Phelps and Tillotson, Jr. — Malonic Acid or its Ester. 273 



From the work recorded here it is evident that the reac- 

 tion between potassium cyanide and sodium chloracetate to 

 form sodium cyan acetate proceeds best in alkaline solution. 

 This reaction may take place vigorously at 110° or slowly at 

 90°-95° without materially affecting the yield of malonic ester. 

 For the best results the alkaline solution of sodium cyan- 

 acetate should not be evaporated to dryness at a high tem- 

 perature or even boiled for a long time, since these conditions 

 are favorable for the formation and decomposition of the 

 sodium malonate formed. The aqueous solution of cyanacetic 

 acid is best evaporated to dryness under diminished pres- 

 sure at a temperature of 70°-80°, and the alcoholic solution 

 at about 60°. In removing the alcohol under diminished presr 

 sure there is a constant loss equivalent to three per cent of 

 malonic ester, and in the process employed for converting the 

 cyanacetic ester to malonic ester and recovering the latter in 

 pure form, there is an additional loss of 4*3 per cent. If 

 these losses be considered we have, in the case of the sev- 

 eral higher results shown in the table, from 94*3 to 95*1 per 

 cent of the theoretical amount of malonic ester accounted 

 for. Further, if we take into account that the chloracetic 

 acid employed was but 95 per cent pure, as shown by anal- 

 ysis, it seems that the results given are from 99*3-100 per 

 cent of the theoretical amount for the chlorine content of 

 the chloracetic acid used. That is to say, potassium cyanide 

 and sodium chloracetate, in alkaline solution at about 100°, 

 react to give a theoretical amount of sodium cyanacetate and 

 potassium chloride. Or, again, the theory for malonic ester 

 obtained from 200 grm. of monochloracetic acid of 95 percent 

 purity is 321*8 grm. and the yields actually obtained, leaving 

 out of account experiments (1) and (4) of series A, average 

 295*18 grm. or 91*7 per cent instead of 87*1 per cent in the 

 table, in which the theory is calculated on the basis of pure 

 monochloracetic acid. 



Thus malonic ester in large quantities may be made in nearly 

 theoretical amount from monochloracetic acid if the procedure 

 as outlined above be followed. The essential points are, an 

 excess of potassium cyanide, reacting in alkaline solution ; the 

 addition of sulphuric acid to the solution of sodium cyan- 

 acetate in only slight excess ; the evaporation of the aqueous 

 and alcoholic solutions of cyanacetic acid at low temperature, 

 which is most readily done under diminished pressure ; the 

 conversion to malonic ester and the purification of the same by 

 the procedure described above. Under these conditions, if the 

 chloracetic acid be only 95 per cent pure, about 87 per cent of 

 the theoretical amount of malonic ester may be obtained, or 



