THE OXIDATION OF PHENOL. 147 



THE ACTIVITY OF THE PHENOL MOLECULE. 



The measurements of the absorption-spectrum of phenol made by 

 Hartley ■** show a broad absorption band with a maximum at A.=272 ft/x. 

 The breadth of this band depends upon the concentration. With 1 milli- 

 gram molecule in 100 cubic centimeters of alcohol the extremities of the 

 band are A=291.6 to 243.1 /jl/j. and with 1 milligram molecule in 500 

 cubic centimeters they are A=283.5 to 261.5 fifi. 



Anisole shows the same absorption band, with the difference that it 

 divides into two bands near the head. This variation shows a marked 

 difference between the constitution of the two compounds which has 

 been traced by Baly and Collie *^ to a certain amount of tautomerism in 

 phenol. The absorption band heading at about A=277 ixft. is characteristic 

 of the labile hydrogen atom. Baly and Eubank state/" "These results 

 leave no doubt but that phenol, under these experimental conditions, has 

 not the same structure as anisole, and that the difference is due to the 

 wandering of the labile phenolic hydrogen atom." 



The active wave lengths are thus seen to be very close to the limit 

 of the sun's rays which escape absorption in the atmosphere and which 

 are capable of penetrating glass. The fact that the coloration of phenol 

 has been found to be more rapid under quartz than under other kinds 

 of glass is evidence upon this point. The failure of Kohn and Fryer ^^ 

 to obtain any coloration of pure phenol is evidently due to the at- 

 mospheric conditions in Liverpool. In Manila, where this investigation 

 has been carried on, the atmosphere is free from smoke and very clear 

 at certain seasons of the year. The altitude of the sun is such that the 

 ultra-violet absorption of the atmosphere is less than in Liverpool, even 

 if the atmospheres in the localities were equally clear. Hartley ^^ says, 



"I have been led to attribute the limited extent of the solar spectrum, as 

 photographed in London, to the selective absorption of rays by the tarry matters 

 in the smoke of the town's atmosphere, especially since my experience of the 

 extraordinary absorptive power of benzene derivatives." 



That the phenol molecule is activated under the conditions of the 

 observations described, appears to be a more reasonable explanation of 

 the phenomenon than that the oxygen molecule is activated by available 

 wave lengths which do not approach the region of the oxygen absorption 



"JoMm. Chem. 8oc. London (1902), 81, 929. 



"Ibid. (1905), 87, 1339. 



'"Ibid., 134S. 



"'■ Loc. cit. 



^'Journ. Chem. 8oc. London (1881), 39, 111. 



