Abstract
Potential energies of 1, 2 hydrogen shift in protonated fluoro- and chlorobenzenes were estimated by MINDO/3. The potential energy curves of the reaction, C6H5XH+ → C6H5+ + XH, were examined for × = H, OH, CH3, F, and Cl. It was found that there were two types of fragmentation, the reaction starting from ipso-protonation (X = H, CH3) and from substituent protonation (X = OH, Cl, and F). There were at least two minima of potential energy in the course of the HF elimination from F-protonated fluorobenzene. The high heat of formation for the F-protonated fluorobenzene suggested that there are two kinds of C6H6F+ ion, i. e., the ring-protonated fluorobenzene and the cluster ion consisting of the phenyl ion and HF. Difference of fragmentation between protonated fluoro- and chlorobenzenes has been discussed.
