BENZYL PHOSPHINES AND THEIR DERIVATIVES. 551 



A quantity of this solid was filtered off, washed with glacial acetic acid, and then 

 boiled with acetic acid until it dissolved. In dissolving it effervesced from the escape of 

 hydrobromic acid. As the solution cooled colourless plate-shaped crystals separated. 

 These were dried in vacuo, and analysed. 



Analysis. 



0-3639 gave 03300 AgBr = 01404 Br = 3858 per cent. 



80 j gave 0-2033 H 2 = 002258 H - 5'04 per cent. 

 ( „ 0-6799 C6„= 0-18542 C = 41-38 „ 





Obtained. 



Calculated for (C 7 H r )PH 2 .HBr 



Bromine, 



38-58 



3902 



Carbon, 



4138 



40-97 



Hydrogen, 



5-04 



4-88 



The crystalline solid was thus shown to be the hydrobromate of the phosphine, and 



all its properties pointed to the same conclusion. One or both of the following reactions 



must have occurred : — 



(C 7 H 7 )PH 2 +Br 2 =HBr + (C 7 H 7 )PHBr 



(C 7 H 7 )PH 2 + 2Br 2 = 2HBr + (C 7 H 7 )PBr 2 . 



The hydrobromic acid set free combining with the phosphine remaining in excess, and 

 thus the quantity of hydrobromate produced would increase until the bromine began to 

 be in excess, when, no doubt, it (the hydrobromate) was also attacked in the same way as 

 the phosphine itself. 



The mother-liquors from which the hydrobromate had separated ought to have 

 contained one or other of the two brominatecl derivatives whose formulae we have 

 written above, but we had not sufficient of the product to be able to isolate either of 

 them. 



On evaporation they left a solid crystalline mass, which dissolved in water (leaving a 

 few oily drops), and when the solution was neutralised with baryta and boiled, a crystal- 

 line salt was precipitated, having the appearance of benzyl phosphinate, but we did not 

 obtain it in sufficient quantity for analysis. 



Action of Bisulphide of Carbon on Monobenzyl Phosphine. — The following experi- 

 ments were made : — 



(1) 2 grms. of the pure phosphine were heated in a sealed tube with 2 grms. of 

 bisulphide of carbon at 120° C. for two days. The contents of the tube then consisted 

 of a viscous colourless substance and a number of colourless needle-shaped crystals. On 

 opening the tube a considerable quantity of sulphuretted hydrogen escaped. 



(2) About 4 "5 grms. of the phosphine and about 9 grms. of the bisulphide of carbon 

 were heated for two days at 130°-160°, when exactly the same phenomena were observed. 

 The contents of each of the two tubes were separately treated with bisulphide of carbon, 

 which dissolved the viscous substance, but left the crystals. The latter were repeatedly 

 washed with bisulphide of carbon, then dried and analysed. 



VOL. XXXV. PART II. (NO. 15). 4 X 



