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Ab initio SCF MO calculations on the reactions of hydroxyl radical with imidazole and monoprotonated imidazole
Author(s) -
Eatock Beverley G.,
Waltz William L.,
Mezey Paul G.
Publication year - 1985
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540060111
Subject(s) - imidazole , chemistry , protonation , adduct , ab initio , ab initio quantum chemistry methods , computational chemistry , allylic rearrangement , radical , photochemistry , yield (engineering) , medicinal chemistry , stereochemistry , molecule , organic chemistry , catalysis , ion , materials science , metallurgy
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.