572 PROF. LETTS AND MR R. F. BLAKE ON 



steamed for about an hour, while a current of carbonic anhydride passed at the same 

 time to prevent oxidation. 



The oily liquid which resulted was washed two or three times with water, afterwards 

 with a dilute and cold potash solution, and then shaken up with ether. A white powder 

 remained undissolved, which was dissolved in a little hot alcohol. The solution deposited 

 on cooling crystals having the characteristic form of tetrabenzyl phosphonium iodide. 

 But we did not obtain sufficient for investigation. 



The results of the above experiments are curious and interesting. We think that only 

 one conclusion can be drawn from them, namely, that the primary phosphine acts upon 

 iodide of benzyl in the same manner that ammonia does upon an alkyl iodide, the three 

 following reactions occurring : — ■ 



(1) (C 7 H 7 )PH 2 + C 7 H 7 I = (C 7 H 7 ) 2 HPHI 



(2) (C 7 H 7 )PH 2 + 2C 7 H 7 I = (C 7 H 7 ) 3 P.HI + HI 



(3) (C 7 H 7 )PH 2 + 3C 7 H 7 I - (C 7 H 7 ) 4 PI + 2HI . 



Thus confirming the results of our investigation of Hofmann's sealed tube reaction (see 

 p. 566). 



The only other explanation, viz., that the primary phosphine used contained both the 

 secondary and tertiary bases as impurities, is, we venture to think, untenable, for it had 

 been repeatedly rectified, and the boiling points of di- and tri-benzyl phosphine, as we 

 have shown, are at very high temperatures — so high indeed that they decompose almost 

 completely when distilled. Moreover, in our experiments on the oxidation of the primary 

 phosphine, no dibenzyl phosphinic acid nor tribenzyl phosphine oxide were obtained, 

 and we should certainly have noticed them had they been produced. These views have 

 been materially strengthened by our experiments on the action of chloride of benzyl on 

 the primary phosphine. 



Action of Chloride of Benzyl on Monobenzyl Pliosphine — Experiment 1. — Five grms. 

 of the primary phosphine (boiling point 175°-185°) were placed in a tube previously filled 

 with carbonic anhydride, and 5 grms. of chloride of benzyl were added. The tube was 

 then sealed and left for a night, but no signs of any reaction having occurred were 

 apparent. The tube was then heated for about six hours at 130° C. Its contents then 

 consisted of a somewhat viscous liquid, and on opening pressure was observed. 



A quantitative oxidation experiment was made with the product. 4 '3255 grms. 

 were evaporated with water in a dish. It fumed, and the mass quickly grew crystal- 

 line. The product was crystallised once from alcohol, and then had a melting point 

 of 213°, and all the appearance of oxide of tribenzyl phosphine. It weighed 0*8373 grms. 

 The alcoholic mother-liquors solidified when warmed with baryta solution, and the solid 

 mass thus obtained appeared to consist of crude tribenzyl phosphine oxide also. It 

 weighed when dry 0*8623 grms. The aqueous extracts and the baryta solution filtered 

 from the crude oxide gave scarcely a trace of dibenzyl phosphinic acid, but they 

 gave the reactions of benzyl phosphinous acid. 



