ON ISOMERIC NAPHTHALENE DERIVATIVES. 



175 



alternative position i. The relationship of the several compounds is 

 therefore as follows : — 



Br Br O 



O 



OH 



Br 



Br Br Br 



'J^^ibronio-;8-naplitliol, Tettabromo /S'liaphtliol, Tribromo-;3-naphtha- 



iji.p. 159°. ni,p. 184°. qniuone, m.p, 183°. 



o 



Bi 



NHPh 



Br 



Br NPh 



Anil. 



The structure has also been determined of the tetrabromo-/?-naphthol, 

 No. 3 (ni.p. 191° ; acetate, m.p. 210°), described in the 1901 report, which 

 differs from all the other highly brominated naphthols in that it fails to 

 give a nitro-bromo-keto- compound, being converted by nitric acid, at the 

 ordinary temperature, into a tetrabromo-/?-naphthaquinone (m.p. 241°). 



This tetrabromo-/7-naphthaquinone is oxidised by dilute nitric acid to 

 a new dibromophthalic acid, which by exclusion must be the hitherto 

 unknown 3 : b-dibromo])hthalic acid ; the quinone is therefore 3:4:6:8- 

 tetrabroino-ft-naphlhaquinune. 



The parent naphthol, which is derived from 1:3: 6-tribromo not 

 from 1:5: 6-tribromo-/3-naphtliol, must therefore contain the bromine 

 atoms in positions 1:3:6:8, the series of compounds being related as 

 shown by the following formulte : — 



Br 



Br 



Br 



O 



Br 



OH 



CO.,H 



Tetrabromo-/8-naphthol, 

 m.p. 191°. 



TctrabroiTio-)3-naphtlia- 

 quinone, m.p. 241°. 



Br y COoH 



1 : ij-Dibromophthalic acid, 

 m.p. 188°; anhydride, 

 m.p. 155°. 



It follows from these results that whilst the product of the further 

 bromination of 1 : 3 : 6-tribromo-/3-naphthol is 1 : 3 : 4 : 6-tetra-bromo- 

 /3-naphthol small quantities of the 1:3:6: 8-tetrabromo- derivative are 

 also formed. 



The investigation of tiie bromo-naphthols has involved incidentally 

 the study of the bromophthalic acids : the discovery of 3:4- and 3 : 5- 

 dibromophthalic acids in the course of the work completes the series of 

 dibromo- acids. 



