Property and Preparation of Dithiophosphates

Dithiophosphates are firstly used as sulfide collector in 1925. The general expression of dithiophosphates is given as follows  

The types of dithiophosphates are many. Dithiophosphates are also called as black powder because the color of most dithiophosphates is black. And it is called as aerofloat in foreign reports. Dithiophosphates can be considered as the derivatives of diester phosphates when the two O atoms are substituted by two S atoms. 

Acid-form aerofloat is insoluble in water, but soluble in organic solvent. The dissociation of acid-form aerofloat in water can be given as follows  

Based on the testing of M.I. Kabachnik, the dissociation constants of acid-form 

But Last proposed that the dissociation constant of ethyl aerofloat acid was 2.3 X 10  

---