Rate and Product Studies of 5-Dimethylamino-Naphthalene-1-Sulfonyl Chloride under Solvolytic Conditions

摘要

The solvolysis rate constants of 5-dimethylamino-naphthalene-1-sulfonyl chloride ((CH3)2NC10H6SO2Cl, 1) in 31 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale with sensitivity values of 0.96 ± 0.09 and 0.53 ± 0.03 for l and m, respectively; the correlation coefficient value was 0.955. These l and m values can be considered to support an SN2 reaction pathway having a transition state (TS) structure similar to that of the benzenesulfonyl chloride reaction. This interpretation is further supported by the activation parameters, i.e., relatively small positive ΔH≠ (12.0 to 15.9 kcal·mol−1) and large negative ΔS≠ (−23.1 to −36.3 cal·mol−1·K−1) values, and the solvent kinetic isotope effects (SKIEs, 1.34 to 1.88). Also, the selectivity values (S = 1.2 to 2.9) obtained in binary solvents are consistent with the proposed mechanism.