydro- 



