CurtinHammett principle

1
Topics
Curtin-Hammett principle intramolecular
electron transfer cyclic voltammetry Nernst
equation steady state kinetics relative rates
of cyclization Thorpe-Ingold effect
2
Despite the doom forecast by these values, the
tetra- hydropyran forms in a respectable
yield! How can this be understood?
Duan Moeller, JACS, 2002, 124, 9368
3
intramolecular electron transfer
Curtin-Hammett principle exemplified
4
What tool(s) is(are) available?Cyclic
voltammetry
Peak potential
Switching potential
Oxidation begins i.e., -e
Electron is beginning to be returned i.e., e
5
Ep/2 (V)
1.42
1.40
1.10
1.20
1.30
Moeller Tinao, J. Am. Chem. Soc. 1992, 114,
1033-1041
6
Communication between the electrophores
Note Use of Nernst equation application of
steady state kinetics
Notice that the Ep/2 values reflect increasing
k2, that they accord with the relative rates
of cyclization, viz., to
k8 k7 gt k6 gt k5 (gem methyls Thorpe-Ingold
effect) gt k5