Calculated Energies, Reaction Paths and Transition States of C-H Bond Cleavage in the Aromatic Molecules

Density functional calculations, of the b3lyp type and (6-31g), as well as (6-311g)gaussian basis sets, for the reaction paths of the aromatic c-h bond cleavage in 2- to 4- (sixmembered ring) aromatic hydrocarbons reveal that, the calculated reaction energies are nearlysimilar 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.