METHYL SALICYLATE IIL. 95 
The oxidation of methyl salicylate, which should give the same 
compound as that obtained from the oxidation of the methyl 
ester of gentisic acid, has been effected by various oxidizing 
agents. Rather dilute solutions of potassium dichromate and 
sulphuric acid in the cold seem to work well, but give poor yields. 
The electrolytic oxidation by means of a rapidly rotating gauze 
anode in a porous cell containing methyl salicylate with dilute 
sulphuric acid as the electrolyte ** seems to produce the best 
result. The rapidly rotating anode stirs the slightly soluble 
ester into an emulsion and hastens the oxidation. The small 
amounts of the yellow compound which have so far been isolated 
behave the same as the compound obtained by the oxidation 
of the methyl ester of gentisic acid. This yellow substance 
is decolorized by sulphurous acid and the quinone yellow is 
restored by oxidizing agents. The compound is not para quinone 
and has every appearance of being the quinone sought. 
SUMMARY. 
This paper records the results of the study of the action of 
sunlight upon various phenolic compounds and is a continuation 
of the investigation of phenol already recorded. 
The coloration of all the compounds investigated is due to 
oxidation, and requires oxygen and sunlight, or active oxidizing 
agents, such as ozone, hydrogen peroxide, oxygen liberated at 
the anode, chromic acid, persulphuric acid, etc., in the dark. 
All of the members of this class of compounds, which color in 
the sunlight, contain the so-called labile hydrogen atom, and 
the behavior in the sunlight is intimately connected with the 
absorption band in the ultra-violet indicating enol-keto tauto- 
merism. 
The fixation of the labile hydrogen atom of the hydroxyl group 
and, in some cases, the fixation of the hydrogen atom, para to 
the hydroxyl group, is sufficient to make the compound stable 
in the presence of sunlight and oxygen. 
The three cresols——The meta compound colors most rapidly 
and the ortho and para more slowly. The ester of p-cresol, 
the only one investigated, remains colorless in the presence of 
sunlight and oxygen. 
The three hydroxy benzoic acids and their esters—The meta 
** Hydrogen peroxide oxidation. Richardz, Ber. d. deutschen chem. Ges. 
(1909), 42, 4674; Ann. d. Phys. u. Chem. (Wiedemann) (1885), 24, 183; 
and (1888), 31, 912. 
