Reaction and kinetics in system of rare earths with p-hippurochlorophosphonazo

The beta-type reactions, in which rare earth ions react with chlorophosphonazo, reagents, are extremely sensitive and have been applied widely to determination of rare earths. The reactions and kinetic behavior of the beta-type homo- and iso-nuclear chelates of rare earth with p-hippurochlorophosphonazo (CPA-pHA) have been investigated by a spectrophotometric method. Some kinetic parameters, such as the reaction rate constants, the half lives and the activation energies, were measured. The competing reactions between lanthanoid ions forming and non-forming beta-type chelates were also studied. The effects and trends of different organic solvents on the beta-type chelates have been discussed. A reaction mechanism of beta-type chelates has been proposed.