METHYL SALICYLATE III. 81 
light, water, alkalies, or acids are not necessary, but the colora- 
tion will take place in the presence of these substances. In 
neutral or acid solutions the color formed is a beautiful golden 
yellow, the substance formed being soluble in the methyl salicylate 
layer and not in the aqueous one. In alkaline solution the 
color is for the greater part to be found in the aqueous layer, 
which becomes dirty brown. This is evidently the result of 
secondary reactions and decompositions. 
While the colored compound has not been isolated from solu- 
tions of methyl salicylate in a condition of purity which will 
permit of its positive identification, the evidence, deduced from 
its behavior and from similar compounds prepared by oxida- 
tions of methyl salicylate and related compounds, is strongly in 
favor of the view that the principal and initial colored com- 
pound formed is the methyl ester of quinone carboxylic acid, 
O 
l 
() COO.CH,. While it is true that this compound is not 
Wwe 
i | 
described in the literature and Nef’s’ attempts to prepare it were 
failures, our efforts, though not completely successful, very 
strongly indicate that the compound is easily formed in a variety 
of ways. The preparation of the mono-oxime has been successful. 
Since it can not be doubted that the coloration is due to oxida- 
tion, with the formation of quinone derivatives, it becomes of 
interest to discuss the mechanism of the reactions. In the 
presence of water, or aqueous solutions, the formation of hydro- 
gen peroxide® will account for all of the phenomena involved. 
Reasoning from the analogous behavior of phenol,® the oxidation 
of which has been proved to be independent of the presence of 
water, and also from the following considerations, the hydrogen 
peroxide assumption does not seem at all necessary, at least in 
the initial stages of the oxidation. Moreover, the rate of for- 
mation of the yellow color seems to be as rapid in the case of 
pure methyl] salicylate as when considerable quantities of water 
are present. 
The phenolic hydrogen is labile in all the free phenols which have been 
observed, and the absorption band heading about 277 “pu is characteristic 
"Ber. d. deutschen chem. Ges. (1885), 18, 3499. 
*The question of the production of hydrogen peroxide by the action 
of sunlight on water and oxygen. See preceding paper, page 69. 
* Loc. cit. 
