Ab initioSCF MO calculations on the reactions of hydroxyl radical with imidazole and monoprotonated imidazole

✍ Scribed by Beverley G. Eatock; William L. Waltz; Paul G. Mezey

• Book ID: 102880613
• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 642 KB
• Volume: 6
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540060111

✦ Synopsis

Abstract

The addition reactions of hydroxyl radical with imidazole and its protonated form to yield radical adducts have been investigated by ab initio SCF MO methods using STO‐3G and 4‐31G basis sets. Analogous radical species are of importance in radiation damage to biological systems. Of the possible radical products, the calculations indicate that the allylic species are generally favored energetically over the nonallylic forms. On an energetic basis, the results show that the allylic adducts formed by addition at the C2 and C5 positions are about equally favorable. Although the C5 species is generally identified as the experimentally observed product in aqueous media for both protonated and unprotonated imidazole, some experimental evidence exists indicating the presence of other forms. Our results suggest that this other form is the C2 adduct. The calculations also point to the protonated form of imidazole being less reactive than imidazole, which is in accord with experimental observations.