Structure of Simpler Organic Compounds. 121 



cyanide, and then hydrolyzing the derivative thus obtained, 

 citric acid is produced 



CH 2 C1 CH 2 CN CH 2 COOH 



| OH | /OH v | OH 



CH< byKCN CH/ by hydrolysis CH< 



| X COOH | X COOH | X CO-OH 



CH 2 C1 CH 2 -CN CH,-CO-OH 



Thus, a fairly complex synthesis has been accom- 

 plished by a series of simple reactions, which have been 

 repeatedly mentioned in the foregoing pages. 



Citric acid crystallizes with one molecule of water; 

 these crystals, which are readily soluble in water, but 

 insoluble in ether, melt at 100. As it is a tribasic acid, 

 citric acid forms three series of salts for example, with 

 potassium, C 6 H 5 7 K 3 , C 6 H 6 7 K 2 , and the most acid salt, 

 C 6 H 7 7 K. 



Part XI. The Unsaturated Acids. 



A type of this class of acids is acrylic acid, 

 CH 2 : CH COOH, which can be obtained by treatment 

 of /3 brompropionic acid with an alcoholic solution of 

 potassium hydroxide 



CH 2 Br CH 2 



i 



to 



H 2 +KOH = CH +H 2 + KB 

 OH COOH 



This is a liquid, smelling like acetic acid, which boils 

 at 139 140, and is miscible w T ith water. Like un- 

 Katurated derivatives generally, it readily forms addition 



