f)40 PROF. LETTS AND MR R. F. BLAKE ON 



which is a well-defined crystalline body, having neither basic nor acid properties, soluble 

 in alkalies with decomposition, and also decomposed when heated with acids. It 

 dissolves, however, without change in glacial acetic acid, and crystallises out on cooling. 

 Boiled with water, it is decomposed into the substances from which it was originally 

 produced. It forms crystalline compounds with aniline, phenyl hydrazine, and toluene 

 diamine. 



On reading over the above, it will be seen that, although a fair amount of work has 

 been done with the phosphines, they have by no means been exhaustively studied, and 

 that many of their properties and reactions remain to be investigated. It was our wish 

 to fill up some of these gaps in their history, and we chose the benzyl phosphines for 

 investigation for several reasons, among which was the fact that the primary 

 phosphine is a liquid at ordinary temperatures, also on account of the well-known 

 chemical activity of the benzyl compounds, and partly because one of us and N. Collie 

 had already studied somewhat exhaustively the compounds of tetrabenzyl phosphonium. 

 Hofmann* was the first to obtain monobenzyl phosphine, and as he believed di- 

 benzyl phosphine also, by heating a mixture of chloride of benzyl, phosphonium iodide, 

 and oxide of zinc in sealed tubes. He apparently submitted the two substances to a 

 somewhat cursory examination, and only determined their leading properties. He 

 mentions that bye products are formed, but these he did not investigate. 



We have repeated Hofmann's experiments, and have submitted both the primary 

 phosphine and also the substance which he regarded as the secondary derivative to a 

 very careful examination. We have also isolated the other products and bye products 

 of the reaction, and have determined their composition, and as far as possible their pro- 

 perties also. In the course of the research we incidentally discovered a method for 

 preparing all the products of the oxidation of the benzyl phosphines. We describe this 

 method, and also the properties of the oxidised substances. 



Monobenzyl Phosphine and its Derivatives. 



Preparation of Monobenzyl Phosphine. — Hofmann recommends digestion during six 

 hours at 160° C. of a mixture of 4 parts of oxide of zinc, 16 of iodide of phosphonium, 

 and 12 of chloride of benzyl. Experiments conducted in this way with commercial 

 chloride of benzyl from Kahlbaum gave in the tubes a viscous semicrystalline mass. To 

 obtain a good result, thorough mixing of the materials in the sealed tubes by shaking 

 before heating seemed to be necessary. On opening the tubes much phosphuretted 

 hydrogen escaped, but on heating for a longer period or to a higher temperature, the 

 escaping gas seemed to consist of hydrochloric acid only. It was soon found that at the 

 temperature of 160° O, a great deal of hydrochloric acid is formed, and but little of the 

 primary phosphine. The best results were obtained by a six hours' digestion of the 



* Hofmann, Berichte, v. (1872) p. 100. 



