74 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



from an alkaline solution. The solution must be firstly acidified to 

 liberate the phenol (see under phenols). The acid, which is formed 

 by hydrolysis with alkali, is liberated by acidifying the cold solution 

 with mineral acid sulphuric acid. If insoluble it is filtered off; if 

 soluble and volatile with steam, distilled ; if soluble and not volatile, 

 it is extracted with ether or precipitated as insoluble calcium or other 

 salt. 



HYDROLYSIS OF ESTERS. 



Ethyl Sulphuric Acid. 



Ethyl sulphuric acid is not readily hydrolysed by alkali, but it is 

 decomposed by boiling with acid. 



The solution of calcium or barium ethyl sulphate obtained above 

 contains one or other of these bases as shown by adding dilute sulphuric 

 acid, the insoluble sulphate being precipitated. 



If a portion of the solution be heated with dilute hydrochloric acid 

 f r 3~5 minutes, the insoluble sulphate is again precipitated : 

 C 3 H 6 . S0 2 . Ov 



/Ba + 2H 2 O = 2C H 5 OH + BaSO 4 + H 2 SO 4 . 

 C 2 H 5 . S0 2 . O/ 



Ethyl Acetate. 



About 10 c.c. of ethyl acetate are placed in a flask with about 80 cc 

 of sodium hydroxide, and the mixture is boiled over a gauze under 

 a reflux condenser for 20-30 minutes until no more oily drops are 

 visible and until the smell of ethyl acetate has disappeared. A piece 

 of unglazed porcelain is added with advantage to prevent bumping of 

 the liquid during the heating : 



CH 3 COOC 2 H 5 + NaOH = CH 3 COONa + HOC 2 H . 



The flask is connected with a condenser and about a quarter of 

 the liquid is distilled over. 



This liquid contains the alcohol. It may be identified by the 

 tests for ethyl alcohol. 



The alcohol is separated and identified by saturating the solution 

 with solid potassium carbonate, collecting the alcohol in a pipette, 

 determining its boiling-point and performing other reactions for the 

 alcohol. 



The liquid remaining in the flask is acidified with dilute sulphuric 

 acid and again distilled as long as the distillate reacts acid to litmus. 



The distillate is neutralised and evaporated down and the acetic 

 acid prepared and identified (p. 97). 



