THE KED COLOR IN PHENOL. 365 



shelves separated a small quantity of an insoluble, red .compound, while 

 those which had been in the siinlight for four days formed a clear 

 solution with no insoluble portion. The red precipitate was collected 

 upon a filter. It was insoluble in water, very slightly so in ligroin and 

 quite soluble in alcohol, forming a red solution. The compound, with 

 the exception of the differences in the solubilities noted, behaves in the 

 same manner as plienoquinone. With alkalies it turns to a blue-green 

 and with concentrated sulphuric acid it forms a brilliant blue-green color. 

 The coloring qualities of the substance are intense. A small amount 

 dissolved in phenol or alcohol produces a brilliant red solution. It is 

 possible that this compound is the ortho modification of phenoquinone. 

 The amounts obtained were so small that no analysis was made. 



Eeactions for catechol were obtained from the clear solutions, which 

 were almost colorless with a slightly yellow tinge. On addition of lead 

 acetate a copious, white precipitate was formed. After treating this 

 precipitate with sulphurous acid and filtering, catechol was extracted 

 with ether from the filtrate. On evaportion of the ether in a vacuum 

 desiccator, crystals which were proved to be catechol by the ferric chloride 

 and sodium hydrogen carbonate reaction, separated. 



On treating 20 cubic centimeters of the phenol which had reddened 

 in the sunlight with a small quantity of sulphurous acid and distilling 

 in steam until all of the phenol had passed over, the residue in the 

 distilling flask was found to contain a very small amount of red precip- 

 itate similar to that obtained from the old samples of phenol upon pouring 

 into water. This was collected upon a filter and was found to react 

 with solvents, sodium hydroxide, and concentrated sulphuric acid in the 

 same manner as the red compound separated from other samples. The 

 filtrate, upon extraction with ether, demonstrated that considerable 

 quantities of catechol and quinol were also present. 



Quinone was demonstrated by the hydrocoerulignon reaction of Lie- 

 bermann.-^ The coerulignon employed in this test was made by the 

 method of Hofmann,^^ except that methyl sulphate was substituted for 

 methyl iodide in the production of the dimethyl ether of pyrogallol. It 

 is to be noted that in the presence of considerable quantities of phenol 

 the coerulignon precipitate has a reddish tinge and it does not under 

 these conditions change readily to the steel-blue color which is charac- 

 teristic of these crystals. Since pure, white crystals of phenol in 

 concentrated, aqueous solution fail to give any coloration whatever, 

 while the red phenol immediately gives a distinct cloudiness which soon 

 becomes red and extends downward throughout the solution, it is fairly 

 safe to assume that the reaction is positive. When the red phenol is 



"^Ibid (1877), 10, 1615. 

 ''Ihid. (1878), 11, 3.36. 

 75034 5 



