Structure of Simpler Organic Compounds. 123 



general formulae R O R/. They can be prepared in the 

 same way as ethyl ether, by the action of an alkyl iodide 

 on the sodium derivative of an alcohol 



Ethyl ether is generally prepared by warming a 

 mixture of alcohol (five parts) with concentrated sulphuric 

 acid (nine parts), which is contained in a flask connected 

 with a condenser, to 140. As soon as ether commences 

 to distil over, more alcohol is added to the mixture from 

 a tap-funnel, the additional alcohol being added at about 

 the same rate that the ether distils over. This process of 

 preparation is what is known as a " continuous " one, a 

 small amount of sulphuric acid being sufficient to convert 

 a large amount of alcohol into ether. The actual reaction 

 is not one of simple dehydration such as might be repre- 

 sented by the equation 



2C 2 H 5 OH-H 2 = (C 2 H 5 ) 2 



In reality the first reaction between ethyl alcohol and 

 sulphuric acid is to form the acid ethyl ester of sulphuric 

 acid (see p. 97) 



C 2 H 5 OH + H 2 S0 4 = C 2 H 5 .HS0 4 + H 2 



The hydrogen ethyl sulphate can then react with alcohol 

 according to the equation 



C 2 H 5 HS0 4 + C 2 H 5 OH = (C 2 H 5 ) 2 + H 2 S0 4 



The sulphuric acid is thus regenerated, and the ether as it 

 is formed distils over, fresh alcohol being added from time 

 to time to replace that which has been converted into 

 ether according to the above equations. It might be 

 thought that a small amount of sulphuric acid would 

 convert an unlimited amount of alcohol into ether. In 

 actual practice this is not, however, the case, as in the 

 course of the reaction the acid becomes dilute, and the 



