58 ORGANIC AGRICULTURAL CHEMISTRY 



Butyric acid in butter, 

 Capric acid in goat milk fat, 

 Laurie acid in laurel fat, 

 Palmitic acid in palm oil, 

 Arachidic acid in peanut oil, 

 etc. 



Glycerol esters. — Glycerol being a trihydroxy alcohol will 

 react with three molecules of a monobasic acid to form an ester. 

 An example may be given of the ester formed from butyric 

 acid, Cs^yCOOH, and glycerol, C3H5(OH)3. 



CH2-(0H H)OOC-C3H7 CH2-OOC-C3H7 



CH -(OH + H)OOC-C3H7-> CH-OOC-C3H7 + 3H2O 



CH2-(0H H)OOC-C3H7 CH2-OOC-C3H7 



Glycerol 3 Butyric acid Glyceryl tri-butyrate 



(an ester) 



Before considering in further detail the more important vege- 

 table and animal fats, we shall discuss the most important re- 

 actions connected with them. 



Esterification. — When an alcohol neutralizes an acid, thereby 

 forming an ester, the process is termed esterification. 



CH3-COO(H+HO)-C2H5 -> CH3-COO-C2H5+H2O, esterification 

 Acetic acid Ethyl alcohol Ethyl acetate 



In this process water is always lost. This reaction, as written 

 above, does not take place in a satisfactory way unless some 

 other reagent like sulphuric acid is present to remove the water 

 which is the other product of the reaction. If the water is not 

 removed, the reaction soon begins to reverse itself, and the ester 

 by taking up water is split into the alcohol and acid originally 

 used. We express these facts by saying that the reaction is 

 reversible and writing it in this way : 



-H20-> 

 CH3 - COO(H + HO) - C2H5 CH3 - COO - C2H6 



<-H20 + 



