Nucleophilic substitution reactions of 5-XC4H2(S)C(O)OC6H3-2-Y-4-NO2 (1) promoted by 4-Z-C6H4O-/4-Z-C6H4OH in 20 mol % dimethyl sulfoxide (DMSO)(aq) have been studied kinetically. The reactions exhibited second-order kinetics with βacyl = -2.52 to -2.83, ρ(x) = 2.81-3.16, βnuc = 0.88-0.04 and βlg = -0.94, respectively. The results have been interpreted with an addition-elimination mechanism in which the nucleophilic attack occurs in the rate-determining step. Comparison with existing data reveals that the ratedetermining step changes from the second to the first step by the change in the nucleophile from R2NH/R2NH2 + to 4-Z-C6H4O-/4-Z-C6H4OH.
- Bronsted and hammett plots
- Concerted and stepwise mechanism
- Nucleophilic substitution
ASJC Scopus subject areas