352 MANDELIC ACID, ETC. 



When this acid is boiled with baryta water, it yields 

 barium bromide and the barium salt of oxymethyl- 

 phenylformic acid. Hydrochloric acid throws down 

 the free acid from the solution thus obtained. Flat 

 needles ; fusing point, 176. Moderately easily soluble 

 in water, particularly in hot water. 



c. Mandelic Add (Fhenylqlycolie Add). 

 Oil * 

 CO.OH. 



C'H'.CH | 



Is formed when a solution of oil of bitter almonds, 

 containing hydrocyanic and dilute hydrochloric acids, 

 is heated for thirty to thirty-six hours in a flask con- 

 nected with an inverted condensing apparatus, and the 

 solution then evaporated. It is also formed by heating 

 amygdalin with concentrated hydrochloric acid. By 

 dissolving it in ether, it may be separated from the 

 sal ammoniac, which is formed at the same time. 

 Crystallizes in prisms or plates. Easily soluble in 

 water, alcohol, and ether. Heated alone, it yields oil 

 of bitter almonds and a resin. Oxidizing agents 

 convert it into benzoic acid. Hydriodic acid reduces 

 it, forming alphatoluic acid ; with hydrochloric and 

 hydrobromic acids it yields water and chlor- and 

 bromalphatoluic acids (p. 340). 



3. Acids, C 9 H 10 3 . 



(OH 

 1. Oxymesitylenic acid, C 6 H 2 1 (CH 3 ) 2 Is pro- 



( CO.OH. 



duced by heating potassium sulphomesitylenate with 

 potassium hydroxide to 240-250. Colorless, fine nee- 

 dles, of a silky lustre. Fusing point, 176. Almost 

 insoluble in cold water, difficultly in boiling water, 

 easily soluble in alcohol and ether. The solution of 

 the free acid and its salts is colored deep blue by iron 

 chloride. "When heated with potassium hydroxide to 

 a high temperature, it is resolved into carbonic anhy- 

 dride and solid xylenol (p. 299). 



