Tetrethylpliosphonium and their Decomposition by Heat. 187 



They possessed the following properties ; they easily volati- 

 lized with water vapour, had a melting-point of 94° C, and 

 when heated with sodium yielded triethylphosphine and 

 sulphide of sodium. These properties indicate that the com- 

 pound was sulphide of triethylphosphine, which was further 

 verified by a determination of sulphur : 



0*526 grm. gave 0*840 BaSO 4 = 0*1106 S = 21*03 per cent. 

 Calculated for (C 2 H 5 ) 3 PS 21*33 per cent. 



The mother liquors from which the sulphide of triethyl- 

 phosphine had separated were evaporated to a small bulk and 

 caustic soda added, when an oily layer separated, containing 

 only a trace of the sulphide. This was removed by redis- 

 solving the oily layer in a small quantity of water, and filtering. 

 Caustic soda was then added to the solution, and the oily 

 layer which separated was then decanted and submitted to 

 distillation. 



The temperature rose rapidly to 240° C, between which 

 and 244° C. the distillate solidified. The boiling-point,, appear- 

 ance, and other properties left no doubt as to its consisting of 

 oxide of triethylphosphine ; but to be perfectly certain that 

 such was its composition, some of it was converted into the 

 highly characteristic double salt which it forms with zinc 

 iodide, in which a determination of iodine was made. 



0*421 grm. required 14*5 cubic centim. of decinormal 

 nitrate of silver solution = 0*18415 grm. iodine = 43*74 per 

 cent. 



Calculated for 2 {(C 2 H 5 ) 3 PO}, Znl 2 . . . = 43*27 percent. 



The gas collected during the decomposition did not turn 

 lime-water milky, nor was it attacked by bromine. It burned 

 with a luminous flame. The wash-water contained traces of 

 sulphurous acid. 



Another experiment was performed in order to see whether 

 any other substances besides the oxide and sulphide of 

 triethylphosphine could be isolated. 



14 grms. of the iodide of tetrethylphosphonium were con- 

 verted into sulphate, and the latter submitted to the action of 

 heat. 3*5 grms. of sulphide, and 30 grms. of oxide of 

 triethylphosphine were obtained ; the theoretical yield [on the 

 assumption that 



{(C 2 H 5 ) 4 P} 2 S0 4 gives (C 2 H 5 ) 3 PS, and (C 2 H 5 ) 3 PO], 



is 3*8 grms. of the former and 3*4 grms. of the latter. ~No 

 other substances could be isolated, so that there can be little 

 doubt that most of the phosphonium salt is decomposed into 



