Question

Which is more stable tertbutyl cation or touluene cation?

Answer 1

Answer:

I am using a very simplistic quantum chemical approach of the following isodesmic reaction:

$$\ce{PhCH2^+ + HC(CH3)3 -> PhCH3 + ^+C(CH3)3}$$

I have used Gaussian 16 Rev. A.03 and the DF-B97D3/def2-TZVPP level of theory. The summaries of the calculations are included below.

On this level of theory the depicted reaction has an energy change of ΔG=− 37.1kJmol−1. Therefore one could assume that the 2-methylpropan-2-ylium cation is more stable than the phenylmethylium cation. These values were estimated at T=298.15 K and p=1 atm.

One certainly can do more calculations, but it is, however, a start.

Answer 2

tertbutyl cation is more stable then touluene cation