METHYL SALICYLATE 11.'— SOLUBILITY IN WATER AT 30° 



By H. D. GiBBS. 

 (From the Lahoratory for the Investigation of Foods and Drugs, Bureau of 



Science, Manila, P. I.) 



In the studies of the hydrolysis of methyl salicylate, the results of 

 which will be published later, it became advisable to determine with 

 some degi'ee of accuracy, the solubility of the ester in water and in some 

 other solutions in which the rate of hydrolysis was being measured. 



No accurate measurements have been found in the literature. Cahours - 

 records that the oil is scarcely soluble in water. The United States 

 Pharmacopoeia^ and the ISTational Standard Dispensatory* say that it 

 is sparingl)^ soluble and the Chemiker-Kalender^ "wenig loslich;" state- 

 ments evidently originating from the observations of Cahours made 

 sixty-five years ago. 



The method of analysis employed is essentially the same as that described in the 

 first paper. The solution in which the methyl salicylate is to be determined is 

 filtered to remove any undissolved ester (the first few drops passing through 

 the filter being discarded), made strongly alkaline with sodium hydrogen car- 

 bonate to unite with and hold back any free salicylic acid, extracted repeatedly, 

 not less than three times, with chloroform and the chloroform extracts run into 

 about 20 cubic centimeters of a 10 per cent solution of sodium hydroxide and 

 saponified in a steam bath. Aft€r evaporation of the chloroform the salicylic 

 acid is extracted and made to a definite volume with water for the color 

 comparisons. 



When the comparison is made with standard solutions prepared with 

 salicylic acid, the color shades are different, owing to the formation of 

 small quantities of other phenolic compounds besides salicylic acid in the 

 hydrolysis of the ester, and are quite difficult to match in the wedge 

 colorimeter. Some eyes read the percentage very much too low, while 



' The first article on the occurrence and determination of salicylic acid in 

 methyl salicylate, the separation and determination of the two substances in 

 foods and drugs, and the hydrolysis of the ester with sodium carbonate and 

 sodium hydroxide appeared in This Journal, See. A. (1908), 3, 101, and J. Am. 

 Chem. Soc. (1908), 30, 1465. 



''Ann. d. Chem. u. Pharm. (1843), 48, 61. 



»8th ed. (1900), 290. 



'(1905), 970. 



=(1907), 1, 164. 



357 



