vni, a, i Gibbs and Pratt: Hydroxyl and Carboxyl 39 



appearance in the presence of 1 equivalent of alkali. It is evident 

 that the intramolecular vibrations of sodium phenolate more 

 nearly approach those of the benzene ring. In fig. 1 the curve 

 with 0.1 equivalent of alkali is plotted from dilution log. 3.5 to 

 log. 2.3 which is the range obtained with 0.01 molar concentra- 

 tion. It is obvious that a dilution of this solution will change 

 the value of d, so that this curve could not be farther continued 

 with accuracy by this method. 



The curve obtained with 1 equivalent of alkali is not plotted 

 in fig. 1 since it falls between the curves of 0.1 and 5 equivalents. 

 Similarly, that with 500 equivalents is omitted since it lies near 

 that with 5 equivalents, but shows a further decrease in per- 

 sistence of the band. The curve obtained in alcohol saturated 

 with hydrogen chloride follows the curve of neutral phenol, 

 except that the persistence of the transmission band at 1/A=4180 

 is reduced from log. 3.34 to log. 2.82. It is thus seen that acids 

 and alkalies have a somewhat similar effect in reducing the per- 

 sistence of the absorption band of phenol, which is to be inter- 

 preted as producing a more stable molecule. 



To test the validity of this assumption, we have exposed to 

 the sunlight tubes of phenol and phenol dissolved in a large excess 

 of a concentrated solution of sodium hydroxide, and find that the 

 former colors in a few hours while the latter fails to show any 

 coloration after weeks of exposure. Sodium phenolate in solu- 

 tion is colored rapidly, but, in the presence of an enormous excess 

 of alkali, the hydrolysis and also the ionization are at a minimum, 

 and we probably have the stable form C 6 H 3 ONa. If it be granted 

 that the oxidation of phenol is capable of explanation by reason 

 of the transformation 



HO-C 6 H 4 -HM):C H 4 :H 2 



the two hydrogen atoms being oxidized with the formation of 

 quinone, then it is readily seen that sodium phenolate will resist 

 this transformation since the sodium atom has greater affinity 

 for the oxygen than for the carbon. 



O-CRESOL. FIG. 2 



The absorption spectrum of o-cresol has been investigated by 

 Hartley 13 and by Baly and Ewbank. The latter authors ob- 

 served the shift in the absorption band toward the red, which 

 takes place in the presence of alkalies. 



"Journ. Chem. Soc. London (1888), 53, 641. 



