Hydrolysis of 8-quinolyl phosphate monoester: kinetic and theoretical studies of the effect of lanthanide ions.
8-Quinolyl phosphate (8QP) in the presence of the trivalent lanthanide ions (Ln = La, Sm, Eu, Tb, and Er) forms a [Ln x 8QP]+ complex where the lanthanide ion catalyzes hydrolysis of 8QP. In reactions with Tb3+ or Er3+, there is evidence of limited intervention by a second lanthanide ion. Rate constants are increased by more than 10(7)-fold, and kinetic data and B3LYP/ECP calculations indicate that the effects are largely driven by leaving group and metaphosphate ion stabilization. The lanthanides favor a single-step D(N)A(N) mechanism with a dissociative transition state, with limited nucleophilic assistance, consistent with the low hydroxide ion dependence and the small kinetic effect of Ln3+ radii.
Souza
Bruno S
BS
Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, 88040-900, Brazil.
Brandão
Tiago A S
TA
Orth
Elisa S
ES
Roma
Ana C
AC
Longo
Ricardo L
RL
Bunton
Clifford A
CA
Nome
Faruk
F
D002384:Catalysis; D006868:Hydrolysis; D006912:Hydroxyquinolines / Q000138:chemical synthesis / Q000737:chemistry; D007700:Kinetics; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D010755:Organophosphates / Q000737:chemistry*; D011199:Potentiometry; D011804:Quinolines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D017186:Titrimetry
C517653:8-quinolyl phosphate; D006912:Hydroxyquinolines; D028581:Lanthanoid Series Elements; D010755:Organophosphates; D011804:Quinolines