ON ISOMERIC NAPHTHALENE DERIVATIVES. 



177 



When bromine (1 molecular proportion) is left in contact with the 

 nitro-keto- compound 



NO2 Br 



O 



Br 



(derived from 1 : 6dibromo-/8-naphthol), suspended in glacial acetic 

 acid and exposed to diffused light, nitrous fumes are slowly evolved and 

 an arborescent mass of needles separates which appears to be the mono- 

 hydrate (I) of the acetate of a dibromo-naphthalene-keto-bromide 



OH 



OAc + HoO II 



Bro 



,0H 



\ 



0Ac-f2H,0 



Br., 



Ill 



Bi 



,0H 



'OAC + 4H2O 



Br 



This substance melts at 63-65° ; from the mother liquors large slightly 

 yellow prisms slowly separate which consist of the tetrahydrate III. 

 The dihydrate II is formed only under very special conditions, namely, 

 when a solution of the nitro-bromo-keto- compound from l-bromo-/i}- 

 naphthol in acetic acid is acted on by bromine ; it separates very slowly 

 from solution in the form of small nearly colourless needles, melting at 81°. 

 If any one of these hydrated acetates be gently warmed with benzene 

 a turbid solution is obtained ; if this be dried with the aid of calcium 

 chloride and slowly evaporated it deposits magnificent nearly colourless 

 plates of the simple keto-bromide. 



Br, 



Br 



Br 



This substance apparently is the first repi'esentative of the class of 

 naphthalene keto-bromides corresponding to the keto-chlorides which have 

 been so fully studied by Zincke. When gently warmed, either alone or 

 in the form of one of its hydrated acetates, with glacial acetic acid, it 

 loses bromine and is converted into 4 : G-dibromo-/5-naphthaquinone 

 (m.p. 171°) ; if the warming be continued the liberated bromine acts on 

 this compound, converting it into 3:4: C-tribromo-/j-naphthaquinone 

 1903. N 



