610 



XIV. " Researches on the Phosphorus-Bases." No. X. Meta- 

 morphoses of Bromide of Bromethylated Triethylphospho- 

 nium. By A. W. HOFMANN, LL.D., F.R.S. Received 

 July 24, 1860. 



Among the several products of transformation into which the bro- 

 mide of bromethyl-triethylphosphonium is converted when submitted 

 to the action of reagents, the substances formed by its union with 

 bodies similar to ammonia, have hitherto almost exclusively occupied 

 my attention. I have, however, of late examined a variety of other 

 changes of this body, which deserve to be noticed. 



When heated, the bromide begins to evolve hydrobromic acid at a 

 temperature of about 200, which continues for a considerable length 

 of time. The product of this reaction is evidently the bromide of 

 vinyl-triethylphosphonium, 



[(C, H 4 Br)(C 2 H 3 ) 3 P] Br=H Br+ [(C, H 3 ) (C, H s ) 3 P] Br. 



It is, however, difficult to obtain the substance pure by this process, 

 since the temperature at which the last portion of hydrobromic acid 

 is eliminated closely approximates the degree of heat at which the 

 vinyl-body is entirely destroyed ; and since the latter compound may 

 be obtained with the greatest facility by other processes*, I have 

 not followed up any further this direction of the inquiry. 



I have already mentioned, in a previous note, the deportment of 



* The hydrated di-oxide of ethylene-hexethyl-diphosphonium, when submitted 

 to distillation, undergoes decomposition ; two different phases are to be distin- 

 guished in this metamorphosis. At about 200 the base begins to disengage the 

 vapour of triethylphosphine, the residuary solution retaining hydrated oxide of 

 vinyl-triethylphosphonium , 



[(C, H 4 )"(C 2 H 5 ) 6 P]"o 2 = (C 2 H a ) 3 P+H 2 0+( C * H >) V* H *>3 P O, 



the latter yielding at a higher temperature the oxide of triethylphosphine together 

 with ethylene, 



C(C 2 H 3 ) (C 2 H 5 ) 3 P] 1 = c 2 H 4 +(C 2 H 5 ) 3 PO. 



The vinyl-compound is even more readily obtained by the action of silver-salts, 

 such as acetate of silver, at the temperature of 100, on the bromethylated 

 bromide. 



