Talk:Isodesmic reaction

Isodesmic reaction

I am not disagreeing with the main article, although it could use editing. My concern is with the science being referred to. The main article virtually makes more sense without the Bickelhaupt, Hermann, and Boche reference. However, I also do not wish to single out this paper specifically as they would not be the first authors to use bond energies to predict ionic properties. I do not have access to the Bickelhaupt, Hermann, and Boche paper therefore I am reluctant to debate its scientific merit and it has been published already. However, I am reluctant to accept bond dissociation energies as equivalent to heterolytic or an ability to predict heterolytic bond strengths. These are fundamentally different reactions. The following gives the bond dissociation energies of several H-X bonds (kJ/mol). Although the bond dissociation energies does correctly predict that HF should be a weaker acid than HCl, HBr, and HI, it should also predict that methane should be a stronger acid than HF.

H--C (413)

H--N (391)

H--O (366)

H--F (568)

H--Cl (432)

H--Br (366)

H--I (298)

The energies to cleave bonds into radicals does not predict the heterolytic bond strengths. Therefore, the acidities referred to in the isodesmic reactions, the halo methane acidities makes simple sense and agrees with known acidities (HI>HBr>HCl>HF or CHBr₃>CHCl₃>CHF₃). The reference to Bickelhaupt, Hermann, and Boche attempts to confuse two different reaction types. —Preceding unsigned comment added by Petedskier (talk • contribs) 14:25, 3 November 2010 (UTC)