PKOPIONIC ACID. 91 



posing the salt formed by means of sulphuric acid. 

 Can also be prepared by boiling iodopropionic acid with 

 chlorine water. Fibrous, fascicular crystals, which 

 fuse at 65. The ethers of the two acids when boiled 

 with potassium cyanide yield two different cyanpro- 

 pionic acids. 



a-Brompropionic acid, CH 3 .CHBr.CO.OH, is pro- 

 duced together with dibrompropionic acid by heating 

 propionic acid with bromine in sealed tubes ; also by 

 heating lactic acid with concentrated hydrobromic acid. 

 It is a liquid, boiling at 202, congealing at 17. 

 Dibrompropionic acid, CHSBi*0*, is also formed by the 

 oxidation of allylalcohol bromide. Colorless crystals 

 that fuse at 65 and boil at 227. 



3-Brompropionic acid, CH 2 Br.CII 2 .CO.OH. Is ob- 

 tained by heating p-iodopropionic acid with bromine 

 and water. Colorless crystals, fusing at 61.5. 



a-Iodopropionic acid, CH 3 .CHLCO.OH. Obtained 

 by the action of phosphorus iodide upon lactic acid. 

 Thick oil, scarcely soluble in water. 



i3-Iodopropionic acid, CH 2 I.CH 2 .CO.OH. Is formed 

 by treating glyceric acid with hydriodic acid (phos- 

 phorus iodide and water). Colorless crystal-plates, 

 easily soluble in hot water ; fusing point, 82. Yields 

 propionic acid, when heated to 180 with hydriodic acid. 



a-Amidopropionic acid (Alanin), C 3 H 7 M) 2 ==CH 3 . 

 CH(NH 2 ).CO.OH. Is produced by heating a-chlorpro- 

 pionic acid or ethyl a-chlorpropionate with an aqueous 

 solution of ammonia. Can be most readily prepared by 

 boiling an aqueous solution of aldehyde-ammonia (2 

 parts) for a long time with hydrocyanic acid (1 part 

 anhydrous) and an excess of hydrochloric acid. Sal- 

 ammoniac is separated from the concentrated solution 

 by means of alcohol, and, from the alanin hydrochlorate 

 in solution, the alanin is obtained in the same manner 

 as glycocol (p. 85) is obtained from its hydrochlorate. 



