ON OUR PRESENT KNOWLEDGE OF AROMATIC DIAZO-COMPOUNDS, 199 



The triazolenes prepared by Bamberger ' by the action of nitrous acid Oft 

 amino-iudazoles were assumed to have the formula, 



/ C — N 



CgH/ /I II 



Hantzsoh, however, advocates tjje constitution ^ 



I >C/|| 



Diazo-sulphonates. — These substances, prepared by the action of 

 potassium sulphite on the diazonium chlorides, appear generally to exist 

 in two modifications, but in most cases the s^/w-isomeride is so unstable 

 that it has not been isolated in a pure state. The fact that both modifica- 

 tions are distinctly coloured suggests that they have the constitution 

 R.N iN.SOjK, analogous to the azo-compounds j the sy?i-isomeride has 

 invariably a more intense colour than the anti-salt. 



Syn-2 : 4-di-iodobenzenediazo-sulphonate, 



I2C6H3.N 

 II 

 KSO3.N 



is an orange substance, whilst the anti-salt, 



I2C6H3.N 



II 



N.SO3K, 

 is yellow. 



The naphthylamines behave exceptionally, yielding only sj/^^-diazo- 

 sulphonates ; these are not converted into the anti-salt on warming, but 

 decompose, yielding the corresponding azo-naphthalenes."* 



Diazo-phenylsuljjhones.'^ — By the action of benzenesulphinic acid on 

 the diazo-cyanides, diazo-sulphones RNo-SOoCcHr, are produced ; the 

 action goes immediately with sy^i-diazo-cyanides, but only slowly with 

 their anti-salts. The products do not exhibit stereo-isomerism, and 

 probably belong to the anti-series ; the syn-series has not been isolated, 



C. Diazoamines considered as Anti-diazo-covtpounds. 



Isodiazotisation of Aromatic Primary Amines. — The action of nitrous 

 acid on the salt of an aromatic amine leads to the production of a 

 diazonium salt, the basic nitrogen atom retaining its pentavalency 

 throughout the operation. When the interaction occurs between nitrous 

 acid and the free base, an iw-diazo-hydroxide is formed which condenses 

 with a molecular proportion of prin\ary amine, yielding a diazoamine, 

 The direct isodiazotisation of the base may also be efiected either by 

 passing nitrous fumes into its solution in dry ether or ethyl acetate,'' 

 or by treating the amine with an alcoholic solution of amyl nitrite 

 9,nfl sodium ethoxide ; ^ in the former case a mixture of normal and 



» Ber., 1899, 32, 177.3. ^ Ber., 1902, 35, 888. 



' Hantzsoh and Schmidt, Ber., 1897, 30, 71. 



•I Hantzsch and Singer, Ber., 1897, 30, 312, 



» Ber., 1894, 27, 1948. • Ber., 1900, 33, 3511. 



