BENZYL PHOSPHINES AND THEIR DERIVATIVES. 571 



The percentage weights of the oxidised products referred to the weights of the original 

 liquid are as follows : — 

 From — 



/P IT \PTT J ( C 7 H 7) PH 2°2 .... 18-8 



^ 7 n 7 ;r±i 2 .... { (C 7 H 7 )PH 2 3 .... ? 



(C 7 H 7 ) 2 PH .... (C 7 H 7 ) 2 PH0 2 653 



(C 7 H 7 ) 3 P .... (C 7 H 7 ) 3 PO 7-84 



Experiment 4. — 22 grms. of benzyl iodide were placed in a flask, and the latter filled 

 with carbonic anhydride, and 12 grms. of the phosphine (several times rectified and 

 boiling from 175°- 185° C.) were then added. The mixture was very slightly warmed, so 

 as to melt the iodide of benzyl, and then agitated to ensure thorough mixing. 



Although the crystallised benzyl iodide had been dried as far as possible by pressure 

 between filter-paper, it must have been wet, as small drops of water were distinctly 

 visible in the mixture. 



The flask containing it was loosely corked, and set aside. In about ten minutes 

 solidification commenced and proceeded gradually, but suddenly, after the lapse of about 

 twenty minutes more, the partially solidified mass grew hot, and emitted a cloud of 

 hydriodic acid. It was left at rest for some hours, and had by that time become brown 

 at the edges. It was now removed from the flask, pounded up, and repeatedly washed 

 with ether until nothing further was extracted. The product consisted of a snow-white 

 powder. It was dried by pressure between filter-paper and finally in vacua. 



The following experiments were made with it : — 



(1) 4 '69 3 grms. were mixed with caustic potash solution, and the mixture evaporated 

 to dryness on a water bath ; redissolved in water, again evaporated, and so on two or three 

 times to ensure complete oxidation. The residue was then treated with water, and 

 the solution filtered from the colourless insoluble matter which remained. 



The solution and washings were then precipitated with hydrochloric acid, when an 

 abundant precipitate of dibenzyl phosphinic acid separated which, when washed and 

 dried, weighed T304 grms. It was identified by its melting point, which after one 

 crystallisation from alcohol, was found to be 193°. 



The insoluble matter was dried, and weighed 0*816 grms. After one crystallisation 

 from alcohol, it had melting point of 211°, that of oxide of tribenzyl phosphine 

 being 2 15° "5. 



Calculating from these numbers the quantities of dibenzyl phosphine hydriodate 

 and tribenzyl phosphine hydriodate in the original product, the first would amount to 

 about 38 per cent., the second to about 23 per cent. 



(2) We wished to ascertain with certainty whether the product contained, in addition 

 to the secondary and tertiary compound, the quarternary iodide also. As the latter gives 

 the oxide when boiled with potash solution, we decided to decompose the product with 

 water. Accordingly, the remainder of it was placed in a small separating funnel, and 



