1919] JUGLONE 51 



THE HYDROJUGLONES 



!N"ot only jiiglone but also "-hyclrojiiglone and its isomer, '^-hy- 

 drojiTglone, have been the subjects of considerable study in the Or- 

 ganic Laboratory of the University of ISTorth Carolina. The first 

 important discovery was the demonstration that the two hydro-jug- 

 lones were isomeric keto and enol forms, their formulas being III 

 and IV : 



OH^ OH oH 



This investigation was begun in the chemical laboratory of the Swiss 

 Federal Polytechnic at Zurich and was completed in Chapel Hill. 

 The report is found in the Berichte d.d.Chcm.Ges., 47, 2796 (1914). 

 That the alpha compound contains three hydroxyl groups is shown 

 by its conversion into a triacetyl derivative with acetic anhydride. 

 That there is no ketone group present is shown by our failure to ob- 

 tain an oxime or a semi-carbazone. The beta-compound also forms 

 a triacetyl derivative but this is because the acetic anhydride has an 

 enolizing action, caui?ing the hydrogen in position 1 to move to posi- 

 tion 4, thus reforming the alpha-compound. However, ketone re- 

 agents such as semicarbazine and phenylsemicarbazine readily con- 

 vert the beta-compound into semicarbazones, V and VI : 



«° H HO H 



These two reagents are successful because of tlicir weak basic ])rop{'r- 

 tios. T]\(' liydrojuglones are very sensitive to alkalies, so that the usual 

 ketone reagent, hydroxy lamine, decomposes them instead of giving 

 an oxime. Semicarbazine is less basic on account of tlie presence 

 of the carbonyl group and phenylsemicarbazine is still less basic since 

 it contains in addition the ])henvl group. This gives a strong hint 

 that phenylsemicarbazine should be a delicate reagent for those keto- 

 phenols wliich are particularly sensitive to alkalies. 



