54 The Philippine Journal of Science iyi» 



The first oonipound thrown out is very slightly colored greenish 

 yellow, melts at 127 . is less soluble in alcohol, the absorption 

 band in less persistent, and the compound absorbs bromine in 

 alcoholic solution and gives an initial pink color with sodium 

 ethoxide. The second precipitate fomied is yellow, melts at 

 123°, is slightly more soluble, its absorption band is the more 

 persistent, does not absorb Ijromine. and gives an initial red 

 color with sodium ethoxide. 



The two specimens were ti'eated in cold alcoholic solution with 

 alcoholic bromine solution by the method of Kurt H. Meyer "'' 

 to determine the percentage of enol and keto forms. The light- 

 colored samples were shown by the average of a number of 

 titrations to be approximately 90 per cent enol, while the yellow 

 specimen reacted only to a very slight extent with the bromine 

 solution (1 or 2 drops producing a bromine color), showing it 

 to be practically all in the keto form. (The calculation is based 

 upon the addition of 4 atoms of bromine to 1 atom of the ester.) 



This behavior of the compound was noted by F. Herrmann,'* 

 while preparing a bromine addition product of ethylsuccinosuc- 

 cinate. His preparations would not absorb the theoretical 

 amount of bromine and he states that the yellow color obtained 

 at the end of the titration was not necessarily due to free 

 bromine but to decomposition products. In the light of our 

 pi-esent knowledge we believe the yellow color of the solution, 

 after complete bromine absorption, to be due to the keto form 

 which has been unacted upon. 



REDUCTION OF ETHYLSUCCINOSUCCINATE 



On treating an alcoholic solution of ethylsuccinosuccinate (90 

 per cent enol form) with a small quantity of concentrated hydro- 

 chloric acid and adding zinc dust in small amounts a colorless 

 crystalline substtmce is thrown out of the solution. This com- 

 pound is practically insoluble in alcohol and water, but is soluble 

 in warm toluene from which it can bogthrown out in beautiful 

 colorless crj'stals by the addition of alcohol; melting point. 120°. 

 It is soluble in alkalies, forming a solution which quickly turns 

 brown in the air. On treatment with acetyl chloride a derivative 

 is formed which melts at 167^, 2 degrees below the melting 

 point of the diacetyl derivative of ethylsuccinosuccinate. It 

 becomes yellow on heating, while the diacetyl derivative of 



"Ann. d. chem. (1911), 380, 212. 



"Brr. d. dctttschcv chem. Ges. (1886). 19. 2229. 



