600 



PROF. LETTS AND MR R. F. BLAKE ON 



formed. It is, however, very difficult, if not indeed impossible, to gain a complete insight 

 into the changes which occur. But, on the other hand, it is easy to write a set of 

 equations to account for the formation of the different products. Thus, the following may 



be written: — 



(1) PI 2 +C 7 H 7 OH + H 2 = (C 7 H 7 )H 2 P0 2 +HI + I. 



(2) PI 2 + C 7 H 7 OH + 2H 2 + 1 = (C 7 H 7 )H 2 P0 3 + 3HI . 



(3) PI 2 +2C 7 H 7 OH =(C 7 H 7 ),HPO„+HI + I. 



(4) PI 2 +3C 7 H 7 OH + HI = (C 7 H 7 ) 3 PO + 2H 2 + 3I. 



(5) PI 2 +4C 7 H 7 OH + 4HI =(C 7 H 7 ) 4 PI + 4H 2 + 5I. 



(6) PI 2 +2H 2 



(7) PI 2 +4H 2 0+3I 



(8) 2HI + C 7 H 7 OH 



(9) P+I 2 



= H 3 P0 2 +HI + I. 

 = H 3 P0 4 +5HI. 

 = C 7 H 8 + H 2 + I 2 . 

 = PL. 



Let us next compare the quantities of the different substances actually obtained with 

 those required for the above reactions, remembering that the "balance sheet" will be 

 extremely rough. In Experiment 3 the following were the quantities employed and 

 produced : — 



Employed in the Reaction. 



Produced by the Reaction. 



Phosphorus, 



555 



Crude monobenzyl phosphinic acid, 



600 







„ dibenzyl „ „ 



53 5 







„ tribenzyl phosphine oxide, 



300 







„ toluol, 



450 



Iodine, ... . 



94-5 



Hydriodic acid (calculated), 

 Phosphoric acid (calculated from 50 



952 







grms. BaHP0 4 ), 



21-0 



Benzyl alcohol, ..... 



1590 



Amorphous phosphorus, 



35 





309 





339-7 



The quantities of phosphorus, water, and benzyl alcohol, taking part in the reaction, may 

 be accounted for as follows : — 



Phosphorus — 



Taken, 

 Remaining, 



55 - 5 grms. 

 350 „ 



Used up in the reactions, . . 20 - 5 „ 

 The phosphorus used up in the reactions is accounted for thus — 



60 grms. (C 7 H 7 )H 2 P0 3 



contains 



10*8 phosphorus 



53-5 „ (C 7 H 7 ) 2 HP0 2 



?» 



6-7 



300 „ (C 7 H 7 ) 3 PO 



» 



2-9 



500 „ BaHP0 4 



!> 



6-6 



270 



