BENZYL PHOSPHINES AND THEIR DERIVATIVES. 583 



phosphinic acid. To obtain them as pure as possible, they were dissolved up by warming, 

 and a current of sulphuretted hydrogen passed through the solution until the whole of 

 the mercury was precipitated. On filtering the hot solution and allowing it to cool the 

 scaly crystalline compound again came down, and a little more of it was obtained on 

 evaporating its mother-liquors. The whole was then recrystallised from water, in which 

 it was very sparingly soluble. 



It was identified as dibenzyl phosphinic acid by its melting point 193° (that of 

 the pure acid being 192° C), by its solubility relations, by its crystalline form, and 

 also, though not very satisfactorily, owing to the small quantity at our disposal, by a 

 combustion. 



Analysis. 



( 01477 H 2 = 0016411 H= 619 per cent. 

 0-647 gave -^ . 6507 C0 „ = 0-177463 C = 6704 „ 





Obtained. 



Calculated for (C 7 H 7 ) 2 HP0 2 



Carbon, 



67-04 



68-29 



Hydrogen, . 



619 



6-09 



We have been unable to go any further with our investigations, as the whole stock of 

 crystalline oil at our disposal became exhausted, and, as we have before stated, we are 

 still in doubt as to its composition. 



That it is an oxidised derivative is shown by the deficiency which remains when the 

 percentages of the constituents both of it and of its cadmium iodide compound (which were 

 actually determined) are added together. 



There can also be no doubt that it gives rise to dibenzyl phosphinic acid when 

 oxidised, and therefore in all probability it contains the element of dibenzyl phos- 

 phine. 



It will be noticed that of the eight analyses made of the crystalline oil itself, Nos. II., 

 III., and IV. agree fairly well with each other, but differ from Nos. V., VI., VII., and 

 VIII. , which also agree (though not so closely) with each other. Thus — 



Mean of II., III., and IV. Mean of V, VI., VII., and VIII. 



Carbon, .... 71*50 7301 



Hydrogen, . . . 6"87 7-14 



The first set of analyses agree with the formula C 13 H 15 PO, so far as the percentage amounts 

 of carbon and hydrogen are concerned, while the second set agree in a similar manner with 

 C 15 H 17 PO. The percentage amount of phosphorus, however, from Nos. VII. and VIII. 

 agrees with the first formula. Thus — 



o 







Obtained. 



Calculated for 



Carbon, 

 Hydrogen, . 

 Phosphorus, 



VOL. XXXV. PART II. (NO. 



I. 

 71-50 



6-87 



15). 



II. 



73-42 



7 23 



1406 



C 13 H 15 PO 

 71-56 

 6-88 

 1442 



C 16 H 17 PO 



73-30 



697 



12-70 



5 B 



