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Sulphur By-Products of the Preparation of Ether. 



p. N. Evans and G. K. Foresman — Purdue University. 



The formation of etliyl ether from alcohol and sulphuiic acid was 

 first explained by Williamson in 1852. According to his theory the 

 first reaction is the formation of ethyl sulphuric acid and water, accord- 

 ing to the equation, 



C2H5OH + H,S04 = C .H5HSO4 + H,0. 



The ethyl sulphuric acid then reacts with more alcohol to form 

 ether and sulphuric acid, 



C..H5HS04 + C2H5OH = C..H50C2H5 + H.SO,. 



If these changes were the only ones taking place a limited quantity 

 of sulphuric acid might convert an unlimited quantity of alcohol into 

 ether and water. 



Experience has shown, however, that there is a limit to the quantity 

 of alcohol that can be converted into ether by a given weight of sul- 

 phuric acid, and two explanations have been offered for the limitation. 



Many writers accept the theory that the water produced in the first 

 reaction so dilutes the sulphuric acid that the change can not continue. 

 It has been shown, however, by Evans and Sutton, that the water does 

 not accumulate enough to prevent the reaction but distills over with 

 the ether, normal results having been obtained when starting with very 

 dilute sulphuric acid, the acid becoming concentrated enough for its 

 normal effect by the time the proper temperature (140°) is reached. 



Others, including the pi-esent writers, accept the explanation that 

 the sulphuric acid employed is gradually converted into other sulphur 

 compounds, either carried out of the generator with the ether and 

 water, or, if remaining, incapable of inducing the formation of ether. 

 The purpose of the work here reported was to determine the quantities 

 of these sulphur by-products formed during the heating. 



Numerous by-products have been reported by previous workers, 

 including the following: Sulphur dioxide, sulphurous acid, ethyl sul- 

 phurous acid; sulphuric anhydride, ethyl sulphuric acid, ethyl sulphate; 



