Ethyl Hydracrylate. 115 



and heated to about 80°. The hot solution was neutralized 

 with calcium carbonate, making use of mechanical stirring to 

 facilitate the solution of the carbonate. The solution was 

 allowed to stand over night for the main portion of the calcium 

 glycerate to crystallize out. This first crop of calcium glycer- 

 ate after washing with a little cold water was sufficiently pure 

 for further use. The mother liquor, after making faintly acid 

 to prevent darkening on heating, was concentrated on the 

 steam bath and set aside to crystallize. After recrystallizing 

 this second crop of calcium glycerate it was sufficiently pure, 

 and was added to the first crop. The calcium glycerate so 

 prepared was dissolved in hot water and treated with the theo- 

 retical amount of dissolved oxalic acid, the calcium oxalate 

 was filtered off and the filtrate concentrated on the steam bath 

 to a specific gravity of 1*26, containing about 61 per cent of 

 glyceric acid. This is the most favorable concentration for 

 converting glyceric acid into beta-iodopropionic acid by the 

 action of phosphorus iodide. 



For the preparation of beta-iodopropionic acid a modifica- 

 tion was introduced into the method of Wislicenus* and 

 Erlenmeyer,f making use of solid yellow phosphorus instead 

 of the carbon disulphide solution, whereby at last 90 per 

 cent of the glyceric acid was converted into the iodopro- 

 pionic acid. One hundred grams of iodine were placed into a 

 750 cm3 round-bottom flask and covered with lOOgrms. of 61 per 

 cent aqueous glyceric acid. Then 15 grms. of yellow phos- 

 phorus were added during the course of five minutes in pieces 

 of about 1 grm. each, shaking the flask after the addition of each 

 piece and cooling the flask by immersing it in a cold water 

 bath from time to time. The flask was next connected with a 

 condenser tube to serve as a reflux condenser, and the mixture 

 cautiously warmed on a water bath to start the reaction of the 

 phosphorus iodide with the glyceric acid. The reaction soon 

 tends to become violent with the loss of large quantities of 

 hydriodic acid. In order to prevent the loss of hydriodic acid 

 as far as possible, the reaction was moderated by immersing 

 the flask in cold water for a few minutes from time to time. 

 After the first vigorous reaction was over the mixture was 

 heated on the boiling water bath for half an hour, poured into 

 a beaker, covered with a watch glass and set aside over night 

 to crystallize. The crystals of pure beta-iodopropionic acid 

 were then filtered off with suction, washed with a little cold 

 water, the filtrate boiled for an hour with a reflux condenser 

 and again set aside to allow more beta-iodopropionic acid to 

 crystallize out. The two crops of crystals were combined and 



* Wislicenus, Ber. Dtsch. Chem. Gesellsch., viii, 1207. 

 f Erlenmeyer, Ann. Chem. Pharm., cxci, 284. 



