Prof. Wanklyn on the Synthesis of Organic Bodies. 303 



phuric acid and gave sulphovinic acid, from which of course alcohol 

 and the ethers might be procured. Liebig denied what Faraday and 

 Hennel had asserted ; and the latter did not insist upon the correct- 

 ness of their work, and did not take the necessary steps for ensuring 

 the reception of their results. 



Shortly before 1854, a most capital addition to the art of organic 

 synthesis was borrowed from the doctrine of the homologous series. 

 I will endeavour to explain it. 



Organic bodies repeat themselves ; thus common alcohol has a 

 whole series of representatives, differing from it in formula by n CH 2 , 

 but resembling it very closely in chemical functions. Alcohol, and 

 these its representatives, constitute an homologous series. Every one 

 of these representatives (homologues) of alcohol possesses a set of 

 ethers and other derivatives, just as common alcohol possesses its 

 ethers and derivatives. With certain limitations, it is true that 

 whatever reaction can be accomplished with one alcohol can be 

 accomplished with any other alcohol of the series. 



Synthesis by series will then be easily understood by an example : — 

 Suppose we obtain a building up by starting with common alcohol, 

 we should infer that an analogous building up could be made by start- 

 ing with any other alcohol of the series. 



Here follows a Table of the homologous series of alcohols, and of 

 the homologous acids which are related to them. 



Methyl e alcohol 



. C H 4 



c 



H 2 O 2 



. Formic acid. 



Ethyle alcohol . 



. C 2 H 6 



c 2 



H 4 O 2 



. Acetic acid. 



Propyle alcohol 



. C 3 H 8 



c 3 



H 6 O 2 



. Propionic acid. 



Tetryle alcohol 



. C 4 H 10 O 



c 4 



H 8 O 2 



Butyric acid. 



Amyle alcohol . 



. C 5 H 12 



c 5 



H 10 O 2 



. Valerianic acid 



Hexyle alcohol . 



. C 6 H 14 



C 6 



H 12 2 



. Caproic acid. 



Cetyle alcohol . 



! c 16 h 34 o 



C 1 



\H 32 2 



, Palmitic acid. 



>» • 



Ceryle alcohol . 



; C 2T£p 



C 2 



r H 54 2 



> »> 



. Cerotic acid. 



A good example of synthesis by series was furnished by Frankland 

 and Kolbe, who showed that various cyanides of the alcohol radicals 

 yield the next higher acid in the series when they are digested with 

 an alcoholic solution of potash, thus : — 



CH 3 CN + 2H 2 = C 2 H 4 2 + NH 3 



Cyanide of methyle. Acetic acid. 



The effect of the alkali is to cause decomposition of water bj^ 

 means of the cyanide ; and the reaction very closely resembles 

 Pelouze's, of which mention has already been made. 



By means of this synthesis, which is general to the whole series, 

 chemists acquired a method of ascending from any given alcohol to 

 the acid belonging to next higher alcohol. It will be evident, how- 

 ever, that this step, important though it was, did not suffice to enable 

 chemists to march regularly up the ladder. The step from acetic 

 acid to alcohol — from an acid to an alcohol of the same carbon-con- 

 densation — was wanting. 



