Mr Jones, Some substituted ammonium compounds, etc. Ill 



Some substituted ammonium compounds of the type NR'R"R^"X. 

 By H. O. Jones, B.A., Clare College (communicated by Mr Fenton). 



[Received 4 March 1901.] 



The isomerism of substituted ammonium compounds has long 

 been the subject of numerous researches; but until quite recently 

 no very definite positive results had been obtained. The course of 

 such investigations is much hampered and complicated, first, by 

 the peculiar mobility of groups attached to the nitrogen atom, 

 necessitating the use of ' heavy ' radicals to render the compounds 

 stable enough to shew isomerism, and further, by the great 

 difficulty or even impossibility of producing the desired com- 

 pounds in a crystalline state or even at all. 



Le Bel (Compt. Rend. cxn. 724) found that an ammonium 

 compound containing four different alkyl radicals acquired a small 

 but fugitive rotatory power under the action of moulds. No 

 isomerism was observed. This remained the only isolated obser- 

 vation on the optical activity of the nitrogen atom until 1899. 



Le Bel also observed certain differences of crystalline form in 

 compounds having three radicals the same. These were attributed 

 to dimorphism. 



Schryver and Collie (Chem. Neius LXIII. 174) prepared diethyl- 

 methylisoamylammonium chlorplatinate in the three possible 

 ways, and found that the crystalline form of one compound 

 differed from that of the other two. This difference however 

 readily disappeared on recrystallisation. 



Wedekind (Be?: xxxii. 517, 3561) found two definite and 

 stable isomers of phenylmethylallylbenzylammonium iodide. All 

 attempts to resolve these compounds into optically active portions 

 were unsuccessful. 



Pope and Peachey (Jour. Chem. Soc. 1899, lxxv. 1127) using 

 Reychler's dextro-camphorsul phonic acid, succeeded in resolving 

 one of Wedekind's compounds into two portions of equal and 

 opposite rotatory power. The optical activity is here due to the 

 asymmetric nitrogen atom. 



Of the many configurations which have been proposed for the 

 groups attached to the nitrogen atom, two seem to explain the 

 phenomena observed satisfactorily, namely Bischoff 's ' pyramidal ' 

 configuration, in which the five groups are supposed to be dis- 

 tributed around the nitrogen atom somewhat after the manner of 



9—2 



