The last effect that was studied is the substitution of the phenyl ring with various substituents, in particular, fluorine (-F), chlorine (-Cl), bromine (-Br), methoxy (-OMe), trifluoromethyl (-CF 3 ), and nitro (-NO 2 ) groups. The resulting changes in the effective reaction barrier are summarized in Figure . From there, we observe (Figure ) that all the electron-withdrawing groups, in general, slow down the conversion reaction, except for the p-Cl substituted PhCNO, where the effective barrier decreases, and the o-and p-OMe substituted cases, where the effective barrier stays almost the same (within 0.5 kcal/mol in difference). The m-substituted derivatives show very similar activation energies, whether in the cases of the o-and p-substituted PhCNO, we see a larger spread in reachable energies.