156 Biological Chemistry. 



occur in coal tar, and, like phenol, are valuable anti- 

 septics. 



Thymol, C 6 H 8 (CH 3 )( r CH./ (H3 yOH), 1:4:3, 

 V ^CH 3 / 



occurs 



in oil of thyme. It is a methyl -isopropyl phenol. The 

 1:4:2 isomer is known as carvacrol, and can be pre- 

 pared by heating camphor with iodine. 



Dihydroxy Phenols. 



The following dihydric phenols are known 

 OH OH OH 



OH 



Catechol Besorcinol Quinol (Hydro- 



cfuuione) 



Catechol occurs in catechu, a substance obtained from 

 Acacia catechu, an Indian tree, and hydroquinone occurs 

 combined with dextrose (p. 193) in arbutin, a glucoside 

 obtained from the bear-berry. Resorcinol is obtained 

 synthetically only by the fusion of the potassium salt of 

 the corresponding disulphonate with potassium hydroxide. 

 It readily oxidizes when treated with mild oxidizing 

 agents to yield quinone, which belongs to a characteristic 

 class of benzene derivatives, which needs no further 

 discussion in this place 



C H 4 (OH) a + = C 6 H 4 2 + H 2 



