“…MO approaches to this problem first appeared in 19502 38 and have continued to appear up to the present. 203,210,211,223,[239][240][241][242][243][244] The most simplistic viewpoint assumes that energy of activation will parallel the heat of reaction, which in turn parallels the energy loss in the reaction.62,63 The 7r-energy loss defines a reactivity index called the paralocalization energy, L14.238,2 45 -247 Semiquantitative correlations of Lu and the rates of Diels-Alder reactions are well known.191,20 3,211,2 2 3 The rates of the maleic anhydride additions to five polycyclic aromatic hydrocarbons were recently determined,244 and the data are summarized in Table II. Localization energies were calculated for either attack at the single most reactive positions (L), or for simultaneous attack at the most reactive 1,4 position (Lu) using a semiempirical SCF-MO method.…”