Elimination Reactions of (E)-2,4,6-TrinitrobenzaldehydeO-Benzoyloximes Promoted by R2NH/R2NH2+in 70 mol% MeCN (aq). Effects of the β-Aryl Group and Leaving Group on Nitrile-Forming Transition States
| Autor: | Sang Yong Pyun, Man So Han, Kyu Cheol Paik, Bong Rae Cho |
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| Rok vydání: | 2016 |
| Předmět: |
Reaction mechanism
Nitrile 010405 organic chemistry Chemistry Stereochemistry Aryl Kinetics Leaving group General Chemistry 010402 general chemistry 01 natural sciences Medicinal chemistry Transition state 0104 chemical sciences chemistry.chemical_compound Elimination reaction E1cB-elimination reaction |
| Zdroj: | Bulletin of the Korean Chemical Society. 37:871-876 |
| ISSN: | 1229-5949 |
| DOI: | 10.1002/bkcs.10791 |
| Popis: | Elimination reactions of (E)-2,4,6-(NO2 ) 3C6H2CHNOC(O)C6H4X (3) promoted by R2NH/R2NH2 + in 70 mol% MeCN (aq) have been studied. The reactions produced elimination products and exhibited second-order kinetics. The β and |βlg| values remained nearly the same for all leaving groups and bases. The results can be described by the negligible pxy interaction coefficient, pxy = ∂β/∂pK lg = ∂βlg/∂pK BH ≈ 0, which provides a strong support for the (E1cb)irr mechanism. For eliminations from (E)-ArCHNOC(O)C6H4X (1, 3) and (E)-2,4,6-(NO2)3C6H2CHNOAr′ (2, 3), the change of the β-aryl group (Ar) from 2,4-dinitrophenyl (1) to 2,4,6-trinitrophenyl (3) increased the rate by 270-fold without appreciable change in the transition state structure. On the other hand, the leaving group (OAr′) variation from benzoate (3) to 4-nitrophenoxy (2) induced a change in reaction mechanism from (E1cb)irr to E2. These results have been attributed to the cyclic transition state for the nitrile-forming eliminations involving the benzoate leaving group. |
| Databáze: | OpenAIRE |
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