5 9 o SCIENCE PROGRESS 



Gattermann, Elbs, Haber, Haussermann, Lob, and others. All 

 these investigators paid special attention to the electro-reduction 

 of the nitro- (N0 2 ) group in aromatic compounds — in particular 

 nitrobenzene — both as a preparative method and also from a 

 purely physical standpoint. 



The first experiments on electro-reduction (as well as electro- 

 oxidation) of organic substances were made between 1875 and 

 1886 by Goppelsroeder, 1 who worked on the production and 

 bleaching of dyestuffs by means of electrolytically produced 

 hydrogen and oxygen. From aniline sulphate by electro- 

 oxidation Goppelsroeder obtained aniline-black, while potas- 

 sium thiocyanate on electrolytic reduction yielded the dye 

 canarin. 



More important, both practically and theoretically, was the 

 work of Gattermann on the electro-reduction of nitrobenzene 

 and its derivatives. The chemical reduction of this substance 

 yields, according to the reducing agent employed, azoxybenzene, 

 azobenzene, hydrazobenzene, aniline, and benzidine. All of 

 these products may also be obtained with the help of the 

 electric current, variations in the conditions of electrolysis 

 corresponding, as noted above, to the use of different chemical 

 reducing agents. 2 



Gattermann, 3 however, and independently Clement and 

 Noyes, 4 succeeded in obtaining an electro-reduction product 

 of nitrobenzene, which all chemical agents had failed to yield, 

 viz. para-amido-phenol. As an intermediate product phenyl- 

 hydroxylamine is formed, subsequently undergoing transfor- 

 mation to amido-phenol, thus : 



NO, NHOH NH 2 



H H OH 



Nitrobenzene. Phenyl-hydroxylamine. Amidophenol. 



Corresponding amidophenols were obtained under similar 

 conditions from other aromatic nitro-compounds, such as nitro- 

 toluene, dinitrobenzenes, etc. When nitrobenzene is reduced 



1 Oesterreich's Wollen und Leine?i Industrie, Reichenberg, 1885. 

 8 See scheme on p. 592. 



3 Ber. der. deut. chem, Gesell. 26 (1893), 1849. 



4 Ibid. 990. 



