1888 - 89 .] Prof. Letts and B. Blake on Bibenzyl Phosphine. 199 
We have, we consider, all the necessary evidence to show that 
in Hofmann’s sealed tube reaction phosphuretted hydrogen acts 
upon chloride of benzyl as ammonia does on an alkyl iodide ; that 
is to say, that all of the following reactions occur : — 
(1) C 7 H 7 C1 + PH 3 = (C 7 H 7 )PH 2 .HC1 
(2) 2C 7 H 7 C1 + PH 3 = (C 7 H 7 ) 2 PH.HC1 + HC1 
(3) 3C 7 H 7 C1 + PH 3 - (C 7 H 7 ) 3 P.HC1 + 2HC1 
(4) 4C 7 H 7 C1 + PH 3 = (C 7 H 7 ) 4 PC1 + 3HC1 
With regard to the reaction (4) we are disposed to think that the 
oxide of tribenzyl-phosphine found by Hofmann, and mistaken by 
him for dibenzyl-phosphine (and by ourselves as well), owes its origin 
to the action of the potash on tetrabenzyl-phosphonium chloride or 
iodide, an action which H. Collie and one of us has already proved 
to occur easily in the following manner : — 
(C 7 H 7 ) 4 PC1 + KHO = (C 7 H 7 ) 3 PO + KC1 + C 7 H 8 
We may here mention that we have also isolated from the pro- 
ducts of Hofmann’s reaction all the possible oxidised derivatives 
which the whole series of benzyl-phosphines can give rise to, viz. 
(C 7 H 7 )H 2 P0 2 — Benzyl phosphinous acid. 
(C 7 H 7 )H 2 P0 3 — Benzyl phosphinic acid. 
(C 7 H 7 ) 2 HP0 2 -— Dibenzyl-phosphinic acid. 
(C 7 H 7 ) 3 PO. — Tribenzyl-phosphine oxide. 
5. We have also investigated the action of monobenzyl-phosphine 
on iodide of benzyl, with the view to obtaining pure dibenzyl- 
phosphine. 
The reaction occurs readily at ordinary temperatures, though no 
sensible heat is evolved, and a solid crystalline product results. 
Although some of this was found to contain the correct percentage 
of iodine for the formula (C 7 H 7 ) 2 HP.HI, it is either a mixture of 
three substances at least, — viz., dibenzyl-phosphine hydriodate, 
tribenzyl - phosphine hydriodate, and tetrabenzyl - phosphonium 
iodide, — or readily decomposes and give rise to them. On decompos- 
ing it with potash a colourless liquid results, together with a solid — 
the latter being undoubtedly oxide of tribenzyl-phosphine. The 
liquid when exposed to the air oxidises readily, and yields both 
dibenzyl - phosphinic acid and oxide of tribenzyl - phosphine. 
