title: Studies on beta-type reaction and kinetics of lanthanides with p-bromochloroarsenazo.
abstract: The reaction behaviour of the beta-type chelates of lanthanide ions (Ln(3+)) with p-bromochloroarsenazo (4-CAsA-pB) in 0.01 mol l(-1) HClO(4) solution has been studied systematically by a spectrophotometric method. All the lanthanide ions can form beta-type chelates with p-bromochloroarsenazo. The maximum absorption wavelength is in the range 727-731 nm, the molar absorptivities are about 6.0 x 10(4) - 9.0 x 10(4) cm(2) mol(-1), the composition ratio of Ln(3+) ions with 4-CAsA-pB is 1:2 and the actual combining ratio is 2:4. The optimum acidity range (DeltapH value) of the formation of beta-type chelates has been obtained. Kinetic parameters, such as the reaction order and rate constants, have also been studied and a formation mechanism for the beta-type chelates has been proposed.
authors.affiliation: Institute of Chemistry, Northwest Normal University, Lanzhou 730070, China.
authors.forename: J
authors.initials: J
authors.lastname: Gao
authors.forename: F
authors.initials: F
authors.lastname: Zha
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Kang