Table 2. Second order rate constants (k) for the reactions of 2a and b with ^XArOH at –80 °C ^a .

X	2a (THF) b	2b (THF) c
NMe2	(1.9 ± 0.3) × 106 c	(6.7 ± 1.0) × 106
OMe	(3.0 ± 0.5) × 105	(1.8 ± 0.3) × 106
Me	(8.9 ± 1.3) × 103	(1.0 ± 0.2) × 106
H	(3.9 ± 0.6) × 102	(1.8 ± 0.3) × 105
Cl	(6.5 ± 1.0) × 102	(1.4 ± 0.2) × 105
NO2	(2.6 ± 0.4) × 102 d	(8.2 ± 2.6) × 102
CF3	(3.0 ± 0.5) × 101 d	(3.0 ± 1.5) × 102

^aAll values in units M^–1 s^–1. In all cases, uncertainties are taken as 15% (resulting from the propagation of maximum possible errors of 10% each for the concentrations of the two compounds) or as the standard error, whichever is greater.

^bValues determined from the pseudo-first order analysis for all reactions except for that for X = NMe₂, in which case the rate constant from the stoichiometric analysis was used. See text for details.

^cDetermined from the method of initial rates for X = NMe₂, OMe, Me, H, and Cl; for X = NO₂ and CF₃, determined from the mixed first- and second-order fits (eqn (S6) see ESI). See text for details.

^dDetermined from single-wavelength analysis. See text for details.