Septembek 30, 1898.] 



SCIENCE. 



421 



flourish, so to speak, and in the reducing 

 side of the current chemists possess a means 

 of attacking these bodies most energetically. 

 Let us take nitro-benzene as the particular 

 subject for consideration. That this yields 

 azobenzene when it is reduced in an alka- 

 line solution, and aniline in an acid solu- 

 tion, are well established facts, Does this 

 hold true when the electric current is the 

 agent of reduction ? 



The reply to this inquiry divides itself. 

 In an alkaline solution azobenzene and 

 hydrazobenzene are formed. In an acid 

 solution the picture is different from that 

 which is generally supposed to represent 

 the course of the reduction, for Gattermann 

 found p-amidophenol. The explanation 

 given for the presence of this body is that 

 when the current reduces nitro-benzene the 

 first product is phenylhydroxylamine, 

 C^HuNH.OH, and that the sulphuric acid 

 present rearranges this compound into p- 

 amidophenol. Aniline was invariably found 

 with the latter body. This led Elbs to 

 subject the process to a more careful and 

 critical study. Gattermann considered 

 that the sulphuric acid figures very seri- 

 ously in the reduction. Indeed, he thought 

 that it played a triple role, as it conducted 

 the current, occasioned the molecular re- 

 arrangement, and served as the solvent. 

 The question which naturally suggested 

 itself to the inquiring mind was : Could the 

 quantity of this reagent in any manner 

 modify the course of the reaction ? Could 

 it affect the yield of the several substances ? 

 So it was proposed to substitute acetic acid 

 of varying concentration. The yield grew 

 larger, but that of the aniline increased 

 with the increased amount of p-amidophe- 

 nol. Evidently then aniline could not be 

 considered in this reduction, by the cur- 

 rent, as a secondary, but rather as a normal 

 product. A kathode of lead was substituted 

 for that of platinum, and, strangely enough, 

 the quantity of aniline became greater. 



Was it possible that the aniline was due to 

 a secondary reduction of the p-amido- 

 phenol ? or are the lead electrodes respon- 

 sible for the direct reduction of nitroben- 

 zene to aniline? Experiments made to 

 test the first point demonstrated that p- 

 amidophenol, when operated upon with the 

 conditions as before, was not reduced to 

 aniline. After much search it was found 

 that p-amidophenol and aniline were pro- 

 duced in equal proportions with platinum 

 electrodes, bj' prolonging the period of 

 action. Therefore, it must have been the 

 spongy lead which effected the reduction of 

 the nitrobenzene to aniline. Gattermann 

 remained firm in his view that nitroben- 

 zene was first reduced to phenylhydrox- 

 ylamine, which in turn became ^-amido- 

 phenol, and contended that the latter ought 

 to be obtained entirely free from aniline. 

 However, azoxybenzene had also been de- 

 tected in the reduction mass, and naturally 

 the thought followed that possibly the p- 

 amidophenol was derived from it. The 

 equation which I add will explain this rea- 

 soning : 



— N 



k 



Observe, by adopting this idea of the re- 

 duction we can plainly comprehend the 

 presence of both aniline andjp-amidophenol. 

 Experiment alone could decide whether 

 this was the true course. Accordingly 

 nitrobenzene and azoxybenzene were elec- 

 trolyzed under similar conditions. The 

 first gave an abundant yield of p-amido- 

 phenol, while scarcely any of it was 

 obtained from the azoxybenzene. The evi- 

 dence, therefore, strongly favored Gatter- 



