1872.] Dr. A. W. Hofmann on the Phosphorus Bases. 235 



The secondary phosphines readily dissolve in acids. The salts, as far as 

 my experience goes, are difficult to crystallize, with the exception of the 

 iodhydrate. The solution of the chlorhydrate gives, with platinum per- 

 chloride, a fine platinum salt, crystallizing in orange-red prisms, which are, 

 however, easily changed. It is interesting to perceive that the salts of 

 diethylphosphine resist the action of water, whilst those of the mono- 

 ethylated base are readily decomposed ; the deportment of the phosphines 

 is thus seen to afford an instructive illustration of the increased basicity 

 the phosphoretted molecule acquires with the number of ethyl groups it 

 has incorporated. 



Products of Oxidation of the Primary and Secondary Ethylphosphines. 



It is my intention to study in detail the products of oxidation of ethyl- 

 and diethylphosphine, which, according to special circumstances, appear 

 to vary to a considerable extent. Hitherto I have examined only the 

 terminal compounds. These are perfectly analogous to the products simi- 

 larly obtained from the methylated bases ; they need not therefore be more 

 than cursorily mentioned. 



Ethylphosphinic Acid. — -Preparation, appearance, and properties of the 

 body obtained by the action of nitric acid upon ethylphosphine resemble 

 in every respect the acid similarly obtained from methylphosphine, and 

 described in a previous communication (comp. p. 228). The ethyl com- 

 pound is likewise exceedingly soluble in water, alcohol, and ether ; it fuses 

 at 44°, and may be distilled without decomposition. The formula 



C,H r P0 1 = (C,H,)H 1 PO, 

 was fixed by the analysis of a silver-salt. This salt was formed by satu- 

 rating the free acid partially with silver oxide, and precipitating the con- 

 centrated liquid by alcohol. It is an amorphous, yellowish powder, in- 

 soluble in Wiiter and alcohol, the composition of which is represented by 

 the formula 



(O a H.) Ag 3 P0 3 . 



Biethylphosphinic Acid. — On treating diethylphosphine with nitric 

 acid, all the phenomena present themselves which are observed in the 

 corresponding experiment in the methyl series. The acid produced, how- 

 ever, has been observed as yet in the liquid state only ; it refuses to solidify 

 even at a temperature of —25°. The composition of the acid, 



C 4 H n PCX = (C, H„) a H P0 2 , 

 was established by the analysis of a silver compound. The latter was 

 obtained by nearly neutralizing the acid by silver oxide and precipitating 

 the evaporated liquid by alcohol. The silver diethylphosphinate contains 



C 4 H 10 Ag PO a = (C„ H,) a Ag PO a . 

 The products of oxidation of the ethylated phosphorus bases are thus 

 proved to be perfectly analogous to the group of methyl bodies previously 

 described (p. 232), as seen by glancing at the following Table : — 



