To further probe the existence of a Wheland intermediate, we considered a Hammett analysis via one-pot competition experiments for both the formation of aryl thianthrenium and aryl(Mes)iodonium salts. However, our initial attempts to construct a Hammett plot in both cases were unsuccessful because electron-rich arenes, such as anisole and toluene completely out competed benzene in the case of thianthrenation. Moreover, we, and others, have found that benzene is unreactive with iodomesitylene diacetate under the conditions we used for the first step of the net dehydrogenation mediated by iodonium leaving groups. Therefore, we conducted a series of competition experiments to construct a qualitative scale of relative arene reactivity for the formation of the two different aryl "onium" species (Scheme 6). We used an equal excess of the two competing arenes relative to TTO or MesI(OAc)2 (Scheme 6). Although the scales for the two processes appear similar, there are some important distinctions that warrant further comment. The order of arene relative reactivity for general classes of arenes is consistent for the two processes: benzene, toluene, chloroanisoles, anisole, dimethoxybenzenes is the order from least to most reac-tive. Additionally, thianthrenation has a broader scope of compatible arenes than iodination (Scheme 6). Although Hammett plots provide a -value which can be a useful metric to describe the electronic properties of the arene during the rate determining step, individual plots must be constructed for a series of substituents at a given position (meta or para). In our relative reactivity scale, we have included polysubstituted arenes which demonstrates how the position and electronic effects of multiple substituents impacts reactivity. For instance, 2-, 3-and 4chloroanisoles, 1c, 1u and 1a, respectively, have relative reactivity between toluene 1m and anisole 1n (Scheme 6). Therefore, although chloro is a deactivating substituent, the combination of chloro (deactivating) and methoxy (activating) is more reactive than a methyl (activating) substituent. Additionally, the relative position of the substituents has an impact on reactivity, which was not necessarily consistent between thianthrenation and iodination (Scheme 6). Again, considering the 2-, 3-and 4chloroanisoles, the 1,4-substitution pattern was the least reactive in both thianthrenation and iodination reactions, in fact 4-chloroanisole 1a was not a viable substrate for iodination (Scheme 6). In the case of thianthrenation, 2chloroanisole 1c was slightly more reactive than 3chloroanisole 1u; though this order was reversed for iodination (Scheme 6). The trends observed for dimethoxybenzenes shared some similarities with those of chloroanisoles. For example, 1,4-dimethoxybeznene 1y was not a viable substrate for thianthrenation or iodination. Moreover, 1,2-dimethoxybenzene 1d was only compatible with thianthrenation but not iodination. In the case of thianthrenation, the 1,3-substitution pattern 1o is more reactive than 1,2-substitution pattern 1d (Scheme 6).