&24 PROF. LETTS AND MR R. F. BLAKE ON 



(4) Tribenzyl Phosphine Oxide, (C 7 H 7 ) 3 PO . 



This body has been obtained by a number of different methods, among which are the 

 following : — 



(1) Action of benzyl chloride on phosphonium iodide (Fleissner).* 



(2) From the products of the action of benzyl chloride on phosphide of sodium 



(Letts and Collie) .1' 



(3) From the products of Hofmann's sealed tube reaction (between benzyl chloride, 



zinc oxide, and phosphonium iodide) (Letts and Blake)4 



(4) From the products of the action of benzyl alcohol on a mixture of phosphorus 



and phosphorus iodide (Letts and Blake). § 



(5) From the products of the action of benzyl alcohol on phosphonium iodide 



(Ledermann).|| 



(6) By the action of alkalies on salts of tetrabenzyl phosphonium (Letts and 



Collie).1T 



(7) By the action of heat on hydrate of tetrabenzyl phosphonium (Letts and 



Collie). ## 



(8) By the oxidation of the tertiary phosphine (Letts and BLAKE).tt 



(9) By the action of fused potash on dibenzyl phosphinic acid (Letts and Blake). tt 



Properties. — Crystallises in colourless highly refractive needles. These are some- 

 times thick, at others quite fine and silky. The body is soluble in alcohol, bisulphide of 

 carbon, glacial acetic acid, and chloroform ; almost insoluble in water and ether. When 

 heated it melts at 216°-216°'5 C. (corr.), and sublimes at a higher temperature with 

 considerable decomposition. 



It combines with hydracids, halogens, and chloride of platinum to form unstable and 

 possibly indefinite compounds, but its compound with iodide of zinc is stable and definite, 

 and so is its nitro body, its sulphonic acid, and some other derivatives. 



Bromide, either 7(C 7 H 7 ) 3 PO,5Br 2 or 5(C 7 H 7 ) 3 PO,4Br 2 . — This compound is highly 

 characteristic, and its production affords a ready means of identifying the oxide. It is 

 readily obtained by adding bromine to a solution of the oxide in glacial acetic acid, and 

 it crystallises in orange needles, which, when seen under the microscope, are found to 

 consist of aggregations of minute rhombic plates. It may be recrystallised from a warm 

 solution in glacial acetic acid (to which a little bromine is added). It is unstable, and 

 loses bromine when boiled with water or glacial acetic acid. It is instantly decomposed 



* Fsleisner, Berichte, xiii. (1880) 1665. + Letts and Collie, these Transactions, xxx. part 1, p. 202. 



J Letts and Blake, this communication, p. 554. § Letts and Blake, this communication, p. 599. 



|| Lkdermann, Berichte, xxi. (1888) 405a. IT Letts and Collie, loc. cit., p. 196. 



** Letts and Collie, loc. cit., p. 215. t+ Letts and Blake, this communication, p. 574. 



