ON OUR PRESENT KNOWLEDGE OF AROMATIC DIAZO-COMPOUNDS. 209 



produced either by rearrangement (I« to II), or more simply by rotating 

 the tetrahedra about their common edge (la to 16). 



The former operation represents the transformation of the labile syn- 

 derivative into its stable a?i^i-isomeride ; the latter indicates the final 

 condition of the st/M-compound itself, and furnishes an explanation of the 

 typical diazo -fission, 



N.X N X 



II ^ l|i + ! 



K.Y N Y 



brought about by the close proximity of the radicles attached to the 

 diazo-complex, 



II. Isolation of the Anti-diazohydroxides R.N:N.OII. — Hantzsch has 

 recently discovered that in certain cases both forms of the anti-dvAzo- 

 hydroxides are capable of separate existence. The nitrosamine forms 

 have already been studied ; they are comparatively stable yellow com- 

 pounds belonging to the category of pseudo-acids, and yield negative 

 results when treated with phosphorus pentachloride, acetyl-chloride, 

 phenyl-carbimide, or a dry ethereal solution of ammonia. 



The newly isolated oxime forms 



E.N 



II 

 N.OH, 



corresponding with the metallic «?i<i"-derivatives R.N: NONa(K), are labile, 

 colourless substances ; they are true acids reacting with the agents 

 enumerated in the preceding sentence. 



The sy?i-diazohydroxides are only known in solution. 



III. Transformation of Diazonium Salts. — The following observations 

 should be added to the summary of miscellaneous substitutions : — 



Meldola and Eyre have shown that in the dinitro-anisidines a nitro- 

 group situated in the ortho- or para- position with respect to amidogen is 

 replaced either by chlorine, when the base is diazotised in the presence of 

 hydrochloric acid,i OMe.C6H2(N02)oN2Cl-> OMe.CuH2Cl(NO,,)N..N02, 

 or by hydroxyl, when the operation is carried out in sulphuric acid. 



The author has quite recently noticed a similar transformation in the 

 case of 1-nitro-p-naphthylamine when diazotised in the presence of hydro- 

 chloric acid, NOa.CinHfjNaCl ^Cl.C,oH6.N2.N02, and further rearrange- 

 ments of this nature have been observed by other investigators.'-^ 



Although under these conditions bromine may be replaced by chlorine, 

 it does not appear possible to remove fluorine or iodine from the aromatic 

 nucleus through the agency of the diazo-reaction (Hantzsch). 



• Meldola and Eyre, Trans., 1001, 79, 1077 ; 1902, 81, 988. 



- Gaess and Ammelburg, ]3er., 1894, 27, 2211 ; Meldola and Strcatfeild, Tram., 

 1895, 67, 909 ; Fr. Pat. 315932, Feb. 28, 1902. 



1902. 



