THE TMIDER OF THE AROMATIC SULPHONIC ACIDS. 17 



Respecting the Reduction by Sulphur Dioxide of the 

 Oximido-Nitrogen not united to Sulphur. 



Nitrogen shows a greater tendency to unite with the sulphonic 

 radical than with carbon. An oximido-nitrogen atom, united with 

 carbon alone, becomes sulphonated when treated with sulphur di- 

 oxide and is, at the same time, detached from the carbon (Krafft 

 and Bourgeois: Ber., 1892, 25, 472). But this tendency of 

 nitrogen to unite with the sulphonic radical becomes considerably 

 weakened, when the nitrogen is already united with other atoms 

 of sulphur. When hydroxylaminedisulphonates are treated with 

 an alkali bisulphite and sulphur dioxide they are converted into 

 the trisulphonates (this Journ., 1901, 17, Art. 2, 2). But, on ac- 

 count of the presence of two sulphonic radicals already in union 

 with the same nitrogen atom, the third sulphonic radical is very 

 readily removable by hydrolysis. In the case of the reduction of 

 dibeuzenesulphohydroxylamine, the sulphonate (CgH,-,S02)2N.SO:;H 

 is, probably, formed as the intermediate product. But, owing, 

 doubtless, to the presence of two benzenesulphonic radicals already 

 united with the nitrogen atom, the sulphonic group is so readily 

 separated from the nitrogen by hydrolysis, that the existence of 

 the intermediate compound can not be proved. 



When a compound contains two oximido-radicals united with 

 two separate carbon atoms in the molecule, reduction with sulphur 

 dioxide produces a remarkable result. Only one of the nitrogen 

 atoms is separated in the form of amidosulphonic acid : the other 

 nitrogen atom, from some unknown cause, resists the action of 

 sulphur dioxide and remains united with the carbon. Acetylacet- 

 onedioxime is a good example of this. 



