370 Phelps and Hubbard — Esterification of Succinic Acid. 



neck flask as a receiver in the usual way for a vacuum distillation. 

 The lower boiling- point impurities in the succinic ester, pre- 

 sumably composed chiefly of ether, alcohol and water, were 

 removed b} r allowing a gentle current of air to pass through 

 the apparatus while the flask containing the ester solution was 

 heated in a waterbath raised finally to 60° until the pressure regis- 

 tered on the manometer — 15 mm — indicated that only succinic 

 ester remained in the flask to be distilled. The ester was then 

 distilled over by heating the 250 cm3 flask in a bath of sulphuric 

 acid and potassium sulphate at 140°-150°, and collected in the 

 second flask, which was cooled by allowing a current of cold 

 water to strike it constantly during distillation. The last 

 traces of ester left on the distilling flask were removed by 

 flaming suitably the side walls of the flask and at the same time 

 increasing the current of air that was passing through the 

 apparatus. The increase in weight of the receiver gave the 

 weight of the succinic ester left in the sideneck flask when the 

 acid was esterified as completely as possible under the condi- 

 tions imposed in each experiment. 



To recover whatever succinic ester might have been carried 

 to the condenser with the alcohol and other vapors during 

 esterification, the acid alcoholic distillate was chilled with ice, 

 diluted with three or four times its volume of water, and 

 shaken out three times in a separating funnel with fresh por- 

 tions of ether. The ethereal solution thus obtained was 

 treated with an excess of sodium carbonate in solution, washed 

 with distilled water, and distilled in vacuo, in the manner 

 described above, to separate the low boiling point materials 

 present, largely ether, alcohol, and water, and finally to distil 

 the succinic ester, which was weighed. 



The sources of loss inherent in this method for the preparation 

 of pure succinic ester were carefully studied. It was found, 

 first, that if a known weight of pure succinic ester — 75 grms 

 — was taken in a separating funnel, shaken with sodium car- 

 bonate solution containing ice, separated from the sodium car- 

 bonate solution, washed with distilled water containing 

 common salt, and united with the portions of ester carried on 

 mechanically and recovered from the water solutions by shak- 

 ing out three times with fresh portions of ether, that the weight 

 of the ester recovered on distilling in vacuo the ethereal solu- 

 tion containing some water was less than the amount taken by 

 only 0'60 grm. 



It was found, further, that when a portion of 5 grms. of suc- 

 cinic ester was put with 300 cm3 of the alcoholic hydrochloric 

 acid mixture used in esterification and treated exactly in the 

 manner described for the recovery of the ester from the acid 

 alcoholic distillate, the mass of succinic ester recovered showed 

 a loss of only 0*50 grm. 



