Similar measurements of kobs were conducted for cyclic ethers with different C-H BDEs. All the reactions exhibited pseudo-first-order kinetics at the initial stage of ~ 4 hours (Figures ). The measured kobs was normalized by the number of abstractable C-H bonds of cyclic ethers, for example, 4 for THF and 1 for methyl 1,3-dioxlane. The plot of log(normalized kobs) and calculated C-H BDEs exhibited a good linear correlation, giving a Brønsted slope α = 0.5 (Figure ). A value of α close to 0.5 is predicted by most rate/driving force relations for reactions with a transition state near the midpoint of the reaction coordinate, including sets of similar HAT reactions with small reaction free energy changes. This finding confirms that the CdS QD gel activates C-H bonds proceeds via a d-HAT mechanism.