Calculated energies, reaction paths and transition states of C-H bond cleavage in the aromatic molecules

Abstract EN

Density Functional calculations, of the B3LYP type and (6-31G), as well as (6-311) Gaussian basis sets, for the reaction paths of the aromatic C-H bond cleavage in 2- to 4- (six membered ring) aromatic hydrocarbons reveal that, the calculated reaction energies are nearly similar to that of the unsubstituted benzene molecule (118.34kcal / mol).

The calculated activation energies of the same reactions are also near that of benzene (169.46kcal / mol), with the exceptions of the C1-H1 and C9-H9 bonds in anthracene, where interaction with the neighbored H atoms is noticed.

The calculated activation energies for these two bonds are (147.44kcal / mol) for C1-H1 and (154.00kcal / mol) for C9-H9.

The departure of the H atom from the aromatic moiety proceeds coplanarily, i.e., in the same plane of the molecule.

It causes a shortening of the C-C bond lengths at the reaction center and a reorientation of the C-C bonds in the aromatic ring forming successive bond alternation.