THE COMPOUNDS WHICH CAUSE THE RED COLOR 

 IN PHENOL. 



By H. D. Gibes. 

 (From the Lahoratory for the Investigation of Foods and Drugs, Bureau of Science, 



Manila, P. I.) 



Much investigation and speculation has been indulged in by various 

 writers concerning the cause of the red coloration of phenol. At this 

 time it is well established that impurities in phenol may produce a 

 discoloration. It is also true that pure, colorless phenol is reddened by 

 the action of moisture, air and the more refrangible light rays; in other 

 words by hydrogen peroxide oxidation. The color has been considered 

 to be due to various compounds, but I have found, after investigating 

 the samjDles which have come under my observation in this laboratory, 

 that the true nature of the colored compounds and the method of their 

 formation is not to be found in the literature. 



A brief review of the literature shows the most prevalent idea to be 

 that the coloration is due to impurities. Some of the latest text-books 

 on organic chemistry still cling to this theory. 



H. Mailer ' states that phenol will keep well if the impurities are resinified by 

 the action of the air on the alkaline solution during the process of purification. 



H. Hager " attributes the formation of color to the action of the oxygen and 

 ammonia of the atmosphere, which, in his opinion, probably produce rosalic acid. 



A. Sicha^ says the coloration is due to copper. He prepared phenol which 

 remained colorless for months in the sunlight by distilling in glass vessels. 

 W. Meyke ' believed the color to be caused by the lead of the containing vessel. 

 P. Ebell ° states that phenol ci-ystals contain substances which are colored through 

 the action of light. These substances are not metals as is claimed by Meyke. 



H. Hager " found some samples to be colored by the presence of iron, and he 

 inclines to the view that the red color can not result from a chemical change of 

 the phenol. The basis for the red color does not lie alone in the iron content 

 and may be caused by the raw material or the method of purifying and washing. 



^Dingl. Poly. Journ. (1866), 179, 462. 

 ''Chem. Centrbl. (1880), 11, 178. 

 V. Soc. Ghem. Ind. (1882), 1, 397. 

 *Jahresb. f. Chem. (1883), 875. 

 = Ber. d. chem. Qes. (1884), 17, 69, Eef. 

 ' Chem. Centrbl. (1885), 16, 120. 



361. 



