Limited Oxidation of Ethyl-crotonic Acid. 291 



acid and the excess of trichloride of phosphorus. The phospho- 

 rous acid has a tendency to split up into phosphuretted hy- 

 drogen and phosphorous acid, thus : — 



4PH 3 3 =PH 3 + 3PH 3 4 . 



And P H 3 , acting on trichloride of phosphorus, is known to yield 

 phosphorous acid and hydrochloric acid, thus : — 



PH 3 + PC1 3 =2P + 3HC1. 



At any rate more than the theoretical quantity of trichloride is 

 required to convert the ether into the new compound. 



Ethyl- or ethocrotonic* ether and acid have been so fully de- 

 scribed that we have little or nothing to remark with regard to 

 them. We titrated the ether with the following result : — 



4*263 grms. required alcoholic potash equivalent to -96423 of 

 potassium. Therefore 100 parts of the ether neutralized 27*31 

 parts of potassium • theory requires 27*53. The ether was there- 

 fore pure. 



The acid was prepared from the ether, and subjected to the 

 action of bichromate of potash and sulphuric acid. An experi- 

 ment on an unknown quantity of substance proved that acetic 

 and carbonic acids were the sole products of the oxidation. This 

 determination was made by methods which have been fully de- 

 scribed elsewhere f. 



The only point remaining to be ascertained, therefore, was, 

 Does the ethyl-crotonic acid split up into two atoms of acetic 

 acid and two of carbonic, or into one atom of acetic acid and four 

 of carbonic ? To ascertain this, and at the same time to check 

 the non-quantitative portion of the work, a determination of the 

 amount of oxygen required to effect the change was made by the 

 method already described by one of us J. If the decomposition 

 took place so as to yield two atoms of acetic acid and two of car- 

 bonic acid, seven atoms of oxygen only would be required, whereas 

 the other decomposition would require eleven atoms. 



(1) C 6 H 10 O 2 + O 7 = 2C 2 H 4 O 2 + 2CO 2 + H 2 O. 



(2) C 6 H 10 O 2 + O u = C 2 H 4 O 2 + 4CO 2 + 3H 2 O. 



A known weight of the acid was sealed up with a known quan- 

 tity of a standard solution of bichromate in dilute sulphuric acid. 

 The tube was heated for some hours in the steam-bath. It was 

 then cooled and opened, and its contents transferred to a small 

 flask. The tube was washed out, and the washings also poured 

 into the same flask. The flask was heated in the water-bath, and 



* Frankland and Duppa, Chem. Soc. Journ. 1865, p. 133. 

 f Chapman and Thorp, Journ. of Chem. Soc. p. 477 (1866). 

 X Chapman, Journ. of Chem. Soc. 1867, p. 227. 

 U2 



