Application of the molecular orbital ω-technique to aromatic substitution

✍ Scribed by A. Streitwieser Jr.; J.I. Brauman; J.B. Bush

• Publisher: Elsevier Science
• Year: 1963
• Tongue: French
• Weight: 628 KB
• Volume: 19
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(63)80027-7

✦ Synopsis

The ~o-technique of the simple MO method is found to provide a reasonably good correlation with the available experimental data on partial rate factors of nitration of altemant and non-altemant polycyclic aromatic hydrocarbons.

THE application of MO methods to orientation and partial rate factors in aromatic substitution has been reviewed recently in some detail. 3 The various criteria that have been applied as theoretical measures of reactivity in aromatic hydrocarbons include the free valence index, Fr, 4 electron densities, qr, 5 localization energy, L,., 6 Dewar's reactivity numbers, N, 7 and the various "charge transfer" indices: superdelocalizability, Sr, 8 and Brown's Z~ 9 index. Partial rate factors are now known for several electrophilic substitution reactions on polycyclic aromatic hydrocarbons 10 but the data apply almost exclusively to alternant hydrocarbons; it has been shown for such systems that all of the reactivity indices cited above are roughly equivalent to a first approximation.3,4,11,12 Hence, further advance requires quantitative data on non-alternant hydrocarbons.