BENZYL PHOSPHINES AND THEIR DERIVATIVES. 561 



of heat was also developed, sufficient indeed to cause the water mechanically mixed 

 with the product to boil. On cooling the product partly solidified. By recrystallising 

 it from alcohol several times, colourless rhombohedral crystals were obtained, identical 

 in form with tetrabenzyl phosphonium iodide, and having a melting point of 18 9° '5 

 (corr.) (that of the pure iodide being 189°). 



These results pointed to the conclusion that after all tribenzyl phosphine is not a 

 solid, but an oily liquid, which is sparingly soluble in alcohol, and that the spontaneous 

 oxidation and heating of the crystalline cake which we have mentioned was due to the 

 oxidation of liquid tribenzyl phosphine adhering to the solid oxide. In our next experi- 

 ment we proceeded somewhat differently. 



Experiment 2. — The contents of twelve sealed tubes were steamed, &c, and 30 grms. 

 of crude primary phosphine obtained. The viscous residue was twice steamed with fresh 

 quantities of water to remove the hydracids and zinc salts. It was then boiled in the 

 flask A with 50 grms. of caustic potash and about 300 c.c. of alcohol for an hour. The 

 tube D was now pushed down below the alcbolic solution, while L was connected with 

 a condenser and the condenser B removed, and a cork substituted for it. Steam was next 

 blown through D until all the alcohol was distilled off and a good deal of water had 

 condensed in A. At the bottom of this was a layer of oxide of zinc, while above it an 

 oily layer floated. The whole was allowed to cool in a current of hydrogen, when the 

 oily layer solidified. A was now inverted, and a current of cold water run in through D, 

 and allowed to run out through L. By this means the solidified oily matter was 

 thoroughly washed without coming in contact with air, and freed from potash and oxide 

 of zinc. Experiments tried with it showed that it reacted energetically with iodide 

 of benzyl, giving tetrabenzyl-phosphonium iodide, also that it dissolved for the greater 

 part in a hot solution of hydriodic acid of constant boiling point, and the solution after 

 filtration through asbestos deposited a bulky crystalline precipitate. It was also found 

 that ether dissolved the greater portion of the solidified oil, but left an insoluble 

 crystalline solid. 



We therefore treated the whole of the solidified oil with ether, and filtered the solution 

 from the solid crystalline mass remaining. The latter, when extracted with spirit and 

 the solution crystallised, gave oxide of tribenzyl phosphine, which was identified by its 

 melting point, 215°-215° # 5, and other properties. 



Now as all the operations had been conducted out of contact with air, this substance 

 could not have been formed by the oxidation of tribenzyl phosphine. We shall consider 

 its probable origin later on. 



We decided to precipitate the ethereal solution with gaseous hydriodic acid, and to 

 examine the crystalline hydriodate which we anticipated would be that of the tertiary 

 phosphine. In a preliminary experiment, we easily obtained a bulky crystalline precipi- 

 tate. This, after washing with ether, was dissolved in hot solution of hydriodic acid, the 

 solution filtered through asbestos, and allowed to cool, when a colourless bulky crystalline 

 precipitate formed. This was thrown into a funnel plugged with glass wool, then drained 



