Substituent Effects. XVI. Acetolysis of 2-Phenylethyl Tosylates
The acetolysis rates of 2-arylethyl tosylates were determined for a series of aryl substituents.The non-linear substituent effect was reasonably accounted for on the basis of two linear LArSR relationships; one for the aryl-assisted (FkΔ) and one for the unassisted (Ks) process, respectively.A precise dissection of the apparent substituent effect into individual effects for both processes was achieved in this manner.The substituent effect on the ks process can be described as a linear function of ?0 with a small ρs of -0.19, and that on the FkΔ process in terms of the LArSR Eq., with a ρΔ=-3.87 and an rΔ=0.631.The use of ?+ for the FkΔ process failed to give any reasonable dissection.The r value for this FkΔ process is essentially identical to that for the neophyl solvolysis.The unique r value oh 0.6 is concluded to be characteristic of β-aryl-assisted ionization processes in general.