BENZYL PHOSPHINES AND THEIR DERIVATIVES. 589 



PAET II.— THE ACTION OF ALCOHOLS ON A MIXTURE OF PHOSPHORUS 



AND ITS IODIDE. 



The methods which have as yet been discovered for the preparation of the phosphines 

 and their derivatives are, as a rule, very tedious, troublesome, and unsatisfactory in point 

 of yield, — a fact which no doubt has considerably retarded the investigation of this 

 interesting group of organic compounds, and which soon becomes unpleasantly apparent 

 to any one who makes them a study. 



To the best of our belief the following are the only methods of any importance : — 



(1) Action of the Haloid Derivatives of Hydrocarbon Radicals on Metallic Phosphides. 

 — It was by this reaction that Paul Thenard # discovered the first members of the 

 phosphine group in 1843-1847. He experimented with chloride of methyl and phos- 

 phide of calcium, the investigation being attended with considerable difficulties, owing to 

 the labour involved in separating the different products and in obtaining them in a pure 

 state; also on account of their poisonous properties and their explosive and inflammable 

 nature. 



In spite, however, of these difficulties, Thenard apparently isolated trimethyl phos- 

 phine, a substance analogous to kakodyle, (CH 3 ) 4 P,, and methylated solid phosphide of 

 hydrogen (CH 3 ) 2 P 4 . The latter he described as an inert solid body, the second as a 

 spontaneously inflammable liquid, boiling at 250° C. — very explosive, poisonous, and 

 unstable. 



Thenard recognised the relationship of trimethyl phosphine to ammonia, and 

 predicted the existence of the then undiscovered organic compounds of nitrogen and 

 antimony. 



Wurtz in 1848, and Hofmann in 1850, verified Thenard's prediction by discovering 

 the compound ammonias ; and Lcewig and Schweitzer a little later obtained stibethyl. 



In 1855 Hofmann and CAHOURst investigated the action of iodide of methyl on 

 phosphide of sodium, and obtained, in addition to trimethyl phosphine and the phos- 

 phorised kakodyle of Thenard, iodide of tetramethyl phosphonium. They found that 

 the reaction was very energetic when iodide of methyl and phosphide of sodium were 

 heated together, and that inflammable and explosive substances were formed, rendering 

 the method dangerous, and exposing, as they said, the fruits of their labour to loss. 

 Moreover, it was unreliable, and furnished mixtures the separation of which presented 

 enormous difficulties. 



Berle I about the same time obtained triethyl phosphine by the action of phosphide 

 of sodium on iodide of ethyl, the former substance being prepared by heating sodium 

 and phosphorus together in rock oil. Iodide of ethyl only acted upon this at a high 

 temperature, and only very small quantities of the phosphine were produced. 



* Comptes Rendus, xxi. p. 144, and xxv. p. 892. 



t Hofmann and Cahours, Phil. Trans., 1857 ; and Ann. de Chim. et de Phys. (3), lxi. p. 5. 



| Bekle!, Jour. f. Prac. Chem., lxvi. p. 73. 



