W. A. Drushel — Simple and Mixed Alkyl Phosphates. 643 



Art. XLY. — On Simple and Mixed Alkyl Phosphates ; by 



W. A. Drushel. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — celxxvi.] 



When a sodium alcoholate free from the alcohol is treated 

 with the theoretical amount of phosphorus oxychloride at 

 room temperature in the presence of ether a good yield of the 

 corresponding trialkyl phosphate is obtained.* By means of 

 this reaction Lossen and Kohlerf in 1891 prepared trimethyl 

 phosphate, triethyl phosphate, and from these esters they pre- 

 pared by a method to be described the mixed esters, dimethyl- 

 ethyl phosphate and methyl-diethyl phosphate. They studied 

 these simple and mixed alkyl phosphates with special reference 

 to their behavior toward barium hydroxide at room tempera- 

 ture. From their observations they drew the following con- 

 clusions: 



(1) That the esters of phosphoric acid are far more stable 

 than the esters of organic acids toward aqueous barium 

 hydroxide. 



(2) That the salts of dialkyl phosphoric acids are much more 

 stable than the trialkyl phosphates. 



(3) That more than one alkyl group of a trialkyl phosphate 

 may be hydrolyzed off only with the greatest difficulty, if at 

 all. 



(4) That the decomposition of mixed alkyl phosphates by 

 aqueous barium hydroxide proceeds in an unusual manner, in 

 that in mixed alkyl phosphates one alkyl group is hydrolyzed 

 off to the exclusion of the other. Apparently the same 

 methyl-ethyl-barium phosphate was obtained by these inves- 

 tigators by the action of barium hydroxide upon both methyl- 

 diethyl phosphate and dimethyl-ethyl phosphate. 



The purpose of the present investigation was to prepare a 

 larger number of the simple and mixed esters of orthophos- 

 phoric acid, to study their properties and rates of hydrolysis in 

 decinormal hydrochloric acid, and to examine the validity of 

 Lossen and Kohler's fourth conclusion since this conclusion is 

 contrary to the rule observed in the case of esters of dibasic 

 and polybasic organic acids. In general the methods described 

 by Lossen and Kohler were used in the preparation of the 

 esters prepared and studied in this investigation. For the 

 preparation of the simple esters sodium alcoholate in each case 

 was prepared by dissolving a weighed amount of pure metallic 

 sodium in a sufficient excess of the desired alcohol. After the 

 sodium was completely used up the excess of alcohol was dis- 

 tilled off in an oil bath, heating the bath finally at 180° as 



*Limpricht, Ann. Chem. Pharm., cxxxiv, 347. 

 f Ann. Chem. Pharm., colxii, 209-14. 



