Elimination reactions of C6H5C(R)HCO 2C6H3-2-X-4-NO2 [R = H (1), Ph (2), X = H (a), Cl (b), NO2 (c)] promoted by R2NH in MeCN have been studied kinetically. The reactions are second-order and exhibit Brönsted β = 0.46-0.89 and |β1g| = 0.37-0.76 and an E2 mechanism is evident. When the base-solvent was changed from R 2NH/R2NH2 +-70 mol% MeCN(aq) to R2NH-MeCN, β and |β1g| values remained nearly the same within experimental error. For eliminations from 1 and 2, β and |β1g| values were nearly identical, although the rate was retarded by the β-Ph group. Noteworthy is the relative insensitivity of the ketene-forming transition state to the base-solvent and β-R group variation.
ASJC Scopus subject areas
- Organic Chemistry
- Physical and Theoretical Chemistry