286 TRIMETHYLBENZENES. 



Para- and Orthonitrethylbenzene, C 6 H 4 (M) 2 ). 

 C 2 H 5 , are formed simultaneously when ethylbcnzene is 

 treated with fuming nitric acid. Both are liquid ; the 

 former boils at 245-246, the latter at 227-228. 

 With tin and hydrochloric acid they yield liquid bases. 



4. Hydrocarbons, C 9 H 12 . 



a. Trimethylbenzenes. 

 C 6 H 3 (CH 3 ) 3 . 



That portion of light coal-oil that boils at 163- 

 168 contains, together with other unknown hydrocar- 

 bons, two isomeric trimethylbenzenes, pseudocumene, 

 and mesitylene. They cannot be separated from the 

 mixture. 



1. Mesitylene (1:3: 5). Is produced, together 

 with other bodies, by the distillation of a mixture of 

 acetone and sulphuric acid, and can be separated from 

 the oily distillate by means of partial distillation. 

 Colorless liquid, boiling at 163. Yields mesitylic and 

 uvitic acids, when oxidized by dilute nitric acid. 

 When heated with phosphonium iodide at 250-300, 

 it is converted into a hydrocarbon C 9 H 18 (boiling point, 

 136), which, under the influence of oxidizing agents, 

 yields the same products as mesitylene. 



Monochlormesitylene, C 6 H 2 C1(CH 3 ) 3 . Colorles* 

 liquid ; does not congeal at 20 ; boiling point, 204- 

 206. Dichlomiesitylene, C 6 H01 2 (CH 3 ) 3 . Prisms; fusing 

 point, 59; boiling point, 243-244. Trichlormesi- 

 tylene, C 6 C1 3 (CH 3 ) 3 . Long, fine needles. Fusing point, 

 204-205. 



Monobrommesitylene, C 6 H 2 Br(CH 3 ) 3 . Colorless 

 liquid, boiling at 225, congeals below 0. Dibromme- 

 sitylene, C 6 HBr 2 (CH 3 ) 3 , and tribrommesitylenefi^^CH 3 ) 3 , 

 are crystalline. The former fuses at 60, the latter at 

 224. 



