(42 ) 



Chemistry. — "Reduction of aromatic nitro-compounds by sodium 

 disulphide." By Dr. J J. Blanksma, (Communicated by Prof. 

 A. F. Holleman). 



(Communicated in the meeting of May 30, 1908). 



I have pointed out previously *) that sodium disulphide may act 

 on aromatic nitro-compounds in two different ways, namely by sub- 

 stitution or by reduction. 



1. Substitution occurs when halogen atoms or nitro-groups are 

 present which under the influence of ortho- or ^zra-placed nitro- 

 groups have become moveable. These on being treated with sodium 

 disulphide are readily replaced by S„ and the disulphides thus formed 

 may be converted by oxidation into sulphonic acids. A fairly large 

 number of these cases have been communicated previously l ). 



2. Reduction takes place when the nitro-compounds do not contain 

 any moveable halogen atoms or nitro-groups ; a nitro-group is then 

 reduced to an amido-group, whilst generally a small quantity of 

 azo-oxycompound is also produced according to the equations : 



RN0 3 + Na, S 2 + H 3 = RNH 3 + Na 3 S 3 0, 

 2 RN0 3 + Na, S 3 = RN — NR -f Na, S, 0, 







A preliminary investigation had shown me previously that alcoholic 

 solutions of nitrobenzene and o-nitrotoluene are readily converted by 

 Na 3 S 3 into aniline and o-toluidine, the Na 3 S 3 being oxidised to 

 Na 3 S 3 8 . ?>i-Dinitrobenzene and ^-dinitrobenzene when treated with 

 Na, S 3 yielded, respectively, ??*-dinitroazo-oxybenzene and p-dinitroazo- 

 benzene. It was then a ) our intention to further investigate the 

 reducing action of Na 3 S,. 



Meanwhile, however, a patent has been granted to Kunz 3 ) for the 

 reduction of aromatic nitro-derivatives to amido-derivatives by means 

 of sodium disulphide in aqueous solution and afterwards sodium 

 disulphide has been used by Brand 4 ) as a partial reducing agent. 



I have now studied the reduction of aromatic nitro-compounds by 

 Na^ in alcoholic solution in a number of cases. The reduction is 

 carried out as follows: 



Six grams of nitrobenzene are added to a boiling solution of 12 

 grams of crystallised sodium sulphide and 1.6 gram of sulphur in 



i) Dissertation. Amsterdam 1900; Rec. 21, 121, 141. 



2) These Proc. 1900, (Oct.) 



8) Chem. Gentr. 1903 II 813. 



*) Journ. f. pract Chem. 1906. (2) 74, 499. 



