EL E C TROS YN THE SIS. 305 



Beyond the two hydrocarbons, ethane and diisobutyl, 

 synthetised by Kolbe, only two, viz., butane and diisoamyl, 

 have been made since his time by electrosynthesis, and it 

 is only quite lately that the method has received any 

 further extension. 



In the case of dibasic acids, no synthetic action has 

 been found to take place, the chief product being always 

 an unsaturated hydrocarbon. For example, from potassium 

 succinate, ethylene is obtained, the equation for the decom- 

 position at the anode being as follows : — 



CH.-COO- CH„ , nr . 

 CH.-COO CH 2 



When, however, instead of the dipotassium salt of a 

 dibasic acid, the potassium ethyl salt is taken, one of the 

 carboxyl groups becomes electrolytically inactive, and the 

 salt behaves virtually as the salt of a monobasic acid. 

 Thus Crum Brown and Walker found that potassium 

 ethyl succinate yielded on electrolysis a synthetic product 

 which proved to be diethyl adipate. The action is re- 

 presented by the equation — 



2 COOEf (CH 2 ) 2 -COO-=COOEt(CH 2 ) 4 -COOEt + 2C0 2 , 



which is quite analogous to equation II. Now diethyl 

 adipate can easily be converted into potassium ethyl adipate, 

 and the electrolysis repeated ; this gives us a new synthetic 

 product, namely, diethyl sebate in the same series of acids, 

 thus — 



2 COOEt(CH 2 ) 4 COO= COOEf (CH 2 ) 8 COOEt+2 C0 2 , 



so that here we have a means of passing synthetically from 

 one acid to a higher member of the same series, and can 

 therefore ascend the series until the method breaks down, 

 a limit which has not yet been reached. 



The following table shows the acids which have been 

 prepared electrosynthetically in this way. It will be ob- 

 served that in the synthesis the group of atoms between 

 the terminal carboxyl groups (COOH) is simply doubled, 



the electrosynthetic products being always symmetrical. 



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