52 Dr. A. W. Hofmann on Aromatic Monamines. [Dec. 5, 



quartary compound thus formed often remains liquid for days, and then 

 suddenly solidifies into a beautiful mass of crystals. 



Examination of the Monamines formed at High Temperatures. 



It has been already stated that the bases into which trimethylated 

 phenylammonium iodide is converted at very high temperatures (melting- 

 point of lead) unmistakably exhibit the character of primary monamines. 

 The only primary base which can arise from trimethylated phenyl- 

 ammonium iodide by intramolecular atomic interchange is a trimethylo- 

 phenylated monamine, i. e. a cumidine. 



C 6 H, (CH 3 ) 3 NI=[C„ H 2 (Cfflyj H 2 N . HI. 



This, I may at once observe, is indeed the principal product of the re- 

 action. It cannot, however, be wondered at that, under the influence of 

 such extreme temperatures, many collateral changes must take place. 

 The presence of by-products is at once perceived when the crystalline 

 contents of the digestion-tube are submitted to distillation in a current 

 of steam. Together with the vapour of water, a colourless oil is volati- 

 lized, consisting of hydrocarbons partly solid, partly liquid, the examina- 

 tion of which will form the subject of a future communication. Addi- 

 tion of an alkali to the liquid in the retort liberates considerable quan- 

 tities of monamines, which, when dried over sodium hydrate, are observed 

 to boil between 225° and 260°. By repeated distillation this range of 

 boiling is still considerably expanded ; at the same time, by far the largest 

 portion of the liquid is found to pass between 217° and 230°. The primary 

 nature not only of this main fraction, but also of the bases having both a 

 lower and higher boiling-point, is at once manifested by the crystallizing 

 power and insolubility of the salts which they produce. At whatever 

 stage of the distillation a drop of the liquid passing be mixed with dilute 

 hydrochloric or nitric acid, invariably splendid needles of chlorhydrates or 

 nitrates are formed, the solutions of which, even when considerably di- 

 luted, solidify with platinum perchloride to double salts generally well 

 crystallized. Another experiment rapidly indicating the primary character 

 of these monamines may here be mentioned. On adding benzoyl chloride 

 to the several basic fractions, much heat is evolved ; and after cooling 

 crystalline masses are produced, which are separated by water into soluble 

 chlorhydrates and insoluble benzoyl compounds which may be crystallized 

 from alcohol. None of the many secondary and tertiary monamines 

 which have passed through my hands in the course of this inquiry exhibit 

 this deportment ; and accordingly benzoyl chloride may be recommended 

 as a valuable reagent, readily applicable for primary bases. The method 

 of recognizing primary monamines which I pointed out some time 

 ago*, and which consists in converting them, by means of alcoholic 



* Hofmann, D. chem. Berichte, 1870, p. 767. 



