. Author manuscript; available in PMC: 2022 Feb 5.

Published in final edited form as: J Org Chem. 2021 Jan 21;86(3):3008–3016. doi: 10.1021/acs.joc.0c03021

Table 2.

Evaluation of Various Brønsted Acids^a

Bronstod Acid	pKa (in water)	$Δ G_{353 K}^{‡^{TS 14 - 15}}$ (kcal/mol)
TfOH(CF₃SO₃H)	−14.7 ± 2.0⁴⁸	13.8
HCIO₄	−15.2 ± 2.0⁴⁸	12.8
FSO₃H	−10.0⁵⁵	12.4
HSO₃H	NA	21.4
CH₃SO₃H	−2.0⁵⁶	22.3

Free energy barrier for the CE (TS14–15) reaction. Calculated at ωB97X-D/6–311++G**/CPCM (benzene).