Table 1.
Catalysta | Half-life (t1/2, min)b | Second-order rate constant (k″, M−1min−1)c |
---|---|---|
TBD | 3±1 | 2.3 |
PHMBG | 11±3 | 1.4 |
XL-PHMBG M1 | 28±5 | 0.60 |
XL-PHMBG M2 | 18±0.4 | 0.94 |
PEI | 41±6 | 0.093 |
XL-PEI | 47±5 | 0.083 |
PVG | 154±13 | 0.067 |
XL-PVG | 214±14 | 0.050 |
The catalysts are abbreviated as follows: TBD: triazabicyclodecene; PHMBG: poly(hexamethylene biguanide); XL-PHMBG M1: cross-linked poly(hexamethylene biguanide) (Method 1); XL-PHMBG M2: cross-linked poly(hexamethylene biguanide) (Method 2); PEI: poly(ethylene imine); XL-PEI: cross-linked poly(ethylene imine); PVG: poly(N-vinylguanidine); XL-PVG-cross-linked poly(N-vinylguanidine).
Half-life was calculated from t1/2=ln(2)/kobs, where kobs is the experimentally observed reaction rate constant.
Apparent second-order rate constants were calculated as a mean of three measurements from k″=ro/CsCcat, where ro=kobsCs is the initial reaction rate, Cs and Ccat are initial effective concentrations of the substrate (oil) and catalyst, respectively. The Ccat values were calculated as effective molar concentrations of the catalytic groups.