134 SOEBIC ACID PALMITOLIC ACID. 



B. MONOBASIC, MONATOMIC ACIDS, C W H 2W ~ 4 2 . 



The acids of this series are formed, like the 

 hydrocarbons, by heating the dibromides of the acids 

 Qnjpn-202 w ith alcoholic potassa. 



1. Sorbic Add. 

 C 6 H 8 2 = C 5 H 7 .CO.OH. 



Occurrence and preparation. Together with rnalic 

 acid in the juice of the unripe berries of the moun- 

 tain-ash. If this is subjected to distillation after being 

 partially neutralized with milk of lime, impure sorbic 

 acid passes over with the vapors of water in the form 

 of a yellow oil. The pure acid is obtained from this 

 by heating gently with potassa or with concentrated 

 sulphuric acid, or by boiling with concentrated hydro- 

 chloric acid. 



* Properties. Long, colorless needles, inodorous, almost 

 insoluble in cold water, more easily soluble in hot 

 water and alcohol ; fuses at 134.5 ; cannot be distilled 

 alone without decomposition, readily with water vapor. 



Barium sorbate, (C 6 H 7 2 ) 2 Ba. Laminae of a silvery 

 lustre, easily soluble in water, scarcely more in boiling 

 than in cold water. Silver sorbate C 6 H 7 2 Ag. "White, 

 insoluble, scarcely crystalline precipitate. 



Ethyl sorbate, C 6 H 7 O.O.C 2 H 5 . Liquid, of a plea- 

 sant, aromatic odor, boiling at 195.5 ; lighter than 

 water. 



Sorbic acid combines with nascent hydrogen, form- 

 ing hydrosorbic acid (p. 125); with bromine forming a 

 tetrabromide C 6 H 8 Br 4 2 , which crystallizes well, fuses 

 at 178-179, and is but slightly soluble in water. 



2. Palmitolic Acid. 

 C 16 H 28 2 = C 15 H 27 .CO.OH. 



Results from heating the dibromide of hypogceic 

 acid or gai'dic acid with alcoholic potassa to 170. 



