( VO) 



intersects the solubility isotherm of the violet chloride at 25°. The 

 receding of the solutions towards the green, on cooling, now proceeds 

 with sufficient slowness to enable us to precipitate the violet chloride 

 at 25° by means of a current of HCl, which diminishes its solubility. 



Chemistry. — "-Nitration of symmetric nitrometaxylene." By Dr. 

 J. J. Blanksma. (Communicated by Prof A. F. Holleman). 



(Communicated in the meeiing of May 27, 1905). 



If symmetric dinitrophenol or symmetric dinitromethylaniline is 

 treated with mixed nitric and sulphuric acids, pentanitrophenol or 

 pentanitrophenyl-methylnitramine is formed ^). Consequentlj^ the pre- 

 sence of the two nitro-groups, which are in the w?e/r<-position with 

 regard to the OH or NHCHj group does not prevent the introduction 

 of another three nitro-groups in the pa/reposition and o/'^Ao-positions 

 in the benzene core. vSym metric dinitroanisol and phenetol yield, 

 however, on nitration tetranitroanisol or tetranitrophenetol "); the 

 hydrogen atom in the y;a?vif-position with regard to the oxyalkyl group 

 is not replaced by NO^ here. As the methyl group on substitution 

 in the benzene core behaves in some respects analogous to the 

 OH and NH^ (or NH CH3) gronps it seemed of importance to inves- 

 tigate the conduct of symmetric dinitrotoluene on nitration in oi-der 

 to ascertain what intluence is exercised here by the NO^-groups 

 in the meta position. 



The symmetric dinitrotoluene was, therefore, heated with mixed 

 nitric and sulphuric acid for two hours on the waterbath ; the sub- 

 stance had not, however, undergone any change. The pi-esence of 

 the nitro-groups in the ?wd^r/-position with regard to the CH, group 

 consequently prevents the further introduction of nitro-groups in the 

 positions 2, 4 and 6. If, however, one of the NO^-groups in sym- 

 metric dinitrotoluene is replaced by bromine, this substance may be 

 successfully nitrated. Symmetric bromonitrololuene yields on treat- 

 ment with mixed nitric and sulphuric acids three isomeric trinitrobro- 

 motoluenes which it is, however, difficult to isolate. 



The question now arose what result is obtained when one of the 

 NOj-groups of symmetric dinitrotoluene is replaced by CH3, in other 

 words what is the behaviour of symmetric nitro-m-xylene on nitra- 

 tion ? For it is known that m-xylene readily yields 2-4-6-trinitro- 



1) Recueil 21, 254. 



3) „ 23, ill; 24, 40. 



