Linear free energy relationships on rate constants for dechlorination by zero-valent iron.
By correlation analysis, molecular structural factors governing surface area-normalized rate constants (k) for dechlorination by zero-valent iron, were identified. Twenty-nine quantum chemical descriptors computed by MNDO, AM1 and PM3 Hamiltonians for gas-phase and the conductor-like screening model (COSMO) for incorporating solvent (H2O) effects were studied. Besides the energy of the lowest unoccupied molecular orbital (E(LUMO)), the character of carbon-chlorine bonds (C-Cl bonds) and especially the strength of C-Cl bonds was found significant in governing the magnitude of log k. By PLS analysis, six two-parameter linear free energy relationships (LFER) were obtained. The best two-parameter LFER model was the one using E(LUMO) and C (the Coulombic interaction energy of the two-center term for the C-Cl bonds) computed by PM3/H2O method as molecular structural descriptors. Chlorinated compounds with high E(LUMO) and C values tend to have low dechlorination rate constants.
Chen
J
J
School of Environmental Science and Technology, Dalian University of Technology, Zhongshan Road 158-129, Dalian 116012, People's Republic of China. jwchen@dlut.edu.cn
Pei
J
J
Quan
X
X
Zhao
Y
Y
Chen
S
S
Schramm
K W
KW
Kettrup
A
A
D002244:Carbon / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002713:Chlorine / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D012044:Regression Analysis; D055672:Static Electricity; D013816:Thermodynamics
D002713:Chlorine; D002244:Carbon; D007501:Iron