258 SCIENCE PROGRESS 



attributed to the primary formation of the aldehyde in each 

 case. In the case of all three alcohols, the reduction of the 

 nitrobenzene is very incomplete, not exceeding 10 per cent. ; it is 

 remarkable that methylic alcohol is almost without action on 

 nitrobenzene in sunlight. The majority of nitro-compounds too 

 are far less affected than nitrobenzene by the alcohols named 

 above. Of the three nitrotoluenes only the meta-compound 

 gives notable quantities of toluidine, whilst o- and m-dinitro- 

 benzene, the three nitranilines, picric acid and nitronaphthalene 

 remain unchanged. 



In the foregoing case of the reduction of nitrobenzene by 

 alcohol, neither nitroso-benzene nor products formed from it, 

 such as azoxybenzene or hydroxyazobenzene, could be isolated ; 

 but when benzaldehyde and nitrobenzene are exposed to light 

 products are obtained which afford proof that in this case the 

 complete series of reduction stages : 



C 6 H 5 N0 2 -> CHsNO -> C 6 H 5 NH(OH) -> C 6 H 5 NH 2 



is passed through ; 1 the benzaldehyde is oxidised to benzoic 

 acid. The products actually isolated were benzanilide; benzoyl- 

 phenylhydroxylamine, C 6 H 5 N(OH). CO.C 6 H 5 ; dibenzoylphenyl- 

 hydroxylamine, C 6 H 5 N(OBz)CO . C 6 H 5 , and their products of 

 transformation: benzoyl-oaminophenol, OH . C 6 H 4 . NHBz, and 

 dibenzoyl-/>-aminophenol, OBz. C 6 H 5 . NHBz, as well as azoxy- 

 benzene and o-hydroxyazobenzene. 



Ciamician and Silber consider that the principal product, 

 dibenzoylphenylhydroxylamine, is formed directly from nitro- 

 benzene and benzaldehyde, thus : 



a. C 6 H 5 NO, + C 6 H 5 CHO = C 6 H s NO <°q c h< 



b. C.H.NCX^ c H + C^CHO = H 2 + QHsN^q ^ 'j£« Hs 



To understand the formation of the other compounds, it must 

 be admitted that nitrosobenzene is formed initially, C 6 H 6 N0 2 + 

 C H 5 CHO = C a H 5 COOH + C 6 H 5 NO The further action of benzal- 

 dehyde on nitrosobenzene gives benzoylphenylhydroxylamine : 



C 6 H 5 NO + C 6 H 5 CHO -> C 6 H 5 N <°^ c ^ 



which is in turn reduced by benzaldehyde giving benzanilide : 



C 6 H 5 N <£**_ c H + C 6 H 4 CHO -> CHsCOOH + C,H 5 N <*? Q Q ^ 



1 Atti. R. Accad. Lincei^ 1905, 14, i. 265 ; Ber. 1905, 38, 1176. 



