OF AROMATIC COMPOUNDS. 69 



a condensation product of formaldehyde and aniline. 



The behavior of p-nitro-toluene is different, since in 

 this case, the p-position being occupied by the nitro- 

 group, an analogous reaction with formaldehyde is 

 impossible. 



While p-nitro-toluene is converted in an alkaline 

 solution smoothly into azo-toluene and in an acid 

 solution into p-toluidene, nearly equal quantities of 

 two different products are obtained in the presence of 

 formaldehyde, viz. : 



1. p-Dimethyl-toluidene. 



2. Dimethylene-ditoluidene. 



The nature of the reaction is such that the reduc- 

 tion proceeds until p-toluidene is formed, and not till 

 then does a condensation with formaldehyde occur: 

 2C 6 H 4 .CH 8 .NH a + 2CH 2 = 



2H,O. 



The dimethylene-ditoluidene thus formed on further 

 reduction breaks up into dimethyl-toluidene and 

 toluidene, the latter becoming again subject to the 

 action of the formaldehyde : 



f 4H=* 



CH 8 ,C 6 H 4 .N(CH 8 ) a + H s N.C.H i CH i . 

 A state of equilibrium exists between the dimethyl- 



