364 GIBBS. 



Quinone and phenol condense readily forming phenoquinone to wliich Jackson 

 and Oenslager -° have assigned the formula : 



HC GH 



il II 

 HC CH 



\/ 

 



CeHsO OH. 



Willstatter and Piceard "* offer the criticism of this formula that it does 

 not explain the color of the compovind or its instability. They suggest the 

 graphic representation : 



0...(0H)CeH5 



=0...(0H)CeH5 



in which the dotted lines are partial valences. This compound is very unstable. 

 The dilute, aqueous, alcoholic and ligroin solutions are almost colorless and in 

 all probability the condensation product is decomposed on solution in these solvents. 

 On evaporating the solvents the red color gradually makes its appearance as 

 the concentration increases. The aqueous solution reacts in such a way as to 

 show the presence of quinone. 



Methods for separating small quantities of qninone from large quan- 

 tities of phenol have all proved unsatisfactory. In some eases the 

 condensation product, phenoquinone, if not already present will be 

 produced, while in others quinone will be obtained by the breaking down 

 of phenoquinone, if the latter is present. The presence or absence of 

 phenoquinone in the solvent phenol can probably only be proved by 

 physico-chemical methods which have not been adopted in this work. 



Samples of colorless phenol to which a few drops of water were added 

 were placed in the sunlight in clear, glass bottles, the liquid half filling the 

 bottle. The samples reddened in a few hours and after four days were 

 so brilliant in color that an analysis was attempted. Other samples 

 which had reddened upon the laboratory shelves upon long standing, 

 were analyzed at the same time. 



On pouring small quantities of the red phenol into ten or twenty 

 times the volume of water, an almost colorless solution is formed. The 

 samples which had reddened upon long standing upon the laboratory 



''Ber. d. chem. Ges. (189.5), 28, 1614. Am. Ghem. Jonr. (1896), 18, 1. 

 "Ber. d. chem. Ges. (1908), 41, 1464. 



