592 PROF. LETTS AND MR R. F. BLAKE ON 



is liberated, which then acts upon phosphuretted hydrogen in the same way as it acts 

 upon ammonia. Hofmann had thus discovered a simple and elegant general reaction 

 for the preparation of tertiary and quaternary compounds, which he employed successfully 

 in the methyl,* ethyl,t propyl, J butyl,§ and amyl|| series. 



But the primary and secondary bases were still wanting, though the possibility of 

 their existence could scarcely be doubted in view of the well-established analogies exist- 

 ing between the derivatives of ammonia and phosphuretted hydrogen. Hofmann there- 

 fore again took up the matter, and began a new series of investigations which led to 

 brilliant results. 



The direction of these new experiments was, as he says, clearly indicated, for as both 

 the tertiary and quaternary derivatives are obtained by direct substitution from phos- 

 phuretted hydrogen, so also ought the primary and secondary bases to be produced. For 

 if three and four molecules respectively of the alcohol can be made to react upon one 

 molecule of phosphonium iodide, one and two molecules ought also to react in a similar 

 manner under suitable conditions — 



(1) PH 4 I + C 2 H 6 =(C 2 H 5 )PH 2 .HI + H 2 0. 



(2) PH 4 I + 2C 2 H 6 = (C 2 H 5 ) 2 PH.HI + 2H 2 . 



Hofmann IT therefore sought to achieve the desired object by altering the proportions 

 of phosphonium iodide and alcohol, but without success, the tertiary base being alone 

 produced, or a mixture of the tertiary and quaternary compounds ; while, with the 

 proportions required for the second of the above equations, the tubes invariably exploded. 



In the meantime Drechsel and Finkenstein ## believed that they had succeeded in 

 obtaining the primary bases of the ethyl and methyl series by saturating the iodides of 

 those radicals with phosphuretted hydrogen, and allowing the solutions to remain for 

 some time at ordinary temperatures or by heating them to 100° C. Under these 

 conditions a crystalline body was obtained, which was not phosphonium iodide, as it 

 dissolved in water without evolution of gas, and which they therefore concluded to be 

 the hydriodate of the primary base. 



Also, by heating an ethereal solution of iodide of zinc saturated with phosphuretted 

 hydrogen, with iodide of methyl, they believed that they had obtained the same 

 substance. 



Hofmann tt repeated these experiments, and showed that the primary bases were not 

 formed at all, whereas the tertiary and quaternary derivatives were. 



The idea then occurred to him of heating the alkyl iodide with iodide of phosphonium 

 in presence of a metallic oxide, with the happiest results ; for on heating a mixture of 

 phosphonium iodide, ethyl iodide, and oxide of zinc, in the proportions of two molecules 

 of each of the former to one molecule of the latter in sealed tubes at 150°C. for from six to 



* Hofmann, Berichte, iv. (1871) p. 209. t Hofmann, Berichte, iv. (1871) p. 205. 



\ Ibid., Berichte,, vi. (1873) p. 292. § Ibid., Berichte, vi. (1873) p. 296. 



|| Ibid., Berichte, vi. (1873) p. 297. 1 Ibid., Berichte, iv. (1871) p. 372. 



** Drechsel and Finkenstein, Berichte, iv. (1871) p. 352. tt Hofmann Berichte, iv. (1871) p. 372. 



